🏷

Classifications

Harrison's Part

🔗

Mappings

MONDO

MONDO:0011972 ovarian hyperstimulation syndrome

👪

Inheritance

1

Autosomal dominant inheritance HP:0000006

In the reported families the affected women were heterozygous for a single activating FSHR allele, and the phenotype segregated through successive pregnancies in more than one family member — the pattern of a dominant gain-of-function receptor variant rather than a recessive loss of function.

Autosomal dominant inheritance

Show evidence (1 reference)

PMID:15080154 SUPPORT Human Clinical

"The affected women were heterozygous for a different mutation involving codon 449, where an alanine was substituted for threonine."

Documents heterozygosity of the causal allele in the affected women of a familial recurrent-OHSS pedigree.

◆

Subtypes

2

Iatrogenic OHSS (complication of controlled ovarian stimulation)

The common form, and effectively the whole clinical burden of the syndrome. Exogenous gonadotropins given for assisted reproduction recruit a large cohort of follicles, and the hCG used to trigger final oocyte maturation — or the endogenous hCG of an implanting pregnancy — drives the VEGF surge that produces the capillary leak. Because both the stimulation and the trigger are under the clinician's control, this form is substantially preventable.

Show evidence (1 reference)

PMID:15080154 SUPPORT Human Clinical

"Ovarian hyperstimulation syndrome (OHSS) occurs mainly after excessive stimulation of the ovaries by exogenous gonadotropins administrated in the context of in vitro fertilization procedures (iatrogenic OHSS)."

Defines the iatrogenic subtype and states that it accounts for most cases.

Familial gestational spontaneous OHSS (FSHR-activating)

A rare autosomal dominant form in which activating germline FSHR variants make the FSH receptor respond to hormones it should ignore. Affected women develop OHSS during spontaneous pregnancy, typically in the first trimester, with no fertility drug involved, and the syndrome recurs in successive pregnancies. This is the arm that gives MONDO:0011972 its hereditary-disease parent and its FSHR gene association.

Show evidence (2 references)

PMID:23941020 SUPPORT Human Clinical

"Since 2003, only six different activating FSHr gene mutations have been reported in cases of familial or habitual sOHSS."

Establishes the familial, FSHR-mutation-defined subtype as a distinct and rare entity.

PMID:23941020 SUPPORT Human Clinical

"Spontaneous forms of the ovarian hyperstimulation syndrome (sOHSS) are nearly always reported between 8 and 14 weeks of pregnancy"

Records the gestational timing that defines the spontaneous presentation.

?

Discussions and Knowledge Gaps

3

Is human chorionic gonadotropin actually necessary for OHSS to develop, and if not, what supplies the VEGF stimulus in the cases that occur without it?

KNOWLEDGE GAP OPEN ohss_hcg_not_obligate

Attached to

pathophysiology#Ovarian VEGF Hypersecretion pathophysiology#hCG-Driven Luteinization of the Recruited Cohort

The whole preventive strategy of modern assisted reproduction — substituting a GnRH agonist trigger for hCG, freezing all embryos to avoid endogenous pregnancy hCG — is built on hCG being the obligatory driver of the VEGF surge. A 2016 review states that recent case reports have shown OHSS occurring without it. If that is right, then either the luteinized ovary can reach the VEGF threshold on LH activity alone in some women, or a second stimulus exists that current protocols do not remove, and the residual OHSS seen in agonist-trigger cycles is explained rather than anomalous. The entry's causal chain is drawn with hCG as the principal but not the sole stimulus for that reason.

Proposed experiments

Serial serum VEGF in agonist-trigger cycles complicated by OHSS

ohss_vegf_in_agonist_trigger_cases

Measure circulating VEGF serially in women who develop OHSS after a GnRH agonist trigger with no hCG exposure, comparing against hCG-triggered cases matched for follicle count, to establish whether the VEGF surge occurs at comparable magnitude without hCG.

Show evidence (1 reference)

PMID:27273307 SUPPORT Human Clinical

"Human chorionic gonadotropin was previously thought to be necessary for OHSS to occur; however, recent case reports have proven otherwise."

States directly that the assumed obligate role of hCG has been contradicted by case reports.

Does the EGR1-Tie1 axis that is required for hCG-induced VEGF in a granulosa-lutein cell line and in the rat model operate in intact human ovarian tissue, and is Tie1 therefore a usable therapeutic target?

HUMAN MODEL MISMATCH OPEN ohss_tie1_human_relevance

Attached to

pathophysiology#EGR1-TIE1 Amplification of Granulosa VEGF Output

The Tie1 result is unusually well constructed for a mechanism at this stage: an association in granulosa cells taken from actual OHSS patients, a loss-of-function experiment abolishing the hCG-VEGF link in a human granulosa-lutein line, attenuation of the syndrome in rats, and an identified transcriptional route via EGR1. What it does not have is any demonstration in intact human ovary or any clinical exposure. The mismatch is mechanistically meaningful because the therapeutic argument for targeting Tie1 rests entirely on it sitting upstream of VEGF: an agent acting there would in principle spare the VEGFR-2-dependent luteal angiogenesis that a direct VEGFR-2 antagonist destroys, which is the specific reason SU5416 was abandoned. If the axis turns out to be a cell-line and rodent phenomenon, that argument disappears and the field is back to dose-separating a dopamine agonist. The reporting authors say as much themselves.

Proposed experiments

Tie1 and EGR1 expression in human ovarian tissue across OHSS risk strata

ohss_tie1_egr1_human_ovarian_tissue

Quantify Tie1 and EGR1 in ovarian tissue or aspirated granulosa cells from women stratified by OHSS risk and by trigger type (hCG versus GnRH agonist), testing whether the induction predicted by the cell-line work is present in vivo and whether it tracks trigger exposure.

Show evidence (1 reference)

PMID:35079118 SUPPORT In Vitro

"Taken together, our results indicate that Tie1 may be a therapeutic target in cases of moderate-to-severe OHSS. Further studies are needed to address its clinical relevance."

The authors state the translational gap explicitly.

Is there any intervention that shortens or attenuates established OHSS, rather than preventing it?

KNOWLEDGE GAP OPEN ohss_established_disease_evidence_base

Attached to

pathophysiology#Third-Space Fluid Shift and Intravascular Volume Depletion

Almost the entire evidence base for this syndrome sits on the preventive side of the hCG trigger — protocol choice, trigger substitution, freeze-all, prophylactic cabergoline. Once the capillary leak is established, management is supportive and, by the reviewing authors' own account, based on consensus rather than evidence. That asymmetry is defensible while prevention keeps working, but it leaves the women who develop severe disease anyway with no treatment aimed at the mechanism. Whether the VEGFR-2 node remains modifiable after the leak has started — that is, whether cabergoline has any therapeutic as opposed to prophylactic effect — is the specific unanswered question, and the cabergoline evidence cited here is prophylactic only.

Proposed experiments

Randomised trial of cabergoline in established moderate-to-severe OHSS

ohss_cabergoline_established_disease_rct

Randomise women hospitalised with established moderate-to-severe OHSS to cabergoline or placebo on top of standard supportive care, with time to resolution of ascites, haematocrit trajectory and length of stay as outcomes, to test whether the VEGFR-2 node is still modifiable once the leak is established.

Show evidence (1 reference)

PMID:27273307 SUPPORT Human Clinical

"Treatment is largely supportive and is based mainly on consensus statements rather than evidence."

States the evidence gap on the treatment side of established disease.

⚙

Pathophysiology

16

Exogenous Gonadotropin Stimulation of the FSH Receptor

The iatrogenic entry point. Controlled ovarian stimulation delivers gonadotropin at doses far above the physiological mid-follicular range, so the FSH receptor on granulosa cells is occupied well beyond what a natural cycle achieves and the normal selection of a single dominant follicle is overridden. Nothing about the receptor is abnormal here — the ligand supply is.

Granulosa cell CL:0000501

follicle-stimulating hormone signaling pathway GO:0042699 ↑ INCREASED

Downstream

Multifollicular Recruitment Supraphysiological FSH receptor occupancy rescues follicles that would normally undergo atresia, producing a large synchronous cohort.

Show evidence (1 reference)

PMID:15080154 SUPPORT Human Clinical

"Ovarian hyperstimulation syndrome (OHSS) occurs mainly after excessive stimulation of the ovaries by exogenous gonadotropins administrated in the context of in vitro fertilization procedures (iatrogenic OHSS)."

States that excessive gonadotropin stimulation of the ovary is the initiating event in the common form of the syndrome.

Promiscuous FSH Receptor Activation by hCG or TSH

The hereditary entry point, and the reason MONDO:0011972 carries an FSHR gene association. The glycoprotein hormone receptors share a common architecture, and their ligand specificity is maintained by an intramolecular activation barrier rather than by binding affinity alone. Activating germline FSHR variants lower that barrier: the receptor becomes abnormally sensitive to hCG, in most reported mutants also to TSH, and shows ligand-independent basal activity. The consequence is that the hCG of an ordinary first trimester stimulates the FSH receptor as though it were FSH. The p.Ser128Tyr allele in the extracellular domain is the mechanistic exception that proves the rule — it raises hCG affinity without conferring constitutive activity or TSH responsiveness, so more than one molecular route reaches the same phenotype.

FSHR hgnc:3969

Genetic context variant_origin: GERMLINE zygosity: HETEROZYGOUS functional_impact_category: GAIN_OF_FUNCTION

Heterozygous germline missense variants in FSHR. Reported alleles include p.Thr449Ile, p.Thr449Ala, p.Asp567Asn, p.Asp567Gly and p.Ile545Thr in the transmembrane helices, and p.Ser128Tyr in the extracellular domain.

follicle-stimulating hormone signaling pathway GO:0042699 ⇑ GAIN OF FUNCTION

Downstream

Multifollicular Recruitment hCG or TSH acting on the mutant FSH receptor reproduces the follicular recruitment that exogenous gonadotropin produces in the iatrogenic form.

Show evidence (5 references)

PMID:15080154 SUPPORT In Vitro

"The two mutant FSHr (T449I, D567N) harbor aminoacid substitutions in the serpentine portion of the receptor and display abnormally high sensitivity to the pregnancy hormone hCG, thus providing a satisfactory explanation to the phenotype."

Demonstrates in transfected cells that the causal variants confer abnormal hCG sensitivity, the mechanism of the spontaneous form.

PMID:15080154 SUPPORT In Vitro

"Similar to D567N, the T449A FSHr mutant shows an increase of its sensitivity to both hCG and TSH, together with an increase in basal activity."

Records the additional TSH cross-reactivity and constitutive activity of the serpentine-domain mutants.

PMID:17721928 SUPPORT In Vitro

"This loss of ligand specificity was attributed to the lowering of an intramolecular barrier of activation rather than to an increase of binding affinity."

Gives the biophysical mechanism by which the serpentine-domain variants abolish ligand specificity.

+ 2 more references

Promiscuous Activation of the Wild-Type FSH Receptor

A third, non-genetic and non-iatrogenic entry point that the same receptor biology predicts. The wild-type FSH receptor is not perfectly specific either; it is simply that the physiological concentrations of hCG and TSH never reach the threshold at which cross-activation matters. When they do — the very high hCG of a multiple or hydatidiform-molar pregnancy, the very high TSH of untreated hypothyroidism, or autonomous FSH secretion from a pituitary adenoma — the syndrome can occur sporadically in a woman with a normal FSHR. This is why an FSHR variant should not be assumed in every spontaneous case.

follicle-stimulating hormone signaling pathway GO:0042699 ↑ INCREASED

Downstream

Multifollicular Recruitment Cross-activation of the normal receptor drives the same follicular response as the mutant receptor does.

Show evidence (2 references)

PMID:23941020 SUPPORT Human Clinical

"The syndrome has been previously reported in rare instances of increased production of human chorionic gonadotrophin (hCG) such as multiple pregnancies, hydatiforme mole, polycystic ovary disease and elevated concentrations of thyroid-stimulating hormone (TSH) in hypothyreoidism."

Enumerates the clinical settings in which excess hCG or TSH precipitates the syndrome without a fertility drug.

PMID:23941020 SUPPORT Human Clinical

"High levels of these hormones are able to stimulate by natural promiscuous activation the wild-type FSHr, resulting in sporadic presentations of the syndrome."

States explicitly that a normal FSH receptor can be cross-activated when ligand concentrations are high enough.

Multifollicular Recruitment

The FSH-driven half of the ovarian response, and the step that sets the size of the problem. Sustained FSH receptor signalling rescues from atresia a large cohort of antral follicles that a natural cycle would have discarded in favour of one dominant follicle. Nothing pathological has happened yet - this is the intended effect of controlled ovarian stimulation, and an exaggerated version of it in the spontaneous forms. Follicle number and oestradiol level predict OHSS risk precisely because they measure this node, which is why it and not the later steps is what protocol individualisation, anti-Mullerian hormone and antral follicle count are aimed at.

Granulosa cell CL:0000501

ovarian follicle development GO:0001541 ↑ INCREASED

Downstream

hCG-Driven Luteinization of the Recruited Cohort The recruited cohort is the substrate the LH-like signal acts on; without multifollicular recruitment there is nothing to luteinize en masse.

Ovarian Enlargement and Multicystic Change Many simultaneously recruited follicles enlarge the ovary mechanically.

Show evidence (2 references)

PMID:24848075 SUPPORT Human Clinical

"Ovarian hyperstimulation syndrome (OHSS) represents an exaggerated response to controlled ovarian stimulation (COS) that in some cases could be life-threatening."

Frames the follicular response as an exaggerated version of the intended one rather than a qualitatively different process.

PMID:24848075 SUPPORT Human Clinical

"In recent years research has focus on identifying biomarkers/hormonal markers that could represent potential predictors of OHSS (anti-Mullerian hormone and antral follicle count)."

Records that the predictive markers used clinically are measurements of the recruitable follicle pool - that is, of this node.

hCG-Driven Luteinization of the Recruited Cohort

The hCG-dependent half, separated from recruitment because the two have different triggers, different timing and different therapeutic handles. Exposure to an LH-like signal - the hCG trigger, or the endogenous hCG of an implanting pregnancy - luteinizes the whole recruited cohort at once, so the ovary comes to contain many simultaneously luteinized follicles instead of one corpus luteum. That expanded mass of luteinized granulosa tissue is the secretory organ of the syndrome. This node, not recruitment, is what the preventive substitution of a GnRH agonist for hCG removes: the follicles are still recruited, but the long-acting luteinizing stimulus is replaced by a short endogenous LH surge. Keeping it distinct is what lets that treatment be linked where it actually acts.

Luteinized granulosa cell CL:0000501

LHCGR hgnc:6585

luteinization GO:0001553 ↑ INCREASED

Downstream

EGR1-TIE1 Amplification of Granulosa VEGF Output The luteinized granulosa cells are the cells in which hCG raises EGR1 and Tie1; without that expanded luteinized compartment there is nothing for the proposed amplifier to act in.

Ovarian Renin-Angiotensin System Activation Gonadotropin stimulation raises prorenin and renin in follicular fluid, so the expanded stimulated follicular compartment is where the intra-ovarian renin-angiotensin system is activated.

Ovarian VEGF Hypersecretion The enlarged mass of luteinized granulosa tissue is the source of the VEGF surge.

Show evidence (2 references)

PMID:9240261 SUPPORT Human Clinical

"In patients undergoing IVF, FF VEGF levels at the time of egg retrieval correlated with the degree of follicular luteinization."

Ties VEGF output to the extent of luteinization specifically, which is the link this node carries downstream.

PMID:28638367 SUPPORT Human Clinical

"The use of GnRH agonist (GnRHa) for final oocyte maturation trigger in oocyte donation and elective frozen embryo transfer cycles is well established due to lower ovarian hyperstimulation syndrome (OHSS) rates as compared to hCG trigger."

Replacing the luteinizing stimulus lowers OHSS rates, which is the interventional evidence that this node is a required step.

Ovarian VEGF Hypersecretion

Luteinized granulosa cells secrete vascular endothelial growth factor, and hCG is the strongest stimulus for that secretion — which is why the syndrome follows the trigger injection or the rise of endogenous hCG rather than the stimulation itself, and why it has an early and a late phase. In a hyperstimulated ovary the output is large enough to raise circulating VEGF, so a local ovarian signal becomes a systemic one. Serum VEGF measured serially in a woman hospitalised with severe OHSS rose and fell with her symptoms.

Luteal cell CL:0000175

vascular endothelial growth factor production GO:0010573 ↑ INCREASED

Downstream

VEGFR-2 Activation on Vascular Endothelium Circulating VEGF-A acts on VEGF receptor 2 borne by vascular endothelium.

Show evidence (3 references)

PMID:16901966 SUPPORT Model Organism

"OHSS is caused by increased vascular permeability (VP) through ovarian hypersecretion of vascular endothelial growth factor (VEGF)-activating VEGF receptor 2 (VEGFR-2)."

States the ovarian hypersecretion step and its receptor target in a single sentence; this is the canonical mechanistic statement for the syndrome.

PMID:9240261 SUPPORT Human Clinical

"There is a significant ovarian contribution to circulating VEGF levels during early gestation."

Establishes in humans that the stimulated ovary raises systemic VEGF, the step that converts a local signal into a systemic illness.

PMID:9240261 SUPPORT Human Clinical

"Elevated serum VEGF levels in a patient with severe OHSS coincided with the clinical onset and recurrence of symptoms."

Human temporal correlation between circulating VEGF and the clinical course, including its recurrence.

Ovarian Renin-Angiotensin System Activation

A second proposed route from the stimulated ovary to VEGF, running in parallel with the direct hCG-driven secretion rather than replacing it. The stimulated ovary contains its own renin-angiotensin system: prorenin and renin were reported in the follicular fluid of gonadotropin-stimulated ovaries at significantly higher levels than in unstimulated ovaries as far back as 1987. Renin secretion is cyclic-AMP-stimulated, and the resulting angiotensin signalling is proposed to raise VEGF expression in human luteinized granulosa cells. Its practical importance is that it is the only mechanistic account of why intravenous calcium - the agent that ranks ABOVE cabergoline in both network meta-analyses of OHSS prophylaxis - should work at all: calcium is proposed to inhibit cAMP-stimulated renin secretion and so reduce VEGF. Curated as a modifier rather than a required step, and as PROVISIONAL. The two sources that describe the calcium mechanism hedge it in their own wording ("could be by inhibiting"), and no primary demonstration in an OHSS cohort is cited anywhere in this entry's reference set. A third source in the reference set is notably NOT hedged - PMID:18956797 calls the ovarian RAS "clearly central to the pathogenesis" - but it asserts that in a single background sentence without supporting data of its own, so it is curated as PARTIAL and does not by itself lift the node above PROVISIONAL. Recording both is the point: the disagreement about how settled this mechanism is exists in the literature, not just in this entry. A note on the process term. This node is deliberately left with a free-text `preferred_term` and NO `term:` binding. The obvious candidate, GO:0002001 "renin secretion into blood stream", is defined as release of renin into the blood by JUXTAGLOMERULAR cells - a systemic, kidney-specific process. What is modelled here is local, intra-ovarian renin acting on granulosa cells, so that term would contradict both the compartment and the cell type recorded in the same node. GO has a precedent for a local RAS (GO:0002035, brain renin-angiotensin system) but no ovarian analogue, which makes this a legitimate new-term request rather than a gap in the search. No term beats a bad one.

Luteinized granulosa cell CL:0000501

intra-ovarian renin secretion ↑ INCREASED

Downstream

Ovarian VEGF Hypersecretion Angiotensin signalling is proposed to raise VEGF expression in luteinized granulosa cells, adding to the hCG-driven secretion rather than replacing it. Curated as INDIRECT_KNOWN_INTERMEDIATES because the angiotensin and ACE steps are named but proposed rather than demonstrated in this disease.

Show evidence (4 references)

PMID:26752241 SUPPORT Human Clinical

"As far back as 1987, there was evidence that a significantly higher level of prerenin and renin were in the ovarian follicular fluid of Gn-stimulated ovaries compared with ovaries without Gn stimulation"

The measured observation the whole proposal rests on: gonadotropin stimulation raises intra-ovarian renin.

PMID:35154015 SUPPORT Human Clinical

"The possible underlying mechanism of calcium preventing OHSS could be by inhibiting cyclic adenosine monophosphate-stimulated renin secretion, which reduces the production of angiotensin-converting enzyme II"

The proposed chain from calcium through cAMP-stimulated renin secretion to ACE, quoted with the authors' own hedge intact - which is why this node is PROVISIONAL.

PMID:35154015 SUPPORT Human Clinical

"This subsequently reduces VEGF expression in human luteinized granulosa cells"

Closes the proposed chain onto VEGF in the cell type this entry already identifies as the source of the surge.

+ 1 more reference

EGR1-TIE1 Amplification of Granulosa VEGF Output

A proposed amplifier sitting between the hCG signal and the VEGF surge, and the most substantial recent addition to the mechanism. Tie1 is an endothelial receptor tyrosine kinase, but it is also expressed in granulosa cells, where hCG raises it through PI3K/AKT signalling and through EGR1 binding directly to the Tie1 promoter. The functional claim is the informative one: silencing Tie1 abolished the hCG-induced rise in VEGF in a human granulosa-lutein cell line and attenuated OHSS in rats. If that holds in humans it identifies a target upstream of VEGF itself, which would avoid the problem that blocking VEGFR-2 also blocks the angiogenesis a pregnancy needs. It is curated as PROVISIONAL and as a modifier rather than a required step because the evidence is entirely from patient-derived cultured cells, a granulosa-lutein cell line and a rat model; the authors state explicitly that clinical relevance is not yet addressed.

Granulosa-lutein cell CL:0000501

TIE1 hgnc:11809 EGR1 hgnc:3238

phosphatidylinositol 3-kinase/protein kinase B signal transduction GO:0043491 ↑ INCREASED

Experimental models

SVOG human granulosa-lutein cell line with Tie1 silencing CELL LINE Tie1 knockdown removes the hCG-to-VEGF link in a human granulosa-lutein background, which is what makes Tie1 a candidate required step rather than a correlate.

Animal models

Induced-OHSS rat with ovarian Tie1 knockdown Rat rescues Tie1 knockdown attenuates OHSS progression in the rat model, which is the whole-organism counterpart of the abolished VEGF rise seen in the cell line.

Downstream

Ovarian VEGF Hypersecretion hCG-driven EGR1-Tie1 induction is proposed to be required for the hCG-induced rise in granulosa VEGF output.

Show evidence (4 references)

PMID:35079118 SUPPORT In Vitro

"Here, we report significantly increased Tie1 and vascular endothelial growth factor (VEGF) expression in cultured granulosa cells from OHSS patients, as well as ovaries from rats with experimentally established OHSS, compared to controls"

Establishes the association of Tie1 with VEGF in patient-derived granulosa cells and in the rat model.

PMID:35079118 SUPPORT In Vitro

"Tie1 silencing abolished the hCG-induced VEGF level in SVOG cells and attenuated the progression of OHSS in rats, as determined by histological analysis."

The loss-of-function result that makes Tie1 a candidate required step between hCG and VEGF rather than a correlate.

PMID:35079118 SUPPORT In Vitro

"We also report that early growth response protein 1 (EGR1), whose expression was also upregulated by hCG, bound directly to the Tie1 promoter and activated its transcription."

Identifies the transcriptional mechanism by which hCG raises Tie1.

+ 1 more reference

VEGFR-2 Activation on Vascular Endothelium

The receptor-level step, and the point every effective therapy acts on. Circulating VEGF-A binds VEGF receptor 2 on vascular endothelium and triggers its phosphorylation. Two experiments in the rodent model make this causal rather than correlative: blocking VEGFR-2 with the antagonist SU5416 prevents the downstream permeability rise, and a low dose of the dopamine agonist cabergoline reverses it by partially dephosphorylating ovarian VEGFR-2. The therapeutic problem lives entirely at this node rather than downstream of it, which is why it is worth separating: the same receptor also drives the luteal angiogenesis a pregnancy needs, so the task is dose-separating two functions of one receptor, not blocking it.

Vascular endothelial cell CL:0002139

vascular endothelial growth factor receptor-2 signaling pathway GO:0036324 ↑ INCREASED

Animal models

Prolactin-supplemented OHSS rat model of VEGFR-2-dependent permeability Rat perturbs Pharmacological manipulation of VEGFR-2 in this model - blockade with SU5416, partial dephosphorylation with low-dose cabergoline - is what establishes the receptor as necessary for the permeability rise and as separable from luteal angiogenesis.

Downstream

Increased Systemic Vascular Permeability VEGFR-2 signalling in endothelium loosens inter-endothelial junctions and raises permeability to protein and water.

Show evidence (2 references)

PMID:16901966 SUPPORT Model Organism

"OHSS is caused by increased vascular permeability (VP) through ovarian hypersecretion of vascular endothelial growth factor (VEGF)-activating VEGF receptor 2 (VEGFR-2)."

Names VEGFR-2 as the receptor the ovarian VEGF surge acts on.

PMID:16901966 SUPPORT Model Organism

"A 100 microg/kg low-dose Dp-r2 agonist cabergoline reversed VEGFR-2-dependent VP without affecting luteal angiogenesis through partial inhibition of ovarian VEGFR-2 phosphorylation levels."

Identifies VEGFR-2 phosphorylation as the modifiable molecular event and shows the permeability and angiogenic functions can be pharmacologically separated.

Increased Systemic Vascular Permeability

The endothelial-barrier consequence: capillary beds throughout the body, not only in the ovary, become permeable to protein and water. That the permeability is systemic rather than local is the whole reason an ovarian problem produces pleural effusion, renal hypoperfusion and thrombosis, and it is why the syndrome is a capillary-leak illness rather than a gynaecological one. The mediator is not regarded as settled. VEGF is the leading candidate and the only one with interventional evidence, but a clinical review is explicit that the pathophysiology is incompletely understood, and an anti-Mullerian-hormone/dendritic-cell/interleukin arm has been proposed alongside it.

Vascular endothelial cell CL:0002139

positive regulation of vascular permeability GO:0043117 ↑ INCREASED

Downstream

Third-Space Fluid Shift and Intravascular Volume Depletion A permeable capillary bed cannot retain protein-rich fluid, which moves down its gradient into the peritoneal and pleural spaces.

Show evidence (3 references)

PMID:34644798 SUPPORT Human Clinical

"Pathogenesis of the disease is based on massive transudation of protein-rich fluid from the vascular compartment into the peritoneal, pleural and pericardial spaces, with a variable picture of clinical manifestations depending on its severity."

States that the barrier failure is systemic and names the three compartments the fluid enters.

PMID:27273307 SUPPORT Human Clinical

"The pathophysiology is still not completely understood; however, vascular endothelial growth factor is likely to be an important mediator."

A deliberate hedge from a clinical review: VEGF is the leading mediator but the human pathophysiology is not regarded as closed.

PMID:27273307 SUPPORT Human Clinical

"The contribution of an attenuated anti-Mullerian hormone signalling pathway and CD11c + HLA-DR + dendritic cells and associated interleukins has been explored recently as contributors to pathogenesis."

Records the proposed non-VEGF contributors, which is why this node is not curated as a pure VEGF effect.

Ovarian Enlargement and Multicystic Change

The ovarian finding that names the syndrome and is what bedside ultrasound sees. Many simultaneously luteinized follicles and their retained fluid enlarge the ovaries, sometimes to many times normal volume. The clinical hazard of this node is mechanical rather than haemodynamic: a heavy, enlarged ovary can undergo adnexal torsion and infarct, which has been reported even outside pregnancy in a woman carrying an activating FSHR variant.

Downstream

Adnexal Torsion and Ovarian Infarction An enlarged, heavy ovary is mechanically predisposed to twist on its vascular pedicle.

Show evidence (2 references)

PMID:26506672 SUPPORT Human Clinical

"The diagnosis of severe OHSS was made, largely based on bedside ultrasonography showing increased ovarian size, mild ascites and bilateral pleural effusions."

Documents ovarian enlargement as an imaging feature used to make the diagnosis.

PMID:25495063 SUPPORT Human Clinical

"In few days, she developed severe pelvic pain and ultrasonographic evidence of increased ovarian volume."

Records ovarian enlargement preceding the torsion complication in an FSHR variant carrier.

Adnexal Torsion and Ovarian Infarction

A surgical complication of the enlarged ovary, distinct from the capillary-leak arm of the disease and not dependent on it. It is presented here as provisional because the direct evidence is a single reported case in an FSHR variant carrier rather than a series; the general association between ovarian enlargement and torsion is not in dispute, but its frequency in OHSS specifically is not quantified in the cited literature. The case is instructive for a second reason: it occurred while the woman was neither pregnant nor receiving fertility treatment, showing that the ovarian risk of an activating FSHR allele is not confined to gestation.

Show evidence (2 references)

PMID:25495063 SUPPORT Human Clinical

"She underwent laparoscopy with unilateral adnexectomy for ovarian ischemic necrosis due to adnexal torsion."

Documents the torsion-infarction outcome in a woman with prior spontaneous OHSS and an FSHR variant.

PMID:25495063 SUPPORT Human Clinical

"Our experience suggests that patients' carrier of a mutation of FSHr gene are at risk of ovarian pathologies also when non-pregnant and in the presence of low TSH levels."

Supports the caveat that the ovarian risk extends outside pregnancy, while making clear this is a suggestion from a single experience.

Third-Space Fluid Shift and Intravascular Volume Depletion

The systemic pivot of the illness. Protein-rich fluid leaving the permeable vasculature accumulates as ascites and pleural effusion while the intravascular compartment is simultaneously depleted, so the patient is fluid-overloaded and hypovolaemic at once. That paradox is the whole management problem: the visible fluid must not be treated as excess. The accompanying picture is rapid weight gain, haemoconcentration, leukocytosis, hyponatraemia and hyperkalaemia.

Downstream

Hypercoagulability and Thromboembolism Haemoconcentration and reduced flow in a depleted intravascular compartment favour thrombus formation.

Renal Hypoperfusion and Oliguria Reduced effective circulating volume lowers renal perfusion.

Pleural Effusion and Respiratory Failure Fluid entering the pleural space, together with a splinted diaphragm from tense ascites, compromises gas exchange.

Show evidence (1 reference)

PMID:26506672 SUPPORT Human Clinical

"Clinical signs may include any or all of the following: rapid weight gain, ascites, oliguria, hemoconcentration, leukocytosis, along with intravascular hypovolemia, hyponatremia, and hyperkalemia."

Enumerates the third-spacing syndrome, including the simultaneous ascites and intravascular hypovolaemia that define it.

Hypercoagulability and Thromboembolism

The complication with the worst reputation in this syndrome, and one worth stating carefully. Haemoconcentration from plasma loss into the third space, combined with reduced venous return and the prothrombotic state of the high-oestrogen luteal phase or early pregnancy, produces venous and occasionally arterial thrombosis. Thromboprophylaxis is curated as a treatment acting on this node. Note though that the risk it addresses is small in absolute terms - venous thromboembolism specifically attributable to OHSS has been estimated at under 0.001% - and that the increment OHSS adds on top of assisted reproduction did not reach statistical significance in a systematic review. The practice rests on the severity of the consequence and the low cost of the intervention rather than on a demonstrated effect size.

Show evidence (1 reference)

PMID:26506672 SUPPORT Human Clinical

"If the patient is not diagnosed early, ascites, pleural and more rarely pericardial effusions, severe respiratory failure and ARDS, hypercoagulability with tromboembolism and multiple organ system failure can occur."

Places hypercoagulability and thromboembolism among the severe consequences of untreated third-spacing.

Renal Hypoperfusion and Oliguria

Falling effective circulating volume reduces renal perfusion, producing oliguria and, at the severe end, acute kidney injury requiring intensive care. The kidney here is a bystander reporting the intravascular volume state, which is why urine output is used as the bedside index of severity.

Show evidence (1 reference)

PMID:26506672 SUPPORT Human Clinical

"The severe form of OHSS varies between 0.5% and 5%, depending on the population studied: intensive care may be required for management of tromboembolic complications, renal failure and severe respiratory failure."

Identifies renal failure as one of the intensive-care-level complications of the severe syndrome.

Pleural Effusion and Respiratory Failure

The other lethal arm. Fluid crossing into the pleural space, with the diaphragm splinted by tense ascites, produces hypoxaemic respiratory failure that can reach ARDS. In the two reported cases managed with non-invasive ventilation the impairment was severe by objective criteria (PaO2/FiO2 below 200), which is the level at which the illness stops being a gynaecological complication and becomes a respiratory one.

Show evidence (2 references)

PMID:26506672 SUPPORT Human Clinical

"We describe two cases of women with extremely severe OHSS presenting bilateral pleural effusions, and severe respiratory failure (paO2/FiO2 < 200) treated with non-invasive ventilation (NIV)."

Documents pleural effusion with objectively severe hypoxaemic respiratory failure as a presentation of the syndrome.

PMID:26506672 SUPPORT Human Clinical

"Due to the increased use of therapeutic strategies for infertility (particularly those using human chorionic gonadotropin), the systemic, particularly the pulmonary, complications of this syndrome must be identified early to allow appropriate diagnosis and management."

Connects the pulmonary complication back to hCG-based fertility treatment as its driver.

⬡

Pathograph

Use the checkboxes to hide or show graph categories. Hover nodes for evidence and cross-linked metadata.

●

Phenotypes

20

Blood 2

Thromboembolism HP:0001907

Show evidence (1 reference)

PMID:26506672 SUPPORT Human Clinical

"The severe form of OHSS varies between 0.5% and 5%, depending on the population studied: intensive care may be required for management of tromboembolic complications, renal failure and severe respiratory failure."

Records thromboembolic complications as a reason for intensive care.

Leukocytosis Increased total leukocyte count HP:0001974

Show evidence (1 reference)

PMID:26506672 SUPPORT Human Clinical

"Clinical signs may include any or all of the following: rapid weight gain, ascites, oliguria, hemoconcentration, leukocytosis, along with intravascular hypovolemia, hyponatremia, and hyperkalemia."

Lists leukocytosis among the defining haematological signs.

Digestive 4

Ascites HP:0001541

Show evidence (1 reference)

PMID:26506672 SUPPORT Human Clinical

"Clinical signs may include any or all of the following: rapid weight gain, ascites, oliguria, hemoconcentration, leukocytosis, along with intravascular hypovolemia, hyponatremia, and hyperkalemia."

Lists ascites among the defining clinical signs.

Abdominal Distension Abdominal distention HP:0003270

Show evidence (2 references)

PMID:35079118 SUPPORT Human Clinical

"accompanied by abdominal bloating and mild abdominal pain"

Direct observation of abdominal bloating, and at the mild end of the grading - which is the point, since distension is the earliest thing a patient notices.

PMID:34644798 SUPPORT Human Clinical

"Pathogenesis of the disease is based on massive transudation of protein-rich fluid from the vascular compartment into the peritoneal, pleural and pericardial spaces, with a variable picture of clinical manifestations depending on its severity."

Mechanistic rather than observational support: peritoneal transudation is what produces the distension, but the source does not itself report distension. Recorded as PARTIAL for that reason.

Nausea HP:0002018

Show evidence (2 references)

PMID:35079118 SUPPORT Human Clinical

"Severe symptoms can include persistent nausea and vomiting, shortness of breath, abdominal and chest pain, pleural effusion, blood clots, kidney failure, and, in some cases, even death"

Names persistent nausea and vomiting among the severe symptoms of the syndrome.

PMID:35079118 SUPPORT Human Clinical

"the patient's assessment of discomfort, abdominal bloating, ascites, or nausea"

Places nausea in the operative definition of moderate OHSS, which is where it functions clinically as a severity criterion rather than an incidental symptom.

Vomiting HP:0002013

Show evidence (1 reference)

PMID:35079118 SUPPORT Human Clinical

"Severe symptoms can include persistent nausea and vomiting, shortness of breath, abdominal and chest pain, pleural effusion, blood clots, kidney failure, and, in some cases, even death"

Names persistent vomiting among the severe symptoms of the syndrome.

Genitourinary 2

Oliguria HP:0100520

Show evidence (1 reference)

PMID:26506672 SUPPORT Human Clinical

"Clinical signs may include any or all of the following: rapid weight gain, ascites, oliguria, hemoconcentration, leukocytosis, along with intravascular hypovolemia, hyponatremia, and hyperkalemia."

Lists oliguria among the defining clinical signs.

Acute Kidney Injury HP:0001919

Show evidence (1 reference)

PMID:26506672 SUPPORT Human Clinical

"The severe form of OHSS varies between 0.5% and 5%, depending on the population studied: intensive care may be required for management of tromboembolic complications, renal failure and severe respiratory failure."

Names renal failure among the complications requiring intensive care.

Metabolism 3

Pleural Effusion HP:0002202

Show evidence (1 reference)

PMID:26506672 SUPPORT Human Clinical

"We describe two cases of women with extremely severe OHSS presenting bilateral pleural effusions, and severe respiratory failure (paO2/FiO2 < 200) treated with non-invasive ventilation (NIV)."

Documents bilateral pleural effusion in extremely severe OHSS.

Hyponatremia HP:0002902

Show evidence (1 reference)

PMID:26506672 SUPPORT Human Clinical

"Clinical signs may include any or all of the following: rapid weight gain, ascites, oliguria, hemoconcentration, leukocytosis, along with intravascular hypovolemia, hyponatremia, and hyperkalemia."

Lists hyponatraemia among the defining biochemical signs.

Hyperkalemia HP:0002153

Show evidence (1 reference)

PMID:26506672 SUPPORT Human Clinical

"Clinical signs may include any or all of the following: rapid weight gain, ascites, oliguria, hemoconcentration, leukocytosis, along with intravascular hypovolemia, hyponatremia, and hyperkalemia."

Lists hyperkalaemia among the defining biochemical signs.

Respiratory 2

Respiratory Failure HP:0002878

Show evidence (1 reference)

PMID:26506672 SUPPORT Human Clinical

"If the patient is not diagnosed early, ascites, pleural and more rarely pericardial effusions, severe respiratory failure and ARDS, hypercoagulability with tromboembolism and multiple organ system failure can occur."

Places severe respiratory failure and ARDS among the consequences of late diagnosis.

Dyspnea HP:0002094

Show evidence (1 reference)

PMID:35079118 SUPPORT Human Clinical

"Severe symptoms can include persistent nausea and vomiting, shortness of breath, abdominal and chest pain, pleural effusion, blood clots, kidney failure, and, in some cases, even death"

Names shortness of breath among the severe symptoms of the syndrome.

Constitutional 1

Pelvic Pain from Adnexal Torsion HP:0034267

Show evidence (1 reference)

PMID:25495063 SUPPORT Human Clinical

"In few days, she developed severe pelvic pain and ultrasonographic evidence of increased ovarian volume."

Documents severe pelvic pain as the presenting symptom of torsion in an enlarged ovary.

Growth 1

Rapid Weight Gain Increased body weight HP:0004324

Show evidence (1 reference)

PMID:26506672 SUPPORT Human Clinical

"Clinical signs may include any or all of the following: rapid weight gain, ascites, oliguria, hemoconcentration, leukocytosis, along with intravascular hypovolemia, hyponatremia, and hyperkalemia."

Lists rapid weight gain first among the clinical signs.

Other 5

Enlarged Multicystic Ovaries Enlarged ovaries HP:0100879

Show evidence (1 reference)

PMID:26506672 SUPPORT Human Clinical

"The diagnosis of severe OHSS was made, largely based on bedside ultrasonography showing increased ovarian size, mild ascites and bilateral pleural effusions."

Records ovarian enlargement as a diagnostic ultrasound finding.

Ovarian Cysts HP:0000138

Show evidence (1 reference)

PMID:23941020 SUPPORT Human Clinical

"In the differential diagnosis, malignancy, pregnancy luteoma and hyperreactio luteinalis would have to be excluded."

The stated differential is an enlarged multicystic ovarian mass, which is what makes this cystic ovarian phenotype the presenting finding.

Intravascular Hypovolemia HP:0011106

Show evidence (1 reference)

PMID:26506672 SUPPORT Human Clinical

"Clinical signs may include any or all of the following: rapid weight gain, ascites, oliguria, hemoconcentration, leukocytosis, along with intravascular hypovolemia, hyponatremia, and hyperkalemia."

Names intravascular hypovolaemia explicitly alongside the fluid overload.

Hemoconcentration Increased hematocrit HP:0001899

Show evidence (2 references)

PMID:26506672 SUPPORT Human Clinical

"Clinical signs may include any or all of the following: rapid weight gain, ascites, oliguria, hemoconcentration, leukocytosis, along with intravascular hypovolemia, hyponatremia, and hyperkalemia."

Lists haemoconcentration among the defining clinical signs.

PMID:34644798 SUPPORT Human Clinical

"Only if severe/critical cases are diagnosed hospitalization is necessary for appropriate rehydration, monitoring of fluid balance and eventual drainage of ascitic fluid."

Supports the clinical consequence of haemoconcentration and fluid loss - admission for rehydration and fluid-balance monitoring.

Hepatic Involvement in Severe Disease Abnormal liver physiology HP:0031865

Show evidence (1 reference)

clinicaltrials:NCT06333691 SUPPORT Human Clinical

"Severe forms are also accompanied by electrolyte disturbances and cardiopulmonary, hepatic, renal, and hemoconcentration associated with increased thromboembolic risk."

Names hepatic involvement among the organ systems affected in severe disease, alongside the cardiopulmonary and renal involvement already curated here.

🧬

Genetic Associations

1

FSHR

Gene: FSHR hgnc:3969 relationship_type: CAUSATIVE variant_origin: GERMLINE

Show evidence (3 references)

PMID:23941020 SUPPORT Human Clinical

"In addition to five mutations which have been found in the transmembrane helices (Asp567Asn, Asp567Gly, Thr449Ile, Thr449Ala, Ile545Thr), the first germline mutation (c.383C > A, p. Ser 128 Tyr) in the extracelullar domain was identified."

Enumerates the reported activating FSHR alleles and their two structural classes.

PMID:23941020 SUPPORT In Vitro

"All five mutants were abnormally activated by TSH and normal levels of hCG while displaying constitutive activity."

Gives the shared functional signature of the transmembrane-helix class.

PMID:15080154 SUPPORT In Vitro

"Together with the two previous studies, this report shows that inappropriate stimulation of the FSHr by hCG is a cause of spontaneous OHSS."

States the causal conclusion drawn across three independent families.

💊

Medical Actions

13

Cabergoline

Action: Pharmacotherapy NCIT:C15986

Agent: cabergoline CHEBI:3286

A dopamine D2 receptor agonist given prophylactically to women identified as high risk. Its mechanism in this setting is specific and dose-dependent: at low dose it partially dephosphorylates ovarian VEGFR-2, which is enough to abolish the permeability response while leaving the VEGFR-2-dependent luteal angiogenesis a pregnancy requires intact. That separation is the reason a dopamine agonist is usable here where a direct VEGFR-2 antagonist such as SU5416 is not — SU5416 prevented the leak in the rodent model but is thromboembolic and disrupts angiogenesis needed for pregnancy.

Mechanism Target:

INHIBITS VEGFR-2 Activation on Vascular Endothelium — Low-dose cabergoline partially inhibits ovarian VEGFR-2 phosphorylation, reversing the VEGFR-2-dependent rise in vascular permeability without blocking luteal angiogenesis.

Show evidence (1 reference)

PMID:16901966 SUPPORT Model Organism

"A 100 microg/kg low-dose Dp-r2 agonist cabergoline reversed VEGFR-2-dependent VP without affecting luteal angiogenesis through partial inhibition of ovarian VEGFR-2 phosphorylation levels."

Identifies VEGFR-2 phosphorylation as the molecular target of the drug at the node it is linked to.

Show evidence (2 references)

PMID:16901966 SUPPORT Human Clinical

"Prophylactic administration of cabergoline (5-10 microg/kg x d) decreased the occurrence of OHSS from 65% (controls) to 25% (treatment)."

Quantifies the clinical prophylactic effect in high-risk oocyte donors.

PMID:16901966 SUPPORT Model Organism

"However, due to its toxicity (thromboembolism) and disruption of VEGFR-2-dependent angiogenic processes critical for pregnancy, this kind of compound cannot be used clinically to prevent OHSS."

Records why direct VEGFR-2 antagonism was abandoned, which is the rationale for choosing a dopamine agonist instead.

GnRH Agonist Trigger in a GnRH Antagonist Cycle

Action: Pharmacotherapy NCIT:C15986

The single most effective preventive change to the stimulation protocol. Substituting a GnRH agonist for hCG to trigger final oocyte maturation removes the long-acting hCG stimulus that drives ovarian VEGF secretion, replacing it with a short endogenous LH surge. The trade-off is a deficient luteal phase, which is why the strategy is paired with luteal support or with elective freezing of all embryos; a meta-analysis of five randomised trials found live birth rates comparable to an hCG trigger when LH activity luteal support was individualised.

Mechanism Target:

INHIBITS hCG-Driven Luteinization of the Recruited Cohort — The substitution acts on luteinization, not on recruitment: the follicles are still recruited, but a short endogenous LH surge replaces the long-acting hCG stimulus that luteinizes the whole cohort and drives the downstream VEGF surge.

Show evidence (1 reference)

PMID:28638367 SUPPORT Human Clinical

"The use of GnRH agonist (GnRHa) for final oocyte maturation trigger in oocyte donation and elective frozen embryo transfer cycles is well established due to lower ovarian hyperstimulation syndrome (OHSS) rates as compared to hCG trigger."

Establishes that replacing the hCG trigger lowers OHSS rates, the clinical read-out of suppressing the VEGF surge.

Show evidence (3 references)

PMID:28638367 SUPPORT Human Clinical

"OHSS was reported in a total of 4/413 cases in the GnRHa group compared to 7/413 in the hCG group (OR 0.48, 95% CI 0.15, 1.60)."

Gives the effect estimate in fresh-transfer cycles specifically, where the confidence interval crosses unity — the benefit is established in donor and freeze-all cycles, not demonstrated in this subgroup.

PMID:28638367 SUPPORT Human Clinical

"GnRHa trigger with LH activity LPS resulted in comparable LBRs compared to hCG trigger."

Records that the preventive substitution need not cost live births when luteal support is individualised.

PMID:27273307 SUPPORT Human Clinical

"Therefore, it is important to prevent this condition by identifying women at risk, allowing the clinician to implement preventive strategies, including the use of GnRH antagonist cycles with agonist triggers."

States the antagonist-cycle-plus-agonist-trigger strategy as the recommended preventive approach.

Intravenous Calcium for OHSS Prophylaxis

Action: Pharmacotherapy NCIT:C15986

Agent: calcium CHEBI:29108

Intravenous calcium given around oocyte retrieval, and on the current network meta-analytic evidence the best-supported prophylaxis in this entry - ranked above cabergoline in both published network meta-analyses, with a risk ratio of 0.14 for moderate-to-severe OHSS at high GRADE and a SUCRA of 92.4% in Wu 2022. "Best-supported" rather than "most effective", deliberately. In Guo 2016 the largest point estimate belongs to ASPIRIN (RR 0.07, rank probability 36% against calcium's 35%), so calcium is not the top-ranked agent in both analyses. What distinguishes it is consistency: it is effective in both, at high GRADE in both, whereas aspirin is graded LOW in Wu 2022 and placed among the agents that could not prevent moderate-to-severe OHSS. Aspirin is curated separately with that discordance recorded. Its proposed mechanism is now curated as a node rather than waved at: calcium is thought to inhibit cyclic-AMP-stimulated renin secretion, damping the intra-ovarian renin-angiotensin system that gonadotropin stimulation activates, and so lowering VEGF expression in luteinized granulosa cells. An earlier revision of this entry claimed no verifiable source for that arm existed; that was wrong, and both network meta-analyses cited here state it. The caveat that remains is about strength, not existence. Both sources hedge ("could be by inhibiting"), neither cites a primary demonstration in an OHSS cohort, and the node is curated PROVISIONAL for that reason. This is still the entry's clearest example of a therapy whose efficacy evidence outruns its mechanistic evidence - it just is not a therapy with no mechanism on record.

Mechanism Target:

INHIBITS Ovarian Renin-Angiotensin System Activation — Calcium is proposed to inhibit cyclic-AMP-stimulated renin secretion, damping the intra-ovarian renin-angiotensin arm and so reducing VEGF expression in luteinized granulosa cells.

Show evidence (2 references)

PMID:35154015 SUPPORT Human Clinical

"The possible underlying mechanism of calcium preventing OHSS could be by inhibiting cyclic adenosine monophosphate-stimulated renin secretion, which reduces the production of angiotensin-converting enzyme II"

States the proposed target of the drug at this node, with the authors' own hedge intact.

PMID:26752241 SUPPORT Human Clinical

"IV calcium is a relatively new method for preventing severe OHSS from occurring by inhibiting the renin-angiotensin system (RAS) and, consequently, reducing VEGF concentration."

Independent statement of the same proposed mechanism of action.

Show evidence (3 references)

PMID:35154015 SUPPORT Human Clinical

"The incidence of moderate-to-severe OHSS was significantly reduced by calcium administration (risk ratios [RR] 0.14, 95% confidence interval [CI]: 0.04, 0.46) (grade: high), HES (RR 0.25, 95% CI 0.07, 0.73) (grade: high), and cabergoline (RR 0.43, 95% CI 0.24, 0.71) (grade: moderate)."

Gives the effect estimate and GRADE rating for calcium, alongside the two comparators, from a network meta-analysis of randomized trials.

PMID:35154015 SUPPORT Human Clinical

"The surface under the cumulative ranking curve (SUCRA) indicated that calcium (SUCRA, 92.4%) was the most effective intervention for preventing moderate-to-severe OHSS."

Ranks calcium above every other prophylactic agent assessed, including cabergoline.

PMID:26752241 SUPPORT Human Clinical

"The rank probability demonstrated aspirin (Rank 1: 36%) and IV calcium (Rank 1: 35%) to be the most efficacious."

An independent network meta-analysis placing intravenous calcium among the top-ranked agents. Note it ranks ASPIRIN marginally above calcium (36% vs 35%), so this is concordant on calcium being highly effective but NOT on calcium being first; aspirin is curated separately for that reason.

Low-Dose Aspirin for OHSS Prophylaxis

Action: Pharmacotherapy NCIT:C15986

Agent: aspirin CHEBI:15365

The agent with the largest point estimate in either network meta-analysis - RR 0.07 in Guo 2016, ranked first at 36% rank probability, ahead of intravenous calcium - and simultaneously the agent those two analyses disagree about most sharply. Wu 2022 grades the aspirin evidence LOW and places it among the agents that could not prevent moderate-to-severe OHSS. It is curated because leaving it out was distorting this entry. The calcium treatment previously opened by calling calcium "the most effective prophylaxis available", while the snippet directly beneath it ranked aspirin above calcium in one of the two analyses. Curating aspirin lets both facts stand and makes the discordance the entry's subject rather than its blind spot. Unlike calcium, it has a concrete and non-speculative proposed mechanism: aspirin inhibits platelet COX-1, and platelet activation with release of vasoactive mediators is one of the proposed amplifiers of the capillary leak. That arm is not curated as a node here - no primary source in this entry's reference set demonstrates it in OHSS - so the treatment carries no target_mechanisms link, for the same reason and with the same discipline applied to calcium before the ovarian RAS node was added.

Show evidence (4 references)

PMID:26752241 SUPPORT Human Clinical

"Five pharmacologic interventions were superior to placebo in decreasing OHSS incidence: aspirin [relative risk (RR) 0.07, 95% credible interval (CrI) 0.01-0.30, p < 0.05], intravenous (IV) calcium [RR 0.11, 95% CrI 0.02-0.54, p < 0.05], cabergoline [RR 0.17, 95% CrI 0.06-0.43, p < 0.05],..."

The effect estimate for aspirin, alongside every other agent curated on this entry, from a single consistent analysis - which is what makes the ranking between them interpretable.

PMID:26752241 SUPPORT Human Clinical

"The rank probability demonstrated aspirin (Rank 1: 36%) and IV calcium (Rank 1: 35%) to be the most efficacious."

Ranks aspirin marginally ahead of intravenous calcium in this analysis.

PMID:35154015 REFUTE Human Clinical

"Contrastingly, letrozole (grade: moderate), aspirin (grade: low), albumin (grade: moderate), metformin (grade: high), glucocorticoids (grade: moderate), and quinagolide (grade: high) could not prevent moderate-to-severe OHSS (P > 0."

The direct contradiction: the later meta-analysis finds aspirin did not prevent moderate-to-severe OHSS and grades the evidence LOW. Recorded as REFUTE so the disagreement is machine-readable, not just narrated.

+ 1 more reference

Hydroxyethyl Starch for OHSS Prophylaxis

Action: Pharmacotherapy NCIT:C15986

Agent: hydroxyethyl starch NCIT:C559

Intravenous hydroxyethyl starch, a plasma volume expander given around retrieval. Both network meta-analyses find it effective (RR 0.25 and RR 0.26) and one grades the evidence high. Its rationale is the one intervention on this entry that acts on the consequence rather than the cause: it counters the intravascular volume depletion produced by the capillary leak instead of reducing the leak itself, which is why it is linked to the third-space node and not to a VEGF node. A note on the binding: NCIT's own "Hydroxyethyl Starch" concept (NCIT:C102744) is retired and is not reachable from Pharmacologic Substance, so `just validate-terms` rejects it. The live term is NCIT:C559 Hetastarch, which is what the agent is bound to; `preferred_term` keeps the name the trials use. Curators should note the context this evidence sits in: hydroxyethyl starch carries regulatory restrictions in critical care for renal and mortality concerns, and the cited meta-analyses assess OHSS outcomes only. This entry records the OHSS efficacy finding, not a recommendation.

Mechanism Target:

MODULATES Third-Space Fluid Shift and Intravascular Volume Depletion — A colloid volume expander opposes the fall in effective circulating volume caused by the leak; it does not act on the permeability lesion upstream.

Show evidence (1 reference)

PMID:26752241 SUPPORT Human Clinical

"Gokman et al. 10 demonstrated that the administration of albumin and hydroxyethyl starch (HES) might prevent moderate to severe OHSS in high-risk patients."

Records the colloid rationale and the outcome it is credited with.

Show evidence (1 reference)

PMID:35154015 SUPPORT Human Clinical

"Calcium, HES, and cabergoline could effectively and safely prevent moderate-to-severe OHSS, with calcium as the most effective intervention."

The meta-analysis conclusion naming HES among the three effective agents.

Metformin for OHSS Prophylaxis

Action: Pharmacotherapy NCIT:C15986

Agent: metformin CHEBI:6801

Metformin given to women at risk, principally those with polycystic ovary syndrome, where it is already indicated for the underlying insulin resistance. One network meta-analysis finds a risk ratio of 0.20; the other did not assess it as effective, and it does not appear among the three agents that meta-analysis concludes for. It is curated because a Phase II-plus evidence base exists and because the discordance between the two analyses is itself worth recording, not because the case is settled.

Show evidence (2 references)

PMID:26752241 SUPPORT Human Clinical

"metformin [RR 0.20, 95% CrI 0.07-0.59, p < 0.05] and IV hydroxyethyl starch (HES) [RR 0.26, 95% CrI 0.05-0.99, p < 0.05]"

Gives the metformin effect estimate from the earlier network meta-analysis.

PMID:35154015 REFUTE Human Clinical

"Contrastingly, letrozole (grade: moderate), aspirin (grade: low), albumin (grade: moderate), metformin (grade: high), glucocorticoids (grade: moderate), and quinagolide (grade: high) could not prevent moderate-to-severe OHSS (P > 0."

The later meta-analysis states directly - at HIGH GRADE - that metformin could not prevent moderate-to-severe OHSS. This replaces an earlier item that quoted the list of agents that DID work and inferred metformin's absence from it; an argument from silence is not snippet support.

Albumin for OHSS Prophylaxis

Action: Pharmacotherapy NCIT:C15986

Agent: human albumin

Intravenous albumin around oocyte retrieval, curated here specifically BECAUSE the signal is unfavourable rather than despite it. Albumin has been widely used on the colloid rationale, but the earlier network meta-analysis found it associated with a lower pregnancy rate than placebo (RR 0.85, 95% CI 0.74-0.97), and the later one does not include it among the effective preventive agents. A prophylaxis that may cost the pregnancy the whole treatment cycle exists to achieve is a different kind of intervention from one that merely fails, and an entry that curated only the drugs that work would misrepresent the decision a clinician is actually making.

Show evidence (3 references)

PMID:26752241 REFUTE Human Clinical

"Additionally, albumin might decrease the pregnancy rate when compared with placebo [RR 0.85, 95% CI 0.74-0.97, p < 0.05]."

The negative signal: albumin prophylaxis was associated with a lower pregnancy rate, which is why this treatment is recorded with REFUTE evidence rather than as an endorsed option.

PMID:35154015 REFUTE Human Clinical

"Contrastingly, letrozole (grade: moderate), aspirin (grade: low), albumin (grade: moderate), metformin (grade: high), glucocorticoids (grade: moderate), and quinagolide (grade: high) could not prevent moderate-to-severe OHSS (P > 0."

The later meta-analysis states directly that albumin could not prevent moderate-to-severe OHSS. The description previously made this claim without citing a source for it.

PMID:26752241 SUPPORT Human Clinical

"Although no available pharmacologic intervention fully prevents the development of OHSS, adjuvant drug therapy can still be adopted to limit the incidence and improve the management of moderate to severe OHSS."

The overall bound on pharmacological prophylaxis, which applies to every drug curated on this entry: none of them fully prevents the syndrome.

Secondary Prevention by Coasting or Cycle Cancellation

Action: Preventive Intervention NCIT:C15843

Two of the manoeuvres available once a cycle is already over-responding, both of which work by denying the recruited follicular cohort its luteinizing stimulus rather than by treating the leak. Coasting withholds further gonadotropin while continuing pituitary suppression, allowing the smaller follicles to undergo atresia before the trigger. Cycle cancellation withholds the trigger altogether. They are grouped because they are one decision made at one point in the cycle, graded by how much of the cycle the clinician is willing to sacrifice. The third manoeuvre named in the same source - elective cryopreservation of all oocytes or embryos - is curated as its own treatment rather than folded in here, because it acts at a different time and on a different arm: it permits the trigger and the retrieval, and prevents only the LATE form driven by the endogenous hCG of an implanting pregnancy. All of these are distinct from primary prevention, which is the choice of stimulation protocol before the response is known.

Mechanism Target:

INHIBITS hCG-Driven Luteinization of the Recruited Cohort — Coasting and cancellation withhold the luteinizing stimulus from the recruited cohort; freeze-all removes the endogenous pregnancy hCG that would sustain luteinization into the late phase.

Show evidence (1 reference)

PMID:24848075 SUPPORT Human Clinical

"Secondary prevention includes all strategies directed to counteract an excessive ovarian response (cycle cancellation, coasting, trigger ovulation by low doses of hCG or by alternative agents, cryopreservation of oocytes/embryos, adequate luteal phase support)."

Names all three manoeuvres as the strategies directed at an excessive ovarian response, which is the node this link targets.

Show evidence (2 references)

PMID:24848075 SUPPORT Human Clinical

"Secondary prevention includes all strategies directed to counteract an excessive ovarian response (cycle cancellation, coasting, trigger ovulation by low doses of hCG or by alternative agents, cryopreservation of oocytes/embryos, adequate luteal phase support)."

The source enumeration of the secondary prevention strategies curated here.

PMID:34644798 SUPPORT Human Clinical

"Nowadays OHSS can easily be avoided by several prevention methods, ranging from identification of high-risk patients, choice of a correct protocol stimulation, trigger with gonadotropin-releasing hormone (GnRH) agonists or, finally, the freeze-all strategy."

Places freeze-all as the last line of the prevention sequence and states the overall preventability of the syndrome.

Elective Embryo or Oocyte Cryopreservation (Freeze-All)

Action: Cryopreservation NCIT:C16475

Curated separately from the grouped secondary-prevention entry because it is the only one of the three that is a distinct laboratory procedure with its own NCIT identity, and because its mechanism is specifically temporal: it does not prevent early OHSS at all, since the trigger is still given and the oocytes still retrieved. What it prevents is the late form, by removing the implanting pregnancy whose endogenous hCG would otherwise sustain the luteinizing stimulus for weeks. It is the reason the GnRH-agonist trigger is so effective in donor and freeze-all cycles specifically and less clearly so in fresh-transfer cycles.

Mechanism Target:

INHIBITS hCG-Driven Luteinization of the Recruited Cohort — Deferring transfer removes the endogenous pregnancy hCG that would sustain luteinization of the recruited cohort into the late phase.

Show evidence (1 reference)

PMID:34644798 SUPPORT Human Clinical

"Nowadays OHSS can easily be avoided by several prevention methods, ranging from identification of high-risk patients, choice of a correct protocol stimulation, trigger with gonadotropin-releasing hormone (GnRH) agonists or, finally, the freeze-all strategy."

Names freeze-all as a prevention method acting alongside the trigger choice on the same luteinizing stimulus.

Show evidence (1 reference)

PMID:28638367 SUPPORT Human Clinical

"The use of GnRH agonist (GnRHa) for final oocyte maturation trigger in oocyte donation and elective frozen embryo transfer cycles is well established due to lower ovarian hyperstimulation syndrome (OHSS) rates as compared to hCG trigger."

Records that the agonist-trigger benefit is established specifically in elective frozen-transfer and donor cycles - that is, in combination with this strategy.

Thromboprophylaxis

Action: Anticoagulation Therapy NCIT:C63341

Anticoagulant prophylaxis in severe OHSS, aimed at the haemoconcentrated, stasis-prone state rather than at the capillary leak that produces it. It is described as cost-effective and widely used, and is one of the few interventions in established disease with any claim to a benefit. The size of the risk it addresses is worth stating precisely, because it is smaller and less certain than the syndrome's reputation suggests. A systematic review of thromboembolism after assisted reproduction found the frequency of venous thromboembolism specifically related to OHSS to be under 0.001%, and the increase in risk conferred by OHSS on top of ART did not reach statistical significance, with a confidence interval spanning two orders of magnitude. The practice is therefore standard on the basis of consequence severity and low cost, not on a demonstrated effect size. Low dose aspirin, by contrast, remains contested.

Mechanism Target:

INHIBITS Hypercoagulability and Thromboembolism — Anticoagulant prophylaxis is directed at the thrombotic consequence of haemoconcentration and stasis, not at the permeability lesion upstream of it.

Show evidence (1 reference)

PMID:34644798 SUPPORT Human Clinical

"One of the most dangerous complications of OHSS is venous thromboembolism (VTE). Thromboprophylaxis has shown to be cost effective and widely used, while there are controversies regarding the usage of low dose aspirin (LDA) as a preventive measure."

States the intervention, its target complication, and the separate controversy over aspirin.

Show evidence (3 references)

PMID:36588288 SUPPORT Human Clinical

"The risk of VTE after ART complicated by OHSS, as compared to ART without OHSS, was higher but not statistically significant (RR: 14.83; 95% CI: 0.86-255.62)."

Quantifies the incremental risk this prophylaxis addresses and shows it is not statistically established - the reason the treatment prose is hedged rather than asserted.

PMID:36588288 SUPPORT Human Clinical

"The overall frequency of VTE specifically related to OHSS was <0.001%."

Gives the absolute frequency of the complication, which is very low.

PMID:36588288 SUPPORT Human Clinical

"Further large prospective studies on risk factors of VTE in women undergoing ART are needed in order to optimize thromboprophylaxis in this context."

The reviewing authors' own statement that the evidence base for thromboprophylaxis in this setting is not yet adequate.

Therapeutic Paracentesis and Thoracentesis

Action: Paracentesis NCIT:C15310

Drainage of tense ascites, and of pleural fluid when the respiratory arm dominates. It is the one manoeuvre in established disease with an immediate, mechanically obvious effect: removing the fluid relieves the intra-abdominal pressure and the diaphragmatic splinting, which is why breathlessness often improves within minutes of a paracentesis that has changed nothing about the underlying leak. Curated separately from general supportive care because it is a procedure with its own NCIT identity and its own mechanistic target, whereas supportive care is the surrounding fluid and monitoring strategy.

Mechanism Target:

MODULATES Third-Space Fluid Shift and Intravascular Volume Depletion — Drainage removes accumulated third-space fluid and relieves the mechanical consequences of tense ascites; it treats the accumulated fluid, not the permeability lesion that produced it.

Show evidence (1 reference)

PMID:26506672 SUPPORT Human Clinical

"Pulmonary intensive care may involve thoracentesis, oxygen supplementation and in more severe cases assisted ventilation."

Documents drainage of third-space fluid as the intervention directed at this node.

Show evidence (2 references)

PMID:34644798 SUPPORT Human Clinical

"Only if severe/critical cases are diagnosed hospitalization is necessary for appropriate rehydration, monitoring of fluid balance and eventual drainage of ascitic fluid."

Places drainage of ascitic fluid among the interventions reserved for severe or critical disease.

PMID:26506672 SUPPORT Human Clinical

"There are only a few studies in English that describe severe respiratory failure treated with non-invasive ventilation, but all of them have had good outcomes."

Supports the respiratory arm of drainage-plus-ventilation while flagging the thinness of the evidence base.

Supportive Care of Established OHSS

Action: Supportive Care NCIT:C15747

The surrounding management: rehydration to correct the intravascular deficit rather than the total-body excess - fluid resuscitation, not diuresis - monitoring of fluid balance, oxygen, and non-invasive ventilation when hypoxaemia is severe. Most cases are managed as outpatients; hospitalisation is reserved for the severe and critical end. The candid limitation, stated by the reviews themselves, is that this rests on consensus rather than trial evidence. The syndrome is self-limiting once the hCG stimulus falls, so the aim is to support the patient across that interval - which is also why the evidence base has never been built.

Mechanism Target:

MODULATES Third-Space Fluid Shift and Intravascular Volume Depletion — Rehydration and fluid-balance monitoring are directed at the intravascular depletion side of the third-spacing paradox, not at the fluid overload that accompanies it.

Show evidence (1 reference)

PMID:34644798 SUPPORT Human Clinical

"Only if severe/critical cases are diagnosed hospitalization is necessary for appropriate rehydration, monitoring of fluid balance and eventual drainage of ascitic fluid."

Names rehydration and fluid-balance monitoring as the interventions directed at this node.

Show evidence (2 references)

PMID:27273307 SUPPORT Human Clinical

"Treatment is largely supportive and is based mainly on consensus statements rather than evidence."

States plainly that established-disease management rests on consensus, not trial evidence - an important limit on any treatment claim here.

PMID:34644798 SUPPORT Human Clinical

"When OHSS occurs, it can usually be managed as outpatient care."

Establishes that most established disease does not require admission, which is what the supportive strategy is scaled against.

Risk Stratification Before Ovarian Stimulation

Action: Preventive Intervention NCIT:C15843

Not a treatment of the syndrome but the intervention with the largest effect on it, and the reason it is included: the identified risk factors — young age, polycystic ovary syndrome, a previous hyper-response — and the quantitative markers anti-Mullerian hormone and antral follicle count are what let the clinician choose a milder protocol, an agonist trigger, or a freeze-all strategy before any stimulation begins. It is deliberately not linked to a pathophysiology node: identifying a susceptible woman does not itself act on any step of the causal chain.

Show evidence (3 references)

PMID:24848075 SUPPORT Human Clinical

"Some well-established risk factors that could rise the risk of OHSS include young age, polycystic ovary syndrome, prior hyper-response/OHSS."

Names the established clinical risk factors used for stratification.

PMID:24848075 SUPPORT Human Clinical

"In recent years research has focus on identifying biomarkers/hormonal markers that could represent potential predictors of OHSS (anti-Mullerian hormone and antral follicle count)."

Records the two quantitative predictors used to grade ovarian reserve before stimulation.

PMID:38099867 SUPPORT Human Clinical

"This systematic review aims to identify who is at high risk for developing ovarian hyperstimulation syndrome, along with evidence-based strategies to prevent it and replaces the document of the same name last published in 2016."

Establishes that risk identification plus prevention is the subject of the current professional-society guideline.

🔬

Diagnosis

2

Pelvic Ultrasonography

Transvaginal or transabdominal ultrasound demonstrating enlarged multicystic ovaries and free peritoneal fluid is the primary diagnostic study, and in the severe form also shows pleural fluid. It is available at the bedside, which matters in a syndrome that can deteriorate over hours.

Show evidence (1 reference)

PMID:26506672 SUPPORT Human Clinical

"The diagnosis of severe OHSS was made, largely based on bedside ultrasonography showing increased ovarian size, mild ascites and bilateral pleural effusions."

Documents bedside ultrasound as the basis on which the severe diagnosis was made.

FSHR Sequencing in Recurrent Spontaneous OHSS

Sequencing FSHR is what separates the familial gestational form from a sporadic spontaneous case, and the distinction is prognostic rather than academic: an activating allele predicts recurrence in every subsequent pregnancy, and family members may carry it. Before sequencing, the differential of an enlarged multicystic ovarian mass in pregnancy — malignancy, pregnancy luteoma, hyperreactio luteinalis — has to be excluded.

Show evidence (2 references)

PMID:23941020 SUPPORT Human Clinical

"In the differential diagnosis, malignancy, pregnancy luteoma and hyperreactio luteinalis would have to be excluded."

States the differential diagnosis that has to be settled before a spontaneous OHSS diagnosis is accepted.

PMID:15080154 SUPPORT Human Clinical

"In this report, we describe a new familial case of recurrent OHSS."

Documents that the familial form presents as recurrent disease, which is what makes identifying the allele worthwhile.

📈

Progression

2

Early OHSS

Early OHSS begins in the days after the hCG trigger and oocyte retrieval and reflects the preovulatory response to stimulation - it is the arm that peak oestradiol and oocyte number predict, and the arm that protocol choice, coasting and trigger substitution can pre-empt. Women with early OHSS have significantly higher serum oestradiol and lower gonadotropin requirements than either late-OHSS or unaffected women, which is the signature of an ovary that responded excessively to a modest dose.

Show evidence (2 references)

PMID:10785214 SUPPORT Human Clinical

"Early OHSS relates to "excessive" preovulatory response to stimulation, whereas late OHSS depends on the occurrence of pregnancy, is likelier to be severe, and is only poorly related to preovulatory events."

The defining statement of the two-phase distinction and of what each phase depends on.

PMID:10785214 SUPPORT Human Clinical

"Women with early OHSS had significantly higher serum E(2) levels and lower gonadotropin requirements than did the other groups."

Gives the biochemical signature that separates early OHSS from the late form and from unaffected cycles.

Late OHSS

Late OHSS begins later and depends on pregnancy: the endogenous hCG of an implanting conceptus sustains the luteinizing stimulus for weeks rather than days. Three consequences follow and all are clinically important. It is likelier to be severe than the early form. It cannot be predicted from preovulatory measurements - serum oestradiol and oocyte number, which work for early OHSS, do not identify who will develop it. And it is the arm that freeze-all abolishes, since deferring transfer removes the pregnancy entirely. In one series clinical pregnancies occurred in every late-OHSS cycle, and in another 77.8% of late-onset cases had a concurrent positive pregnancy test.

Show evidence (4 references)

PMID:10785214 SUPPORT Human Clinical

"Serum E(2) and oocyte numbers did not accurately predict the risk of developing late OHSS."

Establishes that the predictors used for early OHSS fail for the late form, which is why prevention of late OHSS is structural (freeze-all) rather than predictive.

PMID:10785214 SUPPORT Human Clinical

"Clinical pregnancies occurred in all cycles with late OHSS, and multiple pregnancies were significantly more frequent in the late OHSS group than in the other groups."

Ties the late form to pregnancy, and to multiple pregnancy in particular - the higher-hCG case.

PMID:10785214 SUPPORT Human Clinical

"Late OHSS was more likely than early OHSS to be severe."

Records the severity difference between the two phases.

+ 1 more reference

📊

Prevalence

3

Women undergoing assisted reproductive technology treatment (per treatment cycle, not general population)

Period Prevalence 1000.0 per 100,000 >1 in 1,000

Roughly 1% of ART-treated women develop severe OHSS. This is a risk per treatment episode in an exposed population, not a population prevalence — the syndrome does not occur outside gonadotropin exposure or pregnancy, so a general-population denominator would be meaningless. Recorded as PERIOD_PREVALENCE for that reason.

Show evidence (1 reference)

PMID:27273307 SUPPORT Human Clinical

"Severe ovarian hyperstimulation syndrome (OHSS) is an iatrogenic condition that affects 1% of women that undergo treatment with assisted reproductive technology."

Direct statement of the proportion of ART-treated women affected by severe OHSS.

Hospitalized moderate-to-severe OHSS cases per ovum pick-up cycle, China, 2013-2017 (1,581,703 cycles)

Period Prevalence 1140.0 per 100,000 >1 in 1,000

Nationwide inpatient data give 1.14% of ovum pick-up cycles complicated by moderate or severe OHSS, with a year-on-year fall from 1.4% (2014-2015) to 0.9% (2017) that is consistent with the uptake of antagonist protocols and agonist triggers. Denominator is retrieval cycles, not women.

Show evidence (2 references)

PMID:38487201 SUPPORT Human Clinical

"The overall incidence of moderate and severe OHSS between 2013 and 2017 was 1.14%."

Gives the pooled cycle-based rate from a nationwide inpatient dataset.

PMID:38487201 SUPPORT Human Clinical

"We extracted 18,022 eligible patients with moderate or severe OHSS and 1,581,703 OPU cycles."

Records the numerator and denominator behind the rate.

Severe OHSS as a proportion of stimulated populations (range across studies)

Period Prevalence 500.0–5000.0 per 100,000 >1 in 1,000

Reported severe-OHSS rates span an order of magnitude between series, which reflects genuinely different case definitions and stimulation eras rather than measurement error. Recorded as a range for that reason.

Show evidence (1 reference)

PMID:26506672 SUPPORT Human Clinical

"The severe form of OHSS varies between 0.5% and 5%, depending on the population studied"

Gives the reported range and attributes its width to the population studied.

📊

Related Datasets

1

High throughput sequencing data of ovarian hyperstimulation syndrome (OHSS) mouse model geo:GSE183346

RNA sequencing of ovaries from an established mouse OHSS model, reported as showing strengthened cell junctions between ovarian vessels after drug treatment - the transcriptional counterpart of the inter-endothelial junction loosening that this entry curates as the VEGFR-2-mediated permeability node.

house mouse BULK RNA SEQ n=6

PMID:35221672

Identified by GEO DataSets index search (scripts/discover_datasets.py) and verified against NCBI E-utilities on 2026-08-25; title, sample count and organism are GEO's own values. Relevance triaged manually: this is the OHSS syndrome itself in a disease model, not merely a superovulation protocol. Two other DIRECT-scored candidates were rejected on that same triage - GSE229048 (ovine caruncular endometrium after FSH superovulation) studies the uterus after a stimulation protocol rather than the hyperstimulation syndrome, and GSE39402 is an epithelial ovarian tumour model. Both would have resolved perfectly while being about something else.

🔬

Clinical Trials

5

NCT03996434 PHASE_IV COMPLETED

Randomised comparison of coasting against subcutaneous GnRH antagonist administration in patients at high risk of severe OHSS, with embryo quality and ICSI outcome as co-outcomes. Directly tests one of the secondary prevention manoeuvres curated on this entry against an alternative, in the population where the choice actually arises.

Target Phenotypes: Enlarged ovaries HP:0100879

Show evidence (1 reference)

clinicaltrials:NCT03996434 SUPPORT Human Clinical

"The aim of this work is to study the value of GnRH antagonist subcutaneous administration as an alternative to coasting in prevention of severe OHSS"

Establishes that the trial compares two secondary prevention strategies for severe OHSS.

NCT02670304 PHASE_IV COMPLETED

Randomised controlled trial of letrozole for prevention of moderate and severe OHSS in IVF. The rationale is mechanistically specific to this entry's pathograph: an aromatase inhibitor given in the luteal phase lowers oestrogen and suppresses luteal function, acting on the luteinized cohort that is the source of the VEGF surge rather than on the capillary leak.

Target Phenotypes: Ascites HP:0001541

Show evidence (1 reference)

clinicaltrials:NCT02670304 SUPPORT Human Clinical

"Letrozole is one kind of aromatase inhibitors which may have effect on decrease estrogen in luteal phase and inhibit the luteal function of ovary."

States the mechanistic rationale, which acts on the luteinization node rather than downstream.

NCT02392520 NOT_APPLICABLE UNKNOWN

GnRH antagonist administered in the luteal phase versus conventional treatment in women who have ALREADY developed severe early OHSS and have had all embryos cryopreserved. Curated because it is the rare trial addressed to established disease rather than to prevention - the specific evidence gap recorded in the ohss_established_disease_evidence_base discussion on this entry. Its status is UNKNOWN on the registry, which is itself informative about how thin that evidence base is.

Target Phenotypes: Ascites HP:0001541

Show evidence (1 reference)

clinicaltrials:NCT02392520 SUPPORT Human Clinical

"The study aims to compare the novel method of GnRH antagonist administration in the luteal phase versus conventional treatment in IVF patients who develop severe early ovarian hyperstimulation syndrome and have all their embryos cryopreserved."

Confirms the population is women with established severe early OHSS, not women at risk of it.

NCT06333691 NOT_APPLICABLE COMPLETED

Three-arm comparison of calcium gluconate plus diosmin, cabergoline, and cabergoline plus diosmin for prevention of OHSS in high-risk women undergoing ICSI. Relevant because cabergoline is the one pharmacological prophylaxis curated on this entry with a defined molecular target, and this trial places it against non-mechanistic alternatives in the same population.

Target Phenotypes: Ascites HP:0001541

Show evidence (2 references)

clinicaltrials:NCT06333691 SUPPORT Human Clinical

"This syndrome is characterized by a sudden increase of the vascular permeability which results in the development of a massive extravascular exudate in the peritoneal cavity, pleural, pericardium causing ascites, pleural and pericardial effusion."

The trial protocol's own statement of the mechanism this entry curates - a permeability rise producing serosal-cavity exudate - independently corroborating the pathograph from a registered clinical protocol.

clinicaltrials:NCT06333691 SUPPORT Human Clinical

"Severe forms are also accompanied by electrolyte disturbances and cardiopulmonary, hepatic, renal, and hemoconcentration associated with increased thromboembolic risk."

Corroborates the severe-form phenotype cluster curated here - haemoconcentration, electrolyte disturbance, renal and respiratory involvement, thromboembolic risk.

NCT03794037 PHASE_II SUSPENDED

Montelukast with dydrogesterone versus dydrogesterone alone for prevention and treatment of OHSS in freeze-all cycles. Curated as a negative datum about the field rather than as evidence for the drug: it is suspended, and it is the only registered trial found that targets the leukotriene arm.

Target Phenotypes: Ascites HP:0001541

Show evidence (1 reference)

clinicaltrials:NCT03794037 SUPPORT Human Clinical

"montelukast \& dydrgesteron will be given to cases with suspected or proven ovarian hyperstimulation in one group in comparison with dydrogesteron alone in the other group."

States the intervention and comparator; the registry record's typography (including the escaped ampersand and the misspellings) is quoted verbatim.

🧫

Experimental Models

1

SVOG human granulosa-lutein cell line with Tie1 silencing CELL_LINE

A non-tumorigenic human granulosa-lutein cell line in which acute hCG raises Tie1 and VEGF, and in which silencing Tie1 abolishes the hCG-induced VEGF rise. This is the loss-of-function experiment the entry's EGR1-TIE1 node actually rests on, and recording it structurally means the PROVISIONAL status of that node is traceable to a named system with stated limits rather than asserted in prose.

Organism

human NCBITaxon:9606

Publication

PMID:35079118

Pathograph links

EGR1-TIE1 Amplification of Granulosa VEGF Output perturbs fidelity: moderate Tie1 knockdown removes the hCG-to-VEGF link in a human granulosa-lutein background, which is what makes Tie1 a candidate required step rather than a correlate.

Limitations: An immortalised cell line, not primary patient granulosa cells and not an ovary. Acute high-dose hCG in culture compresses a stimulus that acts over days in vivo, and a cell line cannot reproduce the paracrine and vascular context in which the VEGF surge matters. The reporting authors state that clinical relevance is not yet addressed.

Readouts

hCG-induced VEGF level after Tie1 silencing

Direction: ABOLISHED

Interpretation: The hCG-driven VEGF rise does not occur without Tie1, placing Tie1 between the hCG signal and VEGF output.

Show evidence (1 reference)

PMID:35079118 SUPPORT In Vitro

"Tie1 silencing abolished the hCG-induced VEGF level in SVOG cells"

The knockdown readout in the human granulosa-lutein line, quoted apart from the rat clause of the same sentence.

EGR1 binding at the Tie1 promoter

Direction: INCREASED

Interpretation: Identifies the transcriptional route by which hCG raises Tie1, rather than leaving the induction unexplained.

Show evidence (1 reference)

PMID:35079118 SUPPORT In Vitro

"We also report that early growth response protein 1 (EGR1), whose expression was also upregulated by hCG, bound directly to the Tie1 promoter and activated its transcription."

The promoter-binding readout.

Show evidence (2 references)

PMID:35079118 SUPPORT In Vitro

"Further studies in SVOG cells revealed that the hCG-induced upregulation of Tie1 expression involved the phosphoinositide 3-kinase/protein kinase B signaling pathway."

The signalling route established in this cell line - correctly tagged IN_VITRO, SVOG being a human granulosa-lutein line rather than an animal system.

+ 1 more reference

🐁

Animal Models

2

Induced-OHSS rat with ovarian Tie1 knockdown

An experimentally established OHSS rat model in which ovaries show raised Tie1 and VEGF relative to controls, and in which knocking Tie1 down attenuates the syndrome histologically. It is the in vivo half of the evidence for the EGR1-TIE1 node - the cell line shows the molecular link, the rat shows that interrupting it changes the disease.

Species

Rat

Genotype

Wild type with shRNA-mediated ovarian Tie1 knockdown

Publication

PMID:35079118

Pathograph links

EGR1-TIE1 Amplification of Granulosa VEGF Output rescues fidelity: moderate Tie1 knockdown attenuates OHSS progression in the rat model, which is the whole-organism counterpart of the abolished VEGF rise seen in the cell line.

Limitations: Rat ovarian physiology differs from human in cycle length and in the relative roles of FSH and hCG, and an experimentally induced OHSS model compresses the stimulus into a schedule no patient experiences. The histological attenuation is also a structural rather than a functional readout: no measurement of vascular permeability or third-space fluid in the treated animals is reported.

Readouts

Ovarian Tie1 and VEGF expression in induced OHSS

Direction: INCREASED

Interpretation: Both rise together in the model, matching the association seen in patient-derived granulosa cells.

Show evidence (1 reference)

PMID:35079118 SUPPORT Model Organism

"as well as ovaries from rats with experimentally established OHSS, compared to controls"

The rat half of the expression result, quoted separately from the patient-cell half so this MODEL_ORGANISM item does not also carry an in vitro claim.

Histological progression of OHSS after Tie1 knockdown

Direction: DECREASED

Interpretation: Interrupting the proposed amplifier attenuates the disease in vivo, which is the strongest claim available for this node.

Show evidence (1 reference)

PMID:35079118 SUPPORT Model Organism

"attenuated the progression of OHSS in rats, as determined by histological analysis."

The in vivo attenuation readout and the method behind it, quoted apart from the cell-line clause of the same sentence.

Show evidence (2 references)

PMID:35079118 SUPPORT Model Organism

"Ovaries harvested from control and experimentally induced OHSS rats, as well as those from OHSS rats subjected to Tie1 or nontargeting silencing, were used for histological analysis."

Describes the rat model and its knockdown arm directly, which is the claim link-level evidence should make: that THIS model is informative for the target node. (The previous snippet here quoted an SVOG cell-line result, which is neither rat nor in vivo; it is now curated on the SVOG experimental model where it belongs.)

+ 1 more reference

Prolactin-supplemented OHSS rat model of VEGFR-2-dependent permeability

The well-established rodent OHSS model in which the causal role of VEGFR-2 in the permeability rise was demonstrated, first by blockade with the antagonist SU5416 and then by dose-separating the receptor's permeability and angiogenic functions with low-dose cabergoline. Almost everything the entry asserts about VEGFR-2 being the modifiable node comes from this system, so it is recorded structurally rather than left implicit in the treatment description.

Species

Rat

Genotype

Wild type, gonadotropin-induced OHSS with prolactin supplementation

Background

Wistar

Publication

PMID:16901966

Pathograph links

VEGFR-2 Activation on Vascular Endothelium perturbs fidelity: moderate Pharmacological manipulation of VEGFR-2 in this model - blockade with SU5416, partial dephosphorylation with low-dose cabergoline - is what establishes the receptor as necessary for the permeability rise and as separable from luteal angiogenesis.

Limitations: Rat, and a prolactin-supplemented model at that, because the dopamine-agonist arm requires a prolactin-responsive background that human OHSS does not have. The dose that separates permeability from angiogenesis was found in this species; the human prophylactic dose was chosen by extrapolation, and the clinical result reported alongside it is an uncontrolled comparison in oocyte donors rather than a randomised trial.

Readouts

Vascular permeability after VEGFR-2 blockade

Direction: ABOLISHED

Interpretation: Removing VEGFR-2 activity prevents the permeability rise, establishing necessity rather than association.

Show evidence (1 reference)

PMID:16901966 SUPPORT Model Organism

"We previously demonstrated in an OHSS rodent model that increased VP was prevented by inactivating VEGFR-2 with a receptor antagonist (SU5416)."

The blockade readout.

Ovarian VEGFR-2 phosphorylation under low-dose cabergoline

Direction: DECREASED

Interpretation: Partial dephosphorylation is enough to abolish the permeability response while sparing luteal angiogenesis, which is the dose-separation result the whole therapeutic strategy depends on.

Show evidence (1 reference)

PMID:16901966 SUPPORT Model Organism

"A 100 microg/kg low-dose Dp-r2 agonist cabergoline reversed VEGFR-2-dependent VP without affecting luteal angiogenesis through partial inhibition of ovarian VEGFR-2 phosphorylation levels."

The dose-separation readout.

Serum progesterone and luteal apoptosis under cabergoline

Direction: UNCHANGED

Interpretation: A deliberate negative result: the corpus luteum is not damaged at the effective dose, which is what makes the intervention compatible with an ongoing pregnancy.

Show evidence (1 reference)

PMID:16901966 SUPPORT Model Organism

"No luteolytic effects (serum progesterone levels and luteal apoptosis unaffected) were observed."

The negative readout establishing luteal safety at the effective dose.

Show evidence (1 reference)

PMID:16901966 SUPPORT Model Organism

"To test whether VEGFR-2-dependent VP and angiogenesis could be segregated in a dose-dependent fashion with the Dp-r2 agonist cabergoline, a well-established OHSS rat model supplemented with prolactin was used."

Names the model and the question it was built to answer.

{ }

Source YAML

click to show

name: Ovarian Hyperstimulation Syndrome
creation_date: "2026-08-25T00:00:00Z"
description: >-
  Ovarian hyperstimulation syndrome (OHSS) is a systemic capillary-leak illness
  that follows excessive stimulation of the ovarian follicle. Its defining
  lesion is not the ovary itself but what the hyperstimulated ovary secretes:
  luteinized granulosa cells hypersecrete vascular endothelial growth factor,
  which activates VEGF receptor 2 on vascular endothelium and raises vascular
  permeability throughout the body. Fluid moves from the intravascular
  compartment into the peritoneum and pleura, producing the characteristic
  combination of grossly enlarged multicystic ovaries, ascites, pleural
  effusion, haemoconcentration and intravascular volume depletion, with
  thromboembolism, oliguric renal failure and respiratory failure as the
  dangerous end of the spectrum.

  The syndrome reaches that common pathway by two routes, which is why one
  entry covers both. In the overwhelmingly commoner iatrogenic form it is a
  complication of controlled ovarian stimulation for assisted reproduction:
  exogenous gonadotropins recruit far more follicles than a natural cycle, and
  the human chorionic gonadotropin given to trigger final oocyte maturation
  (or produced by an early pregnancy) drives the VEGF surge. In the rare
  familial gestational spontaneous form, no drug is involved at all —
  activating germline variants in FSHR lower the receptor's ligand specificity
  so that the hCG of a normal first trimester, and in most reported mutants
  also TSH, stimulate the FSH receptor promiscuously. The same promiscuous
  activation of a *wild-type* FSH receptor explains the sporadic spontaneous
  cases seen with multiple or molar pregnancy, hypothyroidism and
  FSH-secreting pituitary adenoma. The distinction matters clinically because
  the iatrogenic form is largely preventable by changing the stimulation
  protocol, whereas the familial form recurs in every pregnancy.
category: Complex
parents:
- Ovarian Disorder
synonyms:
- OHSS
- ovarian hyperstimulation syndrome, familial gestational spontaneous
- familial gestational spontaneous ovarian hyperstimulation syndrome
- spontaneous ovarian hyperstimulation syndrome
- sOHSS
disease_term:
  preferred_term: ovarian hyperstimulation syndrome
  term:
    id: MONDO:0011972
    label: ovarian hyperstimulation syndrome
mappings:
  mondo_mappings:
  - term:
      id: MONDO:0011972
      label: ovarian hyperstimulation syndrome
    mapping_predicate: skos:exactMatch
    mapping_source: MONDO
classifications:
  harrisons_chapter:
  - classification_value: ENDOCRINOLOGY_METABOLISM
    evidence:
    - reference: PMID:15080154
      reference_title: "A mutation in the follicle-stimulating hormone receptor as a cause of familial spontaneous ovarian hyperstimulation syndrome."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        Ovarian hyperstimulation syndrome (OHSS) occurs mainly after excessive
        stimulation of the ovaries by exogenous gonadotropins administrated in
        the context of in vitro fertilization procedures (iatrogenic OHSS).
      explanation: >-
        Places the disorder within reproductive endocrinology: it is defined by
        the response of the ovary to gonadotropin stimulation.
  - classification_value: GENETICS_ENVIRONMENT_DISEASE
    evidence:
    - reference: PMID:15080154
      reference_title: "A mutation in the follicle-stimulating hormone receptor as a cause of familial spontaneous ovarian hyperstimulation syndrome."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        Recently, spontaneous and recurrent occurrence of the disease
        (spontaneous OHSS) was shown in two families to be caused by mutations
        affecting the follitropin receptor (FSHr).
      explanation: >-
        Establishes a single-gene germline basis for the familial form, which is
        why the MONDO concept sits under hereditary disease.
  - classification_value: CRITICAL_CARE
    evidence:
    - reference: PMID:26506672
      reference_title: "Non-invasive ventilation for the treatment of acute respiratory failure following ovarian hyperstimulation syndrome: report of two cases and a brief review of the literature."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        The severe form of OHSS varies between 0.5% and 5%, depending on the
        population studied: intensive care may be required for management of
        tromboembolic complications, renal failure and severe respiratory
        failure.
      explanation: >-
        Documents that the severe end of the spectrum is an intensive-care
        illness.
references:
- reference: PMID:15080154
  title: "A mutation in the follicle-stimulating hormone receptor as a cause of familial spontaneous ovarian hyperstimulation syndrome."
- reference: PMID:17721928
  title: "Identification of the first germline mutation in the extracellular domain of the follitropin receptor responsible for spontaneous ovarian hyperstimulation syndrome."
- reference: PMID:23941020
  title: "Spontaneous ovarian hyperstimulation syndrome."
- reference: PMID:16901966
  title: "Low-dose dopamine agonist administration blocks vascular endothelial growth factor (VEGF)-mediated vascular hyperpermeability without altering VEGF receptor 2-dependent luteal angiogenesis in a rat ovarian hyperstimulation model."
- reference: PMID:27273307
  title: "Pathophysiology, treatment and prevention of ovarian hyperstimulation syndrome."
- reference: PMID:26506672
  title: "Non-invasive ventilation for the treatment of acute respiratory failure following ovarian hyperstimulation syndrome: report of two cases and a brief review of the literature."
- reference: PMID:9240261
  title: "Vascular endothelial growth factor levels in serum and follicular fluid of patients undergoing in vitro fertilization."
- reference: PMID:24848075
  title: "Ovarian stimulation in patients in risk of OHSS."
- reference: PMID:28638367
  title: "GnRH Agonist Trigger and LH Activity Luteal Phase Support versus hCG Trigger and Conventional Luteal Phase Support in Fresh Embryo Transfer IVF/ICSI Cycles-A Systematic PRISMA Review and Meta-analysis."
- reference: PMID:38099867
  title: "Prevention of moderate and severe ovarian hyperstimulation syndrome: a guideline."
- reference: PMID:25495063
  title: "A case of ovarian torsion in a patient carrier of a FSH receptor gene mutation previously affected by spontaneous ovarian hyperstimulation syndrome."
- reference: PMID:34644798
  title: "Ovarian Hyperstimulation: Diagnosis, Prevention, and Management."
- reference: PMID:36588288
  title: "Venous Thromboembolism Associated with Assisted Reproductive Technology: A Systematic Review and Meta-analysis."
- reference: PMID:10785214
  title: "Distinction between early and late ovarian hyperstimulation syndrome."
- reference: PMID:18956797
  title: "Are pregnancy rates compromised following embryo freezing to prevent OHSS?"
- reference: PMID:35154015
  title: "Comparison of the Effectiveness of Various Medicines in the Prevention of Ovarian Hyperstimulation Syndrome: A Network Meta-Analysis of Randomized Controlled Trials."
- reference: PMID:26752241
  title: "Pharmacologic Interventions in Preventing Ovarian Hyperstimulation Syndrome: A Systematic Review and Network Meta-Analysis."
- reference: PMID:35079118
  title: "Tie1 contributes to the development of ovarian hyperstimulation syndrome under the regulation of EGR1 in granulosa cells."
- reference: PMID:38487201
  title: "The Incidence of Moderate and Severe Ovarian Hyperstimulation Syndrome in Hospitalized Patients in China."
- reference: clinicaltrials:NCT03996434
  title: "Coasting Versus Gonadotrophin-Releasing Hormone Antagonist Administration in Patients at High Risk of Ovarian Hyperstimulation Syndrome and Its Impact on the Embryos Quality and the Outcome of ICSI"
- reference: clinicaltrials:NCT02670304
  title: "The Randomized Controlled Trial Study of Letrozole in the Prevention of Medium and Severe Ovarian Hyperstimulation Syndrome in Invitro Fertilization Treatment"
- reference: clinicaltrials:NCT02392520
  title: "GnRH Antagonist in the Luteal Phase Compared to Conventional Treatment in Women With Severe Early Ovarian Hyperstimulation Syndrome (OHSS) in Whom All Embryos Are Cryopreserved"
- reference: clinicaltrials:NCT06333691
  title: "Comparative Study Between Calcium Gluconate With Diosmin, Cabergoline and Cabergoline With Diosmin in Prevention of Ovarian Hyperstimulation Syndrome in High-risk Women Undergoing Intracytoplasmic Sperm Injection (ICSI) Procedures"
- reference: clinicaltrials:NCT03794037
  title: "Montelukast for Prevention & Treatment of Ovarian Hyperstimulation Syndrome in Freeze-all Cycles"
has_subtypes:
- name: Iatrogenic OHSS
  display_name: Iatrogenic OHSS (complication of controlled ovarian stimulation)
  description: >-
    The common form, and effectively the whole clinical burden of the syndrome.
    Exogenous gonadotropins given for assisted reproduction recruit a large
    cohort of follicles, and the hCG used to trigger final oocyte maturation —
    or the endogenous hCG of an implanting pregnancy — drives the VEGF surge
    that produces the capillary leak. Because both the stimulation and the
    trigger are under the clinician's control, this form is substantially
    preventable.
  evidence:
  - reference: PMID:15080154
    reference_title: "A mutation in the follicle-stimulating hormone receptor as a cause of familial spontaneous ovarian hyperstimulation syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Ovarian hyperstimulation syndrome (OHSS) occurs mainly after excessive
      stimulation of the ovaries by exogenous gonadotropins administrated in
      the context of in vitro fertilization procedures (iatrogenic OHSS).
    explanation: >-
      Defines the iatrogenic subtype and states that it accounts for most cases.
- name: Familial Spontaneous OHSS
  display_name: Familial gestational spontaneous OHSS (FSHR-activating)
  description: >-
    A rare autosomal dominant form in which activating germline FSHR variants
    make the FSH receptor respond to hormones it should ignore. Affected women
    develop OHSS during spontaneous pregnancy, typically in the first
    trimester, with no fertility drug involved, and the syndrome recurs in
    successive pregnancies. This is the arm that gives MONDO:0011972 its
    hereditary-disease parent and its FSHR gene association.
  evidence:
  - reference: PMID:23941020
    reference_title: "Spontaneous ovarian hyperstimulation syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Since 2003, only six different activating FSHr gene mutations have been
      reported in cases of familial or habitual sOHSS.
    explanation: >-
      Establishes the familial, FSHR-mutation-defined subtype as a distinct and
      rare entity.
  - reference: PMID:23941020
    reference_title: "Spontaneous ovarian hyperstimulation syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Spontaneous forms of the ovarian hyperstimulation syndrome (sOHSS) are
      nearly always reported between 8 and 14 weeks of pregnancy
    explanation: >-
      Records the gestational timing that defines the spontaneous presentation.
inheritance:
- name: Autosomal dominant inheritance
  inheritance_term:
    preferred_term: Autosomal dominant inheritance
    term:
      id: HP:0000006
      label: Autosomal dominant inheritance
  description: >-
    In the reported families the affected women were heterozygous for a single
    activating FSHR allele, and the phenotype segregated through successive
    pregnancies in more than one family member — the pattern of a dominant
    gain-of-function receptor variant rather than a recessive loss of function.
  evidence:
  - reference: PMID:15080154
    reference_title: "A mutation in the follicle-stimulating hormone receptor as a cause of familial spontaneous ovarian hyperstimulation syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The affected women were heterozygous for a different mutation involving
      codon 449, where an alanine was substituted for threonine.
    explanation: >-
      Documents heterozygosity of the causal allele in the affected women of a
      familial recurrent-OHSS pedigree.
pathophysiology:
- name: Exogenous Gonadotropin Stimulation of the FSH Receptor
  biological_scale: MOLECULAR
  role: trigger
  mechanism_confidence: ESTABLISHED
  subtypes:
  - Iatrogenic OHSS
  description: >-
    The iatrogenic entry point. Controlled ovarian stimulation delivers
    gonadotropin at doses far above the physiological mid-follicular range, so
    the FSH receptor on granulosa cells is occupied well beyond what a natural
    cycle achieves and the normal selection of a single dominant follicle is
    overridden. Nothing about the receptor is abnormal here — the ligand supply
    is.
  biological_processes:
  - preferred_term: follicle-stimulating hormone signaling pathway
    modifier: INCREASED
    term:
      id: GO:0042699
      label: follicle-stimulating hormone signaling pathway
  cell_types:
  - preferred_term: Granulosa cell
    term:
      id: CL:0000501
      label: granulosa cell
  evidence:
  - reference: PMID:15080154
    reference_title: "A mutation in the follicle-stimulating hormone receptor as a cause of familial spontaneous ovarian hyperstimulation syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Ovarian hyperstimulation syndrome (OHSS) occurs mainly after excessive
      stimulation of the ovaries by exogenous gonadotropins administrated in
      the context of in vitro fertilization procedures (iatrogenic OHSS).
    explanation: >-
      States that excessive gonadotropin stimulation of the ovary is the
      initiating event in the common form of the syndrome.
  downstream:
  - target: Multifollicular Recruitment
    causal_link_type: DIRECT
    description: >-
      Supraphysiological FSH receptor occupancy rescues follicles that would
      normally undergo atresia, producing a large synchronous cohort.
- name: Promiscuous FSH Receptor Activation by hCG or TSH
  biological_scale: MOLECULAR
  role: trigger
  mechanism_confidence: ESTABLISHED
  subtypes:
  - Familial Spontaneous OHSS
  description: >-
    The hereditary entry point, and the reason MONDO:0011972 carries an FSHR
    gene association. The glycoprotein hormone receptors share a common
    architecture, and their ligand specificity is maintained by an
    intramolecular activation barrier rather than by binding affinity alone.
    Activating germline FSHR variants lower that barrier: the receptor becomes
    abnormally sensitive to hCG, in most reported mutants also to TSH, and
    shows ligand-independent basal activity. The consequence is that the hCG of
    an ordinary first trimester stimulates the FSH receptor as though it were
    FSH. The p.Ser128Tyr allele in the extracellular domain is the mechanistic
    exception that proves the rule — it raises hCG affinity without conferring
    constitutive activity or TSH responsiveness, so more than one molecular
    route reaches the same phenotype.
  genes:
  - preferred_term: FSHR
    term:
      id: hgnc:3969
      label: FSHR
  genetic_context:
    functional_impact_category: GAIN_OF_FUNCTION
    variant_origin: GERMLINE
    zygosity: HETEROZYGOUS
    description: >-
      Heterozygous germline missense variants in FSHR. Reported alleles include
      p.Thr449Ile, p.Thr449Ala, p.Asp567Asn, p.Asp567Gly and p.Ile545Thr in the
      transmembrane helices, and p.Ser128Tyr in the extracellular domain.
  biological_processes:
  - preferred_term: follicle-stimulating hormone signaling pathway
    modifier: GAIN_OF_FUNCTION
    term:
      id: GO:0042699
      label: follicle-stimulating hormone signaling pathway
  evidence:
  - reference: PMID:15080154
    reference_title: "A mutation in the follicle-stimulating hormone receptor as a cause of familial spontaneous ovarian hyperstimulation syndrome."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      The two mutant FSHr (T449I, D567N) harbor aminoacid substitutions in the
      serpentine portion of the receptor and display abnormally high
      sensitivity to the pregnancy hormone hCG, thus providing a satisfactory
      explanation to the phenotype.
    explanation: >-
      Demonstrates in transfected cells that the causal variants confer
      abnormal hCG sensitivity, the mechanism of the spontaneous form.
  - reference: PMID:15080154
    reference_title: "A mutation in the follicle-stimulating hormone receptor as a cause of familial spontaneous ovarian hyperstimulation syndrome."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      Similar to D567N, the T449A FSHr mutant shows an increase of its
      sensitivity to both hCG and TSH, together with an increase in basal
      activity.
    explanation: >-
      Records the additional TSH cross-reactivity and constitutive activity of
      the serpentine-domain mutants.
  - reference: PMID:17721928
    reference_title: "Identification of the first germline mutation in the extracellular domain of the follitropin receptor responsible for spontaneous ovarian hyperstimulation syndrome."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      This loss of ligand specificity was attributed to the lowering of an
      intramolecular barrier of activation rather than to an increase of
      binding affinity.
    explanation: >-
      Gives the biophysical mechanism by which the serpentine-domain variants
      abolish ligand specificity.
  - reference: PMID:17721928
    reference_title: "Identification of the first germline mutation in the extracellular domain of the follitropin receptor responsible for spontaneous ovarian hyperstimulation syndrome."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      Contrary to the mutations described previously, the p.Ser128Tyr FSHR
      mutant displayed increase in affinity and sensitivity toward hCG and did
      not show any constitutive activity, nor promiscuous activation by TSH.
    explanation: >-
      Qualifies the node: one causal allele acts by raised hCG affinity alone,
      so neither constitutive activity nor TSH responsiveness is required.
  - reference: PMID:23941020
    reference_title: "Spontaneous ovarian hyperstimulation syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Accordingly, the mutated FSHrs, may be hyperstimulated by the
      pregnancy-derived hCG or TSH, inducing the occurrence of the syndrome.
    explanation: >-
      Links the receptor lesion to the gestational trigger that precipitates
      the clinical syndrome.
  downstream:
  - target: Multifollicular Recruitment
    causal_link_type: DIRECT
    description: >-
      hCG or TSH acting on the mutant FSH receptor reproduces the follicular
      recruitment that exogenous gonadotropin produces in the iatrogenic form.
    evidence:
    - reference: PMID:15080154
      reference_title: "A mutation in the follicle-stimulating hormone receptor as a cause of familial spontaneous ovarian hyperstimulation syndrome."
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: >-
        Together with the two previous studies, this report shows that
        inappropriate stimulation of the FSHr by hCG is a cause of spontaneous
        OHSS.
      explanation: >-
        States that inappropriate FSH receptor stimulation by hCG is causal for
        the syndrome, which is the claim of this edge.
- name: Promiscuous Activation of the Wild-Type FSH Receptor
  biological_scale: MOLECULAR
  role: trigger
  mechanism_confidence: ESTABLISHED
  description: >-
    A third, non-genetic and non-iatrogenic entry point that the same receptor
    biology predicts. The wild-type FSH receptor is not perfectly specific
    either; it is simply that the physiological concentrations of hCG and TSH
    never reach the threshold at which cross-activation matters. When they do —
    the very high hCG of a multiple or hydatidiform-molar pregnancy, the very
    high TSH of untreated hypothyroidism, or autonomous FSH secretion from a
    pituitary adenoma — the syndrome can occur sporadically in a woman with a
    normal FSHR. This is why an FSHR variant should not be assumed in every
    spontaneous case.
  biological_processes:
  - preferred_term: follicle-stimulating hormone signaling pathway
    modifier: INCREASED
    term:
      id: GO:0042699
      label: follicle-stimulating hormone signaling pathway
  evidence:
  - reference: PMID:23941020
    reference_title: "Spontaneous ovarian hyperstimulation syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The syndrome has been previously reported in rare instances of increased
      production of human chorionic gonadotrophin (hCG) such as multiple
      pregnancies, hydatiforme mole, polycystic ovary disease and elevated
      concentrations of thyroid-stimulating hormone (TSH) in hypothyreoidism.
    explanation: >-
      Enumerates the clinical settings in which excess hCG or TSH precipitates
      the syndrome without a fertility drug.
  - reference: PMID:23941020
    reference_title: "Spontaneous ovarian hyperstimulation syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      High levels of these hormones are able to stimulate by natural
      promiscuous activation the wild-type FSHr, resulting in sporadic
      presentations of the syndrome.
    explanation: >-
      States explicitly that a normal FSH receptor can be cross-activated when
      ligand concentrations are high enough.
  downstream:
  - target: Multifollicular Recruitment
    causal_link_type: DIRECT
    description: >-
      Cross-activation of the normal receptor drives the same follicular
      response as the mutant receptor does.
- name: Multifollicular Recruitment
  biological_scale: TISSUE
  role: central_effector
  mechanism_confidence: ESTABLISHED
  description: >-
    The FSH-driven half of the ovarian response, and the step that sets the size
    of the problem. Sustained FSH receptor signalling rescues from atresia a
    large cohort of antral follicles that a natural cycle would have discarded
    in favour of one dominant follicle. Nothing pathological has happened yet -
    this is the intended effect of controlled ovarian stimulation, and an
    exaggerated version of it in the spontaneous forms. Follicle number and
    oestradiol level predict OHSS risk precisely because they measure this node,
    which is why it and not the later steps is what protocol individualisation,
    anti-Mullerian hormone and antral follicle count are aimed at.
  biological_processes:
  - preferred_term: ovarian follicle development
    modifier: INCREASED
    term:
      id: GO:0001541
      label: ovarian follicle development
  cell_types:
  - preferred_term: Granulosa cell
    term:
      id: CL:0000501
      label: granulosa cell
  evidence:
  - reference: PMID:24848075
    reference_title: "Ovarian stimulation in patients in risk of OHSS."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Ovarian hyperstimulation syndrome (OHSS) represents an exaggerated
      response to controlled ovarian stimulation (COS) that in some cases could
      be life-threatening.
    explanation: >-
      Frames the follicular response as an exaggerated version of the intended
      one rather than a qualitatively different process.
  - reference: PMID:24848075
    reference_title: "Ovarian stimulation in patients in risk of OHSS."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      In recent years research has focus on identifying biomarkers/hormonal
      markers that could represent potential predictors of OHSS
      (anti-Mullerian hormone and antral follicle count).
    explanation: >-
      Records that the predictive markers used clinically are measurements of
      the recruitable follicle pool - that is, of this node.
  downstream:
  - target: hCG-Driven Luteinization of the Recruited Cohort
    causal_link_type: DIRECT
    description: >-
      The recruited cohort is the substrate the LH-like signal acts on; without
      multifollicular recruitment there is nothing to luteinize en masse.
  - target: Ovarian Enlargement and Multicystic Change
    causal_link_type: DIRECT
    description: >-
      Many simultaneously recruited follicles enlarge the ovary mechanically.
- name: hCG-Driven Luteinization of the Recruited Cohort
  biological_scale: TISSUE
  role: central_effector
  mechanism_confidence: ESTABLISHED
  genes:
  - preferred_term: LHCGR
    term:
      id: hgnc:6585
      label: LHCGR
  description: >-
    The hCG-dependent half, separated from recruitment because the two have
    different triggers, different timing and different therapeutic handles.
    Exposure to an LH-like signal - the hCG trigger, or the endogenous hCG of an
    implanting pregnancy - luteinizes the whole recruited cohort at once, so the
    ovary comes to contain many simultaneously luteinized follicles instead of
    one corpus luteum. That expanded mass of luteinized granulosa tissue is the
    secretory organ of the syndrome.

    This node, not recruitment, is what the preventive substitution of a GnRH
    agonist for hCG removes: the follicles are still recruited, but the
    long-acting luteinizing stimulus is replaced by a short endogenous LH surge.
    Keeping it distinct is what lets that treatment be linked where it actually
    acts.
  biological_processes:
  - preferred_term: luteinization
    modifier: INCREASED
    term:
      id: GO:0001553
      label: luteinization
  cell_types:
  - preferred_term: Luteinized granulosa cell
    term:
      id: CL:0000501
      label: granulosa cell
  evidence:
  - reference: PMID:9240261
    reference_title: "Vascular endothelial growth factor levels in serum and follicular fluid of patients undergoing in vitro fertilization."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      In patients undergoing IVF, FF VEGF levels at the time of egg retrieval
      correlated with the degree of follicular luteinization.
    explanation: >-
      Ties VEGF output to the extent of luteinization specifically, which is the
      link this node carries downstream.
  - reference: PMID:28638367
    reference_title: "GnRH Agonist Trigger and LH Activity Luteal Phase Support versus hCG Trigger and Conventional Luteal Phase Support in Fresh Embryo Transfer IVF/ICSI Cycles-A Systematic PRISMA Review and Meta-analysis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The use of GnRH agonist (GnRHa) for final oocyte maturation trigger in
      oocyte donation and elective frozen embryo transfer cycles is well
      established due to lower ovarian hyperstimulation syndrome (OHSS) rates as
      compared to hCG trigger.
    explanation: >-
      Replacing the luteinizing stimulus lowers OHSS rates, which is the
      interventional evidence that this node is a required step.
  downstream:
  - target: EGR1-TIE1 Amplification of Granulosa VEGF Output
    causal_link_type: DIRECT
    description: >-
      The luteinized granulosa cells are the cells in which hCG raises EGR1 and
      Tie1; without that expanded luteinized compartment there is nothing for
      the proposed amplifier to act in.
  - target: Ovarian Renin-Angiotensin System Activation
    causal_link_type: DIRECT
    description: >-
      Gonadotropin stimulation raises prorenin and renin in follicular fluid, so
      the expanded stimulated follicular compartment is where the intra-ovarian
      renin-angiotensin system is activated.
    evidence:
    - reference: PMID:26752241
      reference_title: "Pharmacologic Interventions in Preventing Ovarian Hyperstimulation Syndrome: A Systematic Review and Network Meta-Analysis."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        As far back as 1987, there was evidence that a significantly higher level
        of prerenin and renin were in the ovarian follicular fluid of
        Gn-stimulated ovaries compared with ovaries without Gn stimulation
      explanation: >-
        Ties intra-ovarian renin elevation specifically to gonadotropin
        stimulation, which is the edge this asserts.
  - target: Ovarian VEGF Hypersecretion
    causal_link_type: DIRECT
    description: >-
      The enlarged mass of luteinized granulosa tissue is the source of the VEGF
      surge.
    evidence:
    - reference: PMID:9240261
      reference_title: "Vascular endothelial growth factor levels in serum and follicular fluid of patients undergoing in vitro fertilization."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        In patients undergoing IVF, FF VEGF levels at the time of egg retrieval
        correlated with the degree of follicular luteinization.
      explanation: >-
        Quantitatively ties VEGF output to the extent of luteinization, the
        dependence this edge asserts.
- name: Ovarian VEGF Hypersecretion
  biological_scale: MOLECULAR
  role: central_effector
  mechanism_confidence: ESTABLISHED
  description: >-
    Luteinized granulosa cells secrete vascular endothelial growth factor, and
    hCG is the strongest stimulus for that secretion — which is why the
    syndrome follows the trigger injection or the rise of endogenous hCG rather
    than the stimulation itself, and why it has an early and a late phase. In a
    hyperstimulated ovary the output is large enough to raise circulating VEGF,
    so a local ovarian signal becomes a systemic one. Serum VEGF measured
    serially in a woman hospitalised with severe OHSS rose and fell with her
    symptoms.
  biological_processes:
  - preferred_term: vascular endothelial growth factor production
    modifier: INCREASED
    term:
      id: GO:0010573
      label: vascular endothelial growth factor production
  cell_types:
  - preferred_term: Luteal cell
    term:
      id: CL:0000175
      label: luteal cell
  evidence:
  - reference: PMID:16901966
    reference_title: "Low-dose dopamine agonist administration blocks vascular endothelial growth factor (VEGF)-mediated vascular hyperpermeability without altering VEGF receptor 2-dependent luteal angiogenesis in a rat ovarian hyperstimulation model."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: >-
      OHSS is caused by increased vascular permeability (VP) through ovarian
      hypersecretion of vascular endothelial growth factor (VEGF)-activating
      VEGF receptor 2 (VEGFR-2).
    explanation: >-
      States the ovarian hypersecretion step and its receptor target in a
      single sentence; this is the canonical mechanistic statement for the
      syndrome.
  - reference: PMID:9240261
    reference_title: "Vascular endothelial growth factor levels in serum and follicular fluid of patients undergoing in vitro fertilization."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      There is a significant ovarian contribution to circulating VEGF levels
      during early gestation.
    explanation: >-
      Establishes in humans that the stimulated ovary raises systemic VEGF, the
      step that converts a local signal into a systemic illness.
  - reference: PMID:9240261
    reference_title: "Vascular endothelial growth factor levels in serum and follicular fluid of patients undergoing in vitro fertilization."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Elevated serum VEGF levels in a patient with severe OHSS coincided with
      the clinical onset and recurrence of symptoms.
    explanation: >-
      Human temporal correlation between circulating VEGF and the clinical
      course, including its recurrence.
  downstream:
  - target: VEGFR-2 Activation on Vascular Endothelium
    causal_link_type: DIRECT
    description: >-
      Circulating VEGF-A acts on VEGF receptor 2 borne by vascular endothelium.
    evidence:
    - reference: PMID:16901966
      reference_title: "Low-dose dopamine agonist administration blocks vascular endothelial growth factor (VEGF)-mediated vascular hyperpermeability without altering VEGF receptor 2-dependent luteal angiogenesis in a rat ovarian hyperstimulation model."
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: >-
        OHSS is caused by increased vascular permeability (VP) through ovarian
        hypersecretion of vascular endothelial growth factor (VEGF)-activating
        VEGF receptor 2 (VEGFR-2).
      explanation: >-
        States the ovarian-VEGF-to-VEGFR-2 step as the causal link this edge
        asserts.
- name: Ovarian Renin-Angiotensin System Activation
  biological_scale: MOLECULAR
  role: modifier
  mechanism_confidence: PROVISIONAL
  description: >-
    A second proposed route from the stimulated ovary to VEGF, running in
    parallel with the direct hCG-driven secretion rather than replacing it. The
    stimulated ovary contains its own renin-angiotensin system: prorenin and
    renin were reported in the follicular fluid of gonadotropin-stimulated
    ovaries at significantly higher levels than in unstimulated ovaries as far
    back as 1987. Renin secretion is cyclic-AMP-stimulated, and the resulting
    angiotensin signalling is proposed to raise VEGF expression in human
    luteinized granulosa cells.

    Its practical importance is that it is the only mechanistic account of why
    intravenous calcium - the agent that ranks ABOVE cabergoline in both network
    meta-analyses of OHSS prophylaxis - should work at all: calcium is proposed
    to inhibit cAMP-stimulated renin secretion and so reduce VEGF.

    Curated as a modifier rather than a required step, and as PROVISIONAL. The
    two sources that describe the calcium mechanism hedge it in their own wording
    ("could be by inhibiting"), and no primary demonstration in an OHSS cohort is
    cited anywhere in this entry's reference set. A third source in the reference
    set is notably NOT hedged - PMID:18956797 calls the ovarian RAS "clearly
    central to the pathogenesis" - but it asserts that in a single background
    sentence without supporting data of its own, so it is curated as PARTIAL and
    does not by itself lift the node above PROVISIONAL. Recording both is the
    point: the disagreement about how settled this mechanism is exists in the
    literature, not just in this entry.

    A note on the process term. This node is deliberately left with a free-text
    `preferred_term` and NO `term:` binding. The obvious candidate, GO:0002001
    "renin secretion into blood stream", is defined as release of renin into the
    blood by JUXTAGLOMERULAR cells - a systemic, kidney-specific process. What is
    modelled here is local, intra-ovarian renin acting on granulosa cells, so
    that term would contradict both the compartment and the cell type recorded in
    the same node. GO has a precedent for a local RAS (GO:0002035, brain
    renin-angiotensin system) but no ovarian analogue, which makes this a
    legitimate new-term request rather than a gap in the search. No term beats a
    bad one.
  biological_processes:
  - preferred_term: intra-ovarian renin secretion
    modifier: INCREASED
  cell_types:
  - preferred_term: Luteinized granulosa cell
    term:
      id: CL:0000501
      label: granulosa cell
  evidence:
  - reference: PMID:26752241
    reference_title: "Pharmacologic Interventions in Preventing Ovarian Hyperstimulation Syndrome: A Systematic Review and Network Meta-Analysis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      As far back as 1987, there was evidence that a significantly higher level
      of prerenin and renin were in the ovarian follicular fluid of
      Gn-stimulated ovaries compared with ovaries without Gn stimulation
    explanation: >-
      The measured observation the whole proposal rests on: gonadotropin
      stimulation raises intra-ovarian renin.
  - reference: PMID:35154015
    reference_title: "Comparison of the Effectiveness of Various Medicines in the Prevention of Ovarian Hyperstimulation Syndrome: A Network Meta-Analysis of Randomized Controlled Trials."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The possible underlying mechanism of calcium preventing OHSS could be by
      inhibiting cyclic adenosine monophosphate-stimulated renin secretion,
      which reduces the production of angiotensin-converting enzyme II
    explanation: >-
      The proposed chain from calcium through cAMP-stimulated renin secretion to
      ACE, quoted with the authors' own hedge intact - which is why this node is
      PROVISIONAL.
  - reference: PMID:35154015
    reference_title: "Comparison of the Effectiveness of Various Medicines in the Prevention of Ovarian Hyperstimulation Syndrome: A Network Meta-Analysis of Randomized Controlled Trials."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      This subsequently reduces VEGF expression in human luteinized granulosa
      cells
    explanation: >-
      Closes the proposed chain onto VEGF in the cell type this entry already
      identifies as the source of the surge.
  - reference: PMID:18956797
    reference_title: "Are pregnancy rates compromised following embryo freezing to prevent OHSS?"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The exact pathogenesis of OHSS is still not fully understood but the
      involvement of cytokines, particularly vascular endothelial growth factor
      (VEGF), and the ovarian reninangiotensin system (RAS) are clearly central
      to the pathogenesis of the condition
    explanation: >-
      An UNHEDGED statement placing the ovarian RAS centrally in pathogenesis,
      recorded to balance the two hedged mechanism sources. It is PARTIAL rather
      than SUPPORT because it is a background assertion in a paper about embryo
      freezing, with no supporting data of its own. (The cached text reads
      "reninangiotensin" - the hyphen is lost in extraction - and is quoted
      exactly as cached.)
  downstream:
  - target: Ovarian VEGF Hypersecretion
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    description: >-
      Angiotensin signalling is proposed to raise VEGF expression in luteinized
      granulosa cells, adding to the hCG-driven secretion rather than replacing
      it. Curated as INDIRECT_KNOWN_INTERMEDIATES because the angiotensin and ACE
      steps are named but proposed rather than demonstrated in this disease.
    evidence:
    - reference: PMID:26752241
      reference_title: "Pharmacologic Interventions in Preventing Ovarian Hyperstimulation Syndrome: A Systematic Review and Network Meta-Analysis."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        IV calcium is a relatively new method for preventing severe OHSS from
        occurring by inhibiting the renin-angiotensin system (RAS) and,
        consequently, reducing VEGF concentration.
      explanation: >-
        States the renin-angiotensin-to-VEGF link that this edge asserts, in the
        context of the intervention that exploits it.
- name: EGR1-TIE1 Amplification of Granulosa VEGF Output
  biological_scale: MOLECULAR
  role: modifier
  mechanism_confidence: PROVISIONAL
  description: >-
    A proposed amplifier sitting between the hCG signal and the VEGF surge,
    and the most substantial recent addition to the mechanism. Tie1 is an
    endothelial receptor tyrosine kinase, but it is also expressed in granulosa
    cells, where hCG raises it through PI3K/AKT signalling and through EGR1
    binding directly to the Tie1 promoter. The functional claim is the
    informative one: silencing Tie1 abolished the hCG-induced rise in VEGF in a
    human granulosa-lutein cell line and attenuated OHSS in rats. If that holds
    in humans it identifies a target upstream of VEGF itself, which would avoid
    the problem that blocking VEGFR-2 also blocks the angiogenesis a pregnancy
    needs. It is curated as PROVISIONAL and as a modifier rather than a
    required step because the evidence is entirely from patient-derived
    cultured cells, a granulosa-lutein cell line and a rat model; the authors
    state explicitly that clinical relevance is not yet addressed.
  genes:
  - preferred_term: TIE1
    term:
      id: hgnc:11809
      label: TIE1
  - preferred_term: EGR1
    term:
      id: hgnc:3238
      label: EGR1
  biological_processes:
  - preferred_term: phosphatidylinositol 3-kinase/protein kinase B signal transduction
    modifier: INCREASED
    term:
      id: GO:0043491
      label: phosphatidylinositol 3-kinase/protein kinase B signal transduction
  cell_types:
  - preferred_term: Granulosa-lutein cell
    term:
      id: CL:0000501
      label: granulosa cell
  evidence:
  - reference: PMID:35079118
    reference_title: "Tie1 contributes to the development of ovarian hyperstimulation syndrome under the regulation of EGR1 in granulosa cells."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      Here, we report significantly increased Tie1 and vascular endothelial
      growth factor (VEGF) expression in cultured granulosa cells from OHSS
      patients, as well as ovaries from rats with experimentally established
      OHSS, compared to controls
    explanation: >-
      Establishes the association of Tie1 with VEGF in patient-derived
      granulosa cells and in the rat model.
  - reference: PMID:35079118
    reference_title: "Tie1 contributes to the development of ovarian hyperstimulation syndrome under the regulation of EGR1 in granulosa cells."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      Tie1 silencing abolished the hCG-induced VEGF level in SVOG cells and
      attenuated the progression of OHSS in rats, as determined by histological
      analysis.
    explanation: >-
      The loss-of-function result that makes Tie1 a candidate required step
      between hCG and VEGF rather than a correlate.
  - reference: PMID:35079118
    reference_title: "Tie1 contributes to the development of ovarian hyperstimulation syndrome under the regulation of EGR1 in granulosa cells."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      We also report that early growth response protein 1 (EGR1), whose
      expression was also upregulated by hCG, bound directly to the Tie1
      promoter and activated its transcription.
    explanation: >-
      Identifies the transcriptional mechanism by which hCG raises Tie1.
  - reference: PMID:35079118
    reference_title: "Tie1 contributes to the development of ovarian hyperstimulation syndrome under the regulation of EGR1 in granulosa cells."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      Taken together, our results indicate that Tie1 may be a therapeutic
      target in cases of moderate-to-severe OHSS. Further studies are needed to
      address its clinical relevance.
    explanation: >-
      The authors' own statement that clinical relevance is unresolved, which is
      why this node is curated as provisional.
  downstream:
  - target: Ovarian VEGF Hypersecretion
    causal_link_type: DIRECT
    description: >-
      hCG-driven EGR1-Tie1 induction is proposed to be required for the
      hCG-induced rise in granulosa VEGF output.
- name: VEGFR-2 Activation on Vascular Endothelium
  biological_scale: MOLECULAR
  role: central_effector
  mechanism_confidence: ESTABLISHED
  description: >-
    The receptor-level step, and the point every effective therapy acts on.
    Circulating VEGF-A binds VEGF receptor 2 on vascular endothelium and
    triggers its phosphorylation. Two experiments in the rodent model make this
    causal rather than correlative: blocking VEGFR-2 with the antagonist SU5416
    prevents the downstream permeability rise, and a low dose of the dopamine
    agonist cabergoline reverses it by partially dephosphorylating ovarian
    VEGFR-2.

    The therapeutic problem lives entirely at this node rather than downstream
    of it, which is why it is worth separating: the same receptor also drives
    the luteal angiogenesis a pregnancy needs, so the task is dose-separating
    two functions of one receptor, not blocking it.
  biological_processes:
  - preferred_term: vascular endothelial growth factor receptor-2 signaling pathway
    modifier: INCREASED
    term:
      id: GO:0036324
      label: vascular endothelial growth factor receptor-2 signaling pathway
  cell_types:
  - preferred_term: Vascular endothelial cell
    term:
      id: CL:0002139
      label: endothelial cell of vascular tree
  evidence:
  - reference: PMID:16901966
    reference_title: "Low-dose dopamine agonist administration blocks vascular endothelial growth factor (VEGF)-mediated vascular hyperpermeability without altering VEGF receptor 2-dependent luteal angiogenesis in a rat ovarian hyperstimulation model."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: >-
      OHSS is caused by increased vascular permeability (VP) through ovarian
      hypersecretion of vascular endothelial growth factor (VEGF)-activating
      VEGF receptor 2 (VEGFR-2).
    explanation: >-
      Names VEGFR-2 as the receptor the ovarian VEGF surge acts on.
  - reference: PMID:16901966
    reference_title: "Low-dose dopamine agonist administration blocks vascular endothelial growth factor (VEGF)-mediated vascular hyperpermeability without altering VEGF receptor 2-dependent luteal angiogenesis in a rat ovarian hyperstimulation model."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: >-
      A 100 microg/kg low-dose Dp-r2 agonist cabergoline reversed
      VEGFR-2-dependent VP without affecting luteal angiogenesis through
      partial inhibition of ovarian VEGFR-2 phosphorylation levels.
    explanation: >-
      Identifies VEGFR-2 phosphorylation as the modifiable molecular event and
      shows the permeability and angiogenic functions can be pharmacologically
      separated.
  downstream:
  - target: Increased Systemic Vascular Permeability
    causal_link_type: DIRECT
    description: >-
      VEGFR-2 signalling in endothelium loosens inter-endothelial junctions and
      raises permeability to protein and water.
    evidence:
    - reference: PMID:16901966
      reference_title: "Low-dose dopamine agonist administration blocks vascular endothelial growth factor (VEGF)-mediated vascular hyperpermeability without altering VEGF receptor 2-dependent luteal angiogenesis in a rat ovarian hyperstimulation model."
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: >-
        We previously demonstrated in an OHSS rodent model that increased VP was
        prevented by inactivating VEGFR-2 with a receptor antagonist (SU5416).
      explanation: >-
        Blocking the receptor abolishes the permeability rise, which is the
        interventional evidence that this edge is causal.
- name: Increased Systemic Vascular Permeability
  biological_scale: TISSUE
  role: central_effector
  mechanism_confidence: ESTABLISHED
  description: >-
    The endothelial-barrier consequence: capillary beds throughout the body,
    not only in the ovary, become permeable to protein and water. That the
    permeability is systemic rather than local is the whole reason an ovarian
    problem produces pleural effusion, renal hypoperfusion and thrombosis, and
    it is why the syndrome is a capillary-leak illness rather than a
    gynaecological one.

    The mediator is not regarded as settled. VEGF is the leading candidate and
    the only one with interventional evidence, but a clinical review is explicit
    that the pathophysiology is incompletely understood, and an
    anti-Mullerian-hormone/dendritic-cell/interleukin arm has been proposed
    alongside it.
  biological_processes:
  - preferred_term: positive regulation of vascular permeability
    modifier: INCREASED
    term:
      id: GO:0043117
      label: positive regulation of vascular permeability
  cell_types:
  - preferred_term: Vascular endothelial cell
    term:
      id: CL:0002139
      label: endothelial cell of vascular tree
  evidence:
  - reference: PMID:34644798
    reference_title: "Ovarian Hyperstimulation: Diagnosis, Prevention, and Management."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Pathogenesis of the disease is based on massive transudation of
      protein-rich fluid from the vascular compartment into the peritoneal,
      pleural and pericardial spaces, with a variable picture of clinical
      manifestations depending on its severity.
    explanation: >-
      States that the barrier failure is systemic and names the three
      compartments the fluid enters.
  - reference: PMID:27273307
    reference_title: "Pathophysiology, treatment and prevention of ovarian hyperstimulation syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The pathophysiology is still not completely understood; however, vascular
      endothelial growth factor is likely to be an important mediator.
    explanation: >-
      A deliberate hedge from a clinical review: VEGF is the leading mediator
      but the human pathophysiology is not regarded as closed.
  - reference: PMID:27273307
    reference_title: "Pathophysiology, treatment and prevention of ovarian hyperstimulation syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The contribution of an attenuated anti-Mullerian hormone signalling
      pathway and CD11c + HLA-DR + dendritic cells and associated interleukins
      has been explored recently as contributors to pathogenesis.
    explanation: >-
      Records the proposed non-VEGF contributors, which is why this node is not
      curated as a pure VEGF effect.
  downstream:
  - target: Third-Space Fluid Shift and Intravascular Volume Depletion
    causal_link_type: DIRECT
    description: >-
      A permeable capillary bed cannot retain protein-rich fluid, which moves
      down its gradient into the peritoneal and pleural spaces.
- name: Ovarian Enlargement and Multicystic Change
  biological_scale: TISSUE
  role: consequence
  mechanism_confidence: ESTABLISHED
  description: >-
    The ovarian finding that names the syndrome and is what bedside ultrasound
    sees. Many simultaneously luteinized follicles and their retained fluid
    enlarge the ovaries, sometimes to many times normal volume. The clinical
    hazard of this node is mechanical rather than haemodynamic: a heavy,
    enlarged ovary can undergo adnexal torsion and infarct, which has been
    reported even outside pregnancy in a woman carrying an activating FSHR
    variant.
  evidence:
  - reference: PMID:26506672
    reference_title: "Non-invasive ventilation for the treatment of acute respiratory failure following ovarian hyperstimulation syndrome: report of two cases and a brief review of the literature."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The diagnosis of severe OHSS was made, largely based on bedside
      ultrasonography showing increased ovarian size, mild ascites and
      bilateral pleural effusions.
    explanation: >-
      Documents ovarian enlargement as an imaging feature used to make the
      diagnosis.
  - reference: PMID:25495063
    reference_title: "A case of ovarian torsion in a patient carrier of a FSH receptor gene mutation previously affected by spontaneous ovarian hyperstimulation syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      In few days, she developed severe pelvic pain and ultrasonographic
      evidence of increased ovarian volume.
    explanation: >-
      Records ovarian enlargement preceding the torsion complication in an FSHR
      variant carrier.
  downstream:
  - target: Adnexal Torsion and Ovarian Infarction
    causal_link_type: DIRECT
    description: >-
      An enlarged, heavy ovary is mechanically predisposed to twist on its
      vascular pedicle.
- name: Adnexal Torsion and Ovarian Infarction
  biological_scale: TISSUE
  role: consequence
  mechanism_confidence: PROVISIONAL
  description: >-
    A surgical complication of the enlarged ovary, distinct from the
    capillary-leak arm of the disease and not dependent on it. It is presented
    here as provisional because the direct evidence is a single reported case
    in an FSHR variant carrier rather than a series; the general association
    between ovarian enlargement and torsion is not in dispute, but its
    frequency in OHSS specifically is not quantified in the cited literature.
    The case is instructive for a second reason: it occurred while the woman
    was neither pregnant nor receiving fertility treatment, showing that the
    ovarian risk of an activating FSHR allele is not confined to gestation.
  evidence:
  - reference: PMID:25495063
    reference_title: "A case of ovarian torsion in a patient carrier of a FSH receptor gene mutation previously affected by spontaneous ovarian hyperstimulation syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      She underwent laparoscopy with unilateral adnexectomy for ovarian
      ischemic necrosis due to adnexal torsion.
    explanation: >-
      Documents the torsion-infarction outcome in a woman with prior
      spontaneous OHSS and an FSHR variant.
  - reference: PMID:25495063
    reference_title: "A case of ovarian torsion in a patient carrier of a FSH receptor gene mutation previously affected by spontaneous ovarian hyperstimulation syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Our experience suggests that patients' carrier of a mutation of FSHr gene
      are at risk of ovarian pathologies also when non-pregnant and in the
      presence of low TSH levels.
    explanation: >-
      Supports the caveat that the ovarian risk extends outside pregnancy,
      while making clear this is a suggestion from a single experience.
- name: Third-Space Fluid Shift and Intravascular Volume Depletion
  biological_scale: ORGANISM
  role: consequence
  mechanism_confidence: ESTABLISHED
  description: >-
    The systemic pivot of the illness. Protein-rich fluid leaving the permeable
    vasculature accumulates as ascites and pleural effusion while the
    intravascular compartment is simultaneously depleted, so the patient is
    fluid-overloaded and hypovolaemic at once. That paradox is the whole
    management problem: the visible fluid must not be treated as excess. The
    accompanying picture is rapid weight gain, haemoconcentration,
    leukocytosis, hyponatraemia and hyperkalaemia.
  evidence:
  - reference: PMID:26506672
    reference_title: "Non-invasive ventilation for the treatment of acute respiratory failure following ovarian hyperstimulation syndrome: report of two cases and a brief review of the literature."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Clinical signs may include any or all of the following: rapid weight
      gain, ascites, oliguria, hemoconcentration, leukocytosis, along with
      intravascular hypovolemia, hyponatremia, and hyperkalemia.
    explanation: >-
      Enumerates the third-spacing syndrome, including the simultaneous ascites
      and intravascular hypovolaemia that define it.
  downstream:
  - target: Hypercoagulability and Thromboembolism
    causal_link_type: DIRECT
    description: >-
      Haemoconcentration and reduced flow in a depleted intravascular
      compartment favour thrombus formation.
    evidence:
    - reference: PMID:26506672
      reference_title: "Non-invasive ventilation for the treatment of acute respiratory failure following ovarian hyperstimulation syndrome: report of two cases and a brief review of the literature."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        If the patient is not diagnosed early, ascites, pleural and more rarely
        pericardial effusions, severe respiratory failure and ARDS,
        hypercoagulability with tromboembolism and multiple organ system failure
        can occur.
      explanation: >-
        Places hypercoagulability downstream of the ascitic/third-spacing phase
        in the clinical sequence.
  - target: Renal Hypoperfusion and Oliguria
    causal_link_type: DIRECT
    description: >-
      Reduced effective circulating volume lowers renal perfusion.
  - target: Pleural Effusion and Respiratory Failure
    causal_link_type: DIRECT
    description: >-
      Fluid entering the pleural space, together with a splinted diaphragm from
      tense ascites, compromises gas exchange.
- name: Hypercoagulability and Thromboembolism
  biological_scale: ORGANISM
  role: consequence
  mechanism_confidence: ESTABLISHED
  description: >-
    The complication with the worst reputation in this syndrome, and one worth
    stating carefully. Haemoconcentration from plasma loss into the third space,
    combined with reduced venous return and the prothrombotic state of the
    high-oestrogen luteal phase or early pregnancy, produces venous and
    occasionally arterial thrombosis.

    Thromboprophylaxis is curated as a treatment acting on this node. Note
    though that the risk it addresses is small in absolute terms - venous
    thromboembolism specifically attributable to OHSS has been estimated at
    under 0.001% - and that the increment OHSS adds on top of assisted
    reproduction did not reach statistical significance in a systematic review.
    The practice rests on the severity of the consequence and the low cost of
    the intervention rather than on a demonstrated effect size.
  evidence:
  - reference: PMID:26506672
    reference_title: "Non-invasive ventilation for the treatment of acute respiratory failure following ovarian hyperstimulation syndrome: report of two cases and a brief review of the literature."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      If the patient is not diagnosed early, ascites, pleural and more rarely
      pericardial effusions, severe respiratory failure and ARDS,
      hypercoagulability with tromboembolism and multiple organ system failure
      can occur.
    explanation: >-
      Places hypercoagulability and thromboembolism among the severe
      consequences of untreated third-spacing.
- name: Renal Hypoperfusion and Oliguria
  biological_scale: ORGANISM
  role: consequence
  mechanism_confidence: ESTABLISHED
  description: >-
    Falling effective circulating volume reduces renal perfusion, producing
    oliguria and, at the severe end, acute kidney injury requiring intensive
    care. The kidney here is a bystander reporting the intravascular volume
    state, which is why urine output is used as the bedside index of severity.
  evidence:
  - reference: PMID:26506672
    reference_title: "Non-invasive ventilation for the treatment of acute respiratory failure following ovarian hyperstimulation syndrome: report of two cases and a brief review of the literature."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The severe form of OHSS varies between 0.5% and 5%, depending on the
      population studied: intensive care may be required for management of
      tromboembolic complications, renal failure and severe respiratory
      failure.
    explanation: >-
      Identifies renal failure as one of the intensive-care-level complications
      of the severe syndrome.
- name: Pleural Effusion and Respiratory Failure
  biological_scale: ORGANISM
  role: consequence
  mechanism_confidence: ESTABLISHED
  description: >-
    The other lethal arm. Fluid crossing into the pleural space, with the
    diaphragm splinted by tense ascites, produces hypoxaemic respiratory
    failure that can reach ARDS. In the two reported cases managed with
    non-invasive ventilation the impairment was severe by objective criteria
    (PaO2/FiO2 below 200), which is the level at which the illness stops being
    a gynaecological complication and becomes a respiratory one.
  evidence:
  - reference: PMID:26506672
    reference_title: "Non-invasive ventilation for the treatment of acute respiratory failure following ovarian hyperstimulation syndrome: report of two cases and a brief review of the literature."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      We describe two cases of women with extremely severe OHSS presenting
      bilateral pleural effusions, and severe respiratory failure (paO2/FiO2 <
      200) treated with non-invasive ventilation (NIV).
    explanation: >-
      Documents pleural effusion with objectively severe hypoxaemic respiratory
      failure as a presentation of the syndrome.
  - reference: PMID:26506672
    reference_title: "Non-invasive ventilation for the treatment of acute respiratory failure following ovarian hyperstimulation syndrome: report of two cases and a brief review of the literature."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Due to the increased use of therapeutic strategies for infertility
      (particularly those using human chorionic gonadotropin), the systemic,
      particularly the pulmonary, complications of this syndrome must be
      identified early to allow appropriate diagnosis and management.
    explanation: >-
      Connects the pulmonary complication back to hCG-based fertility treatment
      as its driver.
phenotypes:
- category: Reproductive
  name: Enlarged Multicystic Ovaries
  description: >-
    Bilateral ovarian enlargement with multiple luteinized cysts, the finding
    that gives the syndrome its name and the one bedside ultrasound looks for
    first.
  phenotype_term:
    preferred_term: Enlarged ovaries
    term:
      id: HP:0100879
      label: Enlarged ovaries
  diagnostic: true
  evidence:
  - reference: PMID:26506672
    reference_title: "Non-invasive ventilation for the treatment of acute respiratory failure following ovarian hyperstimulation syndrome: report of two cases and a brief review of the literature."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The diagnosis of severe OHSS was made, largely based on bedside
      ultrasonography showing increased ovarian size, mild ascites and
      bilateral pleural effusions.
    explanation: >-
      Records ovarian enlargement as a diagnostic ultrasound finding.
- category: Reproductive
  name: Ovarian Cysts
  description: >-
    Multiple luteinized follicular cysts within the enlarged ovaries, the
    structural correlate of the simultaneous multifollicular luteinization.
  phenotype_term:
    preferred_term: Ovarian cyst
    term:
      id: HP:0000138
      label: Ovarian cyst
  evidence:
  - reference: PMID:23941020
    reference_title: "Spontaneous ovarian hyperstimulation syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      In the differential diagnosis, malignancy, pregnancy luteoma and
      hyperreactio luteinalis would have to be excluded.
    explanation: >-
      The stated differential is an enlarged multicystic ovarian mass, which is
      what makes this cystic ovarian phenotype the presenting finding.
- category: Gastrointestinal
  name: Ascites
  description: >-
    Accumulation of protein-rich fluid in the peritoneal cavity, the largest
    single third-space compartment in this syndrome and the main determinant of
    abdominal distension and diaphragmatic splinting.
  phenotype_term:
    preferred_term: Ascites
    term:
      id: HP:0001541
      label: Ascites
  diagnostic: true
  evidence:
  - reference: PMID:26506672
    reference_title: "Non-invasive ventilation for the treatment of acute respiratory failure following ovarian hyperstimulation syndrome: report of two cases and a brief review of the literature."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Clinical signs may include any or all of the following: rapid weight
      gain, ascites, oliguria, hemoconcentration, leukocytosis, along with
      intravascular hypovolemia, hyponatremia, and hyperkalemia.
    explanation: >-
      Lists ascites among the defining clinical signs.
- category: Respiratory
  name: Pleural Effusion
  description: >-
    Third-space fluid entering the pleural cavity, often bilateral, and the
    proximate cause of the hypoxaemic respiratory failure that defines the
    severe end of the spectrum.
  phenotype_term:
    preferred_term: Pleural effusion
    term:
      id: HP:0002202
      label: Pleural effusion
  evidence:
  - reference: PMID:26506672
    reference_title: "Non-invasive ventilation for the treatment of acute respiratory failure following ovarian hyperstimulation syndrome: report of two cases and a brief review of the literature."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      We describe two cases of women with extremely severe OHSS presenting
      bilateral pleural effusions, and severe respiratory failure (paO2/FiO2 <
      200) treated with non-invasive ventilation (NIV).
    explanation: >-
      Documents bilateral pleural effusion in extremely severe OHSS.
- category: Respiratory
  name: Respiratory Failure
  description: >-
    Hypoxaemic respiratory failure, up to ARDS, from combined pleural effusion
    and diaphragmatic splinting by tense ascites. This is one of the two
    complications for which intensive care is required.
  phenotype_term:
    preferred_term: Respiratory failure
    term:
      id: HP:0002878
      label: Respiratory failure
  severity: SEVERE
  evidence:
  - reference: PMID:26506672
    reference_title: "Non-invasive ventilation for the treatment of acute respiratory failure following ovarian hyperstimulation syndrome: report of two cases and a brief review of the literature."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      If the patient is not diagnosed early, ascites, pleural and more rarely
      pericardial effusions, severe respiratory failure and ARDS,
      hypercoagulability with tromboembolism and multiple organ system failure
      can occur.
    explanation: >-
      Places severe respiratory failure and ARDS among the consequences of late
      diagnosis.
- category: Cardiovascular
  name: Intravascular Hypovolemia
  description: >-
    Depletion of the effective circulating volume despite gross total-body
    fluid excess. The paradox is the central management hazard of the syndrome:
    diuresis worsens it.
  phenotype_term:
    preferred_term: Hypovolemia
    term:
      id: HP:0011106
      label: Hypovolemia
  evidence:
  - reference: PMID:26506672
    reference_title: "Non-invasive ventilation for the treatment of acute respiratory failure following ovarian hyperstimulation syndrome: report of two cases and a brief review of the literature."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Clinical signs may include any or all of the following: rapid weight
      gain, ascites, oliguria, hemoconcentration, leukocytosis, along with
      intravascular hypovolemia, hyponatremia, and hyperkalemia.
    explanation: >-
      Names intravascular hypovolaemia explicitly alongside the fluid overload.
- category: Cardiovascular
  name: Thromboembolism
  description: >-
    Venous and, less often, arterial thrombosis arising from haemoconcentration
    and stasis on a background of a high-oestrogen state. One of the two
    intensive-care-level complications.
  phenotype_term:
    preferred_term: Thromboembolism
    term:
      id: HP:0001907
      label: Thromboembolism
  evidence:
  - reference: PMID:26506672
    reference_title: "Non-invasive ventilation for the treatment of acute respiratory failure following ovarian hyperstimulation syndrome: report of two cases and a brief review of the literature."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The severe form of OHSS varies between 0.5% and 5%, depending on the
      population studied: intensive care may be required for management of
      tromboembolic complications, renal failure and severe respiratory
      failure.
    explanation: >-
      Records thromboembolic complications as a reason for intensive care.
- category: Renal
  name: Oliguria
  description: >-
    Reduced urine output from renal hypoperfusion, used clinically as the
    bedside index of how depleted the intravascular compartment has become.
  phenotype_term:
    preferred_term: Oliguria
    term:
      id: HP:0100520
      label: Oliguria
  evidence:
  - reference: PMID:26506672
    reference_title: "Non-invasive ventilation for the treatment of acute respiratory failure following ovarian hyperstimulation syndrome: report of two cases and a brief review of the literature."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Clinical signs may include any or all of the following: rapid weight
      gain, ascites, oliguria, hemoconcentration, leukocytosis, along with
      intravascular hypovolemia, hyponatremia, and hyperkalemia.
    explanation: >-
      Lists oliguria among the defining clinical signs.
- category: Renal
  name: Acute Kidney Injury
  description: >-
    Progression of renal hypoperfusion to frank acute kidney injury in severe
    disease.
  phenotype_term:
    preferred_term: Acute kidney injury
    term:
      id: HP:0001919
      label: Acute kidney injury
  severity: SEVERE
  evidence:
  - reference: PMID:26506672
    reference_title: "Non-invasive ventilation for the treatment of acute respiratory failure following ovarian hyperstimulation syndrome: report of two cases and a brief review of the literature."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The severe form of OHSS varies between 0.5% and 5%, depending on the
      population studied: intensive care may be required for management of
      tromboembolic complications, renal failure and severe respiratory
      failure.
    explanation: >-
      Names renal failure among the complications requiring intensive care.
- category: Metabolic
  name: Hyponatremia
  description: >-
    Dilutional hyponatraemia accompanying the fluid shift and the
    antidiuretic response to a fall in effective circulating volume.
  phenotype_term:
    preferred_term: Hyponatremia
    term:
      id: HP:0002902
      label: Hyponatremia
  evidence:
  - reference: PMID:26506672
    reference_title: "Non-invasive ventilation for the treatment of acute respiratory failure following ovarian hyperstimulation syndrome: report of two cases and a brief review of the literature."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Clinical signs may include any or all of the following: rapid weight
      gain, ascites, oliguria, hemoconcentration, leukocytosis, along with
      intravascular hypovolemia, hyponatremia, and hyperkalemia.
    explanation: >-
      Lists hyponatraemia among the defining biochemical signs.
- category: Metabolic
  name: Hyperkalemia
  description: >-
    Rising serum potassium as renal excretion falls with perfusion.
  phenotype_term:
    preferred_term: Hyperkalemia
    term:
      id: HP:0002153
      label: Hyperkalemia
  evidence:
  - reference: PMID:26506672
    reference_title: "Non-invasive ventilation for the treatment of acute respiratory failure following ovarian hyperstimulation syndrome: report of two cases and a brief review of the literature."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Clinical signs may include any or all of the following: rapid weight
      gain, ascites, oliguria, hemoconcentration, leukocytosis, along with
      intravascular hypovolemia, hyponatremia, and hyperkalemia.
    explanation: >-
      Lists hyperkalaemia among the defining biochemical signs.
- category: Hematologic
  name: Leukocytosis
  description: >-
    A raised total white cell count accompanying the inflammatory and
    haemoconcentrated state, and a potential source of diagnostic confusion
    with sepsis in a post-procedure patient.
  phenotype_term:
    preferred_term: Increased total leukocyte count
    term:
      id: HP:0001974
      label: Increased total leukocyte count
  evidence:
  - reference: PMID:26506672
    reference_title: "Non-invasive ventilation for the treatment of acute respiratory failure following ovarian hyperstimulation syndrome: report of two cases and a brief review of the literature."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Clinical signs may include any or all of the following: rapid weight
      gain, ascites, oliguria, hemoconcentration, leukocytosis, along with
      intravascular hypovolemia, hyponatremia, and hyperkalemia.
    explanation: >-
      Lists leukocytosis among the defining haematological signs.
- category: Hematologic
  name: Hemoconcentration
  description: >-
    A rising haematocrit as plasma leaves the intravascular compartment for the
    peritoneum and pleura. Operationally this is the most important single
    laboratory finding in the syndrome: it is a formal severity criterion, it
    is what converts a patient from outpatient observation to admission and
    intravenous rehydration, and it is the same measurement that makes the
    thrombotic risk legible. Note the direction of causation runs opposite to
    intuition - the haematocrit rises because plasma is lost, not because red
    cell mass increases.
  phenotype_term:
    preferred_term: Increased hematocrit
    term:
      id: HP:0001899
      label: Increased hematocrit
  diagnostic: true
  evidence:
  - reference: PMID:26506672
    reference_title: "Non-invasive ventilation for the treatment of acute respiratory failure following ovarian hyperstimulation syndrome: report of two cases and a brief review of the literature."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Clinical signs may include any or all of the following: rapid weight
      gain, ascites, oliguria, hemoconcentration, leukocytosis, along with
      intravascular hypovolemia, hyponatremia, and hyperkalemia.
    explanation: >-
      Lists haemoconcentration among the defining clinical signs.
  - reference: PMID:34644798
    reference_title: "Ovarian Hyperstimulation: Diagnosis, Prevention, and Management."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Only if severe/critical cases are diagnosed hospitalization is necessary
      for appropriate rehydration, monitoring of fluid balance and eventual
      drainage of ascitic fluid.
    explanation: >-
      Supports the clinical consequence of haemoconcentration and fluid loss -
      admission for rehydration and fluid-balance monitoring.
- category: Gastrointestinal
  name: Abdominal Distension
  description: >-
    Increasing abdominal girth from accumulating ascites. Together with serial
    weights it is the earliest thing a patient notices, and the reason
    self-monitoring instructions after oocyte retrieval focus on girth and
    weight rather than on pain.
  phenotype_term:
    preferred_term: Abdominal distention
    term:
      id: HP:0003270
      label: Abdominal distention
  evidence:
  - reference: PMID:35079118
    reference_title: "Tie1 contributes to the development of ovarian hyperstimulation syndrome under the regulation of EGR1 in granulosa cells."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      accompanied by abdominal bloating and mild abdominal pain
    explanation: >-
      Direct observation of abdominal bloating, and at the mild end of the
      grading - which is the point, since distension is the earliest thing a
      patient notices.
  - reference: PMID:34644798
    reference_title: "Ovarian Hyperstimulation: Diagnosis, Prevention, and Management."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Pathogenesis of the disease is based on massive transudation of
      protein-rich fluid from the vascular compartment into the peritoneal,
      pleural and pericardial spaces, with a variable picture of clinical
      manifestations depending on its severity.
    explanation: >-
      Mechanistic rather than observational support: peritoneal transudation is
      what produces the distension, but the source does not itself report
      distension. Recorded as PARTIAL for that reason.
- category: Gastrointestinal
  name: Nausea
  description: >-
    Nausea accompanying tense ascites and bowel oedema. Clinically it matters
    because it is also the commonest early symptom of the syndrome and is easy
    to attribute to the retrieval procedure or to progesterone support instead.
  phenotype_term:
    preferred_term: Nausea
    term:
      id: HP:0002018
      label: Nausea
  evidence:
  - reference: PMID:35079118
    reference_title: "Tie1 contributes to the development of ovarian hyperstimulation syndrome under the regulation of EGR1 in granulosa cells."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Severe symptoms can include persistent nausea and vomiting, shortness of
      breath, abdominal and chest pain, pleural effusion, blood clots, kidney
      failure, and, in some cases, even death
    explanation: >-
      Names persistent nausea and vomiting among the severe symptoms of the
      syndrome.
  - reference: PMID:35079118
    reference_title: "Tie1 contributes to the development of ovarian hyperstimulation syndrome under the regulation of EGR1 in granulosa cells."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      the patient's assessment of discomfort, abdominal bloating, ascites, or
      nausea
    explanation: >-
      Places nausea in the operative definition of moderate OHSS, which is where
      it functions clinically as a severity criterion rather than an incidental
      symptom.
- category: Gastrointestinal
  name: Vomiting
  description: >-
    Persistent vomiting, named among the severe symptoms. It sits with nausea at
    the mild end of the syndrome and becomes a severity marker when persistent -
    and it compounds the problem it signals, since vomiting worsens the
    intravascular depletion that the third-space shift has already caused.
  phenotype_term:
    preferred_term: Vomiting
    term:
      id: HP:0002013
      label: Vomiting
  evidence:
  - reference: PMID:35079118
    reference_title: "Tie1 contributes to the development of ovarian hyperstimulation syndrome under the regulation of EGR1 in granulosa cells."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Severe symptoms can include persistent nausea and vomiting, shortness of
      breath, abdominal and chest pain, pleural effusion, blood clots, kidney
      failure, and, in some cases, even death
    explanation: >-
      Names persistent vomiting among the severe symptoms of the syndrome.
- category: Respiratory
  name: Dyspnea
  description: >-
    Breathlessness, named among the severe symptoms. It is the symptomatic face
    of the pleural and diaphragmatic arm curated separately as pleural effusion
    and respiratory failure, and it is usually what brings a woman back to
    hospital after discharge - which is why it appears in the self-monitoring
    advice given after oocyte retrieval alongside girth and weight.
  phenotype_term:
    preferred_term: Dyspnea
    term:
      id: HP:0002094
      label: Dyspnea
  evidence:
  - reference: PMID:35079118
    reference_title: "Tie1 contributes to the development of ovarian hyperstimulation syndrome under the regulation of EGR1 in granulosa cells."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Severe symptoms can include persistent nausea and vomiting, shortness of
      breath, abdominal and chest pain, pleural effusion, blood clots, kidney
      failure, and, in some cases, even death
    explanation: >-
      Names shortness of breath among the severe symptoms of the syndrome.
- category: Hepatic
  name: Hepatic Involvement in Severe Disease
  description: >-
    Liver involvement accompanying severe OHSS. It is bound to the broad
    "abnormal liver physiology" term rather than to elevated transaminases
    specifically, because that is exactly what the cited source states: severe
    forms are "accompanied by electrolyte disturbances and cardiopulmonary,
    hepatic, renal, and hemoconcentration". Transaminase elevation is the usual
    laboratory expression of it and is widely reported in review literature,
    but no source cited on this entry states it, so the more specific
    HP:0002910 binding is deliberately not used.
  phenotype_term:
    preferred_term: Abnormal liver physiology
    term:
      id: HP:0031865
      label: Abnormal liver physiology
  severity: SEVERE
  evidence:
  - reference: clinicaltrials:NCT06333691
    reference_title: "Comparative Study Between Calcium Gluconate With Diosmin, Cabergoline and Cabergoline With Diosmin in Prevention of Ovarian Hyperstimulation Syndrome in High-risk Women Undergoing Intracytoplasmic Sperm Injection (ICSI) Procedures"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Severe forms are also accompanied by electrolyte disturbances and
      cardiopulmonary, hepatic, renal, and hemoconcentration associated with
      increased thromboembolic risk.
    explanation: >-
      Names hepatic involvement among the organ systems affected in severe
      disease, alongside the cardiopulmonary and renal involvement already
      curated here.
- category: Constitutional
  name: Rapid Weight Gain
  description: >-
    Rapid increase in body weight from retained third-space fluid; serial
    weights are the simplest bedside measure of how fast the syndrome is
    progressing.
  phenotype_term:
    preferred_term: Increased body weight
    term:
      id: HP:0004324
      label: Increased body weight
  evidence:
  - reference: PMID:26506672
    reference_title: "Non-invasive ventilation for the treatment of acute respiratory failure following ovarian hyperstimulation syndrome: report of two cases and a brief review of the literature."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Clinical signs may include any or all of the following: rapid weight
      gain, ascites, oliguria, hemoconcentration, leukocytosis, along with
      intravascular hypovolemia, hyponatremia, and hyperkalemia.
    explanation: >-
      Lists rapid weight gain first among the clinical signs.
- category: Reproductive
  name: Pelvic Pain from Adnexal Torsion
  description: >-
    Acute severe pelvic pain from torsion of an enlarged ovary, a surgical
    emergency distinct from the capillary-leak arm of the illness.
  phenotype_term:
    preferred_term: Pelvic pain
    term:
      id: HP:0034267
      label: Pelvic pain
  evidence:
  - reference: PMID:25495063
    reference_title: "A case of ovarian torsion in a patient carrier of a FSH receptor gene mutation previously affected by spontaneous ovarian hyperstimulation syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      In few days, she developed severe pelvic pain and ultrasonographic
      evidence of increased ovarian volume.
    explanation: >-
      Documents severe pelvic pain as the presenting symptom of torsion in an
      enlarged ovary.
genetic:
- name: FSHR
  gene_term:
    preferred_term: FSHR
    term:
      id: hgnc:3969
      label: FSHR
  relationship_type: CAUSATIVE
  variant_origin: GERMLINE
  presence: PRESENT
  subtype: Familial Spontaneous OHSS
  notes: >-
    FSHR (2p16.3) encodes the follitropin receptor, one of the three
    glycoprotein hormone receptors. Activating germline missense variants cause
    the familial gestational spontaneous form, and this is the gene MONDO
    records as causally associated with MONDO:0011972. Two structurally
    distinct mutation classes have been reported: transmembrane-helix variants
    (p.Thr449Ile, p.Thr449Ala, p.Asp567Asn, p.Asp567Gly, p.Ile545Thr) that
    lower the receptor's intramolecular activation barrier, giving hCG and TSH
    responsiveness plus constitutive activity; and a single extracellular-domain
    variant (c.383C>A, p.Ser128Tyr) that instead raises hCG binding affinity
    with no constitutive activity and no TSH cross-reactivity. Both classes are
    heterozygous in the reported families. Note that FSHR variants explain the
    *familial* spontaneous cases only — sporadic spontaneous OHSS occurs with a
    normal receptor when hCG or TSH is high enough.
  evidence:
  - reference: PMID:23941020
    reference_title: "Spontaneous ovarian hyperstimulation syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      In addition to five mutations which have been found in the transmembrane
      helices (Asp567Asn, Asp567Gly, Thr449Ile, Thr449Ala, Ile545Thr), the
      first germline mutation (c.383C > A, p. Ser 128 Tyr) in the extracelullar
      domain was identified.
    explanation: >-
      Enumerates the reported activating FSHR alleles and their two structural
      classes.
  - reference: PMID:23941020
    reference_title: "Spontaneous ovarian hyperstimulation syndrome."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      All five mutants were abnormally activated by TSH and normal levels of
      hCG while displaying constitutive activity.
    explanation: >-
      Gives the shared functional signature of the transmembrane-helix class.
  - reference: PMID:15080154
    reference_title: "A mutation in the follicle-stimulating hormone receptor as a cause of familial spontaneous ovarian hyperstimulation syndrome."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      Together with the two previous studies, this report shows that
      inappropriate stimulation of the FSHr by hCG is a cause of spontaneous
      OHSS.
    explanation: >-
      States the causal conclusion drawn across three independent families.
treatments:
- name: Cabergoline
  description: >-
    A dopamine D2 receptor agonist given prophylactically to women identified as
    high risk. Its mechanism in this setting is specific and dose-dependent: at
    low dose it partially dephosphorylates ovarian VEGFR-2, which is enough to
    abolish the permeability response while leaving the VEGFR-2-dependent luteal
    angiogenesis a pregnancy requires intact. That separation is the reason a
    dopamine agonist is usable here where a direct VEGFR-2 antagonist such as
    SU5416 is not — SU5416 prevented the leak in the rodent model but is
    thromboembolic and disrupts angiogenesis needed for pregnancy.
  therapeutic_modality: SMALL_MOLECULE
  treatment_term:
    preferred_term: Pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
    therapeutic_agent:
    - preferred_term: cabergoline
      term:
        id: CHEBI:3286
        label: cabergoline
  target_mechanisms:
  - target: VEGFR-2 Activation on Vascular Endothelium
    treatment_effect: INHIBITS
    description: >-
      Low-dose cabergoline partially inhibits ovarian VEGFR-2 phosphorylation,
      reversing the VEGFR-2-dependent rise in vascular permeability without
      blocking luteal angiogenesis.
    evidence:
    - reference: PMID:16901966
      reference_title: "Low-dose dopamine agonist administration blocks vascular endothelial growth factor (VEGF)-mediated vascular hyperpermeability without altering VEGF receptor 2-dependent luteal angiogenesis in a rat ovarian hyperstimulation model."
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: >-
        A 100 microg/kg low-dose Dp-r2 agonist cabergoline reversed
        VEGFR-2-dependent VP without affecting luteal angiogenesis through
        partial inhibition of ovarian VEGFR-2 phosphorylation levels.
      explanation: >-
        Identifies VEGFR-2 phosphorylation as the molecular target of the drug
        at the node it is linked to.
  evidence:
  - reference: PMID:16901966
    reference_title: "Low-dose dopamine agonist administration blocks vascular endothelial growth factor (VEGF)-mediated vascular hyperpermeability without altering VEGF receptor 2-dependent luteal angiogenesis in a rat ovarian hyperstimulation model."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Prophylactic administration of cabergoline (5-10 microg/kg x d) decreased
      the occurrence of OHSS from 65% (controls) to 25% (treatment).
    explanation: >-
      Quantifies the clinical prophylactic effect in high-risk oocyte donors.
  - reference: PMID:16901966
    reference_title: "Low-dose dopamine agonist administration blocks vascular endothelial growth factor (VEGF)-mediated vascular hyperpermeability without altering VEGF receptor 2-dependent luteal angiogenesis in a rat ovarian hyperstimulation model."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: >-
      However, due to its toxicity (thromboembolism) and disruption of
      VEGFR-2-dependent angiogenic processes critical for pregnancy, this kind
      of compound cannot be used clinically to prevent OHSS.
    explanation: >-
      Records why direct VEGFR-2 antagonism was abandoned, which is the
      rationale for choosing a dopamine agonist instead.
- name: GnRH Agonist Trigger in a GnRH Antagonist Cycle
  description: >-
    The single most effective preventive change to the stimulation protocol.
    Substituting a GnRH agonist for hCG to trigger final oocyte maturation
    removes the long-acting hCG stimulus that drives ovarian VEGF secretion,
    replacing it with a short endogenous LH surge. The trade-off is a deficient
    luteal phase, which is why the strategy is paired with luteal support or
    with elective freezing of all embryos; a meta-analysis of five randomised
    trials found live birth rates comparable to an hCG trigger when LH activity
    luteal support was individualised.
  therapeutic_modality: PEPTIDE
  treatment_term:
    preferred_term: Pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
  target_mechanisms:
  - target: hCG-Driven Luteinization of the Recruited Cohort
    treatment_effect: INHIBITS
    description: >-
      The substitution acts on luteinization, not on recruitment: the follicles
      are still recruited, but a short endogenous LH surge replaces the
      long-acting hCG stimulus that luteinizes the whole cohort and drives the
      downstream VEGF surge.
    evidence:
    - reference: PMID:28638367
      reference_title: "GnRH Agonist Trigger and LH Activity Luteal Phase Support versus hCG Trigger and Conventional Luteal Phase Support in Fresh Embryo Transfer IVF/ICSI Cycles-A Systematic PRISMA Review and Meta-analysis."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        The use of GnRH agonist (GnRHa) for final oocyte maturation trigger in
        oocyte donation and elective frozen embryo transfer cycles is well
        established due to lower ovarian hyperstimulation syndrome (OHSS) rates
        as compared to hCG trigger.
      explanation: >-
        Establishes that replacing the hCG trigger lowers OHSS rates, the
        clinical read-out of suppressing the VEGF surge.
  evidence:
  - reference: PMID:28638367
    reference_title: "GnRH Agonist Trigger and LH Activity Luteal Phase Support versus hCG Trigger and Conventional Luteal Phase Support in Fresh Embryo Transfer IVF/ICSI Cycles-A Systematic PRISMA Review and Meta-analysis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      OHSS was reported in a total of 4/413 cases in the GnRHa group compared to
      7/413 in the hCG group (OR 0.48, 95% CI 0.15, 1.60).
    explanation: >-
      Gives the effect estimate in fresh-transfer cycles specifically, where the
      confidence interval crosses unity — the benefit is established in donor
      and freeze-all cycles, not demonstrated in this subgroup.
  - reference: PMID:28638367
    reference_title: "GnRH Agonist Trigger and LH Activity Luteal Phase Support versus hCG Trigger and Conventional Luteal Phase Support in Fresh Embryo Transfer IVF/ICSI Cycles-A Systematic PRISMA Review and Meta-analysis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      GnRHa trigger with LH activity LPS resulted in comparable LBRs compared to
      hCG trigger.
    explanation: >-
      Records that the preventive substitution need not cost live births when
      luteal support is individualised.
  - reference: PMID:27273307
    reference_title: "Pathophysiology, treatment and prevention of ovarian hyperstimulation syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Therefore, it is important to prevent this condition by identifying women
      at risk, allowing the clinician to implement preventive strategies,
      including the use of GnRH antagonist cycles with agonist triggers.
    explanation: >-
      States the antagonist-cycle-plus-agonist-trigger strategy as the
      recommended preventive approach.
- name: Intravenous Calcium for OHSS Prophylaxis
  description: >-
    Intravenous calcium given around oocyte retrieval, and on the current network
    meta-analytic evidence the best-supported prophylaxis in this entry - ranked
    above cabergoline in both published network meta-analyses, with a risk ratio
    of 0.14 for moderate-to-severe OHSS at high GRADE and a SUCRA of 92.4% in Wu
    2022.

    "Best-supported" rather than "most effective", deliberately. In Guo 2016 the
    largest point estimate belongs to ASPIRIN (RR 0.07, rank probability 36%
    against calcium's 35%), so calcium is not the top-ranked agent in both
    analyses. What distinguishes it is consistency: it is effective in both, at
    high GRADE in both, whereas aspirin is graded LOW in Wu 2022 and placed among
    the agents that could not prevent moderate-to-severe OHSS. Aspirin is curated
    separately with that discordance recorded.

    Its proposed mechanism is now curated as a node rather than waved at: calcium
    is thought to inhibit cyclic-AMP-stimulated renin secretion, damping the
    intra-ovarian renin-angiotensin system that gonadotropin stimulation
    activates, and so lowering VEGF expression in luteinized granulosa cells. An
    earlier revision of this entry claimed no verifiable source for that arm
    existed; that was wrong, and both network meta-analyses cited here state it.

    The caveat that remains is about strength, not existence. Both sources hedge
    ("could be by inhibiting"), neither cites a primary demonstration in an OHSS
    cohort, and the node is curated PROVISIONAL for that reason. This is still
    the entry's clearest example of a therapy whose efficacy evidence outruns its
    mechanistic evidence - it just is not a therapy with no mechanism on record.
  therapeutic_modality: SMALL_MOLECULE
  treatment_term:
    preferred_term: Pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
    therapeutic_agent:
    - preferred_term: calcium
      term:
        id: CHEBI:29108
        label: calcium(2+)
  target_mechanisms:
  - target: Ovarian Renin-Angiotensin System Activation
    treatment_effect: INHIBITS
    description: >-
      Calcium is proposed to inhibit cyclic-AMP-stimulated renin secretion,
      damping the intra-ovarian renin-angiotensin arm and so reducing VEGF
      expression in luteinized granulosa cells.
    evidence:
    - reference: PMID:35154015
      reference_title: "Comparison of the Effectiveness of Various Medicines in the Prevention of Ovarian Hyperstimulation Syndrome: A Network Meta-Analysis of Randomized Controlled Trials."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        The possible underlying mechanism of calcium preventing OHSS could be by
        inhibiting cyclic adenosine monophosphate-stimulated renin secretion,
        which reduces the production of angiotensin-converting enzyme II
      explanation: >-
        States the proposed target of the drug at this node, with the authors'
        own hedge intact.
    - reference: PMID:26752241
      reference_title: "Pharmacologic Interventions in Preventing Ovarian Hyperstimulation Syndrome: A Systematic Review and Network Meta-Analysis."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        IV calcium is a relatively new method for preventing severe OHSS from
        occurring by inhibiting the renin-angiotensin system (RAS) and,
        consequently, reducing VEGF concentration.
      explanation: >-
        Independent statement of the same proposed mechanism of action.
  evidence:
  - reference: PMID:35154015
    reference_title: "Comparison of the Effectiveness of Various Medicines in the Prevention of Ovarian Hyperstimulation Syndrome: A Network Meta-Analysis of Randomized Controlled Trials."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The incidence of moderate-to-severe OHSS was significantly reduced by
      calcium administration (risk ratios [RR] 0.14, 95% confidence interval
      [CI]: 0.04, 0.46) (grade: high), HES (RR 0.25, 95% CI 0.07, 0.73) (grade:
      high), and cabergoline (RR 0.43, 95% CI 0.24, 0.71) (grade: moderate).
    explanation: >-
      Gives the effect estimate and GRADE rating for calcium, alongside the two
      comparators, from a network meta-analysis of randomized trials.
  - reference: PMID:35154015
    reference_title: "Comparison of the Effectiveness of Various Medicines in the Prevention of Ovarian Hyperstimulation Syndrome: A Network Meta-Analysis of Randomized Controlled Trials."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The surface under the cumulative ranking curve (SUCRA) indicated that
      calcium (SUCRA, 92.4%) was the most effective intervention for preventing
      moderate-to-severe OHSS.
    explanation: >-
      Ranks calcium above every other prophylactic agent assessed, including
      cabergoline.
  - reference: PMID:26752241
    reference_title: "Pharmacologic Interventions in Preventing Ovarian Hyperstimulation Syndrome: A Systematic Review and Network Meta-Analysis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The rank probability demonstrated aspirin (Rank 1: 36%) and IV calcium
      (Rank 1: 35%) to be the most efficacious.
    explanation: >-
      An independent network meta-analysis placing intravenous calcium among the
      top-ranked agents. Note it ranks ASPIRIN marginally above calcium (36% vs
      35%), so this is concordant on calcium being highly effective but NOT on
      calcium being first; aspirin is curated separately for that reason.
- name: Low-Dose Aspirin for OHSS Prophylaxis
  description: >-
    The agent with the largest point estimate in either network meta-analysis -
    RR 0.07 in Guo 2016, ranked first at 36% rank probability, ahead of
    intravenous calcium - and simultaneously the agent those two analyses
    disagree about most sharply. Wu 2022 grades the aspirin evidence LOW and
    places it among the agents that could not prevent moderate-to-severe OHSS.

    It is curated because leaving it out was distorting this entry. The calcium
    treatment previously opened by calling calcium "the most effective
    prophylaxis available", while the snippet directly beneath it ranked aspirin
    above calcium in one of the two analyses. Curating aspirin lets both facts
    stand and makes the discordance the entry's subject rather than its blind
    spot.

    Unlike calcium, it has a concrete and non-speculative proposed mechanism:
    aspirin inhibits platelet COX-1, and platelet activation with release of
    vasoactive mediators is one of the proposed amplifiers of the capillary leak.
    That arm is not curated as a node here - no primary source in this entry's
    reference set demonstrates it in OHSS - so the treatment carries no
    target_mechanisms link, for the same reason and with the same discipline
    applied to calcium before the ovarian RAS node was added.
  therapeutic_modality: SMALL_MOLECULE
  treatment_term:
    preferred_term: Pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
    therapeutic_agent:
    - preferred_term: aspirin
      term:
        id: CHEBI:15365
        label: acetylsalicylic acid
  evidence:
  - reference: PMID:26752241
    reference_title: "Pharmacologic Interventions in Preventing Ovarian Hyperstimulation Syndrome: A Systematic Review and Network Meta-Analysis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Five pharmacologic interventions were superior to placebo in decreasing
      OHSS incidence: aspirin [relative risk (RR) 0.07, 95% credible interval
      (CrI) 0.01-0.30, p < 0.05], intravenous (IV) calcium [RR 0.11, 95% CrI
      0.02-0.54, p < 0.05], cabergoline [RR 0.17, 95% CrI 0.06-0.43, p < 0.05],
      metformin [RR 0.20, 95% CrI 0.07-0.59, p < 0.05] and IV hydroxyethyl
      starch (HES) [RR 0.26, 95% CrI 0.05-0.99, p < 0.05].
    explanation: >-
      The effect estimate for aspirin, alongside every other agent curated on
      this entry, from a single consistent analysis - which is what makes the
      ranking between them interpretable.
  - reference: PMID:26752241
    reference_title: "Pharmacologic Interventions in Preventing Ovarian Hyperstimulation Syndrome: A Systematic Review and Network Meta-Analysis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The rank probability demonstrated aspirin (Rank 1: 36%) and IV calcium
      (Rank 1: 35%) to be the most efficacious.
    explanation: >-
      Ranks aspirin marginally ahead of intravenous calcium in this analysis.
  - reference: PMID:35154015
    reference_title: "Comparison of the Effectiveness of Various Medicines in the Prevention of Ovarian Hyperstimulation Syndrome: A Network Meta-Analysis of Randomized Controlled Trials."
    supports: REFUTE
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Contrastingly, letrozole (grade: moderate), aspirin (grade: low), albumin
      (grade: moderate), metformin (grade: high), glucocorticoids (grade:
      moderate), and quinagolide (grade: high) could not prevent moderate-to-severe
      OHSS (P > 0.
    explanation: >-
      The direct contradiction: the later meta-analysis finds aspirin did not
      prevent moderate-to-severe OHSS and grades the evidence LOW. Recorded as
      REFUTE so the disagreement is machine-readable, not just narrated.
  - reference: PMID:26752241
    reference_title: "Pharmacologic Interventions in Preventing Ovarian Hyperstimulation Syndrome: A Systematic Review and Network Meta-Analysis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Aspirin inhibits cyclooxygenase-1 (COX-1) in the platelet and results in an
      anti-platelet effect, which may disturb the pathological cascade driven by
      those cellular factors described above
    explanation: >-
      The proposed mechanism, quoted with the authors' hedge ("may disturb")
      intact. The platelet arm it invokes is not curated as a pathophysiology
      node on this entry, so no target_mechanisms link is asserted.
- name: Hydroxyethyl Starch for OHSS Prophylaxis
  description: >-
    Intravenous hydroxyethyl starch, a plasma volume expander given around
    retrieval. Both network meta-analyses find it effective (RR 0.25 and RR 0.26)
    and one grades the evidence high. Its rationale is the one intervention on
    this entry that acts on the consequence rather than the cause: it counters the
    intravascular volume depletion produced by the capillary leak instead of
    reducing the leak itself, which is why it is linked to the third-space node
    and not to a VEGF node.

    A note on the binding: NCIT's own "Hydroxyethyl Starch" concept
    (NCIT:C102744) is retired and is not reachable from Pharmacologic Substance,
    so `just validate-terms` rejects it. The live term is NCIT:C559 Hetastarch,
    which is what the agent is bound to; `preferred_term` keeps the name the
    trials use.

    Curators should note the context this evidence sits in: hydroxyethyl starch
    carries regulatory restrictions in critical care for renal and mortality
    concerns, and the cited meta-analyses assess OHSS outcomes only. This entry
    records the OHSS efficacy finding, not a recommendation.
  therapeutic_modality: OTHER
  treatment_term:
    preferred_term: Pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
    therapeutic_agent:
    - preferred_term: hydroxyethyl starch
      term:
        id: NCIT:C559
        label: Hetastarch
  target_mechanisms:
  - target: Third-Space Fluid Shift and Intravascular Volume Depletion
    treatment_effect: MODULATES
    description: >-
      A colloid volume expander opposes the fall in effective circulating volume
      caused by the leak; it does not act on the permeability lesion upstream.
    evidence:
    - reference: PMID:26752241
      reference_title: "Pharmacologic Interventions in Preventing Ovarian Hyperstimulation Syndrome: A Systematic Review and Network Meta-Analysis."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        Gokman et al. 10 demonstrated that the administration of albumin and
        hydroxyethyl starch (HES) might prevent moderate to severe OHSS in
        high-risk patients.
      explanation: >-
        Records the colloid rationale and the outcome it is credited with.
  evidence:
  - reference: PMID:35154015
    reference_title: "Comparison of the Effectiveness of Various Medicines in the Prevention of Ovarian Hyperstimulation Syndrome: A Network Meta-Analysis of Randomized Controlled Trials."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Calcium, HES, and cabergoline could effectively and safely prevent
      moderate-to-severe OHSS, with calcium as the most effective intervention.
    explanation: >-
      The meta-analysis conclusion naming HES among the three effective agents.
- name: Metformin for OHSS Prophylaxis
  description: >-
    Metformin given to women at risk, principally those with polycystic ovary
    syndrome, where it is already indicated for the underlying insulin
    resistance. One network meta-analysis finds a risk ratio of 0.20; the other
    did not assess it as effective, and it does not appear among the three agents
    that meta-analysis concludes for. It is curated because a Phase II-plus
    evidence base exists and because the discordance between the two analyses is
    itself worth recording, not because the case is settled.
  therapeutic_modality: SMALL_MOLECULE
  treatment_term:
    preferred_term: Pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
    therapeutic_agent:
    - preferred_term: metformin
      term:
        id: CHEBI:6801
        label: metformin
  evidence:
  - reference: PMID:26752241
    reference_title: "Pharmacologic Interventions in Preventing Ovarian Hyperstimulation Syndrome: A Systematic Review and Network Meta-Analysis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      metformin [RR 0.20, 95% CrI 0.07-0.59, p < 0.05] and IV hydroxyethyl
      starch (HES) [RR 0.26, 95% CrI 0.05-0.99, p < 0.05]
    explanation: >-
      Gives the metformin effect estimate from the earlier network
      meta-analysis.
  - reference: PMID:35154015
    reference_title: "Comparison of the Effectiveness of Various Medicines in the Prevention of Ovarian Hyperstimulation Syndrome: A Network Meta-Analysis of Randomized Controlled Trials."
    supports: REFUTE
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Contrastingly, letrozole (grade: moderate), aspirin (grade: low), albumin
      (grade: moderate), metformin (grade: high), glucocorticoids (grade:
      moderate), and quinagolide (grade: high) could not prevent moderate-to-severe
      OHSS (P > 0.
    explanation: >-
      The later meta-analysis states directly - at HIGH GRADE - that metformin
      could not prevent moderate-to-severe OHSS. This replaces an earlier item
      that quoted the list of agents that DID work and inferred metformin's
      absence from it; an argument from silence is not snippet support.
- name: Albumin for OHSS Prophylaxis
  description: >-
    Intravenous albumin around oocyte retrieval, curated here specifically
    BECAUSE the signal is unfavourable rather than despite it. Albumin has been
    widely used on the colloid rationale, but the earlier network meta-analysis
    found it associated with a lower pregnancy rate than placebo (RR 0.85, 95% CI
    0.74-0.97), and the later one does not include it among the effective
    preventive agents.

    A prophylaxis that may cost the pregnancy the whole treatment cycle exists to
    achieve is a different kind of intervention from one that merely fails, and
    an entry that curated only the drugs that work would misrepresent the
    decision a clinician is actually making.
  therapeutic_modality: OTHER
  treatment_term:
    preferred_term: Pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
    therapeutic_agent:
    - preferred_term: human albumin
  notes: >-
    The `therapeutic_agent` is deliberately UNBOUND. The suggested
    `NCIT:C65218 Albumin (Human)` exists and has the right label, but
    `runoak ancestors -p i` places it under `NCIT:C17021 Protein` /
    `NCIT:C26548 Gene Product` - not under `NCIT:C1909 Pharmacologic Substance` -
    so it is not reachable from either root of the `ChemicalEntityTerm` enum and
    `just validate-terms` rejects it. Searching further found no live substitute:
    the NCIT albumin concepts are measurements (`NCIT:C61015`), radiolabelled
    imaging agents (`NCIT:C2557`, `NCIT:C29127`), or non-human (`NCIT:C85253`),
    and CHEBI offers only the class term `CHEBI:166964 albumin type`. Free-text
    `preferred_term` with the search recorded is the honest outcome; no term
    beats a bad one.

    `therapeutic_modality: OTHER`, not `PROTEIN_REPLACEMENT`. Albumin is used
    here as a colloid volume expander opposing the third-space shift, not to
    replace a protein the patient is congenitally missing - which is what
    PROTEIN_REPLACEMENT denotes elsewhere in the schema (enzyme and factor
    replacement in inborn errors). The same reasoning puts hydroxyethyl starch,
    a polysaccharide colloid, on OTHER rather than SMALL_MOLECULE.
  evidence:
  - reference: PMID:26752241
    reference_title: "Pharmacologic Interventions in Preventing Ovarian Hyperstimulation Syndrome: A Systematic Review and Network Meta-Analysis."
    supports: REFUTE
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Additionally, albumin might decrease the pregnancy rate when compared with
      placebo [RR 0.85, 95% CI 0.74-0.97, p < 0.05].
    explanation: >-
      The negative signal: albumin prophylaxis was associated with a lower
      pregnancy rate, which is why this treatment is recorded with REFUTE
      evidence rather than as an endorsed option.
  - reference: PMID:35154015
    reference_title: "Comparison of the Effectiveness of Various Medicines in the Prevention of Ovarian Hyperstimulation Syndrome: A Network Meta-Analysis of Randomized Controlled Trials."
    supports: REFUTE
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Contrastingly, letrozole (grade: moderate), aspirin (grade: low), albumin
      (grade: moderate), metformin (grade: high), glucocorticoids (grade:
      moderate), and quinagolide (grade: high) could not prevent moderate-to-severe
      OHSS (P > 0.
    explanation: >-
      The later meta-analysis states directly that albumin could not prevent
      moderate-to-severe OHSS. The description previously made this claim without
      citing a source for it.
  - reference: PMID:26752241
    reference_title: "Pharmacologic Interventions in Preventing Ovarian Hyperstimulation Syndrome: A Systematic Review and Network Meta-Analysis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Although no available pharmacologic intervention fully prevents the
      development of OHSS, adjuvant drug therapy can still be adopted to limit
      the incidence and improve the management of moderate to severe OHSS.
    explanation: >-
      The overall bound on pharmacological prophylaxis, which applies to every
      drug curated on this entry: none of them fully prevents the syndrome.
- name: Secondary Prevention by Coasting or Cycle Cancellation
  description: >-
    Two of the manoeuvres available once a cycle is already over-responding, both
    of which work by denying the recruited follicular cohort its luteinizing
    stimulus rather than by treating the leak. Coasting withholds further
    gonadotropin while continuing pituitary suppression, allowing the smaller
    follicles to undergo atresia before the trigger. Cycle cancellation withholds
    the trigger altogether.

    They are grouped because they are one decision made at one point in the
    cycle, graded by how much of the cycle the clinician is willing to sacrifice.
    The third manoeuvre named in the same source - elective cryopreservation of
    all oocytes or embryos - is curated as its own treatment rather than folded
    in here, because it acts at a different time and on a different arm: it
    permits the trigger and the retrieval, and prevents only the LATE form driven
    by the endogenous hCG of an implanting pregnancy. All of these are distinct
    from primary prevention, which is the choice of stimulation protocol before
    the response is known.
  therapeutic_modality: BEHAVIORAL
  treatment_term:
    preferred_term: Preventive Intervention
    term:
      id: NCIT:C15843
      label: Preventive Intervention
  target_mechanisms:
  - target: hCG-Driven Luteinization of the Recruited Cohort
    treatment_effect: INHIBITS
    description: >-
      Coasting and cancellation withhold the luteinizing stimulus from the
      recruited cohort; freeze-all removes the endogenous pregnancy hCG that
      would sustain luteinization into the late phase.
    evidence:
    - reference: PMID:24848075
      reference_title: "Ovarian stimulation in patients in risk of OHSS."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        Secondary prevention includes all strategies directed to counteract an
        excessive ovarian response (cycle cancellation, coasting, trigger
        ovulation by low doses of hCG or by alternative agents, cryopreservation
        of oocytes/embryos, adequate luteal phase support).
      explanation: >-
        Names all three manoeuvres as the strategies directed at an excessive
        ovarian response, which is the node this link targets.
  evidence:
  - reference: PMID:24848075
    reference_title: "Ovarian stimulation in patients in risk of OHSS."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Secondary prevention includes all strategies directed to counteract an
      excessive ovarian response (cycle cancellation, coasting, trigger
      ovulation by low doses of hCG or by alternative agents, cryopreservation
      of oocytes/embryos, adequate luteal phase support).
    explanation: >-
      The source enumeration of the secondary prevention strategies curated
      here.
  - reference: PMID:34644798
    reference_title: "Ovarian Hyperstimulation: Diagnosis, Prevention, and Management."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Nowadays OHSS can easily be avoided by several prevention methods, ranging
      from identification of high-risk patients, choice of a correct protocol
      stimulation, trigger with gonadotropin-releasing hormone (GnRH) agonists
      or, finally, the freeze-all strategy.
    explanation: >-
      Places freeze-all as the last line of the prevention sequence and states
      the overall preventability of the syndrome.
  notes: >-
    The same source distinguishes primary prevention - "personalized stimulation
    protocols in order to suit patients' characteristics (individually tailored
    COS, use of GnRH antagonist stimulation protocols, in vitro maturation)" -
    which happens before the ovarian response is known and is therefore a
    different decision from the three curated here.
- name: Elective Embryo or Oocyte Cryopreservation (Freeze-All)
  description: >-
    Curated separately from the grouped secondary-prevention entry because it is
    the only one of the three that is a distinct laboratory procedure with its
    own NCIT identity, and because its mechanism is specifically temporal: it
    does not prevent early OHSS at all, since the trigger is still given and the
    oocytes still retrieved. What it prevents is the late form, by removing the
    implanting pregnancy whose endogenous hCG would otherwise sustain the
    luteinizing stimulus for weeks. It is the reason the GnRH-agonist trigger is
    so effective in donor and freeze-all cycles specifically and less clearly so
    in fresh-transfer cycles.
  therapeutic_modality: OTHER
  treatment_term:
    preferred_term: Cryopreservation
    term:
      id: NCIT:C16475
      label: Cryopreservation
  target_mechanisms:
  - target: hCG-Driven Luteinization of the Recruited Cohort
    treatment_effect: INHIBITS
    description: >-
      Deferring transfer removes the endogenous pregnancy hCG that would sustain
      luteinization of the recruited cohort into the late phase.
    evidence:
    - reference: PMID:34644798
      reference_title: "Ovarian Hyperstimulation: Diagnosis, Prevention, and Management."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        Nowadays OHSS can easily be avoided by several prevention methods,
        ranging from identification of high-risk patients, choice of a correct
        protocol stimulation, trigger with gonadotropin-releasing hormone (GnRH)
        agonists or, finally, the freeze-all strategy.
      explanation: >-
        Names freeze-all as a prevention method acting alongside the trigger
        choice on the same luteinizing stimulus.
  evidence:
  - reference: PMID:28638367
    reference_title: "GnRH Agonist Trigger and LH Activity Luteal Phase Support versus hCG Trigger and Conventional Luteal Phase Support in Fresh Embryo Transfer IVF/ICSI Cycles-A Systematic PRISMA Review and Meta-analysis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The use of GnRH agonist (GnRHa) for final oocyte maturation trigger in
      oocyte donation and elective frozen embryo transfer cycles is well
      established due to lower ovarian hyperstimulation syndrome (OHSS) rates as
      compared to hCG trigger.
    explanation: >-
      Records that the agonist-trigger benefit is established specifically in
      elective frozen-transfer and donor cycles - that is, in combination with
      this strategy.
- name: Thromboprophylaxis
  description: >-
    Anticoagulant prophylaxis in severe OHSS, aimed at the haemoconcentrated,
    stasis-prone state rather than at the capillary leak that produces it. It is
    described as cost-effective and widely used, and is one of the few
    interventions in established disease with any claim to a benefit.

    The size of the risk it addresses is worth stating precisely, because it is
    smaller and less certain than the syndrome's reputation suggests. A
    systematic review of thromboembolism after assisted reproduction found the
    frequency of venous thromboembolism specifically related to OHSS to be
    under 0.001%, and the increase in risk conferred by OHSS on top of ART did
    not reach statistical significance, with a confidence interval spanning two
    orders of magnitude. The practice is therefore standard on the basis of
    consequence severity and low cost, not on a demonstrated effect size. Low
    dose aspirin, by contrast, remains contested.
  therapeutic_modality: OTHER
  treatment_term:
    preferred_term: Anticoagulation Therapy
    term:
      id: NCIT:C63341
      label: Anticoagulation Therapy
  target_mechanisms:
  - target: Hypercoagulability and Thromboembolism
    treatment_effect: INHIBITS
    description: >-
      Anticoagulant prophylaxis is directed at the thrombotic consequence of
      haemoconcentration and stasis, not at the permeability lesion upstream of
      it.
    evidence:
    - reference: PMID:34644798
      reference_title: "Ovarian Hyperstimulation: Diagnosis, Prevention, and Management."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        One of the most dangerous complications of OHSS is venous
        thromboembolism (VTE). Thromboprophylaxis has shown to be cost effective
        and widely used, while there are controversies regarding the usage of
        low dose aspirin (LDA) as a preventive measure.
      explanation: >-
        States the intervention, its target complication, and the separate
        controversy over aspirin.
  evidence:
  - reference: PMID:36588288
    reference_title: "Venous Thromboembolism Associated with Assisted Reproductive Technology: A Systematic Review and Meta-analysis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The risk of VTE after ART complicated by OHSS, as compared to ART without
      OHSS, was higher but not statistically significant (RR: 14.83; 95% CI:
      0.86-255.62).
    explanation: >-
      Quantifies the incremental risk this prophylaxis addresses and shows it is
      not statistically established - the reason the treatment prose is hedged
      rather than asserted.
  - reference: PMID:36588288
    reference_title: "Venous Thromboembolism Associated with Assisted Reproductive Technology: A Systematic Review and Meta-analysis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The overall frequency of VTE specifically related to OHSS was <0.001%.
    explanation: >-
      Gives the absolute frequency of the complication, which is very low.
  - reference: PMID:36588288
    reference_title: "Venous Thromboembolism Associated with Assisted Reproductive Technology: A Systematic Review and Meta-analysis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Further large prospective studies on risk factors of VTE in women
      undergoing ART are needed in order to optimize thromboprophylaxis in this
      context.
    explanation: >-
      The reviewing authors' own statement that the evidence base for
      thromboprophylaxis in this setting is not yet adequate.
- name: Therapeutic Paracentesis and Thoracentesis
  description: >-
    Drainage of tense ascites, and of pleural fluid when the respiratory arm
    dominates. It is the one manoeuvre in established disease with an immediate,
    mechanically obvious effect: removing the fluid relieves the intra-abdominal
    pressure and the diaphragmatic splinting, which is why breathlessness often
    improves within minutes of a paracentesis that has changed nothing about the
    underlying leak.

    Curated separately from general supportive care because it is a procedure
    with its own NCIT identity and its own mechanistic target, whereas supportive
    care is the surrounding fluid and monitoring strategy.
  therapeutic_modality: SURGERY
  treatment_term:
    preferred_term: Paracentesis
    term:
      id: NCIT:C15310
      label: Paracentesis
  target_mechanisms:
  - target: Third-Space Fluid Shift and Intravascular Volume Depletion
    treatment_effect: MODULATES
    description: >-
      Drainage removes accumulated third-space fluid and relieves the mechanical
      consequences of tense ascites; it treats the accumulated fluid, not the
      permeability lesion that produced it.
    evidence:
    - reference: PMID:26506672
      reference_title: "Non-invasive ventilation for the treatment of acute respiratory failure following ovarian hyperstimulation syndrome: report of two cases and a brief review of the literature."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        Pulmonary intensive care may involve thoracentesis, oxygen
        supplementation and in more severe cases assisted ventilation.
      explanation: >-
        Documents drainage of third-space fluid as the intervention directed at
        this node.
  evidence:
  - reference: PMID:34644798
    reference_title: "Ovarian Hyperstimulation: Diagnosis, Prevention, and Management."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Only if severe/critical cases are diagnosed hospitalization is necessary
      for appropriate rehydration, monitoring of fluid balance and eventual
      drainage of ascitic fluid.
    explanation: >-
      Places drainage of ascitic fluid among the interventions reserved for
      severe or critical disease.
  - reference: PMID:26506672
    reference_title: "Non-invasive ventilation for the treatment of acute respiratory failure following ovarian hyperstimulation syndrome: report of two cases and a brief review of the literature."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      There are only a few studies in English that describe severe respiratory
      failure treated with non-invasive ventilation, but all of them have had
      good outcomes.
    explanation: >-
      Supports the respiratory arm of drainage-plus-ventilation while flagging
      the thinness of the evidence base.
- name: Supportive Care of Established OHSS
  description: >-
    The surrounding management: rehydration to correct the intravascular deficit
    rather than the total-body excess - fluid resuscitation, not diuresis -
    monitoring of fluid balance, oxygen, and non-invasive ventilation when
    hypoxaemia is severe. Most cases are managed as outpatients; hospitalisation
    is reserved for the severe and critical end.

    The candid limitation, stated by the reviews themselves, is that this rests
    on consensus rather than trial evidence. The syndrome is self-limiting once
    the hCG stimulus falls, so the aim is to support the patient across that
    interval - which is also why the evidence base has never been built.
  therapeutic_modality: OTHER
  treatment_term:
    preferred_term: Supportive Care
    term:
      id: NCIT:C15747
      label: Supportive Care
  target_mechanisms:
  - target: Third-Space Fluid Shift and Intravascular Volume Depletion
    treatment_effect: MODULATES
    description: >-
      Rehydration and fluid-balance monitoring are directed at the intravascular
      depletion side of the third-spacing paradox, not at the fluid overload that
      accompanies it.
    evidence:
    - reference: PMID:34644798
      reference_title: "Ovarian Hyperstimulation: Diagnosis, Prevention, and Management."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        Only if severe/critical cases are diagnosed hospitalization is necessary
        for appropriate rehydration, monitoring of fluid balance and eventual
        drainage of ascitic fluid.
      explanation: >-
        Names rehydration and fluid-balance monitoring as the interventions
        directed at this node.
  evidence:
  - reference: PMID:27273307
    reference_title: "Pathophysiology, treatment and prevention of ovarian hyperstimulation syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Treatment is largely supportive and is based mainly on consensus
      statements rather than evidence.
    explanation: >-
      States plainly that established-disease management rests on consensus, not
      trial evidence - an important limit on any treatment claim here.
  - reference: PMID:34644798
    reference_title: "Ovarian Hyperstimulation: Diagnosis, Prevention, and Management."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      When OHSS occurs, it can usually be managed as outpatient care.
    explanation: >-
      Establishes that most established disease does not require admission,
      which is what the supportive strategy is scaled against.
- name: Risk Stratification Before Ovarian Stimulation
  description: >-
    Not a treatment of the syndrome but the intervention with the largest effect
    on it, and the reason it is included: the identified risk factors — young
    age, polycystic ovary syndrome, a previous hyper-response — and the
    quantitative markers anti-Mullerian hormone and antral follicle count are
    what let the clinician choose a milder protocol, an agonist trigger, or a
    freeze-all strategy before any stimulation begins. It is deliberately not
    linked to a pathophysiology node: identifying a susceptible woman does not
    itself act on any step of the causal chain.
  therapeutic_modality: BEHAVIORAL
  treatment_term:
    preferred_term: Preventive Intervention
    term:
      id: NCIT:C15843
      label: Preventive Intervention
  notes: >-
    Bound to Preventive Intervention rather than Supportive Care. Supportive Care
    (NCIT:C15747) is symptom-directed care of an established illness; this is
    risk assessment before any stimulation has begun, so that term would validate
    while being misleading - worse than no term. Health Risk Assessment
    (NCIT:C15367) would be the exact concept but is not reachable from
    NCIT:C25218 and so fails the TreatmentTerm enum.
  evidence:
  - reference: PMID:24848075
    reference_title: "Ovarian stimulation in patients in risk of OHSS."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Some well-established risk factors that could rise the risk of OHSS
      include young age, polycystic ovary syndrome, prior hyper-response/OHSS.
    explanation: >-
      Names the established clinical risk factors used for stratification.
  - reference: PMID:24848075
    reference_title: "Ovarian stimulation in patients in risk of OHSS."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      In recent years research has focus on identifying biomarkers/hormonal
      markers that could represent potential predictors of OHSS
      (anti-Mullerian hormone and antral follicle count).
    explanation: >-
      Records the two quantitative predictors used to grade ovarian reserve
      before stimulation.
  - reference: PMID:38099867
    reference_title: "Prevention of moderate and severe ovarian hyperstimulation syndrome: a guideline."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      This systematic review aims to identify who is at high risk for developing
      ovarian hyperstimulation syndrome, along with evidence-based strategies to
      prevent it and replaces the document of the same name last published in
      2016.
    explanation: >-
      Establishes that risk identification plus prevention is the subject of the
      current professional-society guideline.
experimental_models:
- name: SVOG human granulosa-lutein cell line with Tie1 silencing
  description: >-
    A non-tumorigenic human granulosa-lutein cell line in which acute hCG raises
    Tie1 and VEGF, and in which silencing Tie1 abolishes the hCG-induced VEGF
    rise. This is the loss-of-function experiment the entry's EGR1-TIE1 node
    actually rests on, and recording it structurally means the PROVISIONAL status
    of that node is traceable to a named system with stated limits rather than
    asserted in prose.
  experimental_model_type: CELL_LINE
  organism:
    preferred_term: human
    term:
      id: NCBITaxon:9606
      label: Homo sapiens
  cell_types:
  - preferred_term: Granulosa-lutein cell
    term:
      id: CL:0000501
      label: granulosa cell
  publication: PMID:35079118
  modeled_mechanisms:
  - target: EGR1-TIE1 Amplification of Granulosa VEGF Output
    relationship: PERTURBS
    fidelity: MODERATE
    description: >-
      Tie1 knockdown removes the hCG-to-VEGF link in a human granulosa-lutein
      background, which is what makes Tie1 a candidate required step rather than
      a correlate.
    limitations: >-
      An immortalised cell line, not primary patient granulosa cells and not an
      ovary. Acute high-dose hCG in culture compresses a stimulus that acts over
      days in vivo, and a cell line cannot reproduce the paracrine and vascular
      context in which the VEGF surge matters. The reporting authors state that
      clinical relevance is not yet addressed.
    readouts:
    - name: hCG-induced VEGF level after Tie1 silencing
      target: EGR1-TIE1 Amplification of Granulosa VEGF Output
      direction: ABOLISHED
      interpretation: >-
        The hCG-driven VEGF rise does not occur without Tie1, placing Tie1
        between the hCG signal and VEGF output.
      evidence:
      - reference: PMID:35079118
        reference_title: "Tie1 contributes to the development of ovarian hyperstimulation syndrome under the regulation of EGR1 in granulosa cells."
        supports: SUPPORT
        evidence_source: IN_VITRO
        snippet: >-
          Tie1 silencing abolished the hCG-induced VEGF level in SVOG cells
        explanation: >-
          The knockdown readout in the human granulosa-lutein line, quoted apart
          from the rat clause of the same sentence.
    - name: EGR1 binding at the Tie1 promoter
      target: EGR1-TIE1 Amplification of Granulosa VEGF Output
      direction: INCREASED
      interpretation: >-
        Identifies the transcriptional route by which hCG raises Tie1, rather
        than leaving the induction unexplained.
      evidence:
      - reference: PMID:35079118
        reference_title: "Tie1 contributes to the development of ovarian hyperstimulation syndrome under the regulation of EGR1 in granulosa cells."
        supports: SUPPORT
        evidence_source: IN_VITRO
        snippet: >-
          We also report that early growth response protein 1 (EGR1), whose
          expression was also upregulated by hCG, bound directly to the Tie1
          promoter and activated its transcription.
        explanation: >-
          The promoter-binding readout.
    evidence:
    - reference: PMID:35079118
      reference_title: "Tie1 contributes to the development of ovarian hyperstimulation syndrome under the regulation of EGR1 in granulosa cells."
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: >-
        Further studies in SVOG cells revealed that the hCG-induced upregulation
        of Tie1 expression involved the phosphoinositide 3-kinase/protein kinase
        B signaling pathway.
      explanation: >-
        The signalling route established in this cell line - correctly tagged
        IN_VITRO, SVOG being a human granulosa-lutein line rather than an animal
        system.
    - reference: PMID:35079118
      reference_title: "Tie1 contributes to the development of ovarian hyperstimulation syndrome under the regulation of EGR1 in granulosa cells."
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: >-
        Taken together, our results indicate that Tie1 may be a therapeutic
        target in cases of moderate-to-severe OHSS. Further studies are needed to
        address its clinical relevance.
      explanation: >-
        The authors' own statement of the translational gap, which is why this
        model supports a PROVISIONAL node rather than an established one.
animal_models:
- name: Induced-OHSS rat with ovarian Tie1 knockdown
  species: Rat
  genotype: Wild type with shRNA-mediated ovarian Tie1 knockdown
  publication: PMID:35079118
  description: >-
    An experimentally established OHSS rat model in which ovaries show raised
    Tie1 and VEGF relative to controls, and in which knocking Tie1 down
    attenuates the syndrome histologically. It is the in vivo half of the
    evidence for the EGR1-TIE1 node - the cell line shows the molecular link, the
    rat shows that interrupting it changes the disease.
  modeled_mechanisms:
  - target: EGR1-TIE1 Amplification of Granulosa VEGF Output
    relationship: RESCUES
    fidelity: MODERATE
    description: >-
      Tie1 knockdown attenuates OHSS progression in the rat model, which is the
      whole-organism counterpart of the abolished VEGF rise seen in the cell
      line.
    limitations: >-
      Rat ovarian physiology differs from human in cycle length and in the
      relative roles of FSH and hCG, and an experimentally induced OHSS model
      compresses the stimulus into a schedule no patient experiences. The
      histological attenuation is also a structural rather than a functional
      readout: no measurement of vascular permeability or third-space fluid in
      the treated animals is reported.
    readouts:
    - name: Ovarian Tie1 and VEGF expression in induced OHSS
      target: EGR1-TIE1 Amplification of Granulosa VEGF Output
      direction: INCREASED
      interpretation: >-
        Both rise together in the model, matching the association seen in
        patient-derived granulosa cells.
      evidence:
      - reference: PMID:35079118
        reference_title: "Tie1 contributes to the development of ovarian hyperstimulation syndrome under the regulation of EGR1 in granulosa cells."
        supports: SUPPORT
        evidence_source: MODEL_ORGANISM
        snippet: >-
          as well as ovaries from rats with experimentally established OHSS,
          compared to controls
        explanation: >-
          The rat half of the expression result, quoted separately from the
          patient-cell half so this MODEL_ORGANISM item does not also carry an
          in vitro claim.
    - name: Histological progression of OHSS after Tie1 knockdown
      target: EGR1-TIE1 Amplification of Granulosa VEGF Output
      direction: DECREASED
      interpretation: >-
        Interrupting the proposed amplifier attenuates the disease in vivo, which
        is the strongest claim available for this node.
      evidence:
      - reference: PMID:35079118
        reference_title: "Tie1 contributes to the development of ovarian hyperstimulation syndrome under the regulation of EGR1 in granulosa cells."
        supports: SUPPORT
        evidence_source: MODEL_ORGANISM
        snippet: >-
          attenuated the progression of OHSS in rats, as determined by
          histological analysis.
        explanation: >-
          The in vivo attenuation readout and the method behind it, quoted apart
          from the cell-line clause of the same sentence.
    evidence:
    - reference: PMID:35079118
      reference_title: "Tie1 contributes to the development of ovarian hyperstimulation syndrome under the regulation of EGR1 in granulosa cells."
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: >-
        Ovaries harvested from control and experimentally induced OHSS rats, as
        well as those from OHSS rats subjected to Tie1 or nontargeting silencing,
        were used for histological analysis.
      explanation: >-
        Describes the rat model and its knockdown arm directly, which is the
        claim link-level evidence should make: that THIS model is informative for
        the target node. (The previous snippet here quoted an SVOG cell-line
        result, which is neither rat nor in vivo; it is now curated on the SVOG
        experimental model where it belongs.)
    - reference: PMID:35079118
      reference_title: "Tie1 contributes to the development of ovarian hyperstimulation syndrome under the regulation of EGR1 in granulosa cells."
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: >-
        Tie1 silencing attenuates the progression of experimentally induced OHSS
        in rats.
      explanation: >-
        States the in vivo result the model is curated for.
- name: Prolactin-supplemented OHSS rat model of VEGFR-2-dependent permeability
  species: Rat
  background: Wistar
  genotype: Wild type, gonadotropin-induced OHSS with prolactin supplementation
  publication: PMID:16901966
  description: >-
    The well-established rodent OHSS model in which the causal role of VEGFR-2 in
    the permeability rise was demonstrated, first by blockade with the antagonist
    SU5416 and then by dose-separating the receptor's permeability and angiogenic
    functions with low-dose cabergoline. Almost everything the entry asserts
    about VEGFR-2 being the modifiable node comes from this system, so it is
    recorded structurally rather than left implicit in the treatment description.
  modeled_mechanisms:
  - target: VEGFR-2 Activation on Vascular Endothelium
    relationship: PERTURBS
    fidelity: MODERATE
    description: >-
      Pharmacological manipulation of VEGFR-2 in this model - blockade with
      SU5416, partial dephosphorylation with low-dose cabergoline - is what
      establishes the receptor as necessary for the permeability rise and as
      separable from luteal angiogenesis.
    limitations: >-
      Rat, and a prolactin-supplemented model at that, because the dopamine-agonist
      arm requires a prolactin-responsive background that human OHSS does not
      have. The dose that separates permeability from angiogenesis was found in
      this species; the human prophylactic dose was chosen by extrapolation, and
      the clinical result reported alongside it is an uncontrolled comparison in
      oocyte donors rather than a randomised trial.
    readouts:
    - name: Vascular permeability after VEGFR-2 blockade
      target: VEGFR-2 Activation on Vascular Endothelium
      direction: ABOLISHED
      interpretation: >-
        Removing VEGFR-2 activity prevents the permeability rise, establishing
        necessity rather than association.
      evidence:
      - reference: PMID:16901966
        reference_title: "Low-dose dopamine agonist administration blocks vascular endothelial growth factor (VEGF)-mediated vascular hyperpermeability without altering VEGF receptor 2-dependent luteal angiogenesis in a rat ovarian hyperstimulation model."
        supports: SUPPORT
        evidence_source: MODEL_ORGANISM
        snippet: >-
          We previously demonstrated in an OHSS rodent model that increased VP
          was prevented by inactivating VEGFR-2 with a receptor antagonist
          (SU5416).
        explanation: >-
          The blockade readout.
    - name: Ovarian VEGFR-2 phosphorylation under low-dose cabergoline
      target: VEGFR-2 Activation on Vascular Endothelium
      direction: DECREASED
      interpretation: >-
        Partial dephosphorylation is enough to abolish the permeability response
        while sparing luteal angiogenesis, which is the dose-separation result
        the whole therapeutic strategy depends on.
      evidence:
      - reference: PMID:16901966
        reference_title: "Low-dose dopamine agonist administration blocks vascular endothelial growth factor (VEGF)-mediated vascular hyperpermeability without altering VEGF receptor 2-dependent luteal angiogenesis in a rat ovarian hyperstimulation model."
        supports: SUPPORT
        evidence_source: MODEL_ORGANISM
        snippet: >-
          A 100 microg/kg low-dose Dp-r2 agonist cabergoline reversed
          VEGFR-2-dependent VP without affecting luteal angiogenesis through
          partial inhibition of ovarian VEGFR-2 phosphorylation levels.
        explanation: >-
          The dose-separation readout.
    - name: Serum progesterone and luteal apoptosis under cabergoline
      target: VEGFR-2 Activation on Vascular Endothelium
      direction: UNCHANGED
      interpretation: >-
        A deliberate negative result: the corpus luteum is not damaged at the
        effective dose, which is what makes the intervention compatible with an
        ongoing pregnancy.
      evidence:
      - reference: PMID:16901966
        reference_title: "Low-dose dopamine agonist administration blocks vascular endothelial growth factor (VEGF)-mediated vascular hyperpermeability without altering VEGF receptor 2-dependent luteal angiogenesis in a rat ovarian hyperstimulation model."
        supports: SUPPORT
        evidence_source: MODEL_ORGANISM
        snippet: >-
          No luteolytic effects (serum progesterone levels and luteal apoptosis
          unaffected) were observed.
        explanation: >-
          The negative readout establishing luteal safety at the effective dose.
    evidence:
    - reference: PMID:16901966
      reference_title: "Low-dose dopamine agonist administration blocks vascular endothelial growth factor (VEGF)-mediated vascular hyperpermeability without altering VEGF receptor 2-dependent luteal angiogenesis in a rat ovarian hyperstimulation model."
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: >-
        To test whether VEGFR-2-dependent VP and angiogenesis could be segregated
        in a dose-dependent fashion with the Dp-r2 agonist cabergoline, a
        well-established OHSS rat model supplemented with prolactin was used.
      explanation: >-
        Names the model and the question it was built to answer.

clinical_trials:
- name: NCT03996434
  phase: PHASE_IV
  status: COMPLETED
  description: >-
    Randomised comparison of coasting against subcutaneous GnRH antagonist
    administration in patients at high risk of severe OHSS, with embryo quality
    and ICSI outcome as co-outcomes. Directly tests one of the secondary
    prevention manoeuvres curated on this entry against an alternative, in the
    population where the choice actually arises.
  target_phenotypes:
  - preferred_term: Enlarged ovaries
    term:
      id: HP:0100879
      label: Enlarged ovaries
  evidence:
  - reference: clinicaltrials:NCT03996434
    reference_title: "Coasting Versus Gonadotrophin-Releasing Hormone Antagonist Administration in Patients at High Risk of Ovarian Hyperstimulation Syndrome and Its Impact on the Embryos Quality and the Outcome of ICSI"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The aim of this work is to study the value of GnRH antagonist
      subcutaneous administration as an alternative to coasting in prevention of
      severe OHSS
    explanation: >-
      Establishes that the trial compares two secondary prevention strategies
      for severe OHSS.
- name: NCT02670304
  phase: PHASE_IV
  status: COMPLETED
  description: >-
    Randomised controlled trial of letrozole for prevention of moderate and
    severe OHSS in IVF. The rationale is mechanistically specific to this
    entry's pathograph: an aromatase inhibitor given in the luteal phase lowers
    oestrogen and suppresses luteal function, acting on the luteinized cohort
    that is the source of the VEGF surge rather than on the capillary leak.
  target_phenotypes:
  - preferred_term: Ascites
    term:
      id: HP:0001541
      label: Ascites
  evidence:
  - reference: clinicaltrials:NCT02670304
    reference_title: "The Randomized Controlled Trial Study of Letrozole in the Prevention of Medium and Severe Ovarian Hyperstimulation Syndrome in Invitro Fertilization Treatment"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Letrozole is one kind of aromatase inhibitors which may have effect on
      decrease estrogen in luteal phase and inhibit the luteal function of ovary.
    explanation: >-
      States the mechanistic rationale, which acts on the luteinization node
      rather than downstream.
- name: NCT02392520
  phase: NOT_APPLICABLE
  status: UNKNOWN
  description: >-
    GnRH antagonist administered in the luteal phase versus conventional
    treatment in women who have ALREADY developed severe early OHSS and have had
    all embryos cryopreserved. Curated because it is the rare trial addressed to
    established disease rather than to prevention - the specific evidence gap
    recorded in the ohss_established_disease_evidence_base discussion on this
    entry. Its status is UNKNOWN on the registry, which is itself informative
    about how thin that evidence base is.
  target_phenotypes:
  - preferred_term: Ascites
    term:
      id: HP:0001541
      label: Ascites
  evidence:
  - reference: clinicaltrials:NCT02392520
    reference_title: "GnRH Antagonist in the Luteal Phase Compared to Conventional Treatment in Women With Severe Early Ovarian Hyperstimulation Syndrome (OHSS) in Whom All Embryos Are Cryopreserved"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The study aims to compare the novel method of GnRH antagonist
      administration in the luteal phase versus conventional treatment in IVF
      patients who develop severe early ovarian hyperstimulation syndrome and
      have all their embryos cryopreserved.
    explanation: >-
      Confirms the population is women with established severe early OHSS, not
      women at risk of it.
- name: NCT06333691
  phase: NOT_APPLICABLE
  status: COMPLETED
  description: >-
    Three-arm comparison of calcium gluconate plus diosmin, cabergoline, and
    cabergoline plus diosmin for prevention of OHSS in high-risk women
    undergoing ICSI. Relevant because cabergoline is the one pharmacological
    prophylaxis curated on this entry with a defined molecular target, and this
    trial places it against non-mechanistic alternatives in the same population.
  target_phenotypes:
  - preferred_term: Ascites
    term:
      id: HP:0001541
      label: Ascites
  evidence:
  - reference: clinicaltrials:NCT06333691
    reference_title: "Comparative Study Between Calcium Gluconate With Diosmin, Cabergoline and Cabergoline With Diosmin in Prevention of Ovarian Hyperstimulation Syndrome in High-risk Women Undergoing Intracytoplasmic Sperm Injection (ICSI) Procedures"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      This syndrome is characterized by a sudden increase of the vascular
      permeability which results in the development of a massive extravascular
      exudate in the peritoneal cavity, pleural, pericardium causing ascites,
      pleural and pericardial effusion.
    explanation: >-
      The trial protocol's own statement of the mechanism this entry curates -
      a permeability rise producing serosal-cavity exudate - independently
      corroborating the pathograph from a registered clinical protocol.
  - reference: clinicaltrials:NCT06333691
    reference_title: "Comparative Study Between Calcium Gluconate With Diosmin, Cabergoline and Cabergoline With Diosmin in Prevention of Ovarian Hyperstimulation Syndrome in High-risk Women Undergoing Intracytoplasmic Sperm Injection (ICSI) Procedures"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Severe forms are also accompanied by electrolyte disturbances and
      cardiopulmonary, hepatic, renal, and hemoconcentration associated with
      increased thromboembolic risk.
    explanation: >-
      Corroborates the severe-form phenotype cluster curated here -
      haemoconcentration, electrolyte disturbance, renal and respiratory
      involvement, thromboembolic risk.
- name: NCT03794037
  phase: PHASE_II
  status: SUSPENDED
  description: >-
    Montelukast with dydrogesterone versus dydrogesterone alone for prevention
    and treatment of OHSS in freeze-all cycles. Curated as a negative datum
    about the field rather than as evidence for the drug: it is suspended, and
    it is the only registered trial found that targets the leukotriene arm.
  target_phenotypes:
  - preferred_term: Ascites
    term:
      id: HP:0001541
      label: Ascites
  evidence:
  - reference: clinicaltrials:NCT03794037
    reference_title: "Montelukast for Prevention & Treatment of Ovarian Hyperstimulation Syndrome in Freeze-all Cycles"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      montelukast \& dydrgesteron will be given to cases with suspected or
      proven ovarian hyperstimulation in one group in comparison with
      dydrogesteron alone in the other group.
    explanation: >-
      States the intervention and comparator; the registry record's typography
      (including the escaped ampersand and the misspellings) is quoted verbatim.

progression:
- phase: Early OHSS
  notes: >-
    Early OHSS begins in the days after the hCG trigger and oocyte retrieval and
    reflects the preovulatory response to stimulation - it is the arm that peak
    oestradiol and oocyte number predict, and the arm that protocol choice,
    coasting and trigger substitution can pre-empt. Women with early OHSS have
    significantly higher serum oestradiol and lower gonadotropin requirements
    than either late-OHSS or unaffected women, which is the signature of an
    ovary that responded excessively to a modest dose.
  evidence:
  - reference: PMID:10785214
    reference_title: "Distinction between early and late ovarian hyperstimulation syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Early OHSS relates to "excessive" preovulatory response to stimulation,
      whereas late OHSS depends on the occurrence of pregnancy, is likelier to
      be severe, and is only poorly related to preovulatory events.
    explanation: >-
      The defining statement of the two-phase distinction and of what each phase
      depends on.
  - reference: PMID:10785214
    reference_title: "Distinction between early and late ovarian hyperstimulation syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Women with early OHSS had significantly higher serum E(2) levels and lower
      gonadotropin requirements than did the other groups.
    explanation: >-
      Gives the biochemical signature that separates early OHSS from the late
      form and from unaffected cycles.
- phase: Late OHSS
  notes: >-
    Late OHSS begins later and depends on pregnancy: the endogenous hCG of an
    implanting conceptus sustains the luteinizing stimulus for weeks rather than
    days. Three consequences follow and all are clinically important. It is
    likelier to be severe than the early form. It cannot be predicted from
    preovulatory measurements - serum oestradiol and oocyte number, which work
    for early OHSS, do not identify who will develop it. And it is the arm that
    freeze-all abolishes, since deferring transfer removes the pregnancy
    entirely. In one series clinical pregnancies occurred in every late-OHSS
    cycle, and in another 77.8% of late-onset cases had a concurrent positive
    pregnancy test.
  evidence:
  - reference: PMID:10785214
    reference_title: "Distinction between early and late ovarian hyperstimulation syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Serum E(2) and oocyte numbers did not accurately predict the risk of
      developing late OHSS.
    explanation: >-
      Establishes that the predictors used for early OHSS fail for the late
      form, which is why prevention of late OHSS is structural (freeze-all)
      rather than predictive.
  - reference: PMID:10785214
    reference_title: "Distinction between early and late ovarian hyperstimulation syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Clinical pregnancies occurred in all cycles with late OHSS, and multiple
      pregnancies were significantly more frequent in the late OHSS group than
      in the other groups.
    explanation: >-
      Ties the late form to pregnancy, and to multiple pregnancy in particular -
      the higher-hCG case.
  - reference: PMID:10785214
    reference_title: "Distinction between early and late ovarian hyperstimulation syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Late OHSS was more likely than early OHSS to be severe.
    explanation: >-
      Records the severity difference between the two phases.
  - reference: PMID:18956797
    reference_title: "Are pregnancy rates compromised following embryo freezing to prevent OHSS?"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Two distinct incidence peaks of OHSS were identified--early and late.
      77.77% of women who suffered from late onset OHSS had a concurrent
      positive pregnancy test.
    explanation: >-
      Independent confirmation of the bimodal timing and of the pregnancy
      association in the late peak.

prevalence:
- population: >-
    Women undergoing assisted reproductive technology treatment (per treatment
    cycle, not general population)
  measure_type: PERIOD_PREVALENCE
  prevalence_class: ABOVE_1_IN_1000
  rate_per_100000: 1000.0
  notes: >-
    Roughly 1% of ART-treated women develop severe OHSS. This is a risk per
    treatment episode in an exposed population, not a population prevalence —
    the syndrome does not occur outside gonadotropin exposure or pregnancy, so a
    general-population denominator would be meaningless. Recorded as
    PERIOD_PREVALENCE for that reason.
  evidence:
  - reference: PMID:27273307
    reference_title: "Pathophysiology, treatment and prevention of ovarian hyperstimulation syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Severe ovarian hyperstimulation syndrome (OHSS) is an iatrogenic condition
      that affects 1% of women that undergo treatment with assisted reproductive
      technology.
    explanation: >-
      Direct statement of the proportion of ART-treated women affected by severe
      OHSS.
- population: >-
    Hospitalized moderate-to-severe OHSS cases per ovum pick-up cycle, China,
    2013-2017 (1,581,703 cycles)
  measure_type: PERIOD_PREVALENCE
  prevalence_class: ABOVE_1_IN_1000
  rate_per_100000: 1140.0
  notes: >-
    Nationwide inpatient data give 1.14% of ovum pick-up cycles complicated by
    moderate or severe OHSS, with a year-on-year fall from 1.4% (2014-2015) to
    0.9% (2017) that is consistent with the uptake of antagonist protocols and
    agonist triggers. Denominator is retrieval cycles, not women.
  evidence:
  - reference: PMID:38487201
    reference_title: "The Incidence of Moderate and Severe Ovarian Hyperstimulation Syndrome in Hospitalized Patients in China."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The overall incidence of moderate and severe OHSS between 2013 and 2017
      was 1.14%.
    explanation: >-
      Gives the pooled cycle-based rate from a nationwide inpatient dataset.
  - reference: PMID:38487201
    reference_title: "The Incidence of Moderate and Severe Ovarian Hyperstimulation Syndrome in Hospitalized Patients in China."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      We extracted 18,022 eligible patients with moderate or severe OHSS and
      1,581,703 OPU cycles.
    explanation: >-
      Records the numerator and denominator behind the rate.
- population: >-
    Severe OHSS as a proportion of stimulated populations (range across studies)
  measure_type: PERIOD_PREVALENCE
  prevalence_class: ABOVE_1_IN_1000
  rate_low: 500.0
  rate_high: 5000.0
  notes: >-
    Reported severe-OHSS rates span an order of magnitude between series, which
    reflects genuinely different case definitions and stimulation eras rather
    than measurement error. Recorded as a range for that reason.
  evidence:
  - reference: PMID:26506672
    reference_title: "Non-invasive ventilation for the treatment of acute respiratory failure following ovarian hyperstimulation syndrome: report of two cases and a brief review of the literature."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The severe form of OHSS varies between 0.5% and 5%, depending on the
      population studied
    explanation: >-
      Gives the reported range and attributes its width to the population
      studied.
diagnosis:
- name: Pelvic Ultrasonography
  description: >-
    Transvaginal or transabdominal ultrasound demonstrating enlarged multicystic
    ovaries and free peritoneal fluid is the primary diagnostic study, and in
    the severe form also shows pleural fluid. It is available at the bedside,
    which matters in a syndrome that can deteriorate over hours.
  evidence:
  - reference: PMID:26506672
    reference_title: "Non-invasive ventilation for the treatment of acute respiratory failure following ovarian hyperstimulation syndrome: report of two cases and a brief review of the literature."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The diagnosis of severe OHSS was made, largely based on bedside
      ultrasonography showing increased ovarian size, mild ascites and bilateral
      pleural effusions.
    explanation: >-
      Documents bedside ultrasound as the basis on which the severe diagnosis
      was made.
- name: FSHR Sequencing in Recurrent Spontaneous OHSS
  description: >-
    Sequencing FSHR is what separates the familial gestational form from a
    sporadic spontaneous case, and the distinction is prognostic rather than
    academic: an activating allele predicts recurrence in every subsequent
    pregnancy, and family members may carry it. Before sequencing, the
    differential of an enlarged multicystic ovarian mass in pregnancy —
    malignancy, pregnancy luteoma, hyperreactio luteinalis — has to be excluded.
  evidence:
  - reference: PMID:23941020
    reference_title: "Spontaneous ovarian hyperstimulation syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      In the differential diagnosis, malignancy, pregnancy luteoma and
      hyperreactio luteinalis would have to be excluded.
    explanation: >-
      States the differential diagnosis that has to be settled before a
      spontaneous OHSS diagnosis is accepted.
  - reference: PMID:15080154
    reference_title: "A mutation in the follicle-stimulating hormone receptor as a cause of familial spontaneous ovarian hyperstimulation syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      In this report, we describe a new familial case of recurrent OHSS.
    explanation: >-
      Documents that the familial form presents as recurrent disease, which is
      what makes identifying the allele worthwhile.
discussions:
- discussion_id: ohss_hcg_not_obligate
  kind: KNOWLEDGE_GAP
  status: OPEN
  prompt: >-
    Is human chorionic gonadotropin actually necessary for OHSS to develop, and
    if not, what supplies the VEGF stimulus in the cases that occur without it?
  attaches_to:
  - "pathophysiology#Ovarian VEGF Hypersecretion"
  - "pathophysiology#hCG-Driven Luteinization of the Recruited Cohort"
  rationale: >-
    The whole preventive strategy of modern assisted reproduction — substituting
    a GnRH agonist trigger for hCG, freezing all embryos to avoid endogenous
    pregnancy hCG — is built on hCG being the obligatory driver of the VEGF
    surge. A 2016 review states that recent case reports have shown OHSS
    occurring without it. If that is right, then either the luteinized ovary can
    reach the VEGF threshold on LH activity alone in some women, or a second
    stimulus exists that current protocols do not remove, and the residual OHSS
    seen in agonist-trigger cycles is explained rather than anomalous. The
    entry's causal chain is drawn with hCG as the principal but not the sole
    stimulus for that reason.
  proposed_experiments:
  - experiment_id: ohss_vegf_in_agonist_trigger_cases
    name: Serial serum VEGF in agonist-trigger cycles complicated by OHSS
    description: >-
      Measure circulating VEGF serially in women who develop OHSS after a GnRH
      agonist trigger with no hCG exposure, comparing against hCG-triggered
      cases matched for follicle count, to establish whether the VEGF surge
      occurs at comparable magnitude without hCG.
  evidence:
  - reference: PMID:27273307
    reference_title: "Pathophysiology, treatment and prevention of ovarian hyperstimulation syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Human chorionic gonadotropin was previously thought to be necessary for
      OHSS to occur; however, recent case reports have proven otherwise.
    explanation: >-
      States directly that the assumed obligate role of hCG has been
      contradicted by case reports.
- discussion_id: ohss_tie1_human_relevance
  kind: HUMAN_MODEL_MISMATCH
  status: OPEN
  prompt: >-
    Does the EGR1-Tie1 axis that is required for hCG-induced VEGF in a
    granulosa-lutein cell line and in the rat model operate in intact human
    ovarian tissue, and is Tie1 therefore a usable therapeutic target?
  attaches_to:
  - "pathophysiology#EGR1-TIE1 Amplification of Granulosa VEGF Output"
  rationale: >-
    The Tie1 result is unusually well constructed for a mechanism at this stage:
    an association in granulosa cells taken from actual OHSS patients, a
    loss-of-function experiment abolishing the hCG-VEGF link in a human
    granulosa-lutein line, attenuation of the syndrome in rats, and an identified
    transcriptional route via EGR1. What it does not have is any demonstration in
    intact human ovary or any clinical exposure. The mismatch is mechanistically
    meaningful because the therapeutic argument for targeting Tie1 rests entirely
    on it sitting upstream of VEGF: an agent acting there would in principle
    spare the VEGFR-2-dependent luteal angiogenesis that a direct VEGFR-2
    antagonist destroys, which is the specific reason SU5416 was abandoned. If
    the axis turns out to be a cell-line and rodent phenomenon, that argument
    disappears and the field is back to dose-separating a dopamine agonist. The
    reporting authors say as much themselves.
  proposed_experiments:
  - experiment_id: ohss_tie1_egr1_human_ovarian_tissue
    name: Tie1 and EGR1 expression in human ovarian tissue across OHSS risk strata
    description: >-
      Quantify Tie1 and EGR1 in ovarian tissue or aspirated granulosa cells from
      women stratified by OHSS risk and by trigger type (hCG versus GnRH
      agonist), testing whether the induction predicted by the cell-line work is
      present in vivo and whether it tracks trigger exposure.
  evidence:
  - reference: PMID:35079118
    reference_title: "Tie1 contributes to the development of ovarian hyperstimulation syndrome under the regulation of EGR1 in granulosa cells."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      Taken together, our results indicate that Tie1 may be a therapeutic target
      in cases of moderate-to-severe OHSS. Further studies are needed to address
      its clinical relevance.
    explanation: >-
      The authors state the translational gap explicitly.
- discussion_id: ohss_established_disease_evidence_base
  kind: KNOWLEDGE_GAP
  status: OPEN
  prompt: >-
    Is there any intervention that shortens or attenuates established OHSS,
    rather than preventing it?
  attaches_to:
  - "pathophysiology#Third-Space Fluid Shift and Intravascular Volume Depletion"
  rationale: >-
    Almost the entire evidence base for this syndrome sits on the preventive
    side of the hCG trigger — protocol choice, trigger substitution, freeze-all,
    prophylactic cabergoline. Once the capillary leak is established, management
    is supportive and, by the reviewing authors' own account, based on consensus
    rather than evidence. That asymmetry is defensible while prevention keeps
    working, but it leaves the women who develop severe disease anyway with no
    treatment aimed at the mechanism. Whether the VEGFR-2 node remains
    modifiable after the leak has started — that is, whether cabergoline has any
    therapeutic as opposed to prophylactic effect — is the specific unanswered
    question, and the cabergoline evidence cited here is prophylactic only.
  proposed_experiments:
  - experiment_id: ohss_cabergoline_established_disease_rct
    name: Randomised trial of cabergoline in established moderate-to-severe OHSS
    description: >-
      Randomise women hospitalised with established moderate-to-severe OHSS to
      cabergoline or placebo on top of standard supportive care, with time to
      resolution of ascites, haematocrit trajectory and length of stay as
      outcomes, to test whether the VEGFR-2 node is still modifiable once the
      leak is established.
  evidence:
  - reference: PMID:27273307
    reference_title: "Pathophysiology, treatment and prevention of ovarian hyperstimulation syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Treatment is largely supportive and is based mainly on consensus
      statements rather than evidence.
    explanation: >-
      States the evidence gap on the treatment side of established disease.
datasets:
- accession: geo:GSE183346
  title: High throughput sequencing data of ovarian hyperstimulation syndrome (OHSS) mouse model
  description: >-
    RNA sequencing of ovaries from an established mouse OHSS model, reported as
    showing strengthened cell junctions between ovarian vessels after drug
    treatment - the transcriptional counterpart of the inter-endothelial
    junction loosening that this entry curates as the VEGFR-2-mediated
    permeability node.
  organism:
    preferred_term: house mouse
    term:
      id: NCBITaxon:10090
      label: Mus musculus
  data_type: BULK_RNA_SEQ
  sample_count: 6
  publication: PMID:35221672
  notes: >-
    Identified by GEO DataSets index search (scripts/discover_datasets.py) and
    verified against NCBI E-utilities on 2026-08-25; title, sample count and
    organism are GEO's own values. Relevance triaged manually: this is the OHSS
    syndrome itself in a disease model, not merely a superovulation protocol.
    Two other DIRECT-scored candidates were rejected on that same triage -
    GSE229048 (ovine caruncular endometrium after FSH superovulation) studies
    the uterus after a stimulation protocol rather than the hyperstimulation
    syndrome, and GSE39402 is an epithelial ovarian tumour model. Both would
    have resolved perfectly while being about something else.

notes: >-
  On the scope of MONDO:0011972 and why this is one entry with two subtypes.
  The MONDO term is internally conflated: its textual definition is the MeSH
  definition of the iatrogenic complication of ovulation induction, while its
  OMIM xref (608115) and its FSHR gene association and hereditary-disease parent
  all belong to the rare familial gestational spontaneous form. Rather than pick
  one and discard the other, this entry curates the concept as MONDO scopes it —
  a single disease with a shared final common pathway (multifollicular
  luteinization, ovarian VEGF hypersecretion, VEGFR-2-mediated capillary leak)
  reached by an iatrogenic and a hereditary route, modelled as two subtypes. A
  third, non-genetic and non-iatrogenic route — promiscuous activation of the
  wild-type receptor by very high hCG or TSH — is curated as its own trigger
  node because it belongs to neither subtype.

  The non-VEGF mediators. An earlier revision of this note claimed the
  anti-Mullerian-hormone / dendritic-cell / interleukin arm was omitted because
  no quotable source existed. That was wrong, and the correction is recorded
  here rather than silently made: PMID:27273307 - already cited several times in
  this entry - states it directly, and that sentence is now curated as PARTIAL
  evidence on the `Increased Systemic Vascular Permeability` node, where it
  qualifies the claim that the leak is a pure VEGF effect. It is deliberately
  not given its own pathophysiology node: the source describes it as "explored
  recently as contributors", which supports a hedge on an existing node but not
  a separate causal chain.

  The ovarian renin-angiotensin arm: a second correction, of the same kind and in
  the same place. An earlier revision said no verifiable source for it existed.
  That was wrong, and worse, it was wrong about two references added in the very
  commit that said it - PMID:26752241 and PMID:35154015 both state the
  renin-angiotensin-to-VEGF link explicitly. The arm is now curated as its own
  PROVISIONAL modifier node, wired from the luteinization node and into VEGF
  hypersecretion, and it carries the mechanistic rationale for intravenous
  calcium, which ranks above cabergoline in both meta-analyses. The recurrence of
  this defect class - asserting an absence of evidence without re-checking the
  references in hand - is why both corrections are left visible here rather than
  quietly edited away.

  Still not curated: IL-6/IL-8 as named cytokines, and the arm mediated by
  platelet-activating factor. These appear in review literature reachable only
  through the deep-research report's internal citation keys, and no source in
  this entry's reference set states them. That claim was checked against every cached
  reference before being written this time. The angiopoietin/TIE arm IS curated,
  because a primary functional study (PMID:35079118) exists for it.

  Prevalence figures are all cycle-based; there is no meaningful
  general-population denominator for a syndrome that requires gonadotropin
  exposure or pregnancy to occur.

  On LHCGR. The lutropin/choriogonadotropin receptor is the receptor hCG is
  actually specific for, and the entry's pathograph depends on hCG receptor
  signalling at the luteinization node. It is therefore recorded as a `genes:`
  annotation ON that node rather than as a `genetic:` entry: no LHCGR variant
  causes this disease, and a `genetic:` block with `relationship_type: UNKNOWN`
  and no LHCGR-specific evidence was signalling that it did not belong there. The
  mechanistic contrast it exists to mark is worth restating: in iatrogenic OHSS
  hCG acts on its own receptor, whereas in the familial spontaneous form the
  whole point is that hCG acts on a mutant FSHR whose ligand specificity is lost.

  On hepatic involvement. Severe OHSS is reported with hepatic involvement, and
  review literature commonly cites transaminase elevation in roughly 30% of
  severe cases. The phenotype here is bound to the broad `HP:0031865 Abnormal
  liver physiology` rather than to `HP:0002910 Elevated circulating hepatic
  transaminase concentration`, because no source cited on this entry states the
  transaminase finding - only that severe forms are accompanied by hepatic
  involvement. The more specific binding would assert a laboratory abnormality
  the evidence does not carry.

  On the two network meta-analyses. Both were originally cited by DOI, then
  re-resolved to PMID:35154015 and PMID:26752241. This is worth recording as a
  mechanical point: `DOI:` is listed under `skip_prefixes` in
  `conf/reference_validator_config.yaml`, so nine snippets quoted from those two
  papers were silently NOT snippet-checked while they carried DOI references
  (`just count-verified-snippets` reported "9 skipped by prefix"). Re-keying them
  to PMIDs moved all nine into the checked set. Prefer PMIDs wherever a DOI
  resolves to one.

📚

References & Deep Research

References

24

PMID:15080154

A mutation in the follicle-stimulating hormone receptor as a cause of familial spontaneous ovarian hyperstimulation syndrome.