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SMA Syndrome — SCE Medical Oncology MCQ

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HardOncological EmergenciesSMA SyndromeSCE Medical Oncology

A patient with ovarian cancer has lost 20 kg and develops postprandial vomiting. CT shows gastric and proximal duodenal dilatation, an aortomesenteric angle of 10 degrees and a distance of 5 mm. Which mechanism best explains the transition point?

Educational content. Not a substitute for clinical judgement or local policy.

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Correct answer: B — Cachexia has depleted the intervening fat pad, trapping the third duodenal part between the SMA and aorta

Explanation lettering: D = shown as A · A = shown as B · B = shown as C · C = shown as D

A is correct. Severe weight loss removes the fat cushion between the superior mesenteric artery and aorta, reducing both angle and distance and compressing the third part of the duodenum. The proximal dilatation and precise CT geometry support superior mesenteric artery syndrome. B describes neither the observed level nor the relevant vessel. C would produce mesenteric ischaemia rather than this fixed extrinsic compression. D invokes the wrong ligament and obstruction level. E involves the coeliac axis and cannot explain a D3 transition between the SMA and aorta. Imaging measurements support, but do not replace, the clinical and obstructive findings.

Reference: Superior mesenteric artery syndrome review: https://pmc.ncbi.nlm.nih.gov/articles/PMC8212557/