An 89-year-old man presented with a 2-week history of melena. He had a history of abdominal aortic aneurysm (AAA) with endovascular repair 4 years prior. He was anemic (hemoglobin, 6.3 g/dL) and without leukocytosis. He was hemodynamically stable. His blood cultures were sterile and esophagogastroduodenoscopy revealed a normal-appearing esophagus, stomach, and duodenum without evidence of bleeding. A contrast-enhanced computed tomographic image of the abdomen and pelvis demonstrated his repaired AAA had a large endoleak that measured 12 cm. Small locules of gas contained within the aneurysmal sac suggested communication of the AAA with the small intestine (image, red arrows). In the clinical setting of gastrointestinal bleeding, a diagnosis of aortoenteric fistula was confirmed.¹ The patient underwent surgical repair but died of surgical complications. 

Fistulas communicating with the small intestine can be difficult to diagnose with endoscopy. Computed tomography with contrast medium is often the preferred test in emergent cases, with sensitivity and specificity up to 94% and 85%, respectively.² Intravascular air identified on imaging can confirm an aortoenteric fistula without invasive testing.^1,2