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Ischemic colitis — ABIM Board MCQ

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ModerateGastroenterology/HepatologyIschemic colitisABIM Board

A 74-year-old with atrial fibrillation develops crampy left-lower-quadrant pain followed by hematochezia after prolonged hypotension. CT shows segmental thickening at the splenic flexure without free air. What is the most likely diagnosis?

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Correct answer: A — Ischemic colitis involving a watershed region

The best answer is “Ischemic colitis involving a watershed region”. Transient hypoperfusion commonly injures watershed colon, producing sudden crampy pain followed by hematochezia and segmental wall thickening. Ulcerative proctitis has a different distribution and course, Giardia is noninvasive, and angiodysplasia typically causes painless bleeding. The atrial fibrillation and atherosclerosis add embolic and low-flow susceptibility but do not create the typical painless pattern of angiodysplasia.

Reference: ACG Clinical Guideline: Colon Ischemia: https://journals.lww.com/ajg/fulltext/2015/01000/acg_clinical_guideline__epidemiology,_risk.7.aspx