A case of aortocolonic fistula caused by sigmoid diverticulitis.

The development of a secondary aortoenteric fistula is a well-described complication after open or endovascular repair of an abdominal aortic aneurysm. However, evidence regarding aortocolonic fistulas (ACFs) and their pathogenesis is currently limited. We present a case of ACF that developed 18 years after open repair of an abdominal aortic aneurysm with atypical symptoms. The patient was successfully treated with total resection of the involved aorta, prosthetic graft, and sigmoid colon, with extra-anatomic bypass and primary anastomosis of the residual colon. Pathologic examination revealed that the pathogenesis of ACF was attributed to sigmoid diverticulitis. This case report highlights the uncommon pathogenesis of ACF and the importance of considering revascularization and intestinal reconstruction in the surgical strategy for each individual case.