Primary Aortoenteric Fistula: A Rare Case of a Massive Gastrointestinal Bleed

Aortoenteric fistulas (AEFs) are deadly, abnormal connections between the aorta and gastrointestinal (GI) tract. While secondary aortoenteric fistulas (SAEFs) are more common and arise after aortic reconstruction, primary aortoenteric fistulas (PAEFs) are generally caused by abdominal aortic aneurysms (AAAs). PAEFs may present with self-limited GI bleeds called "herald bleeds," and the fistula often goes undiagnosed until patients undergo laparotomy for a massive GI bleed. We describe a case of a PAEF in a 79-year-old man with known AAA. Due to variable clinical presentations and the rarity of the condition, many patients with PAEF die before an accurate diagnosis is made. In interpreting computed tomography (CT) scans of AEFs, the role of the radiologist is critical in the management of PAEF patients.