Computed tomography diagnosis of a primary aortoduodenal fistula in a patient with a partially thrombosed abdominal aortic aneurysm.

Primary aortoenteric fistula is a rare but fatal cause of gastrointestinal bleeding and requires urgent intervention. A high index of clinical suspicion in conjunction with imaging is required because a favorable outcome relies on prompt diagnosis. The primary forms of aortoduodenal fistulas are nearly always associated with abdominal aortic aneurysm, mostly atherosclerotic. Technological advances in imaging, particularly computed tomography (CT), play a pivotal role in the preoperative detection of these fistulas. We report the case of a 76-year-old man who was diagnosed with a large abdominal aortic aneurysm with associated contained rupture and suggestion of an aortoduodenal fistula on CT. This case demonstrated the effectiveness, ease, and low cost of the preoperative evaluation and documentation of a primary aortoduodenal fistula using CT scans.