Inferior mesenteric arteriovenous fistula.

Arteriovenous fistula (AVF) involving the inferior mesenteric artery and vein is very rare with only 33 cases described in the literature and may be of congenital or acquired (iatrogenic or traumatic) or idiopathic etiology. The pathophysiology of AVF that acts as a left-to-right shunt has accounted for clinical signs and symptoms associated with ischemic colitis, portal hypertension, and heart failure. A low incidence and nonspecific clinical signs and symptoms such as abdominal pain, thrill and mass, lower and upper gastrointestinal bleeding make it difficult to establish a diagnosis of inferior mesenteric AVF. Diagnosis of inferior mesenteric AVF is usually established by radiological or intraoperative examination. We report a case of idiopathic inferior mesenteric AVF causing ischemic colitis in a 56-year-old man that was diagnosed preoperatively by multidetector computed tomography and angiography and successfully treated by surgical resection.