Endovascular Treatment of an Iatrogenic Inferior Mesenteric Arteriovenous Fistula Presenting as Massive Lower Gastrointestinal Hemorrhage: A Case Report.

Inferior mesenteric artery arteriovenous fistulae are rare, acquired connections between arterial and venous systems associated with a range of symptoms, from abdominal pain to life-threatening lower gastrointestinal hemorrhage. We report an iatrogenic inferior mesenteric artery arteriovenous fistula in a 30-year-old female, presenting with massive hematochezia 1 month after a left hemicolectomy. Angiography demonstrated a high-flow vascular connection between the inferior mesenteric artery and rectal veins, which was treated with n-butyl-2-cyanoacrylate mixed with ethiodized oil for arteriovenous connection occlusion followed by coil embolization of the feeding arteries. Follow-up imaging at 8 months showed no recanalization of the fistula, and she remains asymptomatic 4 years later. Iatrogenic inferior mesenteric artery arteriovenous fistulae, though rare, should be considered after colorectal surgery as a possible cause of recurrent lower gastrointestinal hemorrhage, even within weeks of the operation; dilated mesenteric varices and premature venous filling on the arterial phase are key CT findings. Endovascular management targeting the arteriovenous communication and feeding arteries can achieve durable occlusion in these high-flow fistulae.