| Domain | Summary | Key structured fields / suggested mappings | Evidence |
|---|---|---|---|
| Definition / category | Superior Mesenteric Artery Syndrome (SMAS, Wilkie syndrome) is a **rare structural/acquired duodenal obstruction** caused by compression of the third/horizontal duodenum in the narrowed space between the abdominal aorta and superior mesenteric artery. | Category: Structural; Disease class: duodenal obstruction / gastrointestinal compression syndrome | (pqac-00000000, pqac-00000002, pqac-00000005) |
| Identifiers / synonyms | Secure identifier present in evidence: **MeSH D013478**. Synonyms documented in retrieved evidence include **Wilkie syndrome**, **chronic duodenal obstruction**, and **CAST syndrome**. A prospective institutional study is linked to **PMID 30291587**; relevant trials include **NCT03416647**, **NCT07115472**, **NCT04515251**, **NCT03937193**, **NCT06970093**. | Exact IDs asserted: MeSH D013478; PMID 30291587; NCT03416647; NCT07115472; NCT04515251; NCT03937193; NCT06970093 | (pqac-00000001, pqac-00000003, pqac-00000005, pqac-00000006, pqac-00000007, pqac-00000008, pqac-00000010) |
| Core anatomy | Primary lesion site is the **third/transverse/horizontal part of the duodenum** compressed between the **SMA** anteriorly and **abdominal aorta/spine** posteriorly; retroperitoneal fat loss narrows this space. | Suggested anatomy labels: duodenum (3rd part), superior mesenteric artery, abdominal aorta, retroperitoneal fat pad | (pqac-00000000, pqac-00000001, pqac-00000002, pqac-00000010) |
| Major phenotypes | Core phenotype cluster: **postprandial epigastric/abdominal pain, nausea, vomiting, reflux, bloating, difficulty eating, weight loss, low BMI/underweight**, sometimes severe complications such as aspiration pneumonia or acute pancreatitis. | Suggested HPO labels: abdominal pain; epigastric pain; nausea; vomiting; abdominal bloating; gastroesophageal reflux; early satiety/feeding difficulty; weight loss; low body mass index; malnutrition; dehydration | (pqac-00000000, pqac-00000001, pqac-00000003, pqac-00000005, pqac-00000006, pqac-00000008) |
| Mechanism / causal chain | Typical causal chain: **rapid weight loss or altered anatomy → loss/reduction of retroperitoneal fat cushion → decreased aortomesenteric angle/distance → extrinsic compression of D3 → impaired chyme passage / proximal obstruction → meal-related symptoms, reduced intake, further weight loss, and possible severe gastric or aspiration/pancreatic complications**. | Suggested process labels: intestinal obstruction; impaired gastric emptying/proximal stasis; nutritional deficiency; positive feedback worsening via weight loss | (pqac-00000000, pqac-00000001, pqac-00000003, pqac-00000004, pqac-00000010) |
| Diagnostic imaging thresholds | Diagnosis is imaging-centered and usually combines symptoms with CT/MR angiography and/or contrast studies. Evidence shows **normal** aortomesenteric angle roughly **35–65°** or **38–80°** and distance **10–28 mm**; commonly used abnormal thresholds are **angle <22°** and **distance <8 mm**; broader abnormal cutoffs **<35°** and **<10 mm** also appear in case literature. | Imaging modalities in evidence: CT with oral contrast, CT/MR angiography, suggestive barium swallow; example case: angle 14°, distance 6 mm | (pqac-00000000, pqac-00000001, pqac-00000002, pqac-00000005, pqac-00000006) |
| Major acquired risk factors | Major non-genetic/acquired drivers are **rapid weight loss**, **underweight/low BMI**, feeding difficulty, and **anatomic distortion**; trial exclusion/observational protocols also flag conditions such as **severe scoliosis/spinal fixation**, abdominal masses, and cachectic states as relevant anatomical confounders/risk contexts. | Suggested risk labels: rapid weight loss; low BMI; loss of retroperitoneal adipose tissue; postoperative/anatomic change; scoliosis-associated distortion | (pqac-00000000, pqac-00000003, pqac-00000006, pqac-00000007, pqac-00000010) |
| First-line management | Initial management is generally conservative: restore nutrition/weight, treat dehydration/electrolyte problems, decompress when needed, and use medical/supportive therapy; the refractory-SMAS trial defines failed conservative care as failure of **gastrointestinal decompression, enteral nutrition, and parenteral nutrition**. | Suggested intervention labels: nutritional rehabilitation; enteral nutrition; parenteral nutrition; gastrointestinal decompression; symptom-directed medical therapy | (pqac-00000001, pqac-00000003, pqac-00000006) |
| Surgical management | For persistent/refractory disease, **duodenojejunostomy** is the most consistently represented operation in the evidence and was used for all patients in the prospective single-institution study; case evidence also describes **laparoscopic Strong’s operation** / duodenal mobilization strategies. A randomized trial is comparing **One Anastomosis Gastric Bypass (OAGB)** vs **Duodenojejunostomy (DJ)**. | Exact trial/intervention IDs: NCT03416647 (duodenojejunostomy cohort), NCT06970093 (OAGB vs DJ); suggested NCIT-style labels: duodenojejunostomy; gastric bypass procedure | (pqac-00000002, pqac-00000003, pqac-00000005, pqac-00000008, pqac-00000009) |
| Epidemiology | SMAS is rare. Retrieved case literature reports prevalence estimates around **0.1%–0.78%**, female predominance around **2:1**, and peak occurrence in **10–30 years**, though it can occur outside this range. One CT normative study planned **500 non-SMAS vs 10 SMAS** cases in a young Chinese cohort, illustrating rarity in imaging datasets. | Epidemiology fields: rare disease; female predominance; pediatric-to-young-adult skew with broader age range possible | (pqac-00000000, pqac-00000010) |
| Prognosis / complications | Prognosis improves with timely recognition and decompressive treatment. Documented serious complications include **gastric perforation, acute pancreatitis, aspiration pneumonia**, ulcer disease, and in older literature/case review **life-threatening deterioration with reported mortality up to 33% if untreated**. Prospective studies track symptom scores, BMI recovery, and reduced need for acid suppression/prokinetics over long follow-up. | Outcome fields: symptom relief; BMI gain; complication prevention; long-term follow-up in prospective cohort median 47 months (IQR 34–72) | (pqac-00000000, pqac-00000003, pqac-00000004, pqac-00000005) |
| Evidence gaps (genetics / omics / models) | No secure evidence in the retrieved materials supports a **causal gene, pathogenic variant, Mendelian inheritance pattern, molecular biomarker, omics signature, infectious etiology, or validated model organism**. Current evidence base is dominated by clinical imaging studies, case reports/series, and small interventional cohorts/trials. | KB note: mark genetics/omics/animal-model fields as **not established in retrieved evidence** rather than negative | (pqac-00000003, pqac-00000005, pqac-00000006, pqac-00000010) |


*Table: This table condenses the highest-yield disease-characteristics fields for Superior Mesenteric Artery Syndrome, including secure identifiers, anatomy, phenotypes, mechanism, diagnostic thresholds, treatment, epidemiology, and major evidence gaps. It is designed for direct use in a structured disease knowledge base.*