Secondary aorto-duodenal fistula: a diagnostic challenge in a patient with fever and anemia

A 69-year-old male, three years post-endovascular exclusion for an abdominal aortic aneurysm, presented with asthenia and fever. An abdominal CT scan showed no gastrointestinal tract communications, abscess, or contrast extravasation. Tc-99m-HMPAO-labeled leukocytes scintigraphy with SPECT/CT revealed increased uptake on the posterior surface of the aortic graft, along with air bubbles in its right iliac limb. Upper gastrointestinal endoscopy was performed, revealing a duodenal ulcer in the transition between the second and third portions. The ulcer exhibited yellow graft tissue at its center. The patient underwent in situ reconstruction, involving the replacement of the infected prosthetic graft, and the duodenal defect was addressed through segmental resection and duodenojejunal anastomosis. Secondary aorto-duodenal fistula (SADF), a rare complication of vascular surgery, may arise from factors such as local infection or graft-bowel contact. SADF, often located in the duodenum, poses a high mortality risk, necessitating early diagnosis. Clinical presentation varies from significant upper gastrointestinal bleeding to obscured bleeding.