Computed tomography diagnosis of primary aorto-enteric fistula.

Primary aorto-enteric fistulae are rare. Preoperative diagnosis is important but is difficult and cannot usually be confirmed by upper gastrointestinal series, aortography and endoscopy. Computed tomography demonstrating an abdominal aortic aneurysm with air bubbles in its wall and "soft tissue" mass posteriorly should raise the possibility of penetration of the aneurysm into the lumen of the bowel and related consequences (hematoma, sepsis, infected operating field).