Gastrointestinal: Aortoduodenal fistulae

An uncommon cause of major gastrointestinal bleeding is that of a fistula between the aorta and the adjacent bowel, usually the third part of the duodenum. The typical patient has been previously treated with a vascular prosthesis for an aortic aneurysm. Approximately 1–2% of these patients develop aortoenteric fistulae, usually after an interval of 2–10 years. Factors that predispose to fistulae include infection and further aortic dissection that result in duodenal damage and erosion of the duodenal wall by the graft. Case reports also describe aortoenteric fistulae without previous surgery in rare patients with atherosclerotic or mycotic aneurysms. The images shown below were from two patients with presumed aortoduodenal fistulae. Figure 1 is a contrast-enhanced computed tomography scan from a 72-year-old man who was admitted to hospital with melena and subsequently had a major episode of gastrointestinal bleeding. The scan shows the lumen of the aorta, blood clot in an aneurysm and contrast around blood clot in the duodenum. The patient died despite multiple blood transfusions and emergency surgery. Figure 2 is an endoscopic image showing a segment of a Dacron graft that had eroded into the lumen of the third part of the duodenum. It was uncertain whether bleeding was a result of a direct communication between the graft and the duodenum or from erosion of vessels in the duodenal wall. The patient was a 69-year-old man who was investigated because of epigastric pain for 1 week and melena for 3 days. Twelve years previously, he had been treated with an aorto-iliac bypass graft because of distal aortic occlusive disease. Subsequent surgery involved resection of the graft as well as the third and fourth parts of the duodenum and the creation of an axillo-bifemoral bypass to revascularize the lower limbs.