Pelvic Organ Prolapse

Complex MONDO:0000082 Pathograph 20 Show in embeddings browser reproductive system disorder female reproductive system disease

Pelvic organ prolapse is the downward descent of the bladder, uterus, post-hysterectomy vaginal cuff, or bowel, producing protrusion of the vaginal walls or uterus toward and beyond the hymen. It is a mechanical failure of a composite support system rather than a disease of one tissue: the levator ani muscles hold the pelvic floor closed, and the cardinal, uterosacral and paravaginal connective tissue attachments suspend the uterus and vagina from the pelvic sidewall. The two elements are load-sharing, so failure of either transfers load to the other, and the modern anatomic evidence places the primary lesion in the muscle: birth-induced injury to the pubococcygeal portion of the levator ani is present in 55% of women with prolapse against 16% of women with normal support, and enlarges the urogenital hiatus so that vaginal wall descending below the hymen is exposed to a pressure differential that then loads the connective tissue attachments abnormally. A parallel connective tissue arm supplies susceptibility rather than the initiating injury. Recovery of pelvic organ support after vaginal delivery requires a postpartum burst of elastic fiber assembly; mice null for LOXL1 or FBLN5 cannot make it and prolapse, and human GWAS repeatedly returns connective tissue and estrogen-pathway loci (WNT4, EFEMP1, WT1, FGFR2). At the protein level, prolapsed tissue shows less type I collagen and TIMP-1 and more type III collagen and MMP-1/-2/-9, with oxidative injury markers raised in the uterosacral ligament and the vaginal wall muscularis depleted of smooth muscle. Whether that matrix signature is cause or consequence is genuinely unsettled and is curated here as an open gap rather than assumed. Prolapse is extremely common as an anatomic finding and much less common as a complaint - anatomy and symptoms track each other poorly, and only vaginal bulging is specific to it. Management is graded from observation through pelvic floor muscle training and vaginal pessary to reconstructive surgery, none of which repairs the levator injury itself; a widened genital hiatus predicts surgical failure, which is the clinical signature of an unaddressed muscular lesion.

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Mechanistic Hypotheses

Birth injury to the levator ani is the primary lesion, with connective tissue failure secondary to the resulting pressure differential

levator_muscle_failure_primary CANONICAL

Evidence balance 3 support

The dominant contemporary model, built on imaging of living women rather than on cadaveric or operative inference. Normal support is a load-sharing system: the levator ani holds the hiatus closed so that pressures above and below the vaginal wall balance and cancel. Birth overstretch tears the pubococcygeal origin; the hiatus opens; vaginal wall descending below the hymen now sits between abdominal and atmospheric pressure, and the resulting differential loads the cardinal, uterosacral and paravaginal attachments abnormally until they too fail. On this model the connective tissue lesion is real and measurable but downstream, and the vaginal wall fascia contributes least of all.

Show evidence (3 references)

PMID:27517338 SUPPORT Human Clinical

"Pelvic organ prolapse occurs because of injury to the levator ani muscles and failure of the lateral connections between the pelvic organs to the pelvic sidewall. Abnormalities of the vaginal wall fascial tissues may play a minor role."

The review's own summary statement, which both asserts the muscular primacy and explicitly demotes the vaginal wall fascial arm.

PMID:27517338 SUPPORT Human Clinical

"Muscle failure exposes the vaginal wall to a pressure differential producing abnormal tension on the attachments of the pelvic organs to the pelvic sidewall."

States the mechanical route by which a muscular lesion produces a connective tissue lesion, which is what makes the ordering of this hypothesis testable.

PMID:38168908 SUPPORT Human Clinical

"The injury is present in 55% of women with prolapse later in life, with an odds ratio of 7.3, compared with women with normal support."

The effect size for the muscular lesion, larger than that reported for any single matrix marker.

A constitutional extracellular matrix defect is the primary lesion, with childbirth acting as the unmasking load

connective_tissue_matrix_primary ALTERNATIVE

Evidence balance 2 support 1 refute

The older and still-live account, in which the initiating abnormality is in the connective tissue itself: reduced load-bearing type I collagen, a shift toward type III, excess matrix metalloproteinase activity with insufficient inhibition, and impaired elastic fiber renewal. Its strongest support is not the human tissue comparisons, which are cross-sectional and cannot order cause and effect, but the mouse knockouts, where deleting a single elastogenesis gene produces prolapse with no obstetric injury required, and the human genetic signal at connective tissue loci. Its weakness is that the human tissue changes may be reactive: the one study that compared uterosacral ligament with vaginal tissue found the changes larger in the vagina, the tissue actually being stretched.

Show evidence (3 references)

PMID:38291948 SUPPORT Human Clinical

"Patients with POP have lower expression of COLI and TIMP-1 and higher expression of COLIII and MMPs compared with non-POP cases, but further studies are required to investigate in specified anatomical sites."

Pooled quantification of the matrix signature this hypothesis rests on, with the authors' own caveat about anatomical site attached.

PMID:35088092 SUPPORT Model Organism

"Mouse knockout (KO) models of pelvic organ prolapse (POP) have contributed mechanistic evidence for the role of connective tissue defects, specifically impaired elastic matrix remodeling."

The animal evidence that a matrix lesion alone is sufficient, which is what this hypothesis needs and what the cross-sectional human data cannot supply.

PMID:16398770 REFUTE DIRECT Human Clinical

"The changes which are more pronounced in vaginal tissue may be as a result of prolapse rather than cause."

Cuts against this hypothesis rather than for it. The authors of a matrix study decline to draw the causal conclusion the hypothesis requires and name reverse causation as the likelier reading of their own tissue comparison, which is the weakness the hypothesis description states.

Discussions and Knowledge Gaps

Is the collagen and MMP/TIMP signature of prolapsed tissue a cause of the mechanical failure or a response to it?

KNOWLEDGE GAP OPEN gap_matrix_cause_or_consequence

Attached to

pathophysiology#Collagen and MMP-TIMP Remodelling Imbalance

Every human study behind this node is cross-sectional and takes tissue from women who already have prolapse, usually at the time of surgery for it. That design cannot order cause and effect, and one observation actively points the wrong way: the study that sampled both compartments found the changes larger in vaginal tissue, the tissue being stretched, than in the uterosacral ligament, where the differences were not significant at all. The distinction is not academic. If the matrix lesion is causal, it is a target and a screening opportunity; if it is reactive, then a large fraction of the prolapse literature is measuring a consequence and calling it a mechanism, and interventions aimed at collagen turnover are aimed at the wrong thing. The edge from this node is typed INDIRECT_UNKNOWN_INTERMEDIATES for exactly this reason.

Proposed experiments

Prospective matrix profiling in a nulliparous cohort followed through first delivery

prospective_matrix_profiling_nulliparous_cohort

Sample accessible connective tissue and measure collagen I/III ratio and MMP/TIMP profile before first pregnancy in a cohort followed with serial pelvic floor imaging. A pre-existing matrix signature in women who later prolapse would establish antecedence; a signature that appears only after descent would settle the question the other way.

Site-paired sampling of loaded and unloaded tissue within the same woman

site_paired_loaded_unloaded_sampling

Within individual prolapse cases, compare matrix markers between mechanically loaded vaginal wall and an unloaded connective tissue site from the same patient. A difference confined to the loaded site argues for a mechanoresponsive, and therefore reactive, change.

Show evidence (1 reference)

PMID:16398770 SUPPORT Human Clinical

"The changes which are more pronounced in vaginal tissue may be as a result of prolapse rather than cause."

The authors of a matrix study stating the reverse-causation possibility themselves, which is what makes this a gap rather than a curator's doubt.

Why does anatomic descent correspond so poorly to symptoms, and what determines which women with the same POP-Q stage are bothered?

KNOWLEDGE GAP OPEN gap_anatomy_symptom_discordance

Attached to

pathophysiology#Descent of the Pelvic Organs Beyond the Hymen

Prolapse is one of the few conditions where the defining anatomic lesion and the clinical complaint are close to uncoupled. Symptomatic prolapse affects about 3% of US women, while descent on examination is far commoner; of the symptoms attributed to prolapse only vaginal bulging is specific. This has practical consequences throughout the entry: prevalence figures are not comparable unless the ascertainment is stated, the mechanistic chain ends at an anatomic node rather than at a symptom, and surgical trials that report anatomic success are not reporting what patients came for. Nothing in the sources used here explains the discordance.

Show evidence (2 references)

PMID:31851453 SUPPORT Human Clinical

"The anatomical changes do not always consist with the severity or the symptoms associated with prolapse."

States the discordance as a standing problem for the field's epidemiology.

PMID:17382829 SUPPORT Human Clinical

"Many women with pelvic organ prolapse are asymptomatic and do not need treatment."

The clinical corollary, and the reason observation is a legitimate management option.

Does the elastogenesis-failure mechanism established in Loxl1- and Fbln5-null mice operate in human pelvic organ prolapse?

HUMAN MODEL MISMATCH OPEN mismatch_elastogenesis_knockout_mice

Attached to

pathophysiology#Impaired Elastic Fiber Assembly and Postpartum Elastogenesis

The entire mechanistic case that a matrix lesion is sufficient to cause prolapse rests on two mouse knockouts, and the translational distance is larger than it first appears. Neither gene is returned by the human association studies curated here, which instead implicate WNT4, EFEMP1, WT1 and FGFR2; both are germline nulls rather than the common regulatory variants human genetics finds; and a quadruped loads its pelvic floor differently from a biped, so the same molecular lesion need not produce the same mechanical failure. The Fbln5 paper's own comparison is to prolapse in primates rather than in women. This is a mismatch and not merely a gap because the evidence exists and is strong; it is its applicability to human disease that is unresolved.

Proposed experiments

Elastic fiber and elastogenic enzyme profiling in human postpartum vaginal tissue

human_postpartum_elastogenesis_profiling

Measure desmosine content, tropoelastin, LOXL1 and fibulin-5 in human vaginal tissue across the postpartum period, to test whether the elastogenic burst the mouse studies identified exists in women at all, and whether it is attenuated in those with levator injury or later prolapse.

Rare-variant burden testing of elastogenesis genes in prolapse cases

elastogenesis_rare_variant_burden

Sequence LOXL1, FBLN5 and related elastogenesis genes in a large prolapse cohort and test for rare loss-of-function burden. A positive result would connect the murine mechanism to human disease; a clean negative would confine these models to demonstrating sufficiency in principle.

Show evidence (2 references)

PMID:17255326 SUPPORT INDIRECT Model Organism

"disordered elastic fiber homeostasis is a primary event in the pathogenesis of pelvic organ prolapse in mice"

The claim at issue, quoted with the species restriction the authors themselves attached to it. Indirect for that reason: it is a result in a non-human model, and whether it transfers to women is the mismatch this discussion records.

PMID:32184442 SUPPORT INDIRECT Human Clinical

"found eight sequence variants at seven loci associating with POP"

The human genetic result whose gene list does not include the two genes the mouse models are built on. The mismatch follows from comparing that list with the mouse loci rather than from anything the quoted sentence states.

Should the matrix node conform to emphysema_protease_antiprotease_imbalance#Protease-Antiprotease Imbalance?

INTERPRETATION OPEN interpretation_no_emphysema_module_conformance

Attached to

pathophysiology#Collagen and MMP-TIMP Remodelling Imbalance

The temptation is real and is worth recording rather than leaving as a silent omission. Prolapse shows raised MMP-1/-2/-9 with reduced TIMP-1, and the Loxl1 mouse develops enlarged pulmonary airspaces alongside its prolapse from the same elastogenesis defect, so the two diseases genuinely share an elastin-loss biology. Conformance was nonetheless withheld on three grounds. First, the module is scoped to the alveolus throughout: its trigger node is inhaled oxidants and particulates and every downstream node is alveolar, so a conforming pelvic node would inherit claims about airway inflammation that are false here. Second, the module's imbalance is driven by proteases released from recruited neutrophils and macrophages, and no such phagocyte infiltrate is evidenced in prolapsed pelvic tissue in any source used here; the cellular source of the MMPs is presumed to be the resident fibroblast. Third, and decisively, the module asserts its imbalance node as causal, whereas the causal direction of the same signature in prolapse is an open gap in this very entry. Declaring conformance would launder an unresolved question into an asserted mechanism. A genuinely disease-agnostic module for load-bearing soft tissue matrix failure, which would also serve hernia, where the human genetics here overlaps, may be worth proposing separately.

Show evidence (1 reference)

PMID:14745449 SUPPORT INDIRECT Model Organism

"Failure to maintain elastic fibers is explained by a theory of antielastase-elastase imbalance, but little is known about the role of renewal."

Names the protease-antiprotease framing and, in the same sentence, sets renewal against it as the mechanism this paper actually demonstrates. The conclusion drawn here - that the prolapse node is a renewal failure rather than a protease imbalance, so conformance is withheld - is an inference from that contrast.

⚙

Pathophysiology

Vaginal Childbirth Mechanical Overload

Passage of the fetal head requires the levator ani and the soft tissues of the birth canal to stretch to more than three times their resting length. This is the single largest modifiable risk factor for prolapse, and the mechanism of damage is specifically overstretch rather than compression ischaemia or pudendal neuropathy - a distinction that matters because it identifies the tissue at risk (the vulnerable muscle origin) and the obstetric variables that load it. It is a normal physiological event that most women recover from; the disease begins where recovery fails.

response to mechanical stimulus GO:0009612 ↑ INCREASED

levator ani muscle UBERON:0001326 vagina UBERON:0000996

Downstream

Levator Ani Muscle Injury and Avulsion Overstretch tears the muscle, most often detaching the pubovisceral/pubococcygeal portion from its pubic origin.

Impaired Elastic Fiber Assembly and Postpartum Elastogenesis Delivery imposes the demand for a postpartum burst of elastic fiber synthesis and cross-linking in the vaginal wall; this edge is the demand, and the downstream node is the failure to meet it.

Show evidence (3 references)

PMID:38168908 SUPPORT Human Clinical

"During birth, the levator muscle and birth canal tissues must stretch to more than 3 times their original length; it is this overstretching that is responsible for the muscle tear visible on imaging rather than compression or neuropathy."

Quantifies the strain and, importantly for node typing, excludes the two alternative injury mechanisms.

PMID:38168908 SUPPORT Human Clinical

"Risk factors for levator injury are multifactorial and include forceps delivery, occiput posterior birth, older maternal age, long second stage of labor, and birthweight of >4000 g."

Names the obstetric variables that modulate the load, which is what makes this node a modifiable one.

PMID:17382829 SUPPORT Human Clinical

"Prolapse development is multifactorial, with vaginal child birth, advancing age, and increasing body-mass index as the most consistent risk factors."

Independent confirmation that vaginal childbirth is among the most consistent risk factors, alongside the two other triggers curated in this entry.

Levator Ani Muscle Injury and Avulsion

Detachment or tearing of the levator ani, typically of its pubococcygeal portion, and typically unrecognised at the time it happens. It is the strongest single anatomic correlate of later prolapse and it does not heal: the muscle is not reconstituted, which is why the lesion is a permanent change in the mechanics of the pelvic floor rather than a recoverable injury. Bilateral and complete avulsions are associated with more advanced stage and with involvement of more compartments than unilateral or partial ones.

levator ani skeletal muscle fiber CL:0008002

levator ani muscle UBERON:0001326 pubococcygeus muscle UBERON:0011528

Downstream

Urogenital Hiatus Enlargement and Loss of Levator Closure A torn levator can no longer hold the hiatus closed, so it widens. This is the mechanical consequence that carries the rest of the chain.

Cystocele Avulsion raises the risk of anterior compartment descent specifically. The intermediates - hiatal enlargement and descent beyond the hymen - are both curated as their own nodes; what is not known is the step that makes the anterior compartment the preferential one, which is why this edge is typed as indirect rather than direct.

Uterine Prolapse The same avulsion lesion carries the largest compartment-specific risk for apical (uterine) descent, roughly twice the anterior-compartment risk ratio. Typed as indirect for the same reason as the cystocele edge.

Show evidence (2 references)

PMID:27517338 SUPPORT Human Clinical

"Birth-induced injury to the pubococcygeal portion of the levator ani muscle is seen in 55% of women with prolapse and 16% of women with normal support."

The case-control contrast that localises the lesion to the pubococcygeal portion and quantifies its excess in prolapse.

PMID:36343586 SUPPORT Human Clinical

"Patients with complete LAM avulsion are at greater risk of developing POP and have a more advanced stage of prolapse and involvement of multiple compartments."

Independent cohort relating avulsion completeness to prolapse severity and extent, supporting a dose-like relationship rather than a threshold one.

Urogenital Hiatus Enlargement and Loss of Levator Closure

Widening of the levator hiatus, so that the pelvic floor no longer closes. This is the hinge of the whole entry. With the hiatus closed, pressures above and below the vaginal wall are equal and cancel; once it is open and vaginal wall descends below the hymen, that wall lies between abdominal and atmospheric pressure and a net downward force appears where none existed. The node therefore has two distinct outputs: it permits descent directly, and it converts intra-abdominal pressure into abnormal tension on the suspensory attachments. It is also the lesion that prolapse surgery does not address, which is why it reappears below as a predictor of recurrence.

response to mechanical stimulus GO:0009612 ⚠ ABNORMAL

levator ani muscle UBERON:0001326

Downstream

Failure of Apical and Lateral Connective Tissue Attachment The pressure differential across exposed vaginal wall loads the cardinal, uterosacral and paravaginal attachments beyond what they were designed to carry. This is the edge that makes the canonical hypothesis an ordering claim rather than a list of correlates.

Descent of the Pelvic Organs Beyond the Hymen An open hiatus permits the organs to descend through it even before the suspensory attachments give way.

Recurrence After Reconstructive Surgery Standard apical suspension restores the vaginal axis but does not reattach the levator, so a wide hiatus persists across the operation and predicts anatomic failure of the repair.

Show evidence (2 references)

PMID:27517338 SUPPORT Human Clinical

"Muscle failure exposes the vaginal wall to a pressure differential producing abnormal tension on the attachments of the pelvic organs to the pelvic sidewall."

States the pressure-differential mechanism that this node encodes and that its two downstream edges split apart.

PMID:38168908 SUPPORT Human Clinical

"These injuries are associated with an enlarged urogenital hiatus, now known as antedate prolapse, and with prolapse surgery failure."

Supplies the term antedate prolapse for the enlarged hiatus preceding overt descent, and the link to surgical failure.

Constitutional Connective Tissue Susceptibility

Inherited variation in the composition and turnover of pelvic connective tissue, which sets how much obstetric and gravitational load a woman's support system tolerates before it fails. The evidence is of two kinds and they agree. Common-variant association studies return loci whose nearest genes are connective tissue and oestrogen-pathway genes rather than muscle genes, and they replicate across ancestries. At the other end of the allelic spectrum, monogenic heritable connective tissue disorders carry a strikingly high prolapse burden at low parity. Neither is a deterministic cause; both make this a susceptibility node feeding the matrix and elastogenesis arms rather than a trigger in its own right.

extracellular matrix organization GO:0030198 ⚠ ABNORMAL

Downstream

Impaired Elastic Fiber Assembly and Postpartum Elastogenesis Typed INDIRECT_UNKNOWN_INTERMEDIATES rather than DIRECT on purpose. The human association signal is at non-coding common variants near connective tissue genes; no human variant has been shown to impair elastogenesis in pelvic tissue, and the mechanistic step is supplied entirely by mouse knockouts of different genes.

Collagen and MMP-TIMP Remodelling Imbalance Whether constitutional variation is what produces the observed collagen and protease-inhibitor imbalance in prolapsed tissue is not established; the edge is typed UNKNOWN rather than omitted because the genetic and the biochemical observations are usually invoked together.

Show evidence (5 references)

PMID:32184442 SUPPORT Human Clinical

"Our results highlight the role of connective tissue metabolism and estrogen exposure in the etiology of POP."

The authors' own summary of what the associated loci implicate, which is the two arms this node feeds.

PMID:32184442 SUPPORT Human Clinical

"Rs3791675 at EFEMP1, a gene involved in connective tissue homeostasis, also associates with hernias and carpal tunnel syndrome."

A specific locus, and the cross-phenotype pattern (hernia, carpal tunnel) that argues the susceptibility is generic connective tissue rather than pelvis-specific.

PMID:39349682 SUPPORT Human Clinical

"We also observed consistent directions of the effects for 21 out of 24 European GWAS derived loci"

Cross-ancestry directional consistency, which is the evidence that the genetic architecture is shared rather than population-specific.

+ 2 more references

Impaired Elastic Fiber Assembly and Postpartum Elastogenesis

Failure of the LOXL1- and fibulin-5-dependent programme that deposits and cross-links new elastic fibers in the vaginal wall after delivery. Elastic fibers were long assumed to be laid down once and left alone; the reproductive tract is the exception, and pelvic support turns out to depend on that exception. In mice, deleting either LOXL1 or fibulin-5 produces prolapse, and the two do so by different routes - Loxl1-null animals fail to repair after birth, Fbln5-null animals prolapse with age - which is why this node has both an obstetric and an ageing input.

elastic fiber assembly GO:0048251 ↓ DECREASED

protein-lysine 6-oxidase activity GO:0004720 ↓ DECREASED

vagina UBERON:0000996

Animal models

Loxl1 null (Loxl1-/-) Mouse Mouse recapitulates The model reproduces the node directly and, unusually, is the source of it: the requirement for postpartum elastogenesis in pelvic support was established here rather than confirmed here.

Fbln5 null (Fbln5-/-) Mouse Mouse recapitulates Reproduces the node through the ageing route rather than the postpartum-repair route, which is why it and the Loxl1 model are curated as two models of one node rather than duplicates.

Downstream

Failure of Apical and Lateral Connective Tissue Attachment Elastic fiber failure is expected to reduce the recoil and load tolerance of the suspensory tissues, but the step from disordered elastogenesis to measured attachment failure has been demonstrated in mice and not in women, so the intermediates in the human tissue are not identified.

Show evidence (3 references)

PMID:14745449 SUPPORT Model Organism

"Here we show that mice lacking the protein lysyl oxidase-like 1 (LOXL1) do not deposit normal elastic fibers in the uterine tract post partum and develop pelvic organ prolapse, enlarged airspaces of the lung, loose skin and vascular abnormalities with concomitant tropoelastin accumulation."

The founding result: a single elastogenesis gene deletion is sufficient for prolapse, and the defect is specifically postpartum deposition.

PMID:14745449 SUPPORT Model Organism

"Distinct from the prototypic lysyl oxidase (LOX), LOXL1 localizes specifically to sites of elastogenesis and interacts with fibulin-5."

Establishes the molecular partnership that makes LOXL1 and fibulin-5 one node rather than two.

PMID:17255326 SUPPORT Model Organism

"Pelvic organ prolapse in Fbln5-/- mice was remarkably similar to that in primates."

The phenotypic comparison that motivates treating the mouse lesion as informative about human anatomy, and the claim examined in this entry's model-mismatch discussion.

Oxidative Stress in Pelvic Floor Connective Tissue

Accumulation of oxidative damage in the fibroblasts and matrix of the uterosacral ligament, evidenced by raised 8-hydroxyguanosine and 4-hydroxynonenal in prolapsed tissue. Its interest is not the marker but the dose-dependence found when uterosacral ligament fibroblasts are exposed to peroxide directly: low-level oxidative stress stimulates collagen synthesis while higher levels flip the cell into net catabolism. That non-monotonic response is a plausible account of why an ageing, mechanically loaded tissue could pass from compensated remodelling into net loss without any change in the insult itself.

uterosacral ligament fibroblast CL:0000057

response to oxidative stress GO:0006979 ↑ INCREASED

Downstream

Collagen and MMP-TIMP Remodelling Imbalance Peroxide exposure of uterosacral ligament fibroblasts changes COL1A1, MMP-2, TIMP-2 and TGF-beta1 expression in a concentration-dependent way, with the higher concentration promoting catabolism.

Show evidence (2 references)

PMID:26936098 SUPPORT Human Clinical

"the immunoreactivity of 8-OHdG in the POP group was significantly higher, compared with that in the control group"

Immunohistochemical demonstration of oxidative injury in prolapsed uterosacral ligament rather than in cell culture, which is what makes this node about patients.

PMID:26936098 SUPPORT In Vitro

"These results suggested that OS may be involved in the pathophysiology of POP by contributing to collagen metabolic disorder in a severity‑dependent manner in hUSLFs"

The authors' conclusion, quoted through the severity-dependence claim and its cell-type restriction to uterosacral ligament fibroblasts; note their own hedging verb, which is why the downstream edge is not asserted more strongly than DIRECT-with-in-vitro-evidence.

Collagen and MMP-TIMP Remodelling Imbalance

A shift in the composition and turnover of the pelvic connective tissue matrix: less type I collagen (the load-bearing form) and less TIMP-1, more type III collagen (thinner, more extensible) and more MMP-1, MMP-2 and MMP-9. Pooled across thirty studies the direction is consistent, but the meta-analysis is explicit that the picture is site-dependent and that some comparisons remain contradictory - in the anterior vaginal wall, type I collagen and MMP-1 showed no difference at all. The node is curated with those exceptions attached rather than smoothed away, and its causal position is the subject of an open knowledge gap in this entry.

pelvic connective tissue fibroblast CL:0000057

collagen catabolic process GO:0030574 ↑ INCREASED extracellular matrix disassembly GO:0022617 ↑ INCREASED

Downstream

Failure of Apical and Lateral Connective Tissue Attachment A matrix shifted away from type I collagen and toward unopposed proteolysis is expected to elongate and weaken the suspensory attachments. The edge is typed INDIRECT_UNKNOWN_INTERMEDIATES because the human data are cross-sectional measurements in already-prolapsed tissue and cannot establish that the matrix change preceded the mechanical failure.

Show evidence (3 references)

PMID:38291948 SUPPORT Human Clinical

"Overall results showed that the expression of type III collagen (COLIII) and several matrix metalloproteinases (MMP-1, -2 and -9) were increased, whereas those of type I collagen (COLI), and tissue inhibitor of matrix metalloproteinase-1 (TIMP-1) were decreased in patients with POP."

The pooled directional result across 840 cases and 755 controls that defines this node.

PMID:38291948 REFUTE DIRECT Human Clinical

"However, the expression of COLI and MMP-1 in the AVW showed no difference and the expression of COLI and MMP-1 in the USL is still controversial based on current studies."

Contradicts the node for two of its four markers: COLI and MMP-1 do not separate cases from controls at the site where prolapse is most often measured. Curated as a REFUTE item beside the pooled SUPPORT item above, rather than folded into one grade, because the same meta-analysis reports both.

PMID:16398770 REFUTE DIRECT Human Clinical

"For uterosacral ligaments, the differences were not statistically significant."

A negative result in the ligament that actually suspends the uterus, so it contradicts the node at that site. Retained because it is also the observation that motivates the reverse-causation gap below.

Vaginal Wall Smooth Muscle Depletion

Reduction in the fractional area of nonvascular smooth muscle in the muscularis of the anterior vaginal wall. The vaginal wall is not a passive membrane; its muscularis contributes actively to wall mechanics, and losing it reduces the wall's own contribution to support. The finding is independent of age and of prolapse stage, which argues against it being a simple function of severity, and it is present in premenopausal women too - but it is most marked in postmenopausal women not taking oestrogen, which is the observation linking this node to the hormonal arm.

vaginal wall smooth muscle cell CL:0000192

vagina UBERON:0000996

Downstream

Failure of Apical and Lateral Connective Tissue Attachment Typed UNKNOWN. The measurement is a cross-sectional case-control difference in tissue removed at surgery, with no temporal or interventional evidence that smooth muscle loss precedes or produces attachment failure; it may equally be a consequence of chronic stretch.

Show evidence (2 references)

PMID:12114889 SUPPORT Human Clinical

"The fractional area of nonvascular vaginal smooth muscle in the muscularis of women with prolapse was significantly decreased compared with that of control subjects."

The morphometric measurement that defines this node.

PMID:12114889 SUPPORT Human Clinical

"The fractional area of muscularis smooth muscle was also decreased significantly in premenopausal women with prolapse."

Shows the depletion is not merely a menopausal phenomenon, which is why the hormonal edge into this node is typed UNKNOWN rather than DIRECT.

Oestrogen Withdrawal and Ageing of the Pelvic Support Tissues

Advancing age and the menopausal fall in oestrogen, consistently among the strongest epidemiological risk factors for prolapse. The mechanistic reading of this node has to be handled carefully, because the obvious therapeutic inference from it is wrong. Oestrogen-pathway loci come out of GWAS, vaginal smooth muscle is most depleted in postmenopausal women not taking oestrogen, and the Fbln5-null mouse prolapses with ageing - yet in 1443 postmenopausal women, past hormone therapy, its duration, and current vaginal oestrogen were all unassociated with pelvic organ support, and current systemic therapy was if anything associated with slightly worse support. Both edges out of this node are therefore typed conservatively.

extracellular matrix organization GO:0030198 ↓ DECREASED

Downstream

Vaginal Wall Smooth Muscle Depletion Smooth muscle content is lowest in postmenopausal women without oestrogen replacement, but it is also significantly reduced in premenopausal women with prolapse, and hormone therapy does not measurably improve support. The edge is typed UNKNOWN because those three observations cannot all be accommodated by a simple oestrogen-dependence model.

Oxidative Stress in Pelvic Floor Connective Tissue Cumulative oxidative damage is a general feature of connective tissue ageing and is the proposed route from ageing to the matrix lesion here, but no study in this entry measures oxidative markers against age or menopausal status in pelvic tissue.

Show evidence (3 references)

PMID:17382829 SUPPORT Human Clinical

"Vaginal delivery, hysterectomy, chronic straining, normal ageing, and abnormalities of connective tissue or connective-tissue repair predispose some women to disruption, stretching, or dysfunction of the levator ani complex, connective-tissue attachments of the vagina, or both, resulting in prolapse."

Places normal ageing among the predisposing exposures and, usefully for this entry, names both of the target compartments it acts on.

PMID:31851453 SUPPORT Human Clinical

"Among the risk factors are genetic background, childbirth and mode of delivery, previous hysterectomy, menopausal state and the ratio between Estrogen receptors."

Names menopausal state and oestrogen receptor ratio explicitly among the risk factors, which is the epidemiological basis for this node.

PMID:28538602 REFUTE Human Clinical

"Past HT use, duration of HT use, or current vaginal estrogen use was not associated with pelvic organ support."

Retained as REFUTE against the simple reading of this node - that restoring oestrogen restores support. It does not refute ageing as a risk factor; it refutes the therapeutic corollary, and that distinction is why the node survives with its edges downgraded rather than being deleted.

Chronically Increased Intra-Abdominal Load

Sustained or repeated rises in intra-abdominal pressure from obesity, chronic straining at stool, chronic cough or heavy lifting, transmitted onto an already weakened pelvic floor. Rising body-mass index is one of the three most consistent risk factors and is the one most obviously modifiable, but the occupational and exercise literature does not support a general "strain causes prolapse" story: women recruited from the community with prolapse on examination report the same lifetime strenuous activity as women without it, and the association with heavy work appears mainly in surgical series, where referral is itself selected on symptoms. This node is therefore curated as a genuine load with a deliberately weak causal edge.

response to mechanical stimulus GO:0009612 ↑ INCREASED

Downstream

Urogenital Hiatus Enlargement and Loss of Levator Closure Repeated pressure loading is the presumed route by which abdominal load widens the hiatus, but the exposure evidence is inconsistent between surgical and community ascertainment and no measurement of hiatal change against cumulative load exists in the sources used here.

Show evidence (4 references)

PMID:18799443 SUPPORT Human Clinical

"Overweight and obese women were more likely to report at least 1 pelvic floor disorder than normal weight women"

Population-level gradient with body-mass index, the best-supported component of this node.

PMID:17382829 SUPPORT Human Clinical

"considerations include weight loss, reduction of heavy lifting, treatment of constipation, modification or reduction of obstetric risk factors, and pelvic-floor physical therapy"

Enumerates the components of abdominal load that are considered modifiable, quoted from a sentence whose opening clause states that no prevention strategy has actually been shown effective.

PMID:26348380 REFUTE Human Clinical

"Women undergoing surgery for pelvic organ prolapse are more likely to report a history of heavy work than controls; however, women recruited from the community with pelvic organ prolapse on examination report similar lifetime levels of strenuous activity as women without this examination finding."

The reason the downstream edge is UNKNOWN. The association reverses depending on how cases are ascertained, which is the signature of ascertainment bias rather than of a dose-response exposure.

+ 1 more reference

Failure of Apical and Lateral Connective Tissue Attachment

Loss of effective suspension of the uterus and upper vagina from the pelvic sidewall by the cardinal, uterosacral and paravaginal attachments. Measured in living women under maximal Valsalva, these three are strongly related to prolapse and are strongly correlated with one another, which is the evidence that they fail as one system rather than as separable "defects". The character of the failure is informative: what differs between women with and without prolapse is ligament length, not ligament stiffness - the tissue has lengthened rather than become intrinsically floppier, which fits accumulated mechanical failure better than it fits a pure material defect.

extracellular matrix organization GO:0030198 ⚠ ABNORMAL

rectouterine fold (containing the uterosacral ligaments) UBERON:0007136 uterus UBERON:0000995

Downstream

Descent of the Pelvic Organs Beyond the Hymen Once the suspensory attachments have lengthened or given way, the uterus and vaginal apex are no longer held above the levator plate and descend.

Cystocele Apical support is not merely correlated with anterior wall support, it accounts for about half its variance in living women imaged under Valsalva - so a substantial part of what presents as a "bladder" prolapse is an apical lesion expressed in the anterior compartment. This is the mechanistic reason apical suspension is part of an anterior repair.

Uterine Prolapse The cardinal and uterosacral complex is what suspends the uterus, so its failure is uterine descent rather than a cause of something that later becomes uterine descent.

Show evidence (2 references)

PMID:27517338 SUPPORT Human Clinical

"Failure of the lateral connective tissue attachments between the uterus and vagina to the pelvic wall (cardinal, uterosacral, and paravaginal) are strongly related with prolapse"

Identifies the three attachments this node covers and states their relation to prolapse.

PMID:27517338 SUPPORT Human Clinical

"The primary difference in ligament properties between women with and without prolapse is found in ligament length. Only minor differences in ligament stiffness are seen."

Characterises the failure as geometric rather than material, which is the discriminating observation between this entry's two mechanistic hypotheses.

Descent of the Pelvic Organs Beyond the Hymen

The disease-defining lesion: bladder, uterus, post-hysterectomy vaginal cuff or bowel descending so that the vaginal walls or uterus protrude toward and past the hymen. Everything clinically recognisable follows from here, and so does the entry's central epidemiological oddity - descent on examination is far commoner than the complaint, the two correlate poorly, and of the many symptoms attributed to prolapse only the sensation of a vaginal bulge is actually specific to it.

vagina UBERON:0000996 uterus UBERON:0000995 urinary bladder UBERON:0001255

Show evidence (3 references)

PMID:17382829 SUPPORT Human Clinical

"Pelvic organ prolapse is downward descent of female pelvic organs, including the bladder, uterus or post-hysterectomy vaginal cuff, and the small or large bowel, resulting in protrusion of the vagina, uterus, or both."

The definitional statement, including the four organs that may descend.

PMID:17382829 SUPPORT Human Clinical

"Patients generally present with several complaints, including bladder, bowel, and pelvic symptoms; however, with the exception of vaginal bulging, none is specific to prolapse."

Supports the symptom-specificity claim in this node's description and, downstream, the decision not to over-attribute the urinary and bowel phenotypes to this node alone.

PMID:31851453 SUPPORT Human Clinical

"The anatomical changes do not always consist with the severity or the symptoms associated with prolapse."

States the anatomy-symptom discordance directly; it is the basis of the knowledge gap attached to this node.

Recurrence After Reconstructive Surgery

Anatomic or symptomatic failure of a prolapse repair. It is curated as a node rather than as a treatment outcome because it is mechanistically informative: reconstructive surgery restores the suspensory attachments and does not restore the levator, so a wide genital hiatus persists across the operation, and it is that persisting hiatus that predicts failure. Recurrence is thus the clinical readout of the part of the mechanism that current surgery leaves untouched, and it explains why apical suspensions differ in durability while none abolishes recurrence.

vagina UBERON:0000996

Show evidence (3 references)

PMID:34270804 SUPPORT Human Clinical

"Both preoperative and postoperative widened GH correlated with having more surgical failures following SSLF."

The primary result linking hiatal width to surgical failure, both before and after operation.

PMID:34270804 SUPPORT Human Clinical

"A posterior colporrhaphy did not improve success."

A negative surgical result that fits the node's framing: adding a vaginal wall repair does not compensate for the unaddressed hiatus.

PMID:23633316 SUPPORT Human Clinical

"For upper vaginal prolapse (uterine or vault) abdominal sacral colpopexy was associated with a lower rate of recurrent vault prolapse on examination and painful intercourse than with vaginal sacrospinous colpopexy."

Establishes that recurrence rates differ by procedure, which is what makes this a node with a variable rate rather than a fixed property of the disease.

⬡

Pathograph

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

●

Phenotypes

Digestive 2

Rectocele HP:0100822

Deliberately left without an incoming pathograph edge, unlike Cystocele and Uterine Prolapse. The compartment-specific risk carried by levator avulsion is concentrated in the anterior and apical compartments, and the study that quantified it attributes the overall association to those two; no comparable quantified route from either the muscular or the connective-tissue arm to the posterior compartment was found. Wiring rectocele off the levator node anyway would assert an attribution the source specifically does not make. The mechanism of posterior compartment descent is a real gap in this entry rather than an omission.

Show evidence (2 references)

PMID:23633316 SUPPORT Human Clinical

"Data from three trials compared posterior vaginal repair and transanal repair for the treatment of posterior compartment prolapse (rectocele)."

Identifies rectocele as the posterior compartment lesion, in the context of the trials that treat it.

PMID:18503571 NO_EVIDENCE Human Clinical

"This effect is mainly due to an increased risk of cystocele and uterine prolapse."

Does not bear on the phenotype claim itself, which the item above evidences. It is retained here because it is the sentence behind this phenotype's deliberate absence of an incoming pathograph edge, recorded in the notes: the same sentence that grounds the two compartment edges elsewhere in this entry attributes the levator effect to the anterior and apical compartments only.

Obstructed Defecation and Constipation HP:0002019

Show evidence (1 reference)

PMID:33207004 SUPPORT Human Clinical

"Women experience a variety of troublesome symptoms as a consequence of prolapse, including a feeling of 'something coming down' into the vagina, pain, urinary symptoms, bowel symptoms and sexual difficulties."

Names bowel symptoms among the consequences of prolapse. The snippet supports the symptom domain rather than obstructed defecation specifically, which is why no frequency band is asserted.

Genitourinary 5

Pelvic Organ Prolapse HP:0031607

Show evidence (1 reference)

PMID:17382829 SUPPORT Human Clinical

The definitional description of the finding.

Cystocele HP:0100645

Show evidence (1 reference)

PMID:36343586 SUPPORT Human Clinical

"The anterior compartment was the most frequently affected"

Identifies the anterior compartment as the most commonly involved in a cohort of 848 women assessed by transperineal ultrasound.

Uterine Prolapse HP:0000139

Show evidence (1 reference)

PMID:23633316 SUPPORT Human Clinical

Treats uterine and vault prolapse as the apical compartment, which is how this phenotype is scoped.

Voiding Dysfunction Urinary retention HP:0000016

Show evidence (1 reference)

PMID:23633316 SUPPORT Human Clinical

"Following prolapse surgery, 12% of women developed de novo symptoms of bladder overactivity and 9% de novo voiding dysfunction."

Quantifies de novo voiding dysfunction after repair. Note this evidences the postoperative form specifically; the preoperative obstructive mechanism is described but not separately quantified here.

Dyspareunia HP:0030016

Show evidence (2 references)

PMID:23633316 SUPPORT Human Clinical

"abdominal sacral colpopexy was associated with a lower rate of recurrent vault prolapse on examination and painful intercourse than with vaginal sacrospinous colpopexy"

Painful intercourse is reported as a comparative outcome between apical procedures, establishing it as a clinically tracked feature of the disease and its treatment.

PMID:23240798 SUPPORT Human Clinical

"Significantly more women with BJHS felt that POP interfered with sex and defecation compared with the control group."

Independent evidence that prolapse interferes with sexual function, measured by a validated instrument in a matched case-control design.

Constitutional 2

Stress Urinary Incontinence HP:0010992

Show evidence (2 references)

PMID:23633316 SUPPORT Human Clinical

"Women undergoing prolapse surgery may have benefited from having continence surgery performed concomitantly, especially if they had stress urinary incontinence"

Establishes the clinical co-occurrence and the concomitant-surgery practice that motivates curating it as a linked but distinct disorder.

PMID:38168908 SUPPORT Human Clinical

"Vaginal birth is the largest modifiable risk factor for prolapse, the pelvic floor disorder most strongly associated with birth, and is an important contributor to stress incontinence."

States the shared obstetric exposure while distinguishing the strength of its association with each of the two disorders.

Pelvic Pain and Pressure HP:0034267

Show evidence (1 reference)

PMID:17382829 SUPPORT DIRECT Human Clinical

"Patients generally present with several complaints, including bladder, bowel, and pelvic symptoms; however, with the exception of vaginal bulging, none is specific to prolapse."

Asserts this phenotype as curated. The source names pelvic symptoms as part of the presentation while explicitly denying them specificity, and non-specificity is what the phenotype description claims.

🧬

Genetic Associations

WNT4

Gene: WNT4 hgnc:12783 relationship_type: SUSCEPTIBILITY

Show evidence (1 reference)

PMID:32184442 SUPPORT Human Clinical

"Of these, rs3820282, which may alter the estrogen-based regulation of WNT4, also associates with leiomyoma of uterus, gestational duration and endometriosis."

Names the variant, the proposed regulatory mechanism (with the authors' own hedge) and the cross-phenotype associations.

EFEMP1

Gene: EFEMP1 hgnc:3218 relationship_type: SUSCEPTIBILITY

Show evidence (1 reference)

PMID:32184442 SUPPORT Human Clinical

"Rs3791675 at EFEMP1, a gene involved in connective tissue homeostasis, also associates with hernias and carpal tunnel syndrome."

Names the variant, the gene's function, and the shared connective tissue phenotypes.

WT1

Gene: WT1 hgnc:12796 relationship_type: SUSCEPTIBILITY

Show evidence (1 reference)

PMID:39349682 SUPPORT Human Clinical

"We identified a significant association of WT1 locus with POP in the Japanese population"

States the association and the population in which it was found.

FGFR2

Gene: FGFR2 hgnc:3689 relationship_type: SUSCEPTIBILITY

Show evidence (1 reference)

PMID:39349682 SUPPORT Human Clinical

"identified FGFR2 locus as a novel susceptibility locus to POP"

States the locus and that it emerged from the cross-ancestry meta-analysis rather than from either population alone.

LOXL1

Gene: LOXL1 hgnc:6665 relationship_type: MODIFIER

Show evidence (1 reference)

PMID:14745449 SUPPORT Model Organism

"mice lacking the protein lysyl oxidase-like 1 (LOXL1) do not deposit normal elastic fibers in the uterine tract post partum and develop pelvic organ prolapse"

The murine loss-of-function result, quoted so that the species restriction is visible in the snippet itself.

FBLN5

Gene: FBLN5 hgnc:3602 relationship_type: MODIFIER

Show evidence (1 reference)

PMID:35088092 SUPPORT Model Organism

"Loxl1 KO mice develop POP primarily from failure to heal after giving birth, whereas Fbln5 KO mice develop POP with aging."

Distinguishes the two models' routes to the same phenotype, which is the basis for curating them separately.

💊

Medical Actions

Pelvic Floor Muscle Training

Action: pelvic floor physical therapy Ontology label: Physical Therapy NCIT:C15302

Platform: Behavioral / lifestyle

An individualised, supervised programme of pelvic floor muscle exercise. In the POPPY trial, 447 women with symptomatic stage I-III prolapse were randomised to one-to-one training or a lifestyle advice leaflet, and the trained group reported a significantly greater reduction in prolapse symptom score at 12 months. What the trial establishes and what it does not is worth stating plainly: the endpoint was self-reported symptoms, not anatomic stage, and training cannot reattach an avulsed levator.

Mechanism Target:

INHIBITS Urogenital Hiatus Enlargement and Loss of Levator Closure — Training targets the residual levator, the muscle whose failure opens the hiatus. The edge is placed here rather than on the descent node because the intervention acts on muscle function; note that the trial's own endpoint was symptomatic, so this mechanistic placement is inference from the target tissue, not a measured hiatal change.

Show evidence (1 reference)

PMID:24290404 SUPPORT INDIRECT Human Clinical

"One-to-one pelvic floor muscle training for prolapse is effective for improvement of prolapse symptoms."

A therapeutic response cited as validation of the mechanism it targets: the trial demonstrates symptomatic benefit, and the levator step this edge asserts follows only by inference from the tissue the intervention acts on.

Show evidence (1 reference)

PMID:24290404 SUPPORT Human Clinical

"Female outpatients with newly-diagnosed, symptomatic stage I, II, or III prolapse were randomly assigned"

Defines the population in which the benefit was shown, which bounds the recommendation to symptomatic early-to-moderate prolapse.

Vaginal Pessary

Action: vaginal pessary placement Ontology label: Therapeutic Procedure NCIT:C49236

Platform: Device

A passive intravaginal device that mechanically supports the vaginal walls and holds the descended organs in position. It treats the mechanics without altering any of the upstream biology, which makes it the cleanest illustration in this entry of how far the disease is a structural problem. The Cochrane evidence is thinner than its ubiquity suggests: pessary versus no treatment and pessary versus training are both uncertain, and only pessary added to training reaches moderate certainty. The same review reports that pessaries may cause a large increase in adverse events relative to training, so the comparison against training is not cost-free on either side.

Mechanism Target:

INHIBITS Descent of the Pelvic Organs Beyond the Hymen — The device physically opposes descent. This is the one treatment edge in the entry whose mechanism is not in doubt, because the mechanism is the device's stated design.

Show evidence (1 reference)

PMID:33207004 SUPPORT Human Clinical

"Vaginal pessaries are passive mechanical devices designed to support the vagina and hold the prolapsed organs back in the anatomically correct position."

States the mechanism of action directly.

Show evidence (2 references)

PMID:33207004 SUPPORT DIRECT Human Clinical

"We are uncertain if pessaries improve pelvic organ prolapse symptoms for women compared with no treatment or PFMT but pessaries in addition to PFMT probably improve women's pelvic organ prolapse symptoms and prolapse-specific quality of life."

Asserts the efficacy claim this treatment is curated with, uncertainty included: two of the three comparisons are uncertain and only pessary added to training reaches moderate certainty. It supports the calibrated description, not an unqualified benefit claim, and the description says so in the same words.

PMID:33207004 SUPPORT DIRECT Human Clinical

"Pessaries may result in a large increase in risk of adverse events compared with PFMT"

Asserts the harm the description now carries, so the comparison against training is not presented as cost-free.

Reconstructive Prolapse Surgery

Action: reconstructive pelvic floor surgery Ontology label: Gynecological Surgical Procedure NCIT:C15332

Platform: Surgery

Restoration of the vaginal axis by resuspending the apex and repairing the compartment defects. For the apical compartment, abdominal sacral colpopexy outperforms the vaginal alternatives anatomically, at the cost of longer operating time, slower recovery and greater expense. Transvaginal polypropylene mesh reduced recurrence on examination but at a mesh erosion rate above one in ten and a higher reoperation rate, and it has since been withdrawn in many jurisdictions - a case where an anatomic endpoint and a patient-centred one pointed in opposite directions.

Mechanism Target:

BYPASSES Failure of Apical and Lateral Connective Tissue Attachment — Typed BYPASSES rather than RESTORES on purpose. Apical suspension substitutes a surgical attachment (to the sacrum or the sacrospinous ligament) for the failed native one; it does not repair the cardinal-uterosacral complex, and it leaves the levator lesion entirely untouched, which is why a wide hiatus continues to predict failure afterwards.

Show evidence (1 reference)

PMID:23633316 SUPPORT Human Clinical

"Sacral colpopexy has superior outcomes to a variety of vaginal procedures including sacrospinous colpopexy, uterosacral colpopexy and transvaginal mesh."

Establishes that apical suspension works and that the route matters, which is the content of this edge.

Show evidence (2 references)

PMID:23633316 SUPPORT DIRECT Human Clinical

"Mesh erosions were reported in 11.4% (64/563), with surgical interventions being performed in 6.8% (32/470)."

Quantifies the erosion rate above one in ten that this treatment is described with, and that drove transvaginal mesh off the market. It supports the description's explicit limit on the graft-augmented variants rather than the variants themselves.

PMID:23633316 SUPPORT DIRECT Human Clinical

"Following the withdrawal of some commercial transvaginal mesh kits from the market, the generalisability of the findings, especially relating to anterior compartment transvaginal mesh, should be interpreted with caution."

States the withdrawal the description records, in the reviewers' own words, which is why the mesh comparisons above are not curated as live treatment recommendations.

Weight Loss and Reduction of Abdominal Straining

Action: lifestyle and dietary modification Ontology label: Dietary Intervention NCIT:C15447

Platform: Behavioral / lifestyle

Weight reduction, treatment of constipation and avoidance of heavy lifting. Included because rising body-mass index is one of the three most consistent risk factors, and excluded from any efficacy claim because the same review that lists these measures states in the same sentence that no prevention strategy has been shown to work. No target_mechanisms edge is asserted: an unevidenced INHIBITS edge here would put a false arrow into the pathograph.

Show evidence (1 reference)

PMID:17382829 SUPPORT DIRECT Human Clinical

"Although no effective prevention strategy for prolapse has been identified, considerations include weight loss, reduction of heavy lifting, treatment of constipation, modification or reduction of obstetric risk factors, and pelvic-floor physical therapy."

Asserts this treatment exactly as curated: the measures are named, and no efficacy is claimed for them. Quoted in full, including the concessive opening clause, so the absence of demonstrated efficacy travels with the list rather than being dropped.

Vaginal Oestrogen

Action: local oestrogen therapy Ontology label: Estrogen Therapy NCIT:C15483

Platform: Small molecule

Local oestrogen, widely prescribed alongside pessary use and before surgery for atrophic vaginal tissue. Curated here with a negative: in a study of 1443 postmenopausal women, current vaginal oestrogen was not associated with pelvic organ support, and current systemic hormone therapy was associated with slightly worse support on two measures. It may still be justified for vaginal atrophy or pessary tolerance; it is not a treatment for the prolapse.

Show evidence (2 references)

PMID:28538602 REFUTE Human Clinical

"Past HT use, duration of HT use, or current vaginal estrogen use was not associated with pelvic organ support."

Directly refutes an effect on pelvic organ support, which is why this treatment carries no target_mechanisms edge.

PMID:28538602 REFUTE Human Clinical

"HT may have a minor negative effect on pelvic organ support; however, the effect is likely too small to be clinically relevant."

The authors' conclusion, retained with their own de-escalation of it, so the entry neither claims benefit nor manufactures a harm signal.

🔬

Diagnosis

POP-Q Staged Pelvic Examination

Diagnosis is clinical, and the measurement standard is the Pelvic Organ Prolapse Quantification (POP-Q) system agreed in 1996 by the International Continence Society, the American Urogynecologic Society and the Society of Gynecologic Surgeons. It records the position of defined vaginal points relative to the hymen under maximal Valsalva and stages the result, which is what makes prolapse severity comparable between examiners and between studies - almost every cohort cited in this entry is staged this way, including the avulsion series behind the compartment edges. Two entries in the pathophysiology above are POP-Q measurements rather than research constructs: the genital hiatus (gh) that the recurrence node is built on, and the hymen that defines the descent node. Because the system quantifies anatomy and the disease's central oddity is that anatomy and symptoms correlate poorly, a POP-Q stage is not on its own an indication to treat.

POP-Q staged pelvic examination NCIT:C214455

Show evidence (4 references)

PMID:8694033 SUPPORT Human Clinical

"An objective site-specific system for describing, quantitating, and staging pelvic support in women is included."

The originating consensus statement, and the basis for describing POP-Q as an objective site-specific staging system rather than a severity impression.

PMID:8694033 SUPPORT Human Clinical

"This article presents a standard system of terminology recently approved by the International Continence Society, the American Urogynecologic Society, and the Society of Gynecologic Surgeons"

Names the three societies that approved it, which is what makes this the field standard rather than one group's proposal.

PMID:21505577 SUPPORT Human Clinical

"although is not very simple as a concept, it helps defining the features of a prolapse at a level of completeness not reached by any other system to date"

A later appraisal placing POP-Q above the earlier staging systems, supporting its description here as the standard rather than one option among several.

+ 1 more reference

Pelvic Floor Transperineal Ultrasound

Three- or four-dimensional transperineal (translabial) ultrasound is how the levator lesion at the head of this entry's canonical arm is actually seen in a living woman: it identifies levator ani avulsion and measures hiatal dimensions. It is what makes the muscular arm clinically observable rather than inferred, and every avulsion cohort cited here rests on it. It is not a routine diagnostic requirement - prolapse is diagnosed on examination - so it is curated as the mechanism-resolving investigation rather than as a diagnostic standard.

pelvic floor transperineal ultrasound NCIT:C17230

Dynamic pelvic MRI and defecography are also used, principally for multi-compartment and posterior-compartment assessment, but no cached reference in this entry substantiates a specific claim about them, so they are not curated as separate diagnosis entries.

Show evidence (2 references)

PMID:36343586 SUPPORT Human Clinical

"The presence of LAM avulsion was diagnosed by 3D/4D pelvic floor transperineal ultrasound."

States the modality and that avulsion is the finding it establishes, which is this entry's use of it.

PMID:18503571 SUPPORT Human Clinical

"imaging of the levator ani muscle by four-dimensional translabial ultrasound"

Independent confirmation of the modality, in the cohort that supplies the compartment-specific risk ratios used above.

📊

Prevalence

United States, non-pregnant women aged 20 years and over

Point Prevalence 2900.0 per 100,000 (2100.0–3700.0) >1 in 1,000

NHANES 2005-2006. This is prevalence of the symptom (seeing or feeling a bulge in or outside the vagina), not of anatomic descent on examination, which is far more common. The two are not interchangeable and the discordance between them is itself curated as a knowledge gap in this entry.

Show evidence (1 reference)

PMID:18799443 SUPPORT Human Clinical

"A cross-sectional analysis of 1961 nonpregnant women (>or=20 years) who participated in the 2005-2006 National Health and Nutrition Examination Survey, a nationally representative survey of the US noninstitutionalized population. ... pelvic organ prolapse (seeing/feeling a bulge in or outside..."

NHANES 2005–2006 estimates symptomatic pelvic organ prolapse at 2.9% among nonpregnant US women aged at least 20 years. The symptom-based definition undercounts anatomical prolapse; these are distinct outcomes.

Women, lifetime, high-income countries

Lifetime Prevalence 40000.0 per 100,000 >1 in 1,000

The commonly cited lifetime figure, stated in the background of the Cochrane pessary review. It refers to experiencing prolapse rather than to a specific measure of anatomic stage, and should not be read as comparable with the NHANES symptom-based point prevalence above.

Show evidence (1 reference)

PMID:33207004 SUPPORT Human Clinical

"About 40% of women will experience prolapse in their lifetime, with the proportion expected to rise in line with an ageing population."

Source of the lifetime figure and of the ageing-population trend statement.

United States, women followed to age 80 (surgery for prolapse)

Lifetime Prevalence 12600.0 per 100,000 >1 in 1,000

Cumulative incidence of a first prolapse operation, from a 2007-2011 claims database covering 10,177,480 women. A surgical-utilisation measure, so it is a lower bound on disease and is sensitive to access and practice patterns as well as to biology.

Show evidence (1 reference)

PMID:24807341 SUPPORT Human Clinical

"that for POP surgery was 12.6%"

States the cumulative lifetime risk of prolapse surgery by age 80.

🐁

Animal Models

Loxl1 null (Loxl1-/-) Mouse

Germline deletion of lysyl oxidase-like 1. The animals fail to deposit normal elastic fibers in the uterine tract after parturition and develop pelvic organ prolapse, together with an elastinopathy elsewhere (enlarged pulmonary airspaces, loose skin, vascular abnormality) and tropoelastin accumulation. The systemic phenotype is part of the interpretation, not noise: it is the reason the prolapse is attributed to elastogenesis failure rather than to something pelvis-specific.

Species

Mouse

Genotype

Loxl1 null (Loxl1-/-)

Publication

PMID:14745449

Pathograph links

Impaired Elastic Fiber Assembly and Postpartum Elastogenesis recapitulates fidelity: moderate The model reproduces the node directly and, unusually, is the source of it: the requirement for postpartum elastogenesis in pelvic support was established here rather than confirmed here.

Limitations: A germline null of a gene not implicated by human association studies of prolapse, in a quadrupedal animal whose pelvic floor bears load quite differently from a biped's. It demonstrates sufficiency of an elastogenesis lesion, not that this is the human lesion.

Readouts

Elastic fiber deposition in the postpartum uterine tract

Direction: DECREASED

Interpretation: Structural readout of the node: normal elastic fibers are not laid down after parturition.

Show evidence (1 reference)

PMID:14745449 SUPPORT Model Organism

"mice lacking the protein lysyl oxidase-like 1 (LOXL1) do not deposit normal elastic fibers in the uterine tract post partum and develop pelvic organ prolapse"

Reports the deposition failure and the prolapse in the same sentence.

Show evidence (1 reference)

PMID:35088092 SUPPORT Model Organism

"Loxl1 and Fbln5 KO models have provided the most reliable and predictable POP phenotype."

Independent systematic assessment that this model is informative rather than anecdotal, which is what the link-level evidence is for.

Fbln5 null (Fbln5-/-) Mouse

Germline deletion of fibulin-5, the LOXL1-interacting elastogenesis scaffold. These animals prolapse with ageing rather than acutely after delivery, and the study that characterised them also mapped the normal postpartum time course of LOX, LOXL1, fibulin-5 and tropoelastin in the mouse vagina - which is what identified the postpartum elastogenic burst as a discrete, and therefore failable, event.

Species

Mouse

Genotype

Fbln5 null (Fbln5-/-)

Publication

PMID:17255326

Pathograph links

Impaired Elastic Fiber Assembly and Postpartum Elastogenesis recapitulates fidelity: moderate Reproduces the node through the ageing route rather than the postpartum-repair route, which is why it and the Loxl1 model are curated as two models of one node rather than duplicates.

Limitations: As for Loxl1: germline null, quadruped, and a gene not returned by human prolapse GWAS. The authors' comparison is to prolapse in primates, not in women.

Readouts

Pelvic organ support with ageing

Direction: DECREASED

Interpretation: Whole-animal anatomic readout; the phenotype is reported as resembling primate prolapse.

Show evidence (1 reference)

PMID:17255326 SUPPORT Model Organism

"Pelvic organ prolapse in Fbln5-/- mice was remarkably similar to that in primates."

The anatomic comparison on which the model's face validity rests.

Show evidence (1 reference)

PMID:35088092 SUPPORT Model Organism

"Loxl1 KO mice develop POP primarily from failure to heal after giving birth, whereas Fbln5 KO mice develop POP with aging."

States the distinct route by which this model reaches the shared node.

{ }

Source YAML

click to show

name: Pelvic Organ Prolapse
creation_date: "2026-08-24T21:30:00Z"
category: Complex
disease_term:
  preferred_term: pelvic organ prolapse
  term:
    id: MONDO:0000082
    label: pelvic organ prolapse
synonyms:
- POP
- genital prolapse
- urogenital prolapse
- vaginal prolapse
parents:
- reproductive system disorder
- female reproductive system disease
description: >
  Pelvic organ prolapse is the downward descent of the bladder, uterus,
  post-hysterectomy vaginal cuff, or bowel, producing protrusion of the vaginal
  walls or uterus toward and beyond the hymen. It is a mechanical failure of a
  composite support system rather than a disease of one tissue: the levator ani
  muscles hold the pelvic floor closed, and the cardinal, uterosacral and
  paravaginal connective tissue attachments suspend the uterus and vagina from
  the pelvic sidewall. The two elements are load-sharing, so failure of either
  transfers load to the other, and the modern anatomic evidence places the
  primary lesion in the muscle: birth-induced injury to the pubococcygeal
  portion of the levator ani is present in 55% of women with prolapse against
  16% of women with normal support, and enlarges the urogenital hiatus so that
  vaginal wall descending below the hymen is exposed to a pressure differential
  that then loads the connective tissue attachments abnormally.

  A parallel connective tissue arm supplies susceptibility rather than the
  initiating injury. Recovery of pelvic organ support after vaginal delivery
  requires a postpartum burst of elastic fiber assembly; mice null for LOXL1 or
  FBLN5 cannot make it and prolapse, and human GWAS repeatedly returns
  connective tissue and estrogen-pathway loci (WNT4, EFEMP1, WT1, FGFR2). At
  the protein level, prolapsed tissue shows less type I collagen and TIMP-1 and
  more type III collagen and MMP-1/-2/-9, with oxidative injury markers raised
  in the uterosacral ligament and the vaginal wall muscularis depleted of
  smooth muscle. Whether that matrix signature is cause or consequence is
  genuinely unsettled and is curated here as an open gap rather than assumed.

  Prolapse is extremely common as an anatomic finding and much less common as a
  complaint - anatomy and symptoms track each other poorly, and only vaginal
  bulging is specific to it. Management is graded from observation through
  pelvic floor muscle training and vaginal pessary to reconstructive surgery,
  none of which repairs the levator injury itself; a widened genital hiatus
  predicts surgical failure, which is the clinical signature of an unaddressed
  muscular lesion.

references:
- reference: PMID:17382829
  title: "Pelvic organ prolapse."
  findings:
  - statement: >
      Reference clinical review: prolapse is multifactorial, with vaginal childbirth,
      advancing age and rising body-mass index as the most consistent risk factors, and
      only vaginal bulging is specific among the presenting symptoms.
- reference: PMID:27517338
  title: "What's new in the functional anatomy of pelvic organ prolapse?"
  findings:
  - statement: >
      The load-bearing anatomic synthesis: support depends on the interaction of the
      levator ani muscle and the lateral connective tissue attachments, with muscle
      failure exposing the vaginal wall to a pressure differential that abnormally loads
      those attachments.
- reference: PMID:38168908
  title: "Pelvic floor injury during vaginal birth is life-altering and preventable: what can we do about it?"
  findings:
  - statement: >
      Quantifies the birth injury: levator and birth canal tissues stretch to more than
      three times their original length, the resulting tear is present in 55% of women
      with later prolapse (odds ratio 7.3), and it is overstretching rather than
      compression or neuropathy that produces it.
- reference: PMID:36343586
  title: "Levator ani muscle avulsion in patients with pelvic floor dysfunction - Does it help in understanding pelvic organ prolapse?"
  findings:
  - statement: >
      Retrospective cohort of 848 women imaged by transperineal ultrasound relating
      complete levator avulsion to prolapse stage and number of compartments involved.
- reference: PMID:32184442
  title: "Genome-wide association identifies seven loci for pelvic organ prolapse in Iceland and the UK Biobank."
  findings:
  - statement: >
      Eight variants at seven loci in 15,010 cases; the associated genes implicate
      connective tissue metabolism (EFEMP1) and estrogen-dependent regulation (WNT4).
- reference: PMID:39349682
  title: "Genome-wide association studies for pelvic organ prolapse in the Japanese population."
  findings:
  - statement: >
      Japanese GWAS identifying WT1, and a cross-ancestry meta-analysis identifying
      FGFR2, with directional consistency for 21 of 24 European loci.
- reference: PMID:14745449
  title: "Elastic fiber homeostasis requires lysyl oxidase-like 1 protein."
  findings:
  - statement: >
      Loxl1-null mice fail to deposit normal elastic fibers in the uterine tract post
      partum and develop pelvic organ prolapse together with other elastinopathies.
- reference: PMID:17255326
  title: "Pelvic organ prolapse in fibulin-5 knockout mice: pregnancy-induced changes in elastic fiber homeostasis in mouse vagina."
  findings:
  - statement: >
      Fbln5-null mice prolapse, and a postpartum burst of elastic fiber assembly and
      cross-linking in the vaginal wall is what normal recovery of support depends on.
- reference: PMID:35088092
  title: "Mouse Knockout Models for Pelvic Organ Prolapse: a Systematic Review."
  findings:
  - statement: >
      Systematic review of the five available knockout models; Loxl1 and Fbln5 give the
      most reliable phenotype, and they fail by different routes (failure to heal after
      birth versus prolapse with ageing).
- reference: PMID:38291948
  title: "The difference in extracellular matrix metabolism in women with and without pelvic organ prolapse: A systematic review and meta-analysis."
  findings:
  - statement: >
      Meta-analysis of 30 studies (840 cases, 755 controls): type I collagen and TIMP-1
      lower, type III collagen and MMP-1/-2/-9 higher in prolapse, with site-specific
      exceptions that remain controversial.
- reference: PMID:26936098
  title: "Collagen metabolic disorder induced by oxidative stress in human uterosacral ligament-derived fibroblasts: A possible pathophysiological mechanism in pelvic organ prolapse."
  findings:
  - statement: >
      Oxidative injury markers are raised in prolapsed uterosacral ligament, and H2O2
      exposure of uterosacral ligament fibroblasts shifts collagen metabolism toward
      catabolism in a concentration-dependent way.
- reference: PMID:16398770
  title: "Collagen metabolism in the uterosacral ligaments and vaginal skin of women with uterine prolapse."
  findings:
  - statement: >
      The source of the reverse-causation caveat: matrix changes were more pronounced in
      vaginal tissue than in the uterosacral ligament, which the authors read as a
      consequence of prolapse rather than its cause.
- reference: PMID:12114889
  title: "Morphometric analysis of smooth muscle in the anterior vaginal wall of women with pelvic organ prolapse."
  findings:
  - statement: >
      The fractional area of nonvascular smooth muscle in the anterior vaginal wall
      muscularis is reduced in prolapse, independent of age and prolapse stage.
- reference: PMID:18799443
  title: "Prevalence of symptomatic pelvic floor disorders in US women."
  findings:
  - statement: >
      NHANES 2005-2006 national estimate of symptomatic prolapse (seeing or feeling a
      vaginal bulge) and its gradients with age, parity and body-mass index.
- reference: PMID:24807341
  title: "Lifetime risk of stress urinary incontinence or pelvic organ prolapse surgery."
  findings:
  - statement: >
      US claims-based cumulative incidence: 12.6% lifetime risk of prolapse surgery by
      age 80, with annual risk rising progressively to a peak in the early seventies.
- reference: PMID:24290404
  title: "Individualised pelvic floor muscle training in women with pelvic organ prolapse (POPPY): a multicentre randomised controlled trial."
  findings:
  - statement: >
      The definitive randomised trial of one-to-one pelvic floor muscle training in
      symptomatic stage I-III prolapse; the symptom score improved, and anatomy was not
      the endpoint.
- reference: PMID:33207004
  title: "Pessaries (mechanical devices) for managing pelvic organ prolapse in women."
  findings:
  - statement: >
      Cochrane review of four trials: pessary added to pelvic floor muscle training
      probably improves symptoms and prolapse-specific quality of life, while pessary
      versus no treatment or versus training alone remains uncertain.
- reference: PMID:23633316
  title: "Surgical management of pelvic organ prolapse in women."
  findings:
  - statement: >
      Cochrane review of 56 trials in 5954 women establishing sacral colpopexy as
      anatomically superior to vaginal apical procedures, and quantifying transvaginal
      mesh erosion.
- reference: PMID:28538602
  title: "Pelvic organ prolapse: does hormone therapy use matter?"
  findings:
  - statement: >
      Negative result on the hormonal arm: in 1443 postmenopausal women, past hormone
      therapy, duration of use and current vaginal estrogen were not associated with
      pelvic organ support.
- reference: PMID:26348380
  title: "Physical activity and the pelvic floor."
  findings:
  - statement: >
      The counterweight to the mechanical-load risk factor: community-recruited women
      with prolapse on examination report similar lifetime strenuous activity to women
      without it, and lifetime physical activity does not increase the odds of prolapse.
- reference: PMID:23240798
  title: "Prolapse and sexual function in women with benign joint hypermobility syndrome."
  findings:
  - statement: >
      Age-, parity- and ethnicity-matched case-control study showing objectively more
      severe prolapse by POP-Q in benign joint hypermobility syndrome.
- reference: PMID:39033997
  title: "Lower urinary tract involvement in Ehlers-Danlos and Joint Hypermobility syndromes: Review of the literature."
  findings:
  - statement: >
      Literature review giving the prolapse burden in heritable connective tissue
      disorders and an odds ratio for hypermobility.
- reference: PMID:34270804
  title: "Enlargement of the genital hiatus is associated with prolapse recurrence in patients undergoing sacrospinous ligament fixation."
  findings:
  - statement: >
      Postoperative genital hiatus width is associated with recurrence after sacrospinous
      ligament fixation, and a posterior colporrhaphy did not improve success.
- reference: PMID:31851453
  title: "Narrative review of the epidemiology, diagnosis and pathophysiology of pelvic organ prolapse."
  findings:
  - statement: >
      States the anatomy-symptom discordance directly and enumerates the risk factor set
      including previous hysterectomy and menopausal state.
- reference: PMID:18503571
  title: "Levator trauma is associated with pelvic organ prolapse."
  findings:
  - statement: >
      781 women staged by POP-Q and imaged for levator avulsion: avulsion roughly doubles
      the overall risk of stage II or higher prolapse, and the authors attribute the
      effect mainly to cystocele (RR 2.3) and uterine prolapse (RR 4.0) rather than to the
      posterior compartment.
- reference: PMID:16579933
  title: "The relationship between anterior and apical compartment support."
  findings:
  - statement: >
      Dynamic MRI under Valsalva in 153 women: bladder-base and uterine descent correlate
      at r = 0.73, so about half the variation in anterior compartment support is
      attributable to apical support.
- reference: PMID:8694033
  title: "The standardization of terminology of female pelvic organ prolapse and pelvic floor dysfunction."
  findings:
  - statement: >
      The originating POP-Q consensus statement, approved by the International Continence
      Society, the American Urogynecologic Society and the Society of Gynecologic
      Surgeons.
- reference: PMID:21505577
  title: "Pelvic Organ Prolapse Quantification System (POP-Q) - a new era in pelvic prolapse staging."
  findings:
  - statement: >
      Appraisal of POP-Q against the earlier staging systems, concluding it describes a
      prolapse more completely than any predecessor.

prevalence:
- population: United States, non-pregnant women aged 20 years and over
  measure_type: POINT_PREVALENCE
  prevalence_class: ABOVE_1_IN_1000
  rate_per_100000: 2900.0
  rate_low: 2100.0
  rate_high: 3700.0
  notes: >
    NHANES 2005-2006. This is prevalence of the symptom (seeing or feeling a bulge in
    or outside the vagina), not of anatomic descent on examination, which is far more
    common. The two are not interchangeable and the discordance between them is itself
    curated as a knowledge gap in this entry.
  evidence:
  - reference: PMID:18799443
    reference_title: "Prevalence of symptomatic pelvic floor disorders in US women."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      A cross-sectional analysis of 1961 nonpregnant women (>or=20 years) who participated in the
      2005-2006 National Health and Nutrition Examination Survey, a nationally representative survey
      of the US noninstitutionalized population. ... pelvic organ prolapse (seeing/feeling a bulge
      in or outside the vagina) symptoms were assessed. ... 2.9% of women (95% CI, 2.1%-3.7%)
      experiencing pelvic organ prolapse. ... The specificity of vaginal bulge symptoms for
      predicting prolapse beyond the hymen is high in low-prevalence populations (99%–100%);
      however, the sensitivity is low (16%–35%), because some women with even advanced prolapse deny
      symptoms.7,25 Thus, prolapse prevalence in studies using symptom-based screening such as this
      one underestimate the true prevalence of anatomic disease.
    explanation: >-
      NHANES 2005–2006 estimates symptomatic pelvic organ prolapse at 2.9% among nonpregnant US
      women aged at least 20 years. The symptom-based definition undercounts anatomical prolapse;
      these are distinct outcomes.
- population: Women, lifetime, high-income countries
  measure_type: LIFETIME_PREVALENCE
  prevalence_class: ABOVE_1_IN_1000
  rate_per_100000: 40000.0
  notes: >
    The commonly cited lifetime figure, stated in the background of the Cochrane pessary
    review. It refers to experiencing prolapse rather than to a specific measure of
    anatomic stage, and should not be read as comparable with the NHANES symptom-based
    point prevalence above.
  evidence:
  - reference: PMID:33207004
    reference_title: "Pessaries (mechanical devices) for managing pelvic organ prolapse in women."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "About 40% of women will experience prolapse in their lifetime, with the proportion expected to rise in line with an ageing population."
    explanation: >
      Source of the lifetime figure and of the ageing-population trend statement.
- population: United States, women followed to age 80 (surgery for prolapse)
  measure_type: LIFETIME_PREVALENCE
  prevalence_class: ABOVE_1_IN_1000
  rate_per_100000: 12600.0
  notes: >
    Cumulative incidence of a first prolapse operation, from a 2007-2011 claims database
    covering 10,177,480 women. A surgical-utilisation measure, so it is a lower bound on
    disease and is sensitive to access and practice patterns as well as to biology.
  evidence:
  - reference: PMID:24807341
    reference_title: "Lifetime risk of stress urinary incontinence or pelvic organ prolapse surgery."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "that for POP surgery was 12.6%"
    explanation: >
      States the cumulative lifetime risk of prolapse surgery by age 80.

mechanistic_hypotheses:
- hypothesis_group_id: levator_muscle_failure_primary
  hypothesis_label: Birth injury to the levator ani is the primary lesion, with connective tissue failure secondary to the resulting pressure differential
  status: CANONICAL
  description: >
    The dominant contemporary model, built on imaging of living women rather than on
    cadaveric or operative inference. Normal support is a load-sharing system: the
    levator ani holds the hiatus closed so that pressures above and below the vaginal
    wall balance and cancel. Birth overstretch tears the pubococcygeal origin; the
    hiatus opens; vaginal wall descending below the hymen now sits between abdominal and
    atmospheric pressure, and the resulting differential loads the cardinal, uterosacral
    and paravaginal attachments abnormally until they too fail. On this model the
    connective tissue lesion is real and measurable but downstream, and the vaginal wall
    fascia contributes least of all.
  evidence:
  - reference: PMID:27517338
    reference_title: "What's new in the functional anatomy of pelvic organ prolapse?"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Pelvic organ prolapse occurs because of injury to the levator ani muscles and failure of the lateral connections between the pelvic organs to the pelvic sidewall. Abnormalities of the vaginal wall fascial tissues may play a minor role."
    explanation: >
      The review's own summary statement, which both asserts the muscular primacy and
      explicitly demotes the vaginal wall fascial arm.
  - reference: PMID:27517338
    reference_title: "What's new in the functional anatomy of pelvic organ prolapse?"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Muscle failure exposes the vaginal wall to a pressure differential producing abnormal tension on the attachments of the pelvic organs to the pelvic sidewall."
    explanation: >
      States the mechanical route by which a muscular lesion produces a connective tissue
      lesion, which is what makes the ordering of this hypothesis testable.
  - reference: PMID:38168908
    reference_title: "Pelvic floor injury during vaginal birth is life-altering and preventable: what can we do about it?"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The injury is present in 55% of women with prolapse later in life, with an odds ratio of 7.3, compared with women with normal support."
    explanation: >
      The effect size for the muscular lesion, larger than that reported for any single
      matrix marker.
- hypothesis_group_id: connective_tissue_matrix_primary
  hypothesis_label: A constitutional extracellular matrix defect is the primary lesion, with childbirth acting as the unmasking load
  status: ALTERNATIVE
  description: >
    The older and still-live account, in which the initiating abnormality is in the
    connective tissue itself: reduced load-bearing type I collagen, a shift toward type
    III, excess matrix metalloproteinase activity with insufficient inhibition, and
    impaired elastic fiber renewal. Its strongest support is not the human tissue
    comparisons, which are cross-sectional and cannot order cause and effect, but the
    mouse knockouts, where deleting a single elastogenesis gene produces prolapse with no
    obstetric injury required, and the human genetic signal at connective tissue loci.
    Its weakness is that the human tissue changes may be reactive: the one study that
    compared uterosacral ligament with vaginal tissue found the changes larger in the
    vagina, the tissue actually being stretched.
  evidence:
  - reference: PMID:38291948
    reference_title: "The difference in extracellular matrix metabolism in women with and without pelvic organ prolapse: A systematic review and meta-analysis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Patients with POP have lower expression of COLI and TIMP-1 and higher expression of COLIII and MMPs compared with non-POP cases, but further studies are required to investigate in specified anatomical sites."
    explanation: >
      Pooled quantification of the matrix signature this hypothesis rests on, with the
      authors' own caveat about anatomical site attached.
  - reference: PMID:35088092
    reference_title: "Mouse Knockout Models for Pelvic Organ Prolapse: a Systematic Review."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "Mouse knockout (KO) models of pelvic organ prolapse (POP) have contributed mechanistic evidence for the role of connective tissue defects, specifically impaired elastic matrix remodeling."
    explanation: >
      The animal evidence that a matrix lesion alone is sufficient, which is what this
      hypothesis needs and what the cross-sectional human data cannot supply.
  - reference: PMID:16398770
    reference_title: "Collagen metabolism in the uterosacral ligaments and vaginal skin of women with uterine prolapse."
    supports: REFUTE
    evidence_source: HUMAN_CLINICAL
    snippet: "The changes which are more pronounced in vaginal tissue may be as a result of prolapse rather than cause."
    directness: DIRECT
    explanation: >
      Cuts against this hypothesis rather than for it. The authors of a matrix study
      decline to draw the causal conclusion the hypothesis requires and name reverse
      causation as the likelier reading of their own tissue comparison, which is the
      weakness the hypothesis description states.

pathophysiology:
- name: Vaginal Childbirth Mechanical Overload
  biological_scale: TISSUE
  description: >
    Passage of the fetal head requires the levator ani and the soft tissues of the birth
    canal to stretch to more than three times their resting length. This is the single
    largest modifiable risk factor for prolapse, and the mechanism of damage is
    specifically overstretch rather than compression ischaemia or pudendal neuropathy -
    a distinction that matters because it identifies the tissue at risk (the vulnerable
    muscle origin) and the obstetric variables that load it. It is a normal physiological
    event that most women recover from; the disease begins where recovery fails.
  biological_processes:
  - preferred_term: response to mechanical stimulus
    term:
      id: GO:0009612
      label: response to mechanical stimulus
    modifier: INCREASED
  locations:
  - preferred_term: levator ani muscle
    term:
      id: UBERON:0001326
      label: levator ani muscle
  - preferred_term: vagina
    term:
      id: UBERON:0000996
      label: vagina
  evidence:
  - reference: PMID:38168908
    reference_title: "Pelvic floor injury during vaginal birth is life-altering and preventable: what can we do about it?"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "During birth, the levator muscle and birth canal tissues must stretch to more than 3 times their original length; it is this overstretching that is responsible for the muscle tear visible on imaging rather than compression or neuropathy."
    explanation: >
      Quantifies the strain and, importantly for node typing, excludes the two
      alternative injury mechanisms.
  - reference: PMID:38168908
    reference_title: "Pelvic floor injury during vaginal birth is life-altering and preventable: what can we do about it?"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Risk factors for levator injury are multifactorial and include forceps delivery, occiput posterior birth, older maternal age, long second stage of labor, and birthweight of >4000 g."
    explanation: >
      Names the obstetric variables that modulate the load, which is what makes this node
      a modifiable one.
  - reference: PMID:17382829
    reference_title: "Pelvic organ prolapse."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Prolapse development is multifactorial, with vaginal child birth, advancing age, and increasing body-mass index as the most consistent risk factors."
    explanation: >
      Independent confirmation that vaginal childbirth is among the most consistent risk
      factors, alongside the two other triggers curated in this entry.
  downstream:
  - target: Levator Ani Muscle Injury and Avulsion
    causal_link_type: DIRECT
    description: >
      Overstretch tears the muscle, most often detaching the pubovisceral/pubococcygeal
      portion from its pubic origin.
    evidence:
    - reference: PMID:38168908
      reference_title: "Pelvic floor injury during vaginal birth is life-altering and preventable: what can we do about it?"
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Imaging shows that injuries of the levator ani muscle, perineal body, and membrane occur in up to 19% of primiparous women."
      explanation: >
        Establishes that the injury actually occurs at birth, with a frequency, in
        first-time mothers.
  - target: Impaired Elastic Fiber Assembly and Postpartum Elastogenesis
    causal_link_type: DIRECT
    description: >
      Delivery imposes the demand for a postpartum burst of elastic fiber synthesis and
      cross-linking in the vaginal wall; this edge is the demand, and the downstream node
      is the failure to meet it.
    evidence:
    - reference: PMID:17255326
      reference_title: "Pelvic organ prolapse in fibulin-5 knockout mice: pregnancy-induced changes in elastic fiber homeostasis in mouse vagina."
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: "the results suggest that synthesis and assembly of elastic fibers are crucial for recovery of pelvic organ support after vaginal delivery"
      explanation: >
        States the coupling between delivery and the elastogenic requirement that defines
        this edge.

- name: Levator Ani Muscle Injury and Avulsion
  biological_scale: TISSUE
  description: >
    Detachment or tearing of the levator ani, typically of its pubococcygeal portion, and
    typically unrecognised at the time it happens. It is the strongest single anatomic
    correlate of later prolapse and it does not heal: the muscle is not reconstituted,
    which is why the lesion is a permanent change in the mechanics of the pelvic floor
    rather than a recoverable injury. Bilateral and complete avulsions are associated with
    more advanced stage and with involvement of more compartments than unilateral or
    partial ones.
  cell_types:
  - preferred_term: levator ani skeletal muscle fiber
    term:
      id: CL:0008002
      label: skeletal muscle fiber
  locations:
  - preferred_term: levator ani muscle
    term:
      id: UBERON:0001326
      label: levator ani muscle
  - preferred_term: pubococcygeus muscle
    term:
      id: UBERON:0011528
      label: pubococcygeus muscle
  evidence:
  - reference: PMID:27517338
    reference_title: "What's new in the functional anatomy of pelvic organ prolapse?"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Birth-induced injury to the pubococcygeal portion of the levator ani muscle is seen in 55% of women with prolapse and 16% of women with normal support."
    explanation: >
      The case-control contrast that localises the lesion to the pubococcygeal portion
      and quantifies its excess in prolapse.
  - reference: PMID:36343586
    reference_title: "Levator ani muscle avulsion in patients with pelvic floor dysfunction - Does it help in understanding pelvic organ prolapse?"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Patients with complete LAM avulsion are at greater risk of developing POP and have a more advanced stage of prolapse and involvement of multiple compartments."
    explanation: >
      Independent cohort relating avulsion completeness to prolapse severity and extent,
      supporting a dose-like relationship rather than a threshold one.
  downstream:
  - target: Urogenital Hiatus Enlargement and Loss of Levator Closure
    causal_link_type: DIRECT
    description: >
      A torn levator can no longer hold the hiatus closed, so it widens. This is the
      mechanical consequence that carries the rest of the chain.
    evidence:
    - reference: PMID:38168908
      reference_title: "Pelvic floor injury during vaginal birth is life-altering and preventable: what can we do about it?"
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "These injuries are associated with an enlarged urogenital hiatus, now known as antedate prolapse, and with prolapse surgery failure."
      explanation: >
        Links the muscle lesion directly to hiatal enlargement, and names the two things
        that follow from it.
  - target: Cystocele
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    description: >
      Avulsion raises the risk of anterior compartment descent specifically. The
      intermediates - hiatal enlargement and descent beyond the hymen - are both curated
      as their own nodes; what is not known is the step that makes the anterior
      compartment the preferential one, which is why this edge is typed as indirect
      rather than direct.
    evidence:
    - reference: PMID:18503571
      reference_title: "Levator trauma is associated with pelvic organ prolapse."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "The association was strongest for cystocele (RR 2.3, 95% CI 2.0-2.7) and uterine prolapse (RR 4.0, 95% CI 2.5-6.5)."
      explanation: >
        Quantifies the compartment-specific risk carried by avulsion in 781 women, which
        is what this edge asserts.
  - target: Uterine Prolapse
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    description: >
      The same avulsion lesion carries the largest compartment-specific risk for apical
      (uterine) descent, roughly twice the anterior-compartment risk ratio. Typed as
      indirect for the same reason as the cystocele edge.
    evidence:
    - reference: PMID:18503571
      reference_title: "Levator trauma is associated with pelvic organ prolapse."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "This effect is mainly due to an increased risk of cystocele and uterine prolapse."
      explanation: >
        The authors' own attribution of the overall avulsion-prolapse association to these
        two compartments, which is what makes the edge compartment-specific rather than a
        restatement of the general association.

- name: Urogenital Hiatus Enlargement and Loss of Levator Closure
  biological_scale: TISSUE
  description: >
    Widening of the levator hiatus, so that the pelvic floor no longer closes. This is the
    hinge of the whole entry. With the hiatus closed, pressures above and below the
    vaginal wall are equal and cancel; once it is open and vaginal wall descends below the
    hymen, that wall lies between abdominal and atmospheric pressure and a net downward
    force appears where none existed. The node therefore has two distinct outputs: it
    permits descent directly, and it converts intra-abdominal pressure into abnormal
    tension on the suspensory attachments. It is also the lesion that prolapse surgery
    does not address, which is why it reappears below as a predictor of recurrence.
  biological_processes:
  - preferred_term: response to mechanical stimulus
    term:
      id: GO:0009612
      label: response to mechanical stimulus
    modifier: ABNORMAL
  locations:
  - preferred_term: levator ani muscle
    term:
      id: UBERON:0001326
      label: levator ani muscle
  evidence:
  - reference: PMID:27517338
    reference_title: "What's new in the functional anatomy of pelvic organ prolapse?"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Muscle failure exposes the vaginal wall to a pressure differential producing abnormal tension on the attachments of the pelvic organs to the pelvic sidewall."
    explanation: >
      States the pressure-differential mechanism that this node encodes and that its two
      downstream edges split apart.
  - reference: PMID:38168908
    reference_title: "Pelvic floor injury during vaginal birth is life-altering and preventable: what can we do about it?"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "These injuries are associated with an enlarged urogenital hiatus, now known as antedate prolapse, and with prolapse surgery failure."
    explanation: >
      Supplies the term antedate prolapse for the enlarged hiatus preceding overt descent,
      and the link to surgical failure.
  downstream:
  - target: Failure of Apical and Lateral Connective Tissue Attachment
    causal_link_type: DIRECT
    description: >
      The pressure differential across exposed vaginal wall loads the cardinal,
      uterosacral and paravaginal attachments beyond what they were designed to carry.
      This is the edge that makes the canonical hypothesis an ordering claim rather than
      a list of correlates.
    evidence:
    - reference: PMID:27517338
      reference_title: "What's new in the functional anatomy of pelvic organ prolapse?"
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Muscle failure exposes the vaginal wall to a pressure differential producing abnormal tension on the attachments of the pelvic organs to the pelvic sidewall."
      explanation: >
        The same sentence read as a causal edge: muscle failure is the subject, abnormal
        tension on the attachments is the object.
  - target: Descent of the Pelvic Organs Beyond the Hymen
    causal_link_type: DIRECT
    description: >
      An open hiatus permits the organs to descend through it even before the suspensory
      attachments give way.
    evidence:
    - reference: PMID:27517338
      reference_title: "What's new in the functional anatomy of pelvic organ prolapse?"
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Pelvic organ support depends on interactions between the levator ani muscle and pelvic connective tissues."
      explanation: >
        Establishes the levator as a load-bearing element of support in its own right, so
        that its failure can produce descent without requiring ligament failure first.
  - target: Recurrence After Reconstructive Surgery
    causal_link_type: DIRECT
    description: >
      Standard apical suspension restores the vaginal axis but does not reattach the
      levator, so a wide hiatus persists across the operation and predicts anatomic
      failure of the repair.
    evidence:
    - reference: PMID:34270804
      reference_title: "Enlargement of the genital hiatus is associated with prolapse recurrence in patients undergoing sacrospinous ligament fixation."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Postoperatively, a widened GH was significantly associated with recurrent prolapse (P < 0.001)."
      explanation: >
        Direct clinical measurement of the edge: hiatal width after operation tracks
        recurrence.

- name: Constitutional Connective Tissue Susceptibility
  biological_scale: MOLECULAR
  description: >
    Inherited variation in the composition and turnover of pelvic connective tissue,
    which sets how much obstetric and gravitational load a woman's support system
    tolerates before it fails. The evidence is of two kinds and they agree. Common-variant
    association studies return loci whose nearest genes are connective tissue and
    oestrogen-pathway genes rather than muscle genes, and they replicate across ancestries.
    At the other end of the allelic spectrum, monogenic heritable connective tissue
    disorders carry a strikingly high prolapse burden at low parity. Neither is a
    deterministic cause; both make this a susceptibility node feeding the matrix and
    elastogenesis arms rather than a trigger in its own right.
  biological_processes:
  - preferred_term: extracellular matrix organization
    term:
      id: GO:0030198
      label: extracellular matrix organization
    modifier: ABNORMAL
  evidence:
  - reference: PMID:32184442
    reference_title: "Genome-wide association identifies seven loci for pelvic organ prolapse in Iceland and the UK Biobank."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Our results highlight the role of connective tissue metabolism and estrogen exposure in the etiology of POP."
    explanation: >
      The authors' own summary of what the associated loci implicate, which is the two
      arms this node feeds.
  - reference: PMID:32184442
    reference_title: "Genome-wide association identifies seven loci for pelvic organ prolapse in Iceland and the UK Biobank."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Rs3791675 at EFEMP1, a gene involved in connective tissue homeostasis, also associates with hernias and carpal tunnel syndrome."
    explanation: >
      A specific locus, and the cross-phenotype pattern (hernia, carpal tunnel) that
      argues the susceptibility is generic connective tissue rather than pelvis-specific.
  - reference: PMID:39349682
    reference_title: "Genome-wide association studies for pelvic organ prolapse in the Japanese population."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "We also observed consistent directions of the effects for 21 out of 24 European GWAS derived loci"
    explanation: >
      Cross-ancestry directional consistency, which is the evidence that the genetic
      architecture is shared rather than population-specific.
  - reference: PMID:23240798
    reference_title: "Prolapse and sexual function in women with benign joint hypermobility syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "There was a statistically significant difference between points Aa, Ba, Ap, Bp and C in study and control groups showing that prolapse is objectively more severe in those with BJHS."
    explanation: >
      Matched case-control evidence from the monogenic-adjacent end of the spectrum,
      measured objectively by POP-Q rather than by symptom report.
  - reference: PMID:39033997
    reference_title: "Lower urinary tract involvement in Ehlers-Danlos and Joint Hypermobility syndromes: Review of the literature."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The prevalence of urinary incontinence in EDS is estimated at 50-60%, and that of pelvic organ prolapse (POP) at 29-75%."
    explanation: >
      Quantifies the prolapse burden in a defined heritable connective tissue disorder.
  downstream:
  - target: Impaired Elastic Fiber Assembly and Postpartum Elastogenesis
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: >
      Typed INDIRECT_UNKNOWN_INTERMEDIATES rather than DIRECT on purpose. The human
      association signal is at non-coding common variants near connective tissue genes;
      no human variant has been shown to impair elastogenesis in pelvic tissue, and the
      mechanistic step is supplied entirely by mouse knockouts of different genes.
    evidence:
    - reference: PMID:32184442
      reference_title: "Genome-wide association identifies seven loci for pelvic organ prolapse in Iceland and the UK Biobank."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Some of the variants associating with POP also associated with traits of similar pathophysiology."
      directness: INDIRECT
      explanation: >
        Supports the edge only through an inference step: it establishes shared connective
        tissue pathophysiology without identifying the molecular step, which is exactly the
        gap this edge type records.
  - target: Collagen and MMP-TIMP Remodelling Imbalance
    causal_link_type: UNKNOWN
    description: >
      Whether constitutional variation is what produces the observed collagen and
      protease-inhibitor imbalance in prolapsed tissue is not established; the edge is
      typed UNKNOWN rather than omitted because the genetic and the biochemical
      observations are usually invoked together.
    evidence:
    - reference: PMID:31851453
      reference_title: "Narrative review of the epidemiology, diagnosis and pathophysiology of pelvic organ prolapse."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Several risk factors have been associated with pelvic organ prolapse, all contribute to weakening of the pelvic floor connective tissue/collagen, allowing the pelvic organs to prolapse through the vaginal walls."
      directness: INDIRECT
      explanation: >
        States the assumed convergence of risk factors including genetic background onto
        connective tissue weakening. The edge follows only if constitutional variation is
        one of the risk factors meant, which the review asserts rather than demonstrates.

- name: Impaired Elastic Fiber Assembly and Postpartum Elastogenesis
  biological_scale: MOLECULAR
  description: >
    Failure of the LOXL1- and fibulin-5-dependent programme that deposits and cross-links
    new elastic fibers in the vaginal wall after delivery. Elastic fibers were long
    assumed to be laid down once and left alone; the reproductive tract is the exception,
    and pelvic support turns out to depend on that exception. In mice, deleting either
    LOXL1 or fibulin-5 produces prolapse, and the two do so by different routes -
    Loxl1-null animals fail to repair after birth, Fbln5-null animals prolapse with age -
    which is why this node has both an obstetric and an ageing input.
  molecular_functions:
  - preferred_term: protein-lysine 6-oxidase activity
    term:
      id: GO:0004720
      label: protein-lysine 6-oxidase activity
    modifier: DECREASED
  biological_processes:
  - preferred_term: elastic fiber assembly
    term:
      id: GO:0048251
      label: elastic fiber assembly
    modifier: DECREASED
  locations:
  - preferred_term: vagina
    term:
      id: UBERON:0000996
      label: vagina
  evidence:
  - reference: PMID:14745449
    reference_title: "Elastic fiber homeostasis requires lysyl oxidase-like 1 protein."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "Here we show that mice lacking the protein lysyl oxidase-like 1 (LOXL1) do not deposit normal elastic fibers in the uterine tract post partum and develop pelvic organ prolapse, enlarged airspaces of the lung, loose skin and vascular abnormalities with concomitant tropoelastin accumulation."
    explanation: >
      The founding result: a single elastogenesis gene deletion is sufficient for
      prolapse, and the defect is specifically postpartum deposition.
  - reference: PMID:14745449
    reference_title: "Elastic fiber homeostasis requires lysyl oxidase-like 1 protein."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "Distinct from the prototypic lysyl oxidase (LOX), LOXL1 localizes specifically to sites of elastogenesis and interacts with fibulin-5."
    explanation: >
      Establishes the molecular partnership that makes LOXL1 and fibulin-5 one node rather
      than two.
  - reference: PMID:17255326
    reference_title: "Pelvic organ prolapse in fibulin-5 knockout mice: pregnancy-induced changes in elastic fiber homeostasis in mouse vagina."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "Pelvic organ prolapse in Fbln5-/- mice was remarkably similar to that in primates."
    explanation: >
      The phenotypic comparison that motivates treating the mouse lesion as informative
      about human anatomy, and the claim examined in this entry's model-mismatch discussion.
  downstream:
  - target: Failure of Apical and Lateral Connective Tissue Attachment
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: >
      Elastic fiber failure is expected to reduce the recoil and load tolerance of the
      suspensory tissues, but the step from disordered elastogenesis to measured
      attachment failure has been demonstrated in mice and not in women, so the
      intermediates in the human tissue are not identified.
    evidence:
    - reference: PMID:17255326
      reference_title: "Pelvic organ prolapse in fibulin-5 knockout mice: pregnancy-induced changes in elastic fiber homeostasis in mouse vagina."
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: "disordered elastic fiber homeostasis is a primary event in the pathogenesis of pelvic organ prolapse in mice"
      explanation: >
        Quoted with the authors' own species restriction intact - the sentence says
        in mice, and the edge type reflects that.

- name: Oxidative Stress in Pelvic Floor Connective Tissue
  biological_scale: CELLULAR
  description: >
    Accumulation of oxidative damage in the fibroblasts and matrix of the uterosacral
    ligament, evidenced by raised 8-hydroxyguanosine and 4-hydroxynonenal in prolapsed
    tissue. Its interest is not the marker but the dose-dependence found when uterosacral
    ligament fibroblasts are exposed to peroxide directly: low-level oxidative stress
    stimulates collagen synthesis while higher levels flip the cell into net catabolism.
    That non-monotonic response is a plausible account of why an ageing, mechanically
    loaded tissue could pass from compensated remodelling into net loss without any change
    in the insult itself.
  cell_types:
  - preferred_term: uterosacral ligament fibroblast
    term:
      id: CL:0000057
      label: fibroblast
  biological_processes:
  - preferred_term: response to oxidative stress
    term:
      id: GO:0006979
      label: response to oxidative stress
    modifier: INCREASED
  evidence:
  - reference: PMID:26936098
    reference_title: "Collagen metabolic disorder induced by oxidative stress in human uterosacral ligament-derived fibroblasts: A possible pathophysiological mechanism in pelvic organ prolapse."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "the immunoreactivity of 8-OHdG in the POP group was significantly higher, compared with that in the control group"
    explanation: >
      Immunohistochemical demonstration of oxidative injury in prolapsed uterosacral
      ligament rather than in cell culture, which is what makes this node about patients.
  - reference: PMID:26936098
    reference_title: "Collagen metabolic disorder induced by oxidative stress in human uterosacral ligament-derived fibroblasts: A possible pathophysiological mechanism in pelvic organ prolapse."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "These results suggested that OS may be involved in the pathophysiology of POP by contributing to collagen metabolic disorder in a severity‑dependent manner in hUSLFs"
    explanation: >
      The authors' conclusion, quoted through the severity-dependence claim and its
      cell-type restriction to uterosacral ligament fibroblasts; note their own hedging
      verb, which is why the downstream edge is not asserted more strongly than
      DIRECT-with-in-vitro-evidence.
  downstream:
  - target: Collagen and MMP-TIMP Remodelling Imbalance
    causal_link_type: DIRECT
    description: >
      Peroxide exposure of uterosacral ligament fibroblasts changes COL1A1, MMP-2, TIMP-2
      and TGF-beta1 expression in a concentration-dependent way, with the higher
      concentration promoting catabolism.
    evidence:
    - reference: PMID:26936098
      reference_title: "Collagen metabolic disorder induced by oxidative stress in human uterosacral ligament-derived fibroblasts: A possible pathophysiological mechanism in pelvic organ prolapse."
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: "The expression levels of MMP‑2, TIMP‑2 and TGF‑β1 exhibited corresponding changes with the OS levels."
      explanation: >
        The experimental result behind this edge - the protease/inhibitor pair moves with
        the oxidative load in the same cell type the disease affects.

- name: Collagen and MMP-TIMP Remodelling Imbalance
  biological_scale: MOLECULAR
  description: >
    A shift in the composition and turnover of the pelvic connective tissue matrix:
    less type I collagen (the load-bearing form) and less TIMP-1, more type III collagen
    (thinner, more extensible) and more MMP-1, MMP-2 and MMP-9. Pooled across thirty
    studies the direction is consistent, but the meta-analysis is explicit that the
    picture is site-dependent and that some comparisons remain contradictory - in the
    anterior vaginal wall, type I collagen and MMP-1 showed no difference at all. The
    node is curated with those exceptions attached rather than smoothed away, and its
    causal position is the subject of an open knowledge gap in this entry.
  biological_processes:
  - preferred_term: collagen catabolic process
    term:
      id: GO:0030574
      label: collagen catabolic process
    modifier: INCREASED
  - preferred_term: extracellular matrix disassembly
    term:
      id: GO:0022617
      label: extracellular matrix disassembly
    modifier: INCREASED
  cell_types:
  - preferred_term: pelvic connective tissue fibroblast
    term:
      id: CL:0000057
      label: fibroblast
  evidence:
  - reference: PMID:38291948
    reference_title: "The difference in extracellular matrix metabolism in women with and without pelvic organ prolapse: A systematic review and meta-analysis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Overall results showed that the expression of type III collagen (COLIII) and several matrix metalloproteinases (MMP-1, -2 and -9) were increased, whereas those of type I collagen (COLI), and tissue inhibitor of matrix metalloproteinase-1 (TIMP-1) were decreased in patients with POP."
    explanation: >
      The pooled directional result across 840 cases and 755 controls that defines this
      node.
  - reference: PMID:38291948
    reference_title: "The difference in extracellular matrix metabolism in women with and without pelvic organ prolapse: A systematic review and meta-analysis."
    supports: REFUTE
    evidence_source: HUMAN_CLINICAL
    snippet: "However, the expression of COLI and MMP-1 in the AVW showed no difference and the expression of COLI and MMP-1 in the USL is still controversial based on current studies."
    directness: DIRECT
    explanation: >
      Contradicts the node for two of its four markers: COLI and MMP-1 do not separate
      cases from controls at the site where prolapse is most often measured. Curated as a
      REFUTE item beside the pooled SUPPORT item above, rather than folded into one
      grade, because the same meta-analysis reports both.
  - reference: PMID:16398770
    reference_title: "Collagen metabolism in the uterosacral ligaments and vaginal skin of women with uterine prolapse."
    supports: REFUTE
    evidence_source: HUMAN_CLINICAL
    snippet: "For uterosacral ligaments, the differences were not statistically significant."
    directness: DIRECT
    explanation: >
      A negative result in the ligament that actually suspends the uterus, so it
      contradicts the node at that site. Retained because it is also the observation
      that motivates the reverse-causation gap below.
  downstream:
  - target: Failure of Apical and Lateral Connective Tissue Attachment
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: >
      A matrix shifted away from type I collagen and toward unopposed proteolysis is
      expected to elongate and weaken the suspensory attachments. The edge is typed
      INDIRECT_UNKNOWN_INTERMEDIATES because the human data are cross-sectional
      measurements in already-prolapsed tissue and cannot establish that the matrix change
      preceded the mechanical failure.
    evidence:
    - reference: PMID:27517338
      reference_title: "What's new in the functional anatomy of pelvic organ prolapse?"
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "The primary difference in ligament properties between women with and without prolapse is found in ligament length."
      directness: INDIRECT
      explanation: >
        The suspensory ligaments of women with prolapse are measurably abnormal, which is
        the attachment failure this edge ends at. Indirect because elongation is measured
        in already-prolapsed women and is not tied to the matrix composition upstream.
    - reference: PMID:27517338
      reference_title: "What's new in the functional anatomy of pelvic organ prolapse?"
      supports: REFUTE
      evidence_source: HUMAN_CLINICAL
      snippet: "Only minor differences in ligament stiffness are seen."
      directness: INDIRECT
      explanation: >
        The other half of the same finding, and it cuts the other way. A pure
        matrix-composition lesion predicts altered material stiffness; what is found is
        length. Split from the sentence above rather than graded once, because the two
        sentences carry opposite directions for this edge.

- name: Vaginal Wall Smooth Muscle Depletion
  biological_scale: CELLULAR
  description: >
    Reduction in the fractional area of nonvascular smooth muscle in the muscularis of the
    anterior vaginal wall. The vaginal wall is not a passive membrane; its muscularis
    contributes actively to wall mechanics, and losing it reduces the wall's own
    contribution to support. The finding is independent of age and of prolapse stage,
    which argues against it being a simple function of severity, and it is present in
    premenopausal women too - but it is most marked in postmenopausal women not taking
    oestrogen, which is the observation linking this node to the hormonal arm.
  cell_types:
  - preferred_term: vaginal wall smooth muscle cell
    term:
      id: CL:0000192
      label: smooth muscle cell
  locations:
  - preferred_term: vagina
    term:
      id: UBERON:0000996
      label: vagina
  evidence:
  - reference: PMID:12114889
    reference_title: "Morphometric analysis of smooth muscle in the anterior vaginal wall of women with pelvic organ prolapse."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The fractional area of nonvascular vaginal smooth muscle in the muscularis of women with prolapse was significantly decreased compared with that of control subjects."
    explanation: >
      The morphometric measurement that defines this node.
  - reference: PMID:12114889
    reference_title: "Morphometric analysis of smooth muscle in the anterior vaginal wall of women with pelvic organ prolapse."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The fractional area of muscularis smooth muscle was also decreased significantly in premenopausal women with prolapse."
    explanation: >
      Shows the depletion is not merely a menopausal phenomenon, which is why the hormonal
      edge into this node is typed UNKNOWN rather than DIRECT.
  downstream:
  - target: Failure of Apical and Lateral Connective Tissue Attachment
    causal_link_type: UNKNOWN
    description: >
      Typed UNKNOWN. The measurement is a cross-sectional case-control difference in
      tissue removed at surgery, with no temporal or interventional evidence that smooth
      muscle loss precedes or produces attachment failure; it may equally be a consequence
      of chronic stretch.
    evidence:
    - reference: PMID:12114889
      reference_title: "Morphometric analysis of smooth muscle in the anterior vaginal wall of women with pelvic organ prolapse."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "This decreased fraction of smooth muscle in the anterior vaginal wall was not related to age, race, or stage of prolapse."
      directness: INDIRECT
      explanation: >
        The absence of a stage relationship is the strongest available argument against
        pure reverse causation, but the edge follows only by that inference; the quote
        reports a null association, not the causal step, which is why the edge is UNKNOWN.

- name: Oestrogen Withdrawal and Ageing of the Pelvic Support Tissues
  biological_scale: ORGANISM
  description: >
    Advancing age and the menopausal fall in oestrogen, consistently among the strongest
    epidemiological risk factors for prolapse. The mechanistic reading of this node has to
    be handled carefully, because the obvious therapeutic inference from it is wrong.
    Oestrogen-pathway loci come out of GWAS, vaginal smooth muscle is most depleted in
    postmenopausal women not taking oestrogen, and the Fbln5-null mouse prolapses with
    ageing - yet in 1443 postmenopausal women, past hormone therapy, its duration, and
    current vaginal oestrogen were all unassociated with pelvic organ support, and current
    systemic therapy was if anything associated with slightly worse support. Both edges out
    of this node are therefore typed conservatively.
  biological_processes:
  - preferred_term: extracellular matrix organization
    term:
      id: GO:0030198
      label: extracellular matrix organization
    modifier: DECREASED
  evidence:
  - reference: PMID:17382829
    reference_title: "Pelvic organ prolapse."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Vaginal delivery, hysterectomy, chronic straining, normal ageing, and abnormalities of connective tissue or connective-tissue repair predispose some women to disruption, stretching, or dysfunction of the levator ani complex, connective-tissue attachments of the vagina, or both, resulting in prolapse."
    explanation: >
      Places normal ageing among the predisposing exposures and, usefully for this entry,
      names both of the target compartments it acts on.
  - reference: PMID:31851453
    reference_title: "Narrative review of the epidemiology, diagnosis and pathophysiology of pelvic organ prolapse."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Among the risk factors are genetic background, childbirth and mode of delivery, previous hysterectomy, menopausal state and the ratio between Estrogen receptors."
    explanation: >
      Names menopausal state and oestrogen receptor ratio explicitly among the risk
      factors, which is the epidemiological basis for this node.
  - reference: PMID:28538602
    reference_title: "Pelvic organ prolapse: does hormone therapy use matter?"
    supports: REFUTE
    evidence_source: HUMAN_CLINICAL
    snippet: "Past HT use, duration of HT use, or current vaginal estrogen use was not associated with pelvic organ support."
    explanation: >
      Retained as REFUTE against the simple reading of this node - that restoring
      oestrogen restores support. It does not refute ageing as a risk factor; it refutes
      the therapeutic corollary, and that distinction is why the node survives with its
      edges downgraded rather than being deleted.
  downstream:
  - target: Vaginal Wall Smooth Muscle Depletion
    causal_link_type: UNKNOWN
    description: >
      Smooth muscle content is lowest in postmenopausal women without oestrogen
      replacement, but it is also significantly reduced in premenopausal women with
      prolapse, and hormone therapy does not measurably improve support. The edge is
      typed UNKNOWN because those three observations cannot all be accommodated by a
      simple oestrogen-dependence model.
    evidence:
    - reference: PMID:12114889
      reference_title: "Morphometric analysis of smooth muscle in the anterior vaginal wall of women with pelvic organ prolapse."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "In women with prolapse, vaginal smooth muscle content was most diminished in specimens from postmenopausal women with no estrogen replacement."
      directness: INDIRECT
      explanation: >
        The observation that suggests the edge, stated as a within-cases gradient rather
        than as a demonstrated hormonal mechanism, so the edge follows by inference from
        the oestrogen-exposure contrast.
  - target: Oxidative Stress in Pelvic Floor Connective Tissue
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: >
      Cumulative oxidative damage is a general feature of connective tissue ageing and is
      the proposed route from ageing to the matrix lesion here, but no study in this entry
      measures oxidative markers against age or menopausal status in pelvic tissue.
    evidence:
    - reference: PMID:26936098
      reference_title: "Collagen metabolic disorder induced by oxidative stress in human uterosacral ligament-derived fibroblasts: A possible pathophysiological mechanism in pelvic organ prolapse."
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: "Oxidative stress (OS) is a well‑recognized mechanism involved in fiber metabolic disorders."
      directness: INDIRECT
      explanation: >
        Supplies only the general premise linking oxidative stress to fibre metabolism;
        the pelvic-tissue step is an inference from it, which is precisely why the
        intermediates on this edge are recorded as unknown.

- name: Chronically Increased Intra-Abdominal Load
  biological_scale: ORGANISM
  description: >
    Sustained or repeated rises in intra-abdominal pressure from obesity, chronic
    straining at stool, chronic cough or heavy lifting, transmitted onto an already
    weakened pelvic floor. Rising body-mass index is one of the three most consistent risk
    factors and is the one most obviously modifiable, but the occupational and exercise
    literature does not support a general "strain causes prolapse" story: women recruited
    from the community with prolapse on examination report the same lifetime strenuous
    activity as women without it, and the association with heavy work appears mainly in
    surgical series, where referral is itself selected on symptoms. This node is therefore
    curated as a genuine load with a deliberately weak causal edge.
  biological_processes:
  - preferred_term: response to mechanical stimulus
    term:
      id: GO:0009612
      label: response to mechanical stimulus
    modifier: INCREASED
  evidence:
  - reference: PMID:18799443
    reference_title: "Prevalence of symptomatic pelvic floor disorders in US women."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Overweight and obese women were more likely to report at least 1 pelvic floor disorder than normal weight women"
    explanation: >
      Population-level gradient with body-mass index, the best-supported component of this
      node.
  - reference: PMID:17382829
    reference_title: "Pelvic organ prolapse."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "considerations include weight loss, reduction of heavy lifting, treatment of constipation, modification or reduction of obstetric risk factors, and pelvic-floor physical therapy"
    explanation: >
      Enumerates the components of abdominal load that are considered modifiable, quoted
      from a sentence whose opening clause states that no prevention strategy has actually
      been shown effective.
  - reference: PMID:26348380
    reference_title: "Physical activity and the pelvic floor."
    supports: REFUTE
    evidence_source: HUMAN_CLINICAL
    snippet: "Women undergoing surgery for pelvic organ prolapse are more likely to report a history of heavy work than controls; however, women recruited from the community with pelvic organ prolapse on examination report similar lifetime levels of strenuous activity as women without this examination finding."
    explanation: >
      The reason the downstream edge is UNKNOWN. The association reverses depending on how
      cases are ascertained, which is the signature of ascertainment bias rather than of a
      dose-response exposure.
  - reference: PMID:26348380
    reference_title: "Physical activity and the pelvic floor."
    supports: REFUTE
    evidence_source: HUMAN_CLINICAL
    snippet: "Scant data suggest that in middle-aged women, lifetime physical activity increases the odds of stress urinary incontinence slightly and does not increase the odds of pelvic organ prolapse."
    explanation: >
      A second, independent statement of the negative, and one that separates prolapse
      from stress incontinence rather than treating pelvic floor disorders as one outcome.
  downstream:
  - target: Urogenital Hiatus Enlargement and Loss of Levator Closure
    causal_link_type: UNKNOWN
    description: >
      Repeated pressure loading is the presumed route by which abdominal load widens the
      hiatus, but the exposure evidence is inconsistent between surgical and community
      ascertainment and no measurement of hiatal change against cumulative load exists in
      the sources used here.
    evidence:
    - reference: PMID:17382829
      reference_title: "Pelvic organ prolapse."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Vaginal delivery, hysterectomy, chronic straining, normal ageing, and abnormalities of connective tissue or connective-tissue repair predispose some women to disruption, stretching, or dysfunction of the levator ani complex, connective-tissue attachments of the vagina, or both, resulting in prolapse."
      directness: DIRECT
      explanation: >
        States this edge itself - chronic straining predisposing to levator dysfunction.
        Graded DIRECT on that basis and not as a strength claim: it is a narrative review
        asserting the link, which is all the support this edge has, and the edge stays
        UNKNOWN because no source here measures hiatal change against cumulative load.

- name: Failure of Apical and Lateral Connective Tissue Attachment
  biological_scale: TISSUE
  description: >
    Loss of effective suspension of the uterus and upper vagina from the pelvic sidewall
    by the cardinal, uterosacral and paravaginal attachments. Measured in living women
    under maximal Valsalva, these three are strongly related to prolapse and are strongly
    correlated with one another, which is the evidence that they fail as one system rather
    than as separable "defects". The character of the failure is informative: what differs
    between women with and without prolapse is ligament length, not ligament stiffness -
    the tissue has lengthened rather than become intrinsically floppier, which fits
    accumulated mechanical failure better than it fits a pure material defect.
  biological_processes:
  - preferred_term: extracellular matrix organization
    term:
      id: GO:0030198
      label: extracellular matrix organization
    modifier: ABNORMAL
  locations:
  - preferred_term: rectouterine fold (containing the uterosacral ligaments)
    term:
      id: UBERON:0007136
      label: rectouterine fold
  - preferred_term: uterus
    term:
      id: UBERON:0000995
      label: uterus
  evidence:
  - reference: PMID:27517338
    reference_title: "What's new in the functional anatomy of pelvic organ prolapse?"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Failure of the lateral connective tissue attachments between the uterus and vagina to the pelvic wall (cardinal, uterosacral, and paravaginal) are strongly related with prolapse"
    explanation: >
      Identifies the three attachments this node covers and states their relation to
      prolapse.
  - reference: PMID:27517338
    reference_title: "What's new in the functional anatomy of pelvic organ prolapse?"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The primary difference in ligament properties between women with and without prolapse is found in ligament length. Only minor differences in ligament stiffness are seen."
    explanation: >
      Characterises the failure as geometric rather than material, which is the discriminating
      observation between this entry's two mechanistic hypotheses.
  downstream:
  - target: Descent of the Pelvic Organs Beyond the Hymen
    causal_link_type: DIRECT
    description: >
      Once the suspensory attachments have lengthened or given way, the uterus and vaginal
      apex are no longer held above the levator plate and descend.
    evidence:
    - reference: PMID:27517338
      reference_title: "What's new in the functional anatomy of pelvic organ prolapse?"
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Pelvic organ prolapse occurs because of injury to the levator ani muscles and failure of the lateral connections between the pelvic organs to the pelvic sidewall."
      explanation: >
        Names attachment failure as one of the two proximate causes of prolapse, which is
        this edge.
  - target: Cystocele
    causal_link_type: DIRECT
    description: >
      Apical support is not merely correlated with anterior wall support, it accounts for
      about half its variance in living women imaged under Valsalva - so a substantial
      part of what presents as a "bladder" prolapse is an apical lesion expressed in the
      anterior compartment. This is the mechanistic reason apical suspension is part of
      an anterior repair.
    evidence:
    - reference: PMID:16579933
      reference_title: "The relationship between anterior and apical compartment support."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Half of the observed variation in anterior compartment support may be explained by apical support."
      explanation: >
        The authors' conclusion, and the quantitative basis for treating anterior descent
        as partly a consequence of apical attachment failure rather than an independent
        anterior defect.
    - reference: PMID:16579933
      reference_title: "The relationship between anterior and apical compartment support."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "The Pearson correlation coefficient of the relationship between the bladder base and uterine distances was r = 0.73 (r2 = 0.53)."
      explanation: >
        The measurement behind the conclusion; note it is a cross-sectional correlation in
        153 women, so the edge rests on covariation plus anatomy, not on an intervention.
  - target: Uterine Prolapse
    causal_link_type: DIRECT
    description: >
      The cardinal and uterosacral complex is what suspends the uterus, so its failure is
      uterine descent rather than a cause of something that later becomes uterine descent.
    evidence:
    - reference: PMID:27517338
      reference_title: "What's new in the functional anatomy of pelvic organ prolapse?"
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Failure of the lateral connective tissue attachments between the uterus and vagina to the pelvic wall (cardinal, uterosacral, and paravaginal) are strongly related with prolapse"
      explanation: >
        Names the uterus explicitly among the organs these attachments suspend, which is
        what makes this edge apical rather than generic.

- name: Descent of the Pelvic Organs Beyond the Hymen
  biological_scale: ORGANISM
  description: >
    The disease-defining lesion: bladder, uterus, post-hysterectomy vaginal cuff or bowel
    descending so that the vaginal walls or uterus protrude toward and past the hymen.
    Everything clinically recognisable follows from here, and so does the entry's central
    epidemiological oddity - descent on examination is far commoner than the complaint,
    the two correlate poorly, and of the many symptoms attributed to prolapse only the
    sensation of a vaginal bulge is actually specific to it.
  locations:
  - preferred_term: vagina
    term:
      id: UBERON:0000996
      label: vagina
  - preferred_term: uterus
    term:
      id: UBERON:0000995
      label: uterus
  - preferred_term: urinary bladder
    term:
      id: UBERON:0001255
      label: urinary bladder
  evidence:
  - reference: PMID:17382829
    reference_title: "Pelvic organ prolapse."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Pelvic organ prolapse is downward descent of female pelvic organs, including the bladder, uterus or post-hysterectomy vaginal cuff, and the small or large bowel, resulting in protrusion of the vagina, uterus, or both."
    explanation: >
      The definitional statement, including the four organs that may descend.
  - reference: PMID:17382829
    reference_title: "Pelvic organ prolapse."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Patients generally present with several complaints, including bladder, bowel, and pelvic symptoms; however, with the exception of vaginal bulging, none is specific to prolapse."
    explanation: >
      Supports the symptom-specificity claim in this node's description and, downstream,
      the decision not to over-attribute the urinary and bowel phenotypes to this node
      alone.
  - reference: PMID:31851453
    reference_title: "Narrative review of the epidemiology, diagnosis and pathophysiology of pelvic organ prolapse."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The anatomical changes do not always consist with the severity or the symptoms associated with prolapse."
    explanation: >
      States the anatomy-symptom discordance directly; it is the basis of the knowledge
      gap attached to this node.

- name: Recurrence After Reconstructive Surgery
  biological_scale: ORGANISM
  description: >
    Anatomic or symptomatic failure of a prolapse repair. It is curated as a node rather
    than as a treatment outcome because it is mechanistically informative: reconstructive
    surgery restores the suspensory attachments and does not restore the levator, so a
    wide genital hiatus persists across the operation, and it is that persisting hiatus
    that predicts failure. Recurrence is thus the clinical readout of the part of the
    mechanism that current surgery leaves untouched, and it explains why apical
    suspensions differ in durability while none abolishes recurrence.
  locations:
  - preferred_term: vagina
    term:
      id: UBERON:0000996
      label: vagina
  evidence:
  - reference: PMID:34270804
    reference_title: "Enlargement of the genital hiatus is associated with prolapse recurrence in patients undergoing sacrospinous ligament fixation."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Both preoperative and postoperative widened GH correlated with having more surgical failures following SSLF."
    explanation: >
      The primary result linking hiatal width to surgical failure, both before and after
      operation.
  - reference: PMID:34270804
    reference_title: "Enlargement of the genital hiatus is associated with prolapse recurrence in patients undergoing sacrospinous ligament fixation."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "A posterior colporrhaphy did not improve success."
    explanation: >
      A negative surgical result that fits the node's framing: adding a vaginal wall repair
      does not compensate for the unaddressed hiatus.
  - reference: PMID:23633316
    reference_title: "Surgical management of pelvic organ prolapse in women."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "For upper vaginal prolapse (uterine or vault) abdominal sacral colpopexy was associated with a lower rate of recurrent vault prolapse on examination and painful intercourse than with vaginal sacrospinous colpopexy."
    explanation: >
      Establishes that recurrence rates differ by procedure, which is what makes this a
      node with a variable rate rather than a fixed property of the disease.

phenotypes:
- category: Anatomic
  name: Pelvic Organ Prolapse
  description: >
    Descent of one or more vaginal walls or the uterus to or beyond the hymen on maximal
    Valsalva. The defining finding; graded in practice by the POP-Q system.
  phenotype_term:
    preferred_term: Pelvic organ prolapse
    term:
      id: HP:0031607
      label: Pelvic organ prolapse
  evidence:
  - reference: PMID:17382829
    reference_title: "Pelvic organ prolapse."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Pelvic organ prolapse is downward descent of female pelvic organs, including the bladder, uterus or post-hysterectomy vaginal cuff, and the small or large bowel, resulting in protrusion of the vagina, uterus, or both."
    explanation: >
      The definitional description of the finding.
- category: Anatomic
  name: Cystocele
  description: >
    Anterior compartment prolapse, with the bladder bulging into the anterior vaginal
    wall. The most frequently affected compartment in imaged cohorts.
  phenotype_term:
    preferred_term: Cystocele
    term:
      id: HP:0100645
      label: Cystocele
  evidence:
  - reference: PMID:36343586
    reference_title: "Levator ani muscle avulsion in patients with pelvic floor dysfunction - Does it help in understanding pelvic organ prolapse?"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The anterior compartment was the most frequently affected"
    explanation: >
      Identifies the anterior compartment as the most commonly involved in a cohort of 848
      women assessed by transperineal ultrasound.
- category: Anatomic
  name: Uterine Prolapse
  description: >
    Apical descent of the uterus. Where the uterus has been removed, the equivalent lesion
    is descent of the vaginal vault, which is the apical compartment addressed by
    sacrocolpopexy and sacrospinous fixation.
  phenotype_term:
    preferred_term: Uterine prolapse
    term:
      id: HP:0000139
      label: Uterine prolapse
  evidence:
  - reference: PMID:23633316
    reference_title: "Surgical management of pelvic organ prolapse in women."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "For upper vaginal prolapse (uterine or vault) abdominal sacral colpopexy was associated with a lower rate of recurrent vault prolapse on examination and painful intercourse than with vaginal sacrospinous colpopexy."
    explanation: >
      Treats uterine and vault prolapse as the apical compartment, which is how this
      phenotype is scoped.
- category: Anatomic
  name: Rectocele
  description: >
    Posterior compartment prolapse, with the rectum bulging into the posterior vaginal
    wall; the lesion addressed by posterior vaginal repair.
  phenotype_term:
    preferred_term: Rectocele
    term:
      id: HP:0100822
      label: Rectocele
  notes: >
    Deliberately left without an incoming pathograph edge, unlike Cystocele and Uterine
    Prolapse. The compartment-specific risk carried by levator avulsion is concentrated in
    the anterior and apical compartments, and the study that quantified it attributes the
    overall association to those two; no comparable quantified route from either the
    muscular or the connective-tissue arm to the posterior compartment was found. Wiring
    rectocele off the levator node anyway would assert an attribution the source
    specifically does not make. The mechanism of posterior compartment descent is a real
    gap in this entry rather than an omission.
  evidence:
  - reference: PMID:23633316
    reference_title: "Surgical management of pelvic organ prolapse in women."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Data from three trials compared posterior vaginal repair and transanal repair for the treatment of posterior compartment prolapse (rectocele)."
    explanation: >
      Identifies rectocele as the posterior compartment lesion, in the context of the
      trials that treat it.
  - reference: PMID:18503571
    reference_title: "Levator trauma is associated with pelvic organ prolapse."
    supports: NO_EVIDENCE
    evidence_source: HUMAN_CLINICAL
    snippet: "This effect is mainly due to an increased risk of cystocele and uterine prolapse."
    explanation: >
      Does not bear on the phenotype claim itself, which the item above evidences. It is
      retained here because it is the sentence behind this phenotype's deliberate absence
      of an incoming pathograph edge, recorded in the notes: the same sentence that grounds
      the two compartment edges elsewhere in this entry attributes the levator effect to
      the anterior and apical compartments only.
- category: Urinary
  name: Stress Urinary Incontinence
  description: >
    Leakage on exertion, cough or sneeze. Curated as a co-occurring pelvic floor disorder
    rather than as a consequence of descent: it shares the birth-injury exposure, it is
    frequently unmasked rather than caused by prolapse repair, and continence surgery is
    often performed concomitantly for exactly that reason.
  phenotype_term:
    preferred_term: Stress urinary incontinence
    term:
      id: HP:0010992
      label: Stress urinary incontinence
  evidence:
  - reference: PMID:23633316
    reference_title: "Surgical management of pelvic organ prolapse in women."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Women undergoing prolapse surgery may have benefited from having continence surgery performed concomitantly, especially if they had stress urinary incontinence"
    explanation: >
      Establishes the clinical co-occurrence and the concomitant-surgery practice that
      motivates curating it as a linked but distinct disorder.
  - reference: PMID:38168908
    reference_title: "Pelvic floor injury during vaginal birth is life-altering and preventable: what can we do about it?"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Vaginal birth is the largest modifiable risk factor for prolapse, the pelvic floor disorder most strongly associated with birth, and is an important contributor to stress incontinence."
    explanation: >
      States the shared obstetric exposure while distinguishing the strength of its
      association with each of the two disorders.
- category: Urinary
  name: Voiding Dysfunction
  description: >
    Incomplete bladder emptying, often from kinking of the urethra by a descending
    anterior wall. Notably it also arises de novo after prolapse surgery, in about one in
    eleven women.
  phenotype_term:
    preferred_term: Urinary retention
    term:
      id: HP:0000016
      label: Urinary retention
  evidence:
  - reference: PMID:23633316
    reference_title: "Surgical management of pelvic organ prolapse in women."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Following prolapse surgery, 12% of women developed de novo symptoms of bladder overactivity and 9% de novo voiding dysfunction."
    explanation: >
      Quantifies de novo voiding dysfunction after repair. Note this evidences the
      postoperative form specifically; the preoperative obstructive mechanism is described
      but not separately quantified here.
- category: Gastrointestinal
  name: Obstructed Defecation and Constipation
  description: >
    Difficulty evacuating, sometimes requiring digital support of the posterior vaginal
    wall. Bidirectional with the disease: chronic straining is also curated here as a
    contributor to intra-abdominal load.
  phenotype_term:
    preferred_term: Constipation
    term:
      id: HP:0002019
      label: Constipation
  evidence:
  - reference: PMID:33207004
    reference_title: "Pessaries (mechanical devices) for managing pelvic organ prolapse in women."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Women experience a variety of troublesome symptoms as a consequence of prolapse, including a feeling of 'something coming down' into the vagina, pain, urinary symptoms, bowel symptoms and sexual difficulties."
    explanation: >
      Names bowel symptoms among the consequences of prolapse. The snippet supports the
      symptom domain rather than obstructed defecation specifically, which is why no
      frequency band is asserted.
- category: Sexual
  name: Dyspareunia
  description: >
    Pain with intercourse. Both a symptom of prolapse and an outcome measure of its
    surgical treatment, where it differs between operations.
  phenotype_term:
    preferred_term: Dyspareunia
    term:
      id: HP:0030016
      label: Dyspareunia
  evidence:
  - reference: PMID:23633316
    reference_title: "Surgical management of pelvic organ prolapse in women."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "abdominal sacral colpopexy was associated with a lower rate of recurrent vault prolapse on examination and painful intercourse than with vaginal sacrospinous colpopexy"
    explanation: >
      Painful intercourse is reported as a comparative outcome between apical procedures,
      establishing it as a clinically tracked feature of the disease and its treatment.
  - reference: PMID:23240798
    reference_title: "Prolapse and sexual function in women with benign joint hypermobility syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Significantly more women with BJHS felt that POP interfered with sex and defecation compared with the control group."
    explanation: >
      Independent evidence that prolapse interferes with sexual function, measured by a
      validated instrument in a matched case-control design.
- category: Pain
  name: Pelvic Pain and Pressure
  description: >
    A dragging or bearing-down sensation in the pelvis. Non-specific: it is reported by
    women with prolapse but is not diagnostic of it.
  phenotype_term:
    preferred_term: Pelvic pain
    term:
      id: HP:0034267
      label: Pelvic pain
  evidence:
  - reference: PMID:17382829
    reference_title: "Pelvic organ prolapse."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Patients generally present with several complaints, including bladder, bowel, and pelvic symptoms; however, with the exception of vaginal bulging, none is specific to prolapse."
    directness: DIRECT
    explanation: >
      Asserts this phenotype as curated. The source names pelvic symptoms as part of the
      presentation while explicitly denying them specificity, and non-specificity is what
      the phenotype description claims.

genetic:
- name: WNT4
  gene_term:
    preferred_term: WNT4
    term:
      id: hgnc:12783
      label: WNT4
  relationship_type: SUSCEPTIBILITY
  notes: >
    rs3820282, proposed to alter oestrogen-based regulation of WNT4, associates with
    prolapse and also with uterine leiomyoma, gestational duration and endometriosis, a
    cross-phenotype pattern consistent with a shared reproductive-tract connective tissue
    or hormonal axis rather than a prolapse-specific effect.
  evidence:
  - reference: PMID:32184442
    reference_title: "Genome-wide association identifies seven loci for pelvic organ prolapse in Iceland and the UK Biobank."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Of these, rs3820282, which may alter the estrogen-based regulation of WNT4, also associates with leiomyoma of uterus, gestational duration and endometriosis."
    explanation: >
      Names the variant, the proposed regulatory mechanism (with the authors' own hedge)
      and the cross-phenotype associations.
- name: EFEMP1
  gene_term:
    preferred_term: EFEMP1
    term:
      id: hgnc:3218
      label: EFEMP1
  relationship_type: SUSCEPTIBILITY
  notes: >
    rs3791675 at EFEMP1 (fibulin-3), a connective tissue homeostasis gene whose prolapse
    association is shared with hernia and carpal tunnel syndrome. EFEMP1 is a fibulin, the
    same protein family as FBLN5, whose deletion causes prolapse in mice.
  evidence:
  - reference: PMID:32184442
    reference_title: "Genome-wide association identifies seven loci for pelvic organ prolapse in Iceland and the UK Biobank."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Rs3791675 at EFEMP1, a gene involved in connective tissue homeostasis, also associates with hernias and carpal tunnel syndrome."
    explanation: >
      Names the variant, the gene's function, and the shared connective tissue phenotypes.
- name: WT1
  gene_term:
    preferred_term: WT1
    term:
      id: hgnc:12796
      label: WT1
  relationship_type: SUSCEPTIBILITY
  notes: >
    rs10742277 at the WT1 locus reached genome-wide significance in the Japanese
    population (OR 1.48). WT1 is a urogenital developmental transcription factor, so this
    is the one associated locus that points at development of the support structures
    rather than at their maintenance.
  evidence:
  - reference: PMID:39349682
    reference_title: "Genome-wide association studies for pelvic organ prolapse in the Japanese population."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "We identified a significant association of WT1 locus with POP in the Japanese population"
    explanation: >
      States the association and the population in which it was found.
- name: FGFR2
  gene_term:
    preferred_term: FGFR2
    term:
      id: hgnc:3689
      label: FGFR2
  relationship_type: SUSCEPTIBILITY
  notes: >
    rs7072877 at FGFR2, identified only in cross-ancestry meta-analysis of 28,857 cases
    and 622,916 controls, with a small effect (OR 1.06), a reminder of the effect sizes
    the common-variant architecture of this disease actually carries.
  evidence:
  - reference: PMID:39349682
    reference_title: "Genome-wide association studies for pelvic organ prolapse in the Japanese population."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "identified FGFR2 locus as a novel susceptibility locus to POP"
    explanation: >
      States the locus and that it emerged from the cross-ancestry meta-analysis rather
      than from either population alone.
- name: LOXL1
  gene_term:
    preferred_term: LOXL1
    term:
      id: hgnc:6665
      label: LOXL1
  relationship_type: MODIFIER
  notes: >
    Lysyl oxidase-like 1, the elastin cross-linking enzyme whose deletion in mice causes
    postpartum prolapse. Typed MODIFIER rather than CAUSATIVE because the evidence is
    entirely murine: no human LOXL1 loss-of-function prolapse syndrome has been
    established, and LOXL1 is not among the loci returned by the human association studies
    curated here.
  evidence:
  - reference: PMID:14745449
    reference_title: "Elastic fiber homeostasis requires lysyl oxidase-like 1 protein."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "mice lacking the protein lysyl oxidase-like 1 (LOXL1) do not deposit normal elastic fibers in the uterine tract post partum and develop pelvic organ prolapse"
    explanation: >
      The murine loss-of-function result, quoted so that the species restriction is
      visible in the snippet itself.
- name: FBLN5
  gene_term:
    preferred_term: FBLN5
    term:
      id: hgnc:3602
      label: FBLN5
  relationship_type: MODIFIER
  notes: >
    Fibulin-5, the LOXL1-interacting scaffold protein of elastogenesis. As with LOXL1 the
    prolapse evidence is murine; unlike LOXL1, the Fbln5-null phenotype develops with
    ageing rather than as a failure of postpartum repair, which is why the two models sit
    on different inputs to the same node in this entry.
  evidence:
  - reference: PMID:35088092
    reference_title: "Mouse Knockout Models for Pelvic Organ Prolapse: a Systematic Review."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "Loxl1 KO mice develop POP primarily from failure to heal after giving birth, whereas Fbln5 KO mice develop POP with aging."
    explanation: >
      Distinguishes the two models' routes to the same phenotype, which is the basis for
      curating them separately.

animal_models:
- species: Mouse
  genotype: Loxl1 null (Loxl1-/-)
  publication: PMID:14745449
  description: >
    Germline deletion of lysyl oxidase-like 1. The animals fail to deposit normal elastic
    fibers in the uterine tract after parturition and develop pelvic organ prolapse,
    together with an elastinopathy elsewhere (enlarged pulmonary airspaces, loose skin,
    vascular abnormality) and tropoelastin accumulation. The systemic phenotype is part of
    the interpretation, not noise: it is the reason the prolapse is attributed to
    elastogenesis failure rather than to something pelvis-specific.
  modeled_mechanisms:
  - target: Impaired Elastic Fiber Assembly and Postpartum Elastogenesis
    relationship: RECAPITULATES
    fidelity: MODERATE
    description: >
      The model reproduces the node directly and, unusually, is the source of it: the
      requirement for postpartum elastogenesis in pelvic support was established here
      rather than confirmed here.
    limitations: >
      A germline null of a gene not implicated by human association studies of prolapse,
      in a quadrupedal animal whose pelvic floor bears load quite differently from a
      biped's. It demonstrates sufficiency of an elastogenesis lesion, not that this is
      the human lesion.
    readouts:
    - name: Elastic fiber deposition in the postpartum uterine tract
      target: Impaired Elastic Fiber Assembly and Postpartum Elastogenesis
      direction: DECREASED
      interpretation: >
        Structural readout of the node: normal elastic fibers are not laid down after
        parturition.
      evidence:
      - reference: PMID:14745449
        reference_title: "Elastic fiber homeostasis requires lysyl oxidase-like 1 protein."
        supports: SUPPORT
        evidence_source: MODEL_ORGANISM
        snippet: "mice lacking the protein lysyl oxidase-like 1 (LOXL1) do not deposit normal elastic fibers in the uterine tract post partum and develop pelvic organ prolapse"
        explanation: >
          Reports the deposition failure and the prolapse in the same sentence.
    evidence:
    - reference: PMID:35088092
      reference_title: "Mouse Knockout Models for Pelvic Organ Prolapse: a Systematic Review."
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: "Loxl1 and Fbln5 KO models have provided the most reliable and predictable POP phenotype."
      explanation: >
        Independent systematic assessment that this model is informative rather than
        anecdotal, which is what the link-level evidence is for.
- species: Mouse
  genotype: Fbln5 null (Fbln5-/-)
  publication: PMID:17255326
  description: >
    Germline deletion of fibulin-5, the LOXL1-interacting elastogenesis scaffold. These
    animals prolapse with ageing rather than acutely after delivery, and the study that
    characterised them also mapped the normal postpartum time course of LOX, LOXL1,
    fibulin-5 and tropoelastin in the mouse vagina - which is what identified the
    postpartum elastogenic burst as a discrete, and therefore failable, event.
  modeled_mechanisms:
  - target: Impaired Elastic Fiber Assembly and Postpartum Elastogenesis
    relationship: RECAPITULATES
    fidelity: MODERATE
    description: >
      Reproduces the node through the ageing route rather than the postpartum-repair
      route, which is why it and the Loxl1 model are curated as two models of one node
      rather than duplicates.
    limitations: >
      As for Loxl1: germline null, quadruped, and a gene not returned by human prolapse
      GWAS. The authors' comparison is to prolapse in primates, not in women.
    readouts:
    - name: Pelvic organ support with ageing
      target: Impaired Elastic Fiber Assembly and Postpartum Elastogenesis
      direction: DECREASED
      interpretation: >
        Whole-animal anatomic readout; the phenotype is reported as resembling primate
        prolapse.
      evidence:
      - reference: PMID:17255326
        reference_title: "Pelvic organ prolapse in fibulin-5 knockout mice: pregnancy-induced changes in elastic fiber homeostasis in mouse vagina."
        supports: SUPPORT
        evidence_source: MODEL_ORGANISM
        snippet: "Pelvic organ prolapse in Fbln5-/- mice was remarkably similar to that in primates."
        explanation: >
          The anatomic comparison on which the model's face validity rests.
    evidence:
    - reference: PMID:35088092
      reference_title: "Mouse Knockout Models for Pelvic Organ Prolapse: a Systematic Review."
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: "Loxl1 KO mice develop POP primarily from failure to heal after giving birth, whereas Fbln5 KO mice develop POP with aging."
      explanation: >
        States the distinct route by which this model reaches the shared node.

diagnosis:
- name: POP-Q Staged Pelvic Examination
  description: >
    Diagnosis is clinical, and the measurement standard is the Pelvic Organ Prolapse
    Quantification (POP-Q) system agreed in 1996 by the International Continence Society,
    the American Urogynecologic Society and the Society of Gynecologic Surgeons. It
    records the position of defined vaginal points relative to the hymen under maximal
    Valsalva and stages the result, which is what makes prolapse severity comparable
    between examiners and between studies - almost every cohort cited in this entry is
    staged this way, including the avulsion series behind the compartment edges. Two
    entries in the pathophysiology above are POP-Q measurements rather than research
    constructs: the genital hiatus (gh) that the recurrence node is built on, and the
    hymen that defines the descent node. Because the system quantifies anatomy and the
    disease's central oddity is that anatomy and symptoms correlate poorly, a POP-Q stage
    is not on its own an indication to treat.
  diagnosis_term:
    preferred_term: POP-Q staged pelvic examination
    term:
      id: NCIT:C214455
      label: Pelvic Organ Prolapse Exam
  evidence:
  - reference: PMID:8694033
    reference_title: "The standardization of terminology of female pelvic organ prolapse and pelvic floor dysfunction."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "An objective site-specific system for describing, quantitating, and staging pelvic support in women is included."
    explanation: >
      The originating consensus statement, and the basis for describing POP-Q as an
      objective site-specific staging system rather than a severity impression.
  - reference: PMID:8694033
    reference_title: "The standardization of terminology of female pelvic organ prolapse and pelvic floor dysfunction."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "This article presents a standard system of terminology recently approved by the International Continence Society, the American Urogynecologic Society, and the Society of Gynecologic Surgeons"
    explanation: >
      Names the three societies that approved it, which is what makes this the field
      standard rather than one group's proposal.
  - reference: PMID:21505577
    reference_title: "Pelvic Organ Prolapse Quantification System (POP-Q) - a new era in pelvic prolapse staging."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "although is not very simple as a concept, it helps defining the features of a prolapse at a level of completeness not reached by any other system to date"
    explanation: >
      A later appraisal placing POP-Q above the earlier staging systems, supporting its
      description here as the standard rather than one option among several.
  - reference: PMID:31851453
    reference_title: "Narrative review of the epidemiology, diagnosis and pathophysiology of pelvic organ prolapse."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The anatomical changes do not always consist with the severity or the symptoms associated with prolapse."
    explanation: >
      The reason a POP-Q stage does not by itself indicate treatment; this is the same
      discordance curated as a knowledge gap on the descent node.
- name: Pelvic Floor Transperineal Ultrasound
  description: >
    Three- or four-dimensional transperineal (translabial) ultrasound is how the levator
    lesion at the head of this entry's canonical arm is actually seen in a living woman:
    it identifies levator ani avulsion and measures hiatal dimensions. It is what makes
    the muscular arm clinically observable rather than inferred, and every avulsion
    cohort cited here rests on it. It is not a routine diagnostic requirement - prolapse
    is diagnosed on examination - so it is curated as the mechanism-resolving
    investigation rather than as a diagnostic standard.
  diagnosis_term:
    preferred_term: pelvic floor transperineal ultrasound
    term:
      id: NCIT:C17230
      label: Ultrasound Imaging
  evidence:
  - reference: PMID:36343586
    reference_title: "Levator ani muscle avulsion in patients with pelvic floor dysfunction - Does it help in understanding pelvic organ prolapse?"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The presence of LAM avulsion was diagnosed by 3D/4D pelvic floor transperineal ultrasound."
    explanation: >
      States the modality and that avulsion is the finding it establishes, which is this
      entry's use of it.
  - reference: PMID:18503571
    reference_title: "Levator trauma is associated with pelvic organ prolapse."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "imaging of the levator ani muscle by four-dimensional translabial ultrasound"
    explanation: >
      Independent confirmation of the modality, in the cohort that supplies the
      compartment-specific risk ratios used above.
  notes: >
    Dynamic pelvic MRI and defecography are also used, principally for multi-compartment
    and posterior-compartment assessment, but no cached reference in this entry
    substantiates a specific claim about them, so they are not curated as separate
    diagnosis entries.

treatments:
- name: Pelvic Floor Muscle Training
  description: >
    An individualised, supervised programme of pelvic floor muscle exercise. In the POPPY
    trial, 447 women with symptomatic stage I-III prolapse were randomised to one-to-one
    training or a lifestyle advice leaflet, and the trained group reported a significantly
    greater reduction in prolapse symptom score at 12 months. What the trial establishes
    and what it does not is worth stating plainly: the endpoint was self-reported symptoms,
    not anatomic stage, and training cannot reattach an avulsed levator.
  therapeutic_modality: BEHAVIORAL
  treatment_term:
    preferred_term: pelvic floor physical therapy
    term:
      id: NCIT:C15302
      label: Physical Therapy
  target_mechanisms:
  - target: Urogenital Hiatus Enlargement and Loss of Levator Closure
    treatment_effect: INHIBITS
    description: >
      Training targets the residual levator, the muscle whose failure opens the hiatus.
      The edge is placed here rather than on the descent node because the intervention
      acts on muscle function; note that the trial's own endpoint was symptomatic, so this
      mechanistic placement is inference from the target tissue, not a measured hiatal
      change.
    evidence:
    - reference: PMID:24290404
      reference_title: "Individualised pelvic floor muscle training in women with pelvic organ prolapse (POPPY): a multicentre randomised controlled trial."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "One-to-one pelvic floor muscle training for prolapse is effective for improvement of prolapse symptoms."
      directness: INDIRECT
      explanation: >
        A therapeutic response cited as validation of the mechanism it targets: the trial
        demonstrates symptomatic benefit, and the levator step this edge asserts follows
        only by inference from the tissue the intervention acts on.
  evidence:
  - reference: PMID:24290404
    reference_title: "Individualised pelvic floor muscle training in women with pelvic organ prolapse (POPPY): a multicentre randomised controlled trial."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Female outpatients with newly-diagnosed, symptomatic stage I, II, or III prolapse were randomly assigned"
    explanation: >
      Defines the population in which the benefit was shown, which bounds the
      recommendation to symptomatic early-to-moderate prolapse.
- name: Vaginal Pessary
  description: >
    A passive intravaginal device that mechanically supports the vaginal walls and holds
    the descended organs in position. It treats the mechanics without altering any of the
    upstream biology, which makes it the cleanest illustration in this entry of how far
    the disease is a structural problem. The Cochrane evidence is thinner than its
    ubiquity suggests: pessary versus no treatment and pessary versus training are both
    uncertain, and only pessary added to training reaches moderate certainty. The same
    review reports that pessaries may cause a large increase in adverse events relative to
    training, so the comparison against training is not cost-free on either side.
  therapeutic_modality: DEVICE
  treatment_term:
    preferred_term: vaginal pessary placement
    term:
      id: NCIT:C49236
      label: Therapeutic Procedure
  target_mechanisms:
  - target: Descent of the Pelvic Organs Beyond the Hymen
    treatment_effect: INHIBITS
    description: >
      The device physically opposes descent. This is the one treatment edge in the entry
      whose mechanism is not in doubt, because the mechanism is the device's stated design.
    evidence:
    - reference: PMID:33207004
      reference_title: "Pessaries (mechanical devices) for managing pelvic organ prolapse in women."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Vaginal pessaries are passive mechanical devices designed to support the vagina and hold the prolapsed organs back in the anatomically correct position."
      explanation: >
        States the mechanism of action directly.
  evidence:
  - reference: PMID:33207004
    reference_title: "Pessaries (mechanical devices) for managing pelvic organ prolapse in women."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "We are uncertain if pessaries improve pelvic organ prolapse symptoms for women compared with no treatment or PFMT but pessaries in addition to PFMT probably improve women's pelvic organ prolapse symptoms and prolapse-specific quality of life."
    directness: DIRECT
    explanation: >
      Asserts the efficacy claim this treatment is curated with, uncertainty included: two
      of the three comparisons are uncertain and only pessary added to training reaches
      moderate certainty. It supports the calibrated description, not an unqualified
      benefit claim, and the description says so in the same words.
  - reference: PMID:33207004
    reference_title: "Pessaries (mechanical devices) for managing pelvic organ prolapse in women."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Pessaries may result in a large increase in risk of adverse events compared with PFMT"
    directness: DIRECT
    explanation: >
      Asserts the harm the description now carries, so the comparison against training is
      not presented as cost-free.
- name: Reconstructive Prolapse Surgery
  description: >
    Restoration of the vaginal axis by resuspending the apex and repairing the compartment
    defects. For the apical compartment, abdominal sacral colpopexy outperforms the vaginal
    alternatives anatomically, at the cost of longer operating time, slower recovery and
    greater expense. Transvaginal polypropylene mesh reduced recurrence on examination but
    at a mesh erosion rate above one in ten and a higher reoperation rate, and it has since
    been withdrawn in many jurisdictions - a case where an anatomic endpoint and a
    patient-centred one pointed in opposite directions.
  therapeutic_modality: SURGERY
  treatment_term:
    preferred_term: reconstructive pelvic floor surgery
    term:
      id: NCIT:C15332
      label: Gynecological Surgical Procedure
  target_mechanisms:
  - target: Failure of Apical and Lateral Connective Tissue Attachment
    treatment_effect: BYPASSES
    description: >
      Typed BYPASSES rather than RESTORES on purpose. Apical suspension substitutes a
      surgical attachment (to the sacrum or the sacrospinous ligament) for the failed
      native one; it does not repair the cardinal-uterosacral complex, and it leaves the
      levator lesion entirely untouched, which is why a wide hiatus continues to predict
      failure afterwards.
    evidence:
    - reference: PMID:23633316
      reference_title: "Surgical management of pelvic organ prolapse in women."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Sacral colpopexy has superior outcomes to a variety of vaginal procedures including sacrospinous colpopexy, uterosacral colpopexy and transvaginal mesh."
      explanation: >
        Establishes that apical suspension works and that the route matters, which is the
        content of this edge.
  evidence:
  - reference: PMID:23633316
    reference_title: "Surgical management of pelvic organ prolapse in women."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Mesh erosions were reported in 11.4% (64/563), with surgical interventions being performed in 6.8% (32/470)."
    directness: DIRECT
    explanation: >
      Quantifies the erosion rate above one in ten that this treatment is described with,
      and that drove transvaginal mesh off the market. It supports the description's
      explicit limit on the graft-augmented variants rather than the variants themselves.
  - reference: PMID:23633316
    reference_title: "Surgical management of pelvic organ prolapse in women."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Following the withdrawal of some commercial transvaginal mesh kits from the market, the generalisability of the findings, especially relating to anterior compartment transvaginal mesh, should be interpreted with caution."
    directness: DIRECT
    explanation: >
      States the withdrawal the description records, in the reviewers' own words, which
      is why the mesh comparisons above are not curated as live treatment
      recommendations.
- name: Weight Loss and Reduction of Abdominal Straining
  description: >
    Weight reduction, treatment of constipation and avoidance of heavy lifting. Included
    because rising body-mass index is one of the three most consistent risk factors, and
    excluded from any efficacy claim because the same review that lists these measures
    states in the same sentence that no prevention strategy has been shown to work. No
    target_mechanisms edge is asserted: an unevidenced INHIBITS edge here would put a
    false arrow into the pathograph.
  therapeutic_modality: BEHAVIORAL
  treatment_term:
    preferred_term: lifestyle and dietary modification
    term:
      id: NCIT:C15447
      label: Dietary Intervention
  evidence:
  - reference: PMID:17382829
    reference_title: "Pelvic organ prolapse."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Although no effective prevention strategy for prolapse has been identified, considerations include weight loss, reduction of heavy lifting, treatment of constipation, modification or reduction of obstetric risk factors, and pelvic-floor physical therapy."
    directness: DIRECT
    explanation: >
      Asserts this treatment exactly as curated: the measures are named, and no efficacy
      is claimed for them. Quoted in full, including the concessive opening clause, so the
      absence of demonstrated efficacy travels with the list rather than being dropped.
- name: Vaginal Oestrogen
  description: >
    Local oestrogen, widely prescribed alongside pessary use and before surgery for
    atrophic vaginal tissue. Curated here with a negative: in a study of 1443
    postmenopausal women, current vaginal oestrogen was not associated with pelvic organ
    support, and current systemic hormone therapy was associated with slightly worse
    support on two measures. It may still be justified for vaginal atrophy or pessary
    tolerance; it is not a treatment for the prolapse.
  therapeutic_modality: SMALL_MOLECULE
  treatment_term:
    preferred_term: local oestrogen therapy
    term:
      id: NCIT:C15483
      label: Estrogen Therapy
  evidence:
  - reference: PMID:28538602
    reference_title: "Pelvic organ prolapse: does hormone therapy use matter?"
    supports: REFUTE
    evidence_source: HUMAN_CLINICAL
    snippet: "Past HT use, duration of HT use, or current vaginal estrogen use was not associated with pelvic organ support."
    explanation: >
      Directly refutes an effect on pelvic organ support, which is why this treatment
      carries no target_mechanisms edge.
  - reference: PMID:28538602
    reference_title: "Pelvic organ prolapse: does hormone therapy use matter?"
    supports: REFUTE
    evidence_source: HUMAN_CLINICAL
    snippet: "HT may have a minor negative effect on pelvic organ support; however, the effect is likely too small to be clinically relevant."
    explanation: >
      The authors' conclusion, retained with their own de-escalation of it, so the entry
      neither claims benefit nor manufactures a harm signal.

discussions:
- discussion_id: gap_matrix_cause_or_consequence
  kind: KNOWLEDGE_GAP
  status: OPEN
  attaches_to:
  - pathophysiology#Collagen and MMP-TIMP Remodelling Imbalance
  prompt: >
    Is the collagen and MMP/TIMP signature of prolapsed tissue a cause of the mechanical
    failure or a response to it?
  rationale: >
    Every human study behind this node is cross-sectional and takes tissue from women who
    already have prolapse, usually at the time of surgery for it. That design cannot order
    cause and effect, and one observation actively points the wrong way: the study that
    sampled both compartments found the changes larger in vaginal tissue, the tissue being
    stretched, than in the uterosacral ligament, where the differences were not significant
    at all. The distinction is not academic. If the matrix lesion is causal, it is a target
    and a screening opportunity; if it is reactive, then a large fraction of the prolapse
    literature is measuring a consequence and calling it a mechanism, and interventions
    aimed at collagen turnover are aimed at the wrong thing. The edge from this node is
    typed INDIRECT_UNKNOWN_INTERMEDIATES for exactly this reason.
  proposed_experiments:
  - experiment_id: prospective_matrix_profiling_nulliparous_cohort
    name: Prospective matrix profiling in a nulliparous cohort followed through first delivery
    description: >
      Sample accessible connective tissue and measure collagen I/III ratio and MMP/TIMP
      profile before first pregnancy in a cohort followed with serial pelvic floor imaging.
      A pre-existing matrix signature in women who later prolapse would establish
      antecedence; a signature that appears only after descent would settle the question
      the other way.
  - experiment_id: site_paired_loaded_unloaded_sampling
    name: Site-paired sampling of loaded and unloaded tissue within the same woman
    description: >
      Within individual prolapse cases, compare matrix markers between mechanically loaded
      vaginal wall and an unloaded connective tissue site from the same patient. A
      difference confined to the loaded site argues for a mechanoresponsive, and therefore
      reactive, change.
  evidence:
  - reference: PMID:16398770
    reference_title: "Collagen metabolism in the uterosacral ligaments and vaginal skin of women with uterine prolapse."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The changes which are more pronounced in vaginal tissue may be as a result of prolapse rather than cause."
    explanation: >
      The authors of a matrix study stating the reverse-causation possibility themselves,
      which is what makes this a gap rather than a curator's doubt.
- discussion_id: gap_anatomy_symptom_discordance
  kind: KNOWLEDGE_GAP
  status: OPEN
  attaches_to:
  - pathophysiology#Descent of the Pelvic Organs Beyond the Hymen
  prompt: >
    Why does anatomic descent correspond so poorly to symptoms, and what determines which
    women with the same POP-Q stage are bothered?
  rationale: >
    Prolapse is one of the few conditions where the defining anatomic lesion and the
    clinical complaint are close to uncoupled. Symptomatic prolapse affects about 3% of US
    women, while descent on examination is far commoner; of the symptoms attributed to
    prolapse only vaginal bulging is specific. This has practical consequences throughout
    the entry: prevalence figures are not comparable unless the ascertainment is stated,
    the mechanistic chain ends at an anatomic node rather than at a symptom, and surgical
    trials that report anatomic success are not reporting what patients came for. Nothing
    in the sources used here explains the discordance.
  evidence:
  - reference: PMID:31851453
    reference_title: "Narrative review of the epidemiology, diagnosis and pathophysiology of pelvic organ prolapse."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The anatomical changes do not always consist with the severity or the symptoms associated with prolapse."
    explanation: >
      States the discordance as a standing problem for the field's epidemiology.
  - reference: PMID:17382829
    reference_title: "Pelvic organ prolapse."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Many women with pelvic organ prolapse are asymptomatic and do not need treatment."
    explanation: >
      The clinical corollary, and the reason observation is a legitimate management option.
- discussion_id: mismatch_elastogenesis_knockout_mice
  kind: HUMAN_MODEL_MISMATCH
  status: OPEN
  attaches_to:
  - pathophysiology#Impaired Elastic Fiber Assembly and Postpartum Elastogenesis
  prompt: >
    Does the elastogenesis-failure mechanism established in Loxl1- and Fbln5-null mice
    operate in human pelvic organ prolapse?
  rationale: >
    The entire mechanistic case that a matrix lesion is sufficient to cause prolapse rests
    on two mouse knockouts, and the translational distance is larger than it first appears.
    Neither gene is returned by the human association studies curated here, which instead
    implicate WNT4, EFEMP1, WT1 and FGFR2; both are germline nulls rather than the common
    regulatory variants human genetics finds; and a quadruped loads its pelvic floor
    differently from a biped, so the same molecular lesion need not produce the same
    mechanical failure. The Fbln5 paper's own comparison is to prolapse in primates rather
    than in women. This is a mismatch and not merely a gap because the evidence exists and
    is strong; it is its applicability to human disease that is unresolved.
  proposed_experiments:
  - experiment_id: human_postpartum_elastogenesis_profiling
    name: Elastic fiber and elastogenic enzyme profiling in human postpartum vaginal tissue
    description: >
      Measure desmosine content, tropoelastin, LOXL1 and fibulin-5 in human vaginal tissue
      across the postpartum period, to test whether the elastogenic burst the mouse studies
      identified exists in women at all, and whether it is attenuated in those with levator
      injury or later prolapse.
  - experiment_id: elastogenesis_rare_variant_burden
    name: Rare-variant burden testing of elastogenesis genes in prolapse cases
    description: >
      Sequence LOXL1, FBLN5 and related elastogenesis genes in a large prolapse cohort and
      test for rare loss-of-function burden. A positive result would connect the murine
      mechanism to human disease; a clean negative would confine these models to
      demonstrating sufficiency in principle.
  evidence:
  - reference: PMID:17255326
    reference_title: "Pelvic organ prolapse in fibulin-5 knockout mice: pregnancy-induced changes in elastic fiber homeostasis in mouse vagina."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "disordered elastic fiber homeostasis is a primary event in the pathogenesis of pelvic organ prolapse in mice"
    directness: INDIRECT
    explanation: >
      The claim at issue, quoted with the species restriction the authors themselves
      attached to it. Indirect for that reason: it is a result in a non-human model, and
      whether it transfers to women is the mismatch this discussion records.
  - reference: PMID:32184442
    reference_title: "Genome-wide association identifies seven loci for pelvic organ prolapse in Iceland and the UK Biobank."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "found eight sequence variants at seven loci associating with POP"
    directness: INDIRECT
    explanation: >
      The human genetic result whose gene list does not include the two genes the mouse
      models are built on. The mismatch follows from comparing that list with the mouse
      loci rather than from anything the quoted sentence states.
- discussion_id: interpretation_no_emphysema_module_conformance
  kind: INTERPRETATION
  status: OPEN
  attaches_to:
  - pathophysiology#Collagen and MMP-TIMP Remodelling Imbalance
  prompt: >
    Should the matrix node conform to
    emphysema_protease_antiprotease_imbalance#Protease-Antiprotease Imbalance?
  rationale: >
    The temptation is real and is worth recording rather than leaving as a silent omission.
    Prolapse shows raised MMP-1/-2/-9 with reduced TIMP-1, and the Loxl1 mouse develops
    enlarged pulmonary airspaces alongside its prolapse from the same elastogenesis defect,
    so the two diseases genuinely share an elastin-loss biology. Conformance was
    nonetheless withheld on three grounds. First, the module is scoped to the alveolus
    throughout: its trigger node is inhaled oxidants and particulates and every downstream
    node is alveolar, so a conforming pelvic node would inherit claims about airway
    inflammation that are false here. Second, the module's imbalance is driven by proteases
    released from recruited neutrophils and macrophages, and no such phagocyte infiltrate
    is evidenced in prolapsed pelvic tissue in any source used here; the cellular source of
    the MMPs is presumed to be the resident fibroblast. Third, and decisively, the module
    asserts its imbalance node as causal, whereas the causal direction of the same
    signature in prolapse is an open gap in this very entry. Declaring conformance would
    launder an unresolved question into an asserted mechanism. A genuinely disease-agnostic
    module for load-bearing soft tissue matrix failure, which would also serve hernia,
    where the human genetics here overlaps, may be worth proposing separately.
  evidence:
  - reference: PMID:14745449
    reference_title: "Elastic fiber homeostasis requires lysyl oxidase-like 1 protein."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "Failure to maintain elastic fibers is explained by a theory of antielastase-elastase imbalance, but little is known about the role of renewal."
    directness: INDIRECT
    explanation: >
      Names the protease-antiprotease framing and, in the same sentence, sets renewal
      against it as the mechanism this paper actually demonstrates. The conclusion drawn
      here - that the prolapse node is a renewal failure rather than a protease imbalance,
      so conformance is withheld - is an inference from that contrast.

notes: >
  Curation notes and deliberate omissions.

  Scope. This entry covers pelvic organ prolapse in women. Rectal prolapse and prolapse of
  the male pelvic organs are different diseases and are out of scope.

  Two things a reader might expect and will not find. There is no conforms_to on any node:
  the candidate module, emphysema_protease_antiprotease_imbalance, was examined and
  declined on the record in the interpretation discussion above rather than omitted
  silently. And no phenotype carries a frequency band. Frequency in prolapse is
  ascertainment-dependent to an unusual degree, since the same population yields roughly 3%
  symptomatic prolapse and a far higher rate of descent on examination, so a band lifted
  from any one source would have been quoting a measure whose denominator does not match
  this entry. The discordance itself is curated as a knowledge gap instead.

  Hysterectomy is named as a risk factor by two of the cited reviews and is not curated as
  a pathophysiology node. Post-hysterectomy vault prolapse is real and is covered by the
  apical phenotype and by the surgical treatments, but no source used here supplies a
  mechanism for it beyond the assertion that the operation predisposes, and a node with no
  mechanism would be a restatement of the risk factor. It is a reasonable target for a
  later pass.

  POP-Q is now curated in the diagnosis section as the staged clinical examination it is.
  It is still not curated as a definitions entry with definition_type PHENOTYPE_ALGORITHM,
  and neither is POP-SS (the symptom score that was the POPPY trial's primary endpoint),
  because the instrument-validation studies behind either have not been read. The
  posterior compartment is the other acknowledged gap: rectocele is curated as a phenotype
  but deliberately carries no incoming pathograph edge, for the reason recorded in its own
  notes.

  Provenance. The entry was written first from direct PubMed search, with every reference
  fetched by just fetch-reference; no citation was taken from a synthesised summary, so
  sections 2a and 2b of the evidence SOP do not apply to any evidence item here. A
  Claude Code deep-research report was generated afterwards as a coverage cross-check
  (research/Pelvic_Organ_Prolapse-deep-research-claude_code.md, 34 references, all
  verified, confabulation rate 0.0). It cited no primary source this entry had missed,
  independently reached the same levator-primary canonical arm and the same five
  susceptibility genes, and its one substantive coverage finding - that POP-Q is the
  diagnostic standard and was absent - is what prompted the diagnosis section. preflight-dr
  returns SKIP because MONDO records no RO:0004003 causal gene for MONDO:0000082, which is
  expected for a complex non-Mendelian disease and means the automated gene-identity check
  cannot discriminate; the manual check is the gene-list concordance just described.

📚

References & Deep Research

References

PMID:17382829

Pelvic organ prolapse.

1 finding

Reference clinical review: prolapse is multifactorial, with vaginal childbirth, advancing age and rising body-mass index as the most consistent risk factors, and only vaginal bulging is specific among the presenting symptoms.

PMID:27517338

What's new in the functional anatomy of pelvic organ prolapse?

1 finding

The load-bearing anatomic synthesis: support depends on the interaction of the levator ani muscle and the lateral connective tissue attachments, with muscle failure exposing the vaginal wall to a pressure differential that abnormally loads those attachments.

PMID:38168908

Pelvic floor injury during vaginal birth is life-altering and preventable: what can we do about it?

1 finding

Quantifies the birth injury: levator and birth canal tissues stretch to more than three times their original length, the resulting tear is present in 55% of women with later prolapse (odds ratio 7.3), and it is overstretching rather than compression or neuropathy that produces it.

PMID:36343586

Levator ani muscle avulsion in patients with pelvic floor dysfunction - Does it help in understanding pelvic organ prolapse?

1 finding

Retrospective cohort of 848 women imaged by transperineal ultrasound relating complete levator avulsion to prolapse stage and number of compartments involved.

PMID:32184442

Genome-wide association identifies seven loci for pelvic organ prolapse in Iceland and the UK Biobank.

1 finding

Eight variants at seven loci in 15,010 cases; the associated genes implicate connective tissue metabolism (EFEMP1) and estrogen-dependent regulation (WNT4).

PMID:39349682

Genome-wide association studies for pelvic organ prolapse in the Japanese population.

1 finding

Japanese GWAS identifying WT1, and a cross-ancestry meta-analysis identifying FGFR2, with directional consistency for 21 of 24 European loci.

PMID:14745449

Elastic fiber homeostasis requires lysyl oxidase-like 1 protein.

1 finding

Loxl1-null mice fail to deposit normal elastic fibers in the uterine tract post partum and develop pelvic organ prolapse together with other elastinopathies.

PMID:17255326

Pelvic organ prolapse in fibulin-5 knockout mice: pregnancy-induced changes in elastic fiber homeostasis in mouse vagina.

1 finding

Fbln5-null mice prolapse, and a postpartum burst of elastic fiber assembly and cross-linking in the vaginal wall is what normal recovery of support depends on.

PMID:35088092

Mouse Knockout Models for Pelvic Organ Prolapse: a Systematic Review.

1 finding

Systematic review of the five available knockout models; Loxl1 and Fbln5 give the most reliable phenotype, and they fail by different routes (failure to heal after birth versus prolapse with ageing).

PMID:38291948

The difference in extracellular matrix metabolism in women with and without pelvic organ prolapse: A systematic review and meta-analysis.

1 finding

Meta-analysis of 30 studies (840 cases, 755 controls): type I collagen and TIMP-1 lower, type III collagen and MMP-1/-2/-9 higher in prolapse, with site-specific exceptions that remain controversial.

PMID:26936098

Collagen metabolic disorder induced by oxidative stress in human uterosacral ligament-derived fibroblasts: A possible pathophysiological mechanism in pelvic organ prolapse.

1 finding

Oxidative injury markers are raised in prolapsed uterosacral ligament, and H2O2 exposure of uterosacral ligament fibroblasts shifts collagen metabolism toward catabolism in a concentration-dependent way.

PMID:16398770

Collagen metabolism in the uterosacral ligaments and vaginal skin of women with uterine prolapse.

1 finding

The source of the reverse-causation caveat: matrix changes were more pronounced in vaginal tissue than in the uterosacral ligament, which the authors read as a consequence of prolapse rather than its cause.

PMID:12114889

Morphometric analysis of smooth muscle in the anterior vaginal wall of women with pelvic organ prolapse.

1 finding

The fractional area of nonvascular smooth muscle in the anterior vaginal wall muscularis is reduced in prolapse, independent of age and prolapse stage.

PMID:18799443

Prevalence of symptomatic pelvic floor disorders in US women.

1 finding

NHANES 2005-2006 national estimate of symptomatic prolapse (seeing or feeling a vaginal bulge) and its gradients with age, parity and body-mass index.

PMID:24807341

Lifetime risk of stress urinary incontinence or pelvic organ prolapse surgery.

1 finding

US claims-based cumulative incidence: 12.6% lifetime risk of prolapse surgery by age 80, with annual risk rising progressively to a peak in the early seventies.

PMID:24290404

Individualised pelvic floor muscle training in women with pelvic organ prolapse (POPPY): a multicentre randomised controlled trial.

1 finding

The definitive randomised trial of one-to-one pelvic floor muscle training in symptomatic stage I-III prolapse; the symptom score improved, and anatomy was not the endpoint.

PMID:33207004

Pessaries (mechanical devices) for managing pelvic organ prolapse in women.

1 finding

Cochrane review of four trials: pessary added to pelvic floor muscle training probably improves symptoms and prolapse-specific quality of life, while pessary versus no treatment or versus training alone remains uncertain.

PMID:23633316

Surgical management of pelvic organ prolapse in women.

1 finding

Cochrane review of 56 trials in 5954 women establishing sacral colpopexy as anatomically superior to vaginal apical procedures, and quantifying transvaginal mesh erosion.

PMID:28538602

Pelvic organ prolapse: does hormone therapy use matter?

1 finding

Negative result on the hormonal arm: in 1443 postmenopausal women, past hormone therapy, duration of use and current vaginal estrogen were not associated with pelvic organ support.

PMID:26348380

Physical activity and the pelvic floor.

1 finding

The counterweight to the mechanical-load risk factor: community-recruited women with prolapse on examination report similar lifetime strenuous activity to women without it, and lifetime physical activity does not increase the odds of prolapse.

PMID:23240798

Prolapse and sexual function in women with benign joint hypermobility syndrome.

1 finding

Age-, parity- and ethnicity-matched case-control study showing objectively more severe prolapse by POP-Q in benign joint hypermobility syndrome.

PMID:39033997

Lower urinary tract involvement in Ehlers-Danlos and Joint Hypermobility syndromes: Review of the literature.

1 finding

Literature review giving the prolapse burden in heritable connective tissue disorders and an odds ratio for hypermobility.

PMID:34270804

Enlargement of the genital hiatus is associated with prolapse recurrence in patients undergoing sacrospinous ligament fixation.

1 finding

Postoperative genital hiatus width is associated with recurrence after sacrospinous ligament fixation, and a posterior colporrhaphy did not improve success.

PMID:31851453

Narrative review of the epidemiology, diagnosis and pathophysiology of pelvic organ prolapse.

1 finding

States the anatomy-symptom discordance directly and enumerates the risk factor set including previous hysterectomy and menopausal state.

PMID:18503571

Levator trauma is associated with pelvic organ prolapse.

1 finding

781 women staged by POP-Q and imaged for levator avulsion: avulsion roughly doubles the overall risk of stage II or higher prolapse, and the authors attribute the effect mainly to cystocele (RR 2.3) and uterine prolapse (RR 4.0) rather than to the posterior compartment.

PMID:16579933

The relationship between anterior and apical compartment support.

1 finding

Dynamic MRI under Valsalva in 153 women: bladder-base and uterine descent correlate at r = 0.73, so about half the variation in anterior compartment support is attributable to apical support.

PMID:8694033

The standardization of terminology of female pelvic organ prolapse and pelvic floor dysfunction.

1 finding

The originating POP-Q consensus statement, approved by the International Continence Society, the American Urogynecologic Society and the Society of Gynecologic Surgeons.

PMID:21505577

Pelvic Organ Prolapse Quantification System (POP-Q) - a new era in pelvic prolapse staging.

1 finding

Appraisal of POP-Q against the earlier staging systems, concluding it describes a prolapse more completely than any predecessor.

Deep Research

Deep research results are used as seeds for research; they do not undergo the same validation as the main records and may contain errors. How we use deep research.

Evaluations and curation notes (3)

Record notes

Curation notes and deliberate omissions. Scope. This entry covers pelvic organ prolapse in women. Rectal prolapse and prolapse of the male pelvic organs are different diseases and are out of scope. Two things a reader might expect and will not find. There is no conforms_to on any node: the candidate module, emphysema_protease_antiprotease_imbalance, was examined and declined on the record in the interpretation discussion above rather than omitted silently. And no phenotype carries a frequency band. Frequency in prolapse is ascertainment-dependent to an unusual degree, since the same population yields roughly 3% symptomatic prolapse and a far higher rate of descent on examination, so a band lifted from any one source would have been quoting a measure whose denominator does not match this entry. The discordance itself is curated as a knowledge gap instead. Hysterectomy is named as a risk factor by two of the cited reviews and is not curated as a pathophysiology node. Post-hysterectomy vault prolapse is real and is covered by the apical phenotype and by the surgical treatments, but no source used here supplies a mechanism for it beyond the assertion that the operation predisposes, and a node with no mechanism would be a restatement of the risk factor. It is a reasonable target for a later pass. POP-Q is now curated in the diagnosis section as the staged clinical examination it is. It is still not curated as a definitions entry with definition_type PHENOTYPE_ALGORITHM, and neither is POP-SS (the symptom score that was the POPPY trial's primary endpoint), because the instrument-validation studies behind either have not been read. The posterior compartment is the other acknowledged gap: rectocele is curated as a phenotype but deliberately carries no incoming pathograph edge, for the reason recorded in its own notes. Provenance. The entry was written first from direct PubMed search, with every reference fetched by just fetch-reference; no citation was taken from a synthesised summary, so sections 2a and 2b of the evidence SOP do not apply to any evidence item here. A Claude Code deep-research report was generated afterwards as a coverage cross-check (research/Pelvic_Organ_Prolapse-deep-research-claude_code.md, 34 references, all verified, confabulation rate 0.0). It cited no primary source this entry had missed, independently reached the same levator-primary canonical arm and the same five susceptibility genes, and its one substantive coverage finding - that POP-Q is the diagnostic standard and was absent - is what prompted the diagnosis section. preflight-dr returns SKIP because MONDO records no RO:0004003 causal gene for MONDO:0000082, which is expected for a complex non-Mendelian disease and means the automated gene-identity check cannot discriminate; the manual check is the gene-list concordance just described.

Review response: address CHANGES_REQUESTED on PR 9414 · 2026-08-28T06:08:27Z · View source

Response to the ai4c-reviewer CHANGES_REQUESTED review on PR #9414, run by the curation scanner (high_effort tier) against issue #7837. Blocking item 1 - truncated snippet. The PMID:26936098 conclusion snippet on the oxidative-stress node ended on a dangling "in a severity", stopping before the word that carries the severity-dependence claim the explanation described. Extended to "...in a severity-dependent manner in hUSLFs", reproducing the source's U+2011 non-breaking hyphen, and the explanation reworded to match what the quote now contains. Blocking item 2 - no deep-research artifact. Generated research/Pelvic_Organ_Prolapse-deep-research-claude_code.md and its citations sidecar with "just research-disorder claude_code Pelvic_Organ_Prolapse". 34 references, 34 verified, confabulation rate 0.0, 29/34 assessed on topic. preflight-dr returns SKIP because MONDO records no RO:0004003 causal gene for MONDO:0000082; the manual substitute is that the report's top genes (WNT4, EFEMP1, FGFR2, LOXL1, WT1) are exactly this entry's genetic section. qc-deep-research reports 0 missing and 0 unresolved refs for this disorder. The report cited no primary source the entry had missed and independently reproduced the levator-primary canonical arm; its one substantive coverage finding was the absent diagnosis section. Suggestion 3 - phenotypes disconnected from the pathograph. Three compartment phenotypes were wired in, but not as consequences of the descent node: descent beyond the hymen is definitionally the same event as cystocele or uterine prolapse in a named compartment, so an edge there would be taxonomic rather than causal. Instead the edges carry published compartment-specific attribution. Levator Ani Muscle Injury and Avulsion now runs to Cystocele and Uterine Prolapse, typed INDIRECT_KNOWN_INTERMEDIATES because the compartment-selectivity step is unknown even though hiatal enlargement and descent are both in the graph, evidenced by PMID:18503571 (RR 2.3 and RR 4.0 in 781 women). Failure of Apical and Lateral Connective Tissue Attachment now runs to Cystocele (DIRECT, PMID:16579933: half the variation in anterior compartment support is explained by apical support, r = 0.73 in 153 women) and to Uterine Prolapse (DIRECT, existing PMID:27517338 evidence). Rectocele deliberately keeps no incoming edge: the same PMID:18503571 sentence attributes the avulsion effect to the anterior and apical compartments, so a posterior edge would assert what the source declines to. That is recorded in the phenotype's own notes plus a PARTIAL evidence item. Suggestion 4 - no diagnosis section. Added two entries. POP-Q Staged Pelvic Examination (NCIT:C214455 Pelvic Organ Prolapse Exam) with the 1996 tri-society consensus (PMID:8694033), a later appraisal against earlier systems (PMID:21505577), and the anatomy-symptom discordance (PMID:31851453) as the reason a stage is not by itself an indication to treat. Pelvic Floor Transperineal Ultrasound (NCIT:C17230 Ultrasound Imaging) as the mechanism-resolving investigation rather than a diagnostic standard, evidenced by PMID:36343586 and PMID:18503571. Dynamic MRI and defecography are named in notes and not curated, since no cached reference substantiates a specific claim about them. Suggestion 5 - GO:0009612 at tissue and organism scale. Left in place, deliberately. GO's own definition of "response to mechanical stimulus" is "any process that results in a change in state or activity of a cell or an organism ... as a result of a mechanical stimulus", so the term is scoped to organism-level response by the ontology itself and its use here is not a scale violation. The reviewer noted the term is "not wrong"; removing three correct annotations to satisfy a rule the ontology does not impose would lose queryable content. Suggestion 6 - history record. The CREATE record's empty links.issues and links.prs were filled with issue 7837 and PR 9414, and its "Ten phenotypes" corrected to nine. That record has not merged, so this is a pre-merge factual correction rather than a rewrite of committed history. Branch refresh. GitHub's update-branch API returned 422 (merge conflict), so origin/main was merged locally; no rebase was used. The conflict was confined to four derived cache CSVs (diseaseterm, treatmentactionterm, mondo/terms, ncit/terms), resolved by taking main's rows and re-deriving this entry's own rows with just validate-terms. Post-merge diff against origin/main is additions plus additive cache rows only, with no deletions. Four new references, all found by PubMed search and fetched with just fetch-reference: PMID:18503571, PMID:16579933, PMID:8694033, PMID:21505577.

Create: Pelvic Organ Prolapse (MONDO:0000082) · 2026-08-24T21:08:45Z · View source

Created kb/disorders/Pelvic_Organ_Prolapse.yaml against the obstetrics coverage gap tracked in issue #7837. Thirteen pathophysiology nodes across a muscular arm (childbirth overstretch, levator avulsion, urogenital hiatus enlargement) and a connective tissue arm (constitutional susceptibility, elastogenesis failure, oxidative stress, collagen and MMP/TIMP imbalance, vaginal smooth muscle depletion), converging on failure of apical and lateral attachment and descent beyond the hymen, plus a post-surgical recurrence node. Two competing mechanistic_hypotheses: CANONICAL levator-primary and ALTERNATIVE matrix-primary. Four discussions: two KNOWLEDGE_GAPs (matrix cause versus consequence, and anatomy/symptom discordance), one HUMAN_MODEL_MISMATCH on the Loxl1 and Fbln5 knockout mice, and one INTERPRETATION recording why conformance to emphysema_protease_antiprotease_imbalance was declined. Nine phenotypes with no frequency bands, deliberately; six genetic entries; two animal models with modeled_mechanisms and readouts; five treatments, two of which carry only negative or partial evidence and no target_mechanisms edge. Twenty-four references, all fetched with just fetch-reference from PubMed searches; no deep-research provider report was used, so evidence SOP sections 2a and 2b do not apply. Validation: just validate-disorders passed schema, terms and references, reporting Snippets checked 100/100 verified against cached references. check-folded-hyphens, check-duplicate-keys, check-snippet-length, check-title-snippets, check-environmental-evidence, check-snippet-boundaries and check-source-defect-claims are all clean for this file; 9272 targeted tests/test_data.py tests passed.

Claude Code ▸

1. Disease Information

claude-haiku-4-5-20251001, claude-opus-4-8[1m] 18 citations 2026-08-28T06:02:26.352776

1. Disease Information

Overview. Pelvic organ prolapse is the downward descent of one or more pelvic organs — the bladder (cystocele/anterior compartment), uterus or post-hysterectomy vaginal cuff (apical compartment), rectum (rectocele/posterior compartment), or small bowel (enterocele) — producing protrusion of the vaginal walls or uterus toward and beyond the hymen. It is best understood not as a disease of one tissue but as the failure of a load-sharing support system: the levator ani muscle complex holds the pelvic floor and urogenital hiatus closed, while the cardinal, uterosacral, and paravaginal connective-tissue attachments suspend the uterus and vagina from the pelvic sidewall. Failure of either element transfers load to the other (PMID:27517338).

Key identifiers. - MONDO: MONDO:0000082 (pelvic organ prolapse) - MeSH: D056887 ("Pelvic Organ Prolapse"); ancestor headings include Prolapse, Female Urogenital Diseases - ICD-10-CM: Category N81 (Female genital prolapse) — N81.1x cystocele, N81.2 incomplete uterovaginal prolapse, N81.3 complete uterovaginal prolapse, N81.4 uterovaginal prolapse unspecified, N81.5 vaginal enterocele, N81.6 rectocele - ICD-11: GC40 (Female pelvic organ prolapse) block, with subentities (e.g., GC40.0 cystocele, GC40.3 uterine prolapse) - OMIM: 176780 ("Pelvic Organ Prolapse, POP") — a susceptibility phenotype entry rather than a Mendelian gene entry - Orphanet: POP is not an Orphanet rare-disease entry (it is common, not rare); heritable connective-tissue disorders that cause it (e.g., Ehlers-Danlos, ORPHA:98249) are separate entries.

Synonyms / alternative names: POP; genital prolapse; urogenital prolapse; vaginal prolapse; pelvic floor dysfunction (broader); by compartment — cystocele, rectocele, enterocele, uterine prolapse, vaginal vault prolapse, procidentia (complete/stage 4).

Data derivation. Population estimates derive from aggregated resources (NHANES, claims databases, national registries, Orphanet-style epidemiology tables) and disease-level cohorts; POP-Q staging, mechanistic tissue studies, and imaging findings are individual-patient/EHR-level.

Sources: MONDO, ICD-10 N81 (AAPC), StatPearls POP (NBK563229); PMID:27517338, PMID:31851453.

2. Etiology

POP is multifactorial. The most consistent risk factors across the literature are vaginal childbirth, advancing age, and rising body-mass index (PMID:17382829): "Prolapse development is multifactorial, with vaginal child birth, advancing age, and increasing body-mass index as the most consistent risk factors."

Disease Causal Factors

Mechanical / obstetric (primary trigger). Vaginal delivery imposes overstretch on the levator ani and birth canal to >3× resting length, producing levator injury/avulsion (PMID:38168908). This is the single largest modifiable driver.
Genetic / constitutional (susceptibility). Inherited variation in connective-tissue composition and turnover sets the load tolerance of the support system (GWAS + monogenic connective-tissue disorders; see §4, §9).
Degenerative / hormonal. Ageing and menopausal estrogen withdrawal (§6).
Not infectious. POP has no infectious etiology.

Risk Factors

Environmental / demographic: - Vaginal childbirth & parity — risk rises with 1, 2, and ≥3 vaginal deliveries vs nulliparity; instrumental (forceps) delivery, occiput-posterior birth, prolonged second stage, macrosomia (>4000 g), older maternal age increase levator-injury risk (PMID:38168908). - Age — POP prevalence on exam rises from ~26.5% (age 40–59) to 36.8% (60–79) to 49.7% (≥80); incidence in menopausal women rises ~40% per decade (PMID:31851453; Current Opinion in Urology, PMID:23619578). - Obesity / high BMI — overweight and obese women more likely to report ≥1 pelvic-floor disorder (PMID:18799443). - Chronic straining — constipation, IBS, chronic cough, heavy lifting. - Prior hysterectomy (esp. for prolapse) predisposes to later vault prolapse (PMID:31851453). - Family history / ethnicity — Hispanic and White women report higher rates than Black/Asian women in several US cohorts.

Genetic risk factors: susceptibility loci near WNT4, EFEMP1, WT1, FGFR2, FAT4, IMPDH1, TBX5, SALL1, GDF7, LOXL1 (see §4). Monogenic: Ehlers-Danlos and joint-hypermobility syndromes carry POP prevalence of 29–75% (PMID:39033997).

Protective Factors

Cesarean delivery (avoids levator overstretch) and nulliparity are strongly protective.
Weight management plausibly protective (inference from BMI gradient).
Genetic protective alleles: the reciprocal (support-favoring) alleles at GWAS loci; no single validated protective variant is established.
Notable negative results: lifetime physical activity does not increase POP odds in community cohorts (PMID:26348380), so avoidance of exercise is not protective; and hormone therapy does not improve pelvic support (PMID:28538602) — so estrogen is not a validated protective intervention.

Gene-Environment Interaction

The central G×E model: childbirth (environment) acts as the load that unmasks a constitutional connective-tissue susceptibility (genetics). Recovery of pelvic support after delivery requires a postpartum burst of elastic-fiber assembly; animals genetically unable to make it (Loxl1-null, Fbln5-null) prolapse specifically after parturition (PMID:14745449; PMID:17255326) — a direct demonstration that a genetic defect and the obstetric load combine to produce disease.

Sources: PMID:17382829, PMID:38168908, PMID:31851453, PMID:18799443, PMID:26348380, PMID:28538602, PMID:39033997; IUGA epidemiology consultation.

3. Phenotypes

POP is characterized by anatomic descent (sign) that correlates poorly with symptoms — only vaginal bulging is specific to prolapse (PMID:17382829, PMID:31851453).

Phenotype	Type	Suggested HPO	Frequency / notes
Vaginal bulge / "something coming down"	Symptom (specific)	HP:0000005-adjacent; use Pelvic organ prolapse HP:0100615	The only symptom specific to POP; sensitivity of the symptom is limited
Pelvic organ prolapse (anatomic)	Clinical sign	HP:0100615 (Pelvic organ prolapse)	Root phenotype
Cystocele (anterior)	Sign	HP:0009611 (Cystocele)	Most common compartment (~68.6%)
Rectocele (posterior)	Sign	HP:0100823 (Rectocele)	~16%
Uterine/apical prolapse	Sign	HP:0000139 (Uterine prolapse)	~38.6% apical
Pelvic pressure / heaviness	Symptom	HP:0030496-adjacent (pelvic pain HP:0012648)	Common, non-specific
Stress urinary incontinence	Symptom	HP:0000020 (Urinary incontinence) / stress-specific	Frequent co-occurring pelvic-floor disorder
Voiding dysfunction / incomplete emptying	Symptom	HP:0000012 (Urinary bladder dysfunction)	Advanced anterior/apical POP; may require splinting
Obstructed defecation / splinting	Symptom	HP:0002015 (dysphagia-adjacent → use HP:0002019 Constipation)	Posterior compartment
Dyspareunia / sexual dysfunction	Symptom	HP:0030016 (Dyspareunia)	QoL impact
Vaginal mucosal erosion/ulceration	Sign	HP:0100699 (Vaginal neoplasm-adjacent; use erosion)	Advanced procidentia

Onset / severity / progression: adult-onset, typically peri-/postmenopausal; severity graded by POP-Q stage 0–4 (§10); course is chronic and generally slowly progressive, though anatomic descent can fluctuate and mild descent may regress. Symptom threshold is classically when the leading edge reaches or passes the hymen.

Frequency among affected: anterior > apical > posterior compartment involvement; multi-compartment disease common in advanced/high-avulsion cases (PMID:36343586).

Quality-of-life impact: measured with condition-specific instruments — PFDI-20 / PFIQ-7, P-QoL, PISQ-12 (sexual function). Bulge symptoms, voiding/defecatory dysfunction, and dyspareunia drive impairment; generic tools (SF-36, EQ-5D) also used.

Sources: PMID:17382829, PMID:31851453, PMID:36343586; StatPearls, Merck Manual.

4. Genetic / Molecular Information

POP is a complex/polygenic trait, not Mendelian, but with clear connective-tissue genetic architecture.

GWAS susceptibility loci

Iceland + UK Biobank (2020): 8 variants at 7 loci in 15,010 cases; implicated genes WNT4 (estrogen-pathway/urogenital development) and EFEMP1/fibulin-3 (connective-tissue homeostasis). "Our results highlight the role of connective tissue metabolism and estrogen exposure in the etiology of POP" and rs3791675 at EFEMP1 also associates with hernias and carpal tunnel syndrome (PMID:32184442).
European meta-analysis (2022, Nat Commun): 28,086 cases / 546,291 controls → 19 novel loci, implicating connective-tissue, urogenital, and cardiometabolic systems; replicated WNT4, EFEMP1, FAT4, IMPDH1, TBX5, SALL1 (Nat Commun 2022).
Japanese GWAS + cross-ancestry (2024, Commun Biol): identified WT1 (rs10742277, OR 1.48, P=6.7×10⁻⁹) and, cross-ancestry, FGFR2 (rs7072877, OR 1.06, P=4.1×10⁻⁸); 21 of 24 European loci showed directionally consistent effects — evidence for a shared cross-ancestry genetic architecture (PMID:39349682).

HGNC / gene annotations (suggested, lowercase hgnc): WNT4 (hgnc:12782), EFEMP1 (hgnc:3218), WT1 (hgnc:12796), FGFR2 (hgnc:3689), LOXL1 (hgnc:6664), FBLN5 (hgnc:3602), COL1A1 (hgnc:2197), COL3A1 (hgnc:2201), MMP2 (hgnc:7166), MMP9 (hgnc:7176), TIMP1 (hgnc:11820).

Variant classification / type

GWAS signals are common non-coding regulatory variants (SNPs) of small effect (OR ~1.05–1.5), not coding pathogenic variants. No ACMG "pathogenic" single-gene classification applies to idiopathic POP. In the monogenic connective-tissue disorders that cause secondary POP (COL5A1/COL5A2 in classical EDS; FBN1 in Marfan), variants are pathogenic missense/null per ClinVar.

Somatic vs germline: entirely germline susceptibility; POP is a degenerative/mechanical condition, not neoplastic — no somatic driver landscape.

Functional consequences: the implicated genes converge on extracellular-matrix organization and elastogenesis (EFEMP1/fibulin-3, LOXL1, FBLN5) and urogenital development / estrogen signaling (WNT4, WT1, FGFR2). Mechanistic causality at these human loci is not yet demonstrated at the protein level.

Modifier genes

Estrogen-receptor ratio (ESR1/ESR2 balance) is proposed as a modifier of connective-tissue remodeling (PMID:31851453).

Epigenetic information

Under-studied for POP; candidate work reports altered methylation/microRNA regulation of collagen and MMP genes in prolapsed tissue, but no ENCODE/Roadmap-level consensus dataset exists. This is a genuine gap.

Chromosomal abnormalities

None specific to idiopathic POP.

Sources: PMID:32184442, PMID:39349682, Nat Commun 2022 (PMC9226158); PMID:31851453.

5. Environmental Information

Environmental / occupational: heavy manual labor and repetitive heavy lifting appear as risk factors in surgical series but not in community-recruited cohorts — a discordance suggesting ascertainment bias rather than a true dose-response (PMID:26348380): "women recruited from the community with pelvic organ prolapse on examination report similar lifetime levels of strenuous activity as women without this examination finding." No chemical toxicant (CTD-type) etiology.
Lifestyle: obesity/high BMI (robust, PMID:18799443); chronic constipation and chronic cough (chronic straining); smoking (via chronic cough — modest/indirect). Physical activity per se does not increase POP risk (PMID:26348380).
Infectious agents: none. POP has no microbial etiology (not applicable).

Sources: PMID:18799443, PMID:26348380, PMID:17382829.

6. Mechanism / Pathophysiology

The contemporary model, built on imaging of living women, places the primary lesion in the levator ani muscle, with connective-tissue failure largely downstream — though an older "constitutional matrix defect" model remains live. The KB entry curates both explicitly as competing hypotheses.

Causal chain (canonical hypothesis — levator-primary)

Vaginal childbirth mechanical overload (TISSUE; GO:0009612 response to mechanical stimulus). Levator ani + birth-canal tissues stretch to >3× resting length; damage is by overstretch, not compression ischemia or neuropathy (PMID:38168908).
→ Levator ani muscle injury / avulsion (TISSUE; UBERON:0001326 levator ani, UBERON:0011528 pubococcygeus; CL skeletal muscle fiber). Birth-induced pubococcygeal injury is present in 55% of women with prolapse vs 16% with normal support (PMID:27517338), OR 7.3 (PMID:38168908); occurs in up to 19% of primiparas; does not heal (permanent mechanical change). Complete/bilateral avulsion → more advanced stage, more compartments (PMID:36343586).
→ Urogenital hiatus enlargement / loss of levator closure (the mechanical hinge). With the hiatus closed, pressures above/below the vaginal wall cancel; once open, exposed vaginal wall lies between abdominal and atmospheric pressure → net downward force. Enlarged hiatus "antedates prolapse" and predicts surgical failure (PMID:38168908). 4a. → Descent of pelvic organs beyond the hymen (direct mechanical effect). 4b. → Failure of apical/lateral connective-tissue attachments (cardinal/uterosacral/paravaginal): the pressure differential "produces abnormal tension on the attachments of the pelvic organs to the pelvic sidewall" (PMID:27517338). Notably, the measurable ligament difference is in length, not stiffness (PMID:27517338), constraining pure matrix-composition explanations.
→ Recurrence after reconstructive surgery: standard apical suspension does not reattach the levator, so a wide hiatus persists and predicts anatomic recurrence (PMID:34270804).

Parallel / upstream molecular arms (susceptibility)

Constitutional connective-tissue susceptibility (MOLECULAR; GO:0030198 ECM organization). GWAS connective-tissue/estrogen loci + heritable connective-tissue disorders (PMID:32184442, PMID:39349682, PMID:39033997, PMID:23240798).
Impaired elastic-fiber assembly / postpartum elastogenesis (MOLECULAR; GO:0004720 protein-lysine 6-oxidase activity ↓, GO:0048251 elastic fiber assembly ↓; UBERON:0000996 vagina). LOXL1–fibulin-5 program deposits new elastic fibers after delivery; deletion of either gene causes prolapse in mice (PMID:14745449, PMID:17255326).
Collagen / MMP-TIMP remodeling imbalance (MOLECULAR; GO:0030574 collagen catabolic process ↑, GO:0022617 ECM disassembly ↑). Meta-analysis of 30 studies (840 cases/755 controls): ↓ type I collagen, ↓ TIMP-1; ↑ type III collagen, ↑ MMP-1/-2/-9 (PMID:38291948) — but site-dependent, with the anterior vaginal wall showing no difference in COL-I and MMP-1, and uterosacral-ligament findings controversial or non-significant (PMID:38291948, PMID:16398770). Causal direction unsettled (open knowledge gap).
Oxidative stress in pelvic connective tissue (CELLULAR; GO:0006979 response to oxidative stress ↑; CL:0000057 fibroblast). ↑ 8-OHdG in prolapsed uterosacral ligament; H₂O₂ shifts uterosacral-ligament fibroblasts toward collagen catabolism in a concentration-dependent (non-monotonic) way — low OS stimulates synthesis, high OS flips to catabolism (PMID:26936098).
Vaginal-wall smooth-muscle depletion (CELLULAR; CL:0000192 smooth muscle cell; UBERON:0000996 vagina). Reduced fractional area of nonvascular smooth muscle in anterior vaginal wall muscularis, independent of age/stage, present premenopausally, most marked in postmenopausal women off estrogen (PMID:12114889).
Estrogen withdrawal / ageing (ORGANISM; GO:0030198 ↓). Strong epidemiologic risk factor, BUT the therapeutic corollary is refuted: past HT, HT duration, and current vaginal estrogen are not associated with pelvic support (PMID:28538602).
Chronically increased intra-abdominal load (ORGANISM; GO:0009612 ↑). Obesity, straining, cough, lifting — best-supported is the BMI gradient (PMID:18799443); occupational/exercise causal edge is weak/inconsistent (PMID:26348380).

Molecular pathways / processes

Wnt signaling (WNT4), FGF signaling (FGFR2), estrogen-receptor signaling, TGF-β1 (modulated by oxidative stress in fibroblasts, PMID:26936098), MMP/TIMP proteolytic balance, elastic-fiber assembly (fibulin-5/LOXL1/tropoelastin), collagen fibrillogenesis.

Molecular profiling

Transcriptomics/proteomics: vaginal fibroblasts from POP produce stiffer, higher-collagen matrices in some studies (Nature Sci Rep) — an apparent contradiction with the "weaker matrix" narrative, reinforcing site/context dependence.
Metabolomics/lipidomics/single-cell/spatial: largely absent for POP — a genuine data gap.

Sources: PMID:27517338, PMID:38168908, PMID:36343586, PMID:34270804, PMID:38291948, PMID:16398770, PMID:26936098, PMID:12114889, PMID:14745449, PMID:17255326, PMID:28538602, PMID:18799443, PMID:26348380, PMID:32184442, PMID:39349682.

7. Anatomical Structures Affected

Organ level (primary): vagina (UBERON:0000996), uterus (UBERON:0000995), urinary bladder (UBERON:0001255 → cystocele), rectum (UBERON:0001052 → rectocele), small intestine (enterocele). Secondary: urethra (voiding dysfunction), ureters (hydronephrosis in procidentia). Body systems: female reproductive + lower urinary tract + lower GI (pelvic floor).

Support-structure level: levator ani muscle (UBERON:0001326), pubococcygeus (UBERON:0011528), pubovisceralis/puborectalis; cardinal ligament, uterosacral ligament (UBERON:0012332), paravaginal/pubocervical fascia, perineal body, urogenital hiatus.

Tissue level: skeletal muscle (levator), dense connective tissue/ligament, vaginal wall muscularis (smooth muscle), fibroelastic ECM.

Cell level: levator skeletal muscle fibers (CL:0008002), fibroblasts (CL:0000057, uterosacral-ligament and pelvic connective-tissue fibroblasts), vaginal smooth-muscle cells (CL:0000192).

Subcellular / GO cellular component: extracellular matrix (GO:0031012), collagen-containing ECM (GO:0062023), elastic fiber (GO:0071953), fibroblast cytoplasm/mitochondria (oxidative stress).

Localization / lateralization: compartmentalized — anterior (cystocele, most common ~69%), apical (uterine/vault, ~39%), posterior (rectocele, ~16%); levator avulsion may be unilateral or bilateral (bilateral → worse).

Sources: PMID:27517338, PMID:36343586, POP-Q compartment review.

8. Temporal Development

Onset: adult, typically peri- to post-menopausal; anatomic descent may begin in reproductive years post-delivery ("antedate" hiatal enlargement precedes overt prolapse; PMID:38168908). Onset is chronic/insidious, punctuated by the acute levator injury event at delivery.
Progression / staging: POP-Q stages 0–4 (§10); course is generally slowly progressive with ageing/estrogen loss, but individual anatomic points can fluctuate and mild prolapse can regress. Symptom onset classically at leading edge ≈ hymen.
Duration: chronic, lifelong tendency; the levator lesion is permanent and untreated by current surgery.
Remission: spontaneous regression of mild descent occurs; symptomatic relief via pessary or surgery is treatment-induced, not cure of the underlying muscular lesion.
Critical periods / windows of intervention: the peripartum window (birth injury prevention; postpartum elastogenesis) is the key modifiable window; menopause is a secondary inflection.

Sources: PMID:38168908, PMID:31851453; StatPearls.

9. Inheritance and Population

Epidemiology

Symptomatic point prevalence (US, NHANES 2005-06, women ≥20): 2.9% (95% CI 2.1–3.7%) report seeing/feeling a vaginal bulge (PMID:18799443). "2.9% of women (95% CI, 2.1%-3.7%) experiencing pelvic organ prolapse." (≈2,900 / 100,000)
Anatomic prevalence on exam is far higher: 26.5% (40–59 y), 36.8% (60–79 y), 49.7% (≥80 y) (PMID:31851453). Reported prevalence ranges 1–65% depending on ascertainment (symptom 1–31%; exam 10–50%; both 20–65%).
Lifetime prevalence (high-income): ~40% of women will experience prolapse in their lifetime (PMID:33207004): "About 40% of women will experience prolapse in their lifetime, with the proportion expected to rise in line with an ageing population."
Lifetime risk of prolapse surgery (US, to age 80): 12.6% (PMID:24807341), from a claims database of 10.2M women — a lower bound sensitive to access/practice patterns.
Trend: burden rising with population ageing (elderly population expected to double by ~2030).

Genetic epidemiology

Inheritance pattern: multifactorial / polygenic (complex trait); familial clustering and twin studies support heritability; not simple Mendelian for idiopathic POP.
Penetrance/expressivity: not applicable in Mendelian terms; polygenic risk with variable expressivity modulated by parity, BMI, age.
Carrier frequency / founder effects: GWAS risk alleles are common across populations; cross-ancestry directional consistency (21/24 European loci) in Japanese data argues shared architecture rather than population-specific founder effects (PMID:39349682).
Monogenic contribution: heritable connective-tissue disorders (EDS, Marfan, joint hypermobility) show markedly elevated POP burden — POP prevalence 29–75% in EDS, urinary incontinence 50–60% (PMID:39033997); POP is objectively more severe by POP-Q in benign joint hypermobility syndrome (PMID:23240798).

Population demographics

Sex: essentially female-specific (analogous male pelvic-floor descent is rare/distinct).
Age distribution: strongly skewed to older/postmenopausal women.
Ethnicity/geography: higher reported rates in Hispanic and White women; lower in Black and Asian women in several US cohorts — partly true biology, partly ascertainment.

Sources: PMID:18799443, PMID:33207004, PMID:24807341, PMID:31851453, PMID:39349682, PMID:39033997, PMID:23240798; IUGA epidemiology consultation, Current Opinion in Urology (PMID:23619578).

10. Diagnostics

Primary diagnosis is clinical, by history (specific symptom = vaginal bulge) plus physical examination.

Clinical examination & staging — POP-Q (gold standard)

POP-Q (Pelvic Organ Prolapse Quantification, 1996/ICS) measures 9 points relative to the hymen: anterior Aa, Ba; apical C, D; posterior Ap, Bp; plus genital hiatus (gh), perineal body (pb), total vaginal length (tvl).
Stages: 0 = no prolapse; I = leading edge >1 cm above hymen; II = −1 to +1 cm (at hymen); III = >+1 cm but < (tvl−2); IV = complete eversion/procidentia.
Examination during Valsalva/cough, split-speculum/Sims technique, evaluating all 3 compartments.
Historic Baden-Walker halfway system still used clinically.

Imaging & functional tests

Translabial/transperineal ultrasound — quantifies levator avulsion and hiatal area; correlates with POP-Q (PMID:36343586).
Dynamic (defecography) MRI — evaluates multi-compartment and posterior/enterocele.
Urodynamics — when concurrent urinary symptoms/occult stress incontinence (reduce prolapse to unmask).
Post-void residual, uroflow — voiding dysfunction assessment.

Laboratory / biomarkers

No validated diagnostic blood/urine biomarker. Urinalysis to exclude infection; renal function/renal ultrasound in procidentia (obstructive uropathy).
Research biomarkers (tissue collagen I/III ratio, MMP/TIMP, elastin) are not clinically deployed.

Genetic / omics testing

Not indicated for idiopathic POP. Consider connective-tissue-disorder work-up (clinical criteria ± gene panel: COL5A1/COL5A2, FBN1, etc.) when EDS/Marfan/hypermobility features present.

Clinical criteria & differential diagnosis

Society guidance: ACOG/AUGS, ICS/IUGA, NICE.
Differential: vaginal/cervical cysts or masses, urethral diverticulum, Gartner duct cyst, vaginal/cervical malignancy, large introital condyloma, prolapsed uterine fibroid — distinguished by exam ± imaging.

Screening

No population screening for asymptomatic POP is recommended (anatomy-symptom discordance; treatment is symptom-driven).

Sources: POP-Q staging (PMID:21505577), StatPearls, IUGA clinical evaluation (PMC10682140), PMID:36343586.

11. Outcome / Prognosis

Mortality: POP is not directly life-threatening; disease-specific mortality is negligible except rare complications (obstructive uropathy → renal failure, or ulcerated procidentia). No 5-/10-year survival framework applies.
Morbidity / function: substantial QoL and functional impairment — voiding/defecatory dysfunction, sexual dysfunction, physical/social limitation. Measured by PFDI-20, PFIQ-7, PISQ-12, P-QoL.
Complications: vaginal erosion/ulceration and bleeding (advanced), urinary retention/recurrent UTI, hydronephrosis (procidentia), obstructed defecation; mesh-related complications after surgery (erosion/exposure, pain).
Recovery / recurrence: conservative therapy manages symptoms without anatomic cure. Surgery is effective but recurrence is common; enlarged genital hiatus predicts recurrence after apical suspension (PMID:34270804). Sacrocolpopexy is anatomically superior to vaginal apical procedures (PMID:23633316).
Prognostic factors: POP-Q stage, levator avulsion (esp. bilateral/complete — worse; PMID:36343586), genital hiatus width, BMI, connective-tissue disorder, prior failed repair. No validated molecular prognostic biomarker.

Sources: PMID:34270804, PMID:23633316, PMID:36343586; StatPearls.

12. Treatment

Management is graded and symptom-driven; none of the current options repairs the underlying levator injury.

Conservative / first-line

Observation/expectant management — for asymptomatic or mildly symptomatic (NCIT:C64263 Watchful Waiting / NCIT:C15747 Supportive Care).
Pelvic floor muscle training (PFMT) — NCIT:C15302 (Physical Therapy). The POPPY multicentre RCT showed symptom-score improvement with one-to-one PFMT in stage I–III POP; anatomy was not the endpoint (PMID:24290404).
Vaginal pessary (mechanical device) — NCIT:C50077-type device. Cochrane: pessary added to PFMT probably improves symptoms and prolapse-specific QoL; pessary vs no treatment/vs PFMT alone remains uncertain (PMID:33207004).
Lifestyle: weight loss, constipation treatment, reduction of heavy lifting (modifiable-load components; note no prevention strategy is proven effective — PMID:17382829).

Pharmacotherapy

Vaginal estrogen — commonly used adjunct, especially with atrophy/pessary use; but does not improve pelvic support in a 1443-woman study (PMID:28538602). NCIT:C15986 Pharmacotherapy + therapeutic_agent estradiol (CHEBI:23965). Evidence for POP outcomes is weak.
No disease-modifying drug exists.

Surgical / interventional

Apical suspension is the cornerstone. Sacrocolpopexy (abdominal/laparoscopic/robotic, Y-shaped polypropylene mesh to sacral promontory) — anatomically superior "gold standard" for apical/vault prolapse (PMID:23633316) — NCIT:C15329 Surgical Procedure.
Native-tissue vaginal repairs: sacrospinous ligament fixation, uterosacral ligament suspension, anterior/posterior colporrhaphy.
Obliterative: colpocleisis (for frail patients not desiring vaginal function).
Hysterectomy ± apical suspension for uterine prolapse; uterine-preserving hysteropexy as alternative.
Transvaginal synthetic mesh: durable anatomically but FDA reclassified to Class III (2016) and withdrew from US market (2019) over erosion/pain; restricted internationally to complex recurrent cases in specialist centers (PMID:23633316; synthetic mesh review).
Recurrence after sacrocolpopexy remains a surgical challenge; hiatus width predicts failure (PMID:34270804).

Treatment outcomes / adverse events

Sacrocolpopexy: high anatomic success; risks include mesh exposure, bowel injury, sacral bleeding. Transvaginal mesh: mesh erosion/exposure, dyspareunia, chronic pelvic pain. Native-tissue repair: higher recurrence but no mesh risk.

Experimental / regenerative

Regenerative approaches (ECM hydrogels for birth-injured pelvic muscle in animal models; stem-cell/tissue-engineering scaffolds) are preclinical/early-phase (bioRxiv ECM hydrogel); ongoing trials on ClinicalTrials.gov (e.g., laser therapy NCT05000957 — investigational, evidence limited).

Suggested NCIT terms: C15302 (Physical Therapy), C15747 (Supportive Care), C15329 (Surgical Procedure), C15986 (Pharmacotherapy), C64263 (Watchful Waiting).

Sources: PMID:24290404, PMID:33207004, PMID:23633316, PMID:34270804, PMID:28538602, PMID:17382829; surgical guideline review (IJGO 2024).

13. Prevention

Primary prevention: the key lever is reducing obstetric levator injury — the birth-injury literature frames it as "life-altering and preventable" (PMID:38168908) via management of forceps use, prolonged second stage, macrosomia; cesarean avoids levator overstretch but is not recommended solely for POP prevention. Weight management, constipation treatment. Caveat: no prevention strategy has been definitively proven effective (PMID:17382829), and restricting physical activity is not warranted (PMID:26348380).
Secondary prevention (early detection): no population screening; opportunistic identification of at-risk women (post-instrumental delivery, connective-tissue disorders); postpartum PFMT.
Tertiary prevention: PFMT and pessary to slow progression/manage symptoms; optimizing genital-hiatus management at surgery to reduce recurrence (PMID:34270804).
Behavioral: postpartum and ongoing pelvic-floor exercise; weight/constipation management.
Counseling: genetic/family counseling relevant only in heritable connective-tissue disorders.
Immunization / public health / prophylaxis: not applicable (non-infectious).

Sources: PMID:38168908, PMID:17382829, PMID:26348380, PMID:34270804.

14. Other Species / Natural Disease

Taxonomy: naturally occurring pelvic organ/vaginal/uterine prolapse is documented in several mammals — cattle (Bos taurus, NCBITaxon:9913) and sheep (Ovis aries, NCBITaxon:9940) show peri-/postpartum vaginal and uterine prolapse of major veterinary importance; also swine, dogs (NCBITaxon:9615), and non-human primates.
Comparative biology: Fbln5-null mouse prolapse is "remarkably similar to that in primates" (PMID:17255326), supporting cross-species conservation of the elastic-fiber-dependent support mechanism. Non-human primates develop spontaneous POP and are used as a translational model.
Veterinary relevance: bovine/ovine vaginal-uterine prolapse is a recognized peripartum emergency (genetic predisposition, hypocalcemia, high intra-abdominal pressure) — an economically important condition managed surgically/with retention devices.
Transmission / zoonosis: not applicable (non-communicable).

Sources: PMID:17255326; OMIA (veterinary), general veterinary obstetrics literature.

15. Model Organisms

Mouse knockouts are the workhorse (systematic review of 5 models, PMID:35088092): "Loxl1 and Fbln5 give the most reliable phenotype, and they fail by different routes (failure to heal after birth versus prolapse with ageing)."

Model	Type	Gene	Phenotype recapitulation	Fidelity / limitation
Loxl1−/− mouse	Knockout	LOXL1	Fails to deposit normal elastic fibers in uterine tract post partum; develops POP + lax skin, emphysema, vascular abnormality (PMID:14745449)	Systemic elastinopathy, not pelvis-restricted; failure-to-heal-after-birth route
Fbln5−/− mouse	Knockout	FBLN5/fibulin-5	POP developing with age; postpartum elastic-fiber assembly is what normal recovery depends on; "remarkably similar to primates" (PMID:17255326)	Age-driven; humanization/translational validity is an open question
Other KO models	Various	e.g., elastin/matrix genes	Less reliable phenotypes	Reviewed PMID:35088092
Non-human primate	Natural/spontaneous	—	Spontaneous POP; closest anatomic homology	Cost, availability
iPSC / vaginal-fibroblast cultures	In vitro	—	Model ECM production; POP fibroblasts alter matrix stiffness/collagen (Sci Rep)	Loss of 3D mechanical context
Simulated/induced (ovariectomy, mechanical/birth-injury rodent)	Induced	—	Model hormonal and birth-injury contributions; ECM hydrogel rescue tested (bioRxiv)	Rodent hiatal anatomy differs from human

Model characteristics. Strength: KO models demonstrate that an elastogenesis defect alone is sufficient to cause POP without obstetric trauma — the key support for the "constitutional matrix defect" hypothesis that cross-sectional human data cannot supply (PMID:35088092). Limitations: mice are quadrupedal with different pelvic-floor loading; systemic elastinopathies (Loxl1) affect multiple organs; the human primary lesion (levator avulsion) is not captured by these matrix-gene KOs — a genuine human-model mismatch flagged in the KB entry.

Resources: MGI, IMPC/KOMP (Loxl1, Fbln5 alleles), Alliance of Genome Resources.

Sources: PMID:35088092, PMID:14745449, PMID:17255326; ECM hydrogel birth-injury model (bioRxiv).

Summary of Key Ontology Term Suggestions

Disease: MONDO:0000082
Phenotypes (HP): HP:0100615 (POP), HP:0009611 (Cystocele), HP:0100823 (Rectocele), HP:0000139 (Uterine prolapse), HP:0000020 (Urinary incontinence), HP:0030016 (Dyspareunia), HP:0002019 (Constipation)
Biological processes (GO): GO:0030198 (ECM organization), GO:0048251 (elastic fiber assembly), GO:0030574 (collagen catabolic process), GO:0022617 (ECM disassembly), GO:0006979 (response to oxidative stress), GO:0009612 (response to mechanical stimulus)
Molecular function (GO): GO:0004720 (protein-lysine 6-oxidase activity)
Cell types (CL): CL:0008002 (skeletal muscle fiber), CL:0000057 (fibroblast), CL:0000192 (smooth muscle cell)
Anatomy (UBERON): UBERON:0001326 (levator ani), UBERON:0011528 (pubococcygeus), UBERON:0000996 (vagina), UBERON:0000995 (uterus), UBERON:0012332 (uterosacral ligament)
Genes (hgnc): WNT4, EFEMP1, WT1, FGFR2, LOXL1, FBLN5, COL1A1, COL3A1, MMP2, MMP9, TIMP1
Treatments (NCIT): C15302, C15747, C15329, C15986, C64263
Species (NCBITaxon): 9606 (human), 10090 (mouse), 9913 (cattle), 9940 (sheep)

Consolidated Source List

Primary literature (PMIDs): 17382829, 27517338, 38168908, 36343586, 32184442, 39349682, 14745449, 17255326, 35088092, 38291948, 26936098, 16398770, 12114889, 18799443, 24807341, 24290404, 33207004, 23633316, 28538602, 26348380, 23240798, 39033997, 34270804, 31851453, 23619578, 21505577.

Web sources: - MONDO:0000082 (Monarch) - StatPearls — Pelvic Organ Prolapse (NBK563229) - Narrative review of POP epidemiology/pathophysiology (PMC6968909) - IUGA consultation — epidemiology (Int Urogynecol J) - IUGA consultation — clinical evaluation (PMC10682140) - GWAS meta-analysis, 19 novel loci (Nat Commun 2022, PMC9226158) - Japanese/cross-ancestry GWAS (Commun Biol 2024, PMC11443051) - Iceland+UKB GWAS (Commun Biol 2020) - ECM meta-analysis (BJOG 2024) - Molecular mechanism of ECM disorder in POP (PMC7716395) - POP-Q staging (PMID:21505577) - ICD-10 N81 (AAPC) - Surgical guideline review (IJGO 2024) - Synthetic meshes in POP — narrative review (MDPI 2024) - Merck Manual — Overview of POP - ECM hydrogel birth-injury model (bioRxiv)

Overall assessment / curation note. POP is a paradigm "complex" entry: its strongest, largest-effect mechanistic claim (birth-induced levator avulsion, OR 7.3) rests on human imaging, while its molecular story (collagen/MMP/elastin imbalance) rests on cross-sectional tissue studies whose causal direction is genuinely unsettled — best curated as competing hypotheses (levator-primary vs constitutional-matrix-primary) rather than a single linear pathway. The animal (Loxl1/Fbln5) evidence uniquely establishes sufficiency of a matrix defect but does not capture the human primary lesion. The therapeutic corollary of the estrogen/ageing risk factor is refuted (hormone therapy does not restore support), a nuance worth preserving. The existing kb/disorders/Pelvic_Organ_Prolapse.yaml entry already models this structure faithfully with verified snippets; this report corroborates it and adds current identifier, staging (POP-Q), GWAS (19-loci meta-analysis; FGFR2/WT1 cross-ancestry), and surgical-guideline detail.

Reference Validation

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Unresolved (possible confabulation)	0
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References weighed for topical relevance	34
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Mechanistic Hypotheses

Discussions and Knowledge Gaps

Pathophysiology

Pathograph

Phenotypes

Genetic Associations

Medical Actions

Diagnosis

Prevalence

Animal Models

Source YAML

References & Deep Research

References

Deep Research

1. Disease Information

2. Etiology

Disease Causal Factors

Risk Factors

Protective Factors

Gene-Environment Interaction

3. Phenotypes

4. Genetic / Molecular Information

GWAS susceptibility loci

Variant classification / type

Modifier genes

Epigenetic information

Chromosomal abnormalities

5. Environmental Information

6. Mechanism / Pathophysiology

Causal chain (canonical hypothesis — levator-primary)

Parallel / upstream molecular arms (susceptibility)

Molecular pathways / processes

Molecular profiling

7. Anatomical Structures Affected

8. Temporal Development

9. Inheritance and Population

Epidemiology

Genetic epidemiology

Population demographics

10. Diagnostics

Clinical examination & staging — POP-Q (gold standard)

Imaging & functional tests

Laboratory / biomarkers

Genetic / omics testing

Clinical criteria & differential diagnosis

Screening

11. Outcome / Prognosis

12. Treatment

Conservative / first-line

Pharmacotherapy

Surgical / interventional

Treatment outcomes / adverse events

Experimental / regenerative

13. Prevention

14. Other Species / Natural Disease

15. Model Organisms

Summary of Key Ontology Term Suggestions

Consolidated Source List

Reference Validation