Ischemic Colitis Secondary to Mesenteric Arteriovenous Malformation: A Rare Cause of Bowel Ischemia—Case Report and Literature Review

Ischemic colitis is the most common form of intestinal ischemia, typically caused by a temporary reduction in blood flow to the colon. It is often linked to atherosclerosis, low blood pressure, or embolism. We present a case of ischemic colitis with atypical location due to an inferior mesenteric arteriovenous malformation (inferior mesenteric artery-vein) in a 77-year-old woman with Child-Turcotte-Pugh Class A hepatitis C cirrhosis. She had a 2-day history of rectal bleeding, mild abdominal pain, and nausea. Colonoscopy findings show segmental erythematous and edematous mucosa with multiple discrete shallow ulcers in the sigmoid and descending colons (23-30 cm from the anal verge). Computed tomography (CT) and CT angiography showed an arteriovenous malformation (AVM) supplied by the inferior mesenteric artery, draining into the inferior mesenteric vein, consistent with ischemic colitis caused by a steal phenomenon. Given the high risk of worsening ischemia with embolization, the patient underwent surgical resection and ligation of the AVM, with complete resolution of symptoms postoperatively. This case highlights the importance of considering mesenteric AVMs in the diagnosis of ischemic colitis, particularly when classic risk factors are absent, and underscores the role of early CT angiography in facilitating prompt diagnosis and treatment.