Fistula formation between perianeurysmal hematoma and sigmoid colon: rare cause of lower gastrointestinal bleeding.

Abstract

Aortoenteric fistula is a rare but potentially fatal condition, causing acute gastrointestinal bleeding. Typical symptoms include abdominal pain, gastrointestinal bleeding, and a pulsatile abdominal mass; however, these may be clinically occult. The initial harbinger of the disease in a majority of patients is gastrointestinal bleeding followed by massive exsanguination.1, 2 Although the diagnosis of aortoenteric fistula can be challenging, abdominal computed tomography (CT) and endoscopic examination are the preferred initial diagnostic tools.3 We report a rare case of acute lower gastrointestinal bleeding caused by fistula formation between the sigmoid colon and a perianeurysmal hematoma because of rupture of left common iliac artery aneurysm. A 76-year-old Asian man was referred to St. Luke's International Hospital because of several episodes of bloody stool 5 days after aortic replacement with vascular prosthesis for rupture of left common iliac artery aneurysm. On admission, preoperative abdominal CT scan revealed perianeurysmal hematoma caused by the aneurysmal rupture, but no signs of bowel perforation or active bleeding were observed (Fig. 1). Colonoscopy revealed a large mucosal defect in the sigmoid colon, with fistula formation in the hollow cavity (Fig. 2A). The endoscope was introduced through the fenestration into this hollow cavity, which was suspected to be the perianeurysmal hematoma observed on CT (Fig. 2B). There was no other bleeding site identified on total colonoscopy. Air leak inside the hematoma was seen on subsequent abdominal CT scan, confirming the penetration of hematoma into the sigmoid colon. The repair strategy of the colonic defect of aortoenteric fistula is still debated, and the type of surgical intervention generally depends on the situation. In the present study, we carried out transverse colostomy to anticipate spontaneous closure of the fistula.4 After confirming complete closure of the fistula (Fig. 2C) after 4 months, the patient successfully underwent stoma closure. Authors disclose no conflicts of interest for this article.