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Superior mesenteric artery (SMA) syndrome, also known as Wilkie’s syndrome, is a rare cause of proximal small bowel obstruction caused by compression of the third part of the duodenum between the SMA and the aorta, due to a narrowed aortomesenteric angle and distance.
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https://www.youtube.com/watch?v=65JcrKj4NkM
Most often occurs after significant weight loss, leading to loss of mesenteric fat pad.
| Category | Examples |
|---|---|
| Rapid weight loss | Trauma, eating disorders (e.g., anorexia), malignancy, burns, bariatric surgery |
| Congenital/anatomic | High insertion of duodenum or low origin of SMA |
| Postoperative | Scoliosis correction or aortic aneurysm repair (spine straightening reduces angle) |
| Asthenic body habitus | Thin individuals with minimal retroperitoneal fat |
| Condition | SMA-aortic angle | Aortomesenteric distance |
|---|---|---|
| Normal | ~45°–60° | 10–28 mm |
| SMA syndrome | <22° | <8 mm |
(A) No duodenum compression; (B) duodenum compression (superior mesmeric artery compression syndrome); (C) no duodenum or left renal vein compression; (D) duodenum and left renal vein compression (superior mesmeric artery compression syndrome and renal vein compression syndrome).
Liu Y, Zheng H, Wang X, Wang Z, Zhu Q, Wen C and Tong Y (2023) Ultrasound characteristics of abdominal vascular compression syndromes. Front. Cardiovasc. Med. 10:1282597. doi: 10.3389/fcvm.2023.1282597
| Symptom | Notes |
|---|---|
| Postprandial epigastric pain | Crampy or colicky, due to obstruction |
| Early satiety and bloating | Gastric/duodenal distention |
| Nausea and bilious vomiting | Especially after meals |
| Weight loss | Vicious cycle: further narrows angle |
| Relief in prone/knees-chest position | Improves angle → symptom relief |
| Modality | Imaging features |
|---|---|
| CTA | • Aortomesenteric angle <22° (normal = 28–65°) |
| • Aortomesenteric distance <8 mm (normal = 10–28 mm) | |
| • Duodenal dilation (1st–2nd part) with abrupt narrowing at 3rd part (D3) | |
| • Collapse of bowel distal to obstruction: Confirms mechanical compression | |
| • Stomach dilatation: Suggests more proximal backup | |
| Barium swallow | • SMA crossing: Dilated stomach and duodenum with abrupt vertical compression at D3 |
| • "To-and-fro" peristalsis: Reflux of contrast due to functional obstruction | |
| • Relief in prone or left lateral position | |
| US | Operator dependent, less reliable than CT |
| • Can demonstrate reduced aortomesenteric angle, especially in thin patients |
Superior mesenteric artery syndrome. Arterial phase of an abdominal CT study of a female adolescent (a) shows dilatation of the duodenum (asterisk) upstream to the point where it crosses the SMA and the aorta (arrow). Note paucity of abdominal fat. Oblique sagittal reformation of another patient (b) shows reduction of the normal aortomesenteric angle (9º) and aortomesenteric distance (6 mm). Fluoroscopic series of a 10-year-old girl after surgical correction of kyphosis c shows obstruction at D3 with delayed passage of contrast through the stenosis (asterisk) and proximal dilatation of D2(arrows). This was due to SMA syndrome caused by lengthening of the vertebral column
Terra, C., Ramos-Andrade, D., Sá-Marques, I. et al. Duodenal imaging on the spotlight: from A to Z. Insights Imaging 12, 94 (2021). https://doi.org/10.1186/s13244-021-01045-y
| Condition | Distinguishing Feature |
|---|---|
| Duodenal web or stricture | Fixed focal narrowing; congenital or peptic disease |
| Annular pancreas | Circular pancreatic tissue on imaging |
| Gastroparesis | Functional motility disorder; no transition point |
| Chronic mesenteric ischemia | Postprandial pain but no obstruction on imaging |