Internal Iliac Aneurysm Rupture into the Rectum following Endovascular Exclusion: An Unusual Cause of Massive Lower Gastrointestinal Bleeding

Purpose: To report a rare iliorectal fistula following endovascular treatment of an internal iliac aneurysm. Case Report: A 76-year-old man developed lower gastrointestinal bleeding 3 months after successful endovascular exclusion of a left internal iliac aneurysm with coil embolization, attempted stent-grafting, ligation of the distal external iliac artery, and a femorofemoral crossover bypass. Aortography showed no clear intestinal bleeding point, but demonstrated recanalization and continued perfusion of the aneurysm. At laparotomy, an iliorectal fistula was detected. The common iliac artery was ligated proximally, the aneurysm sac was opened, and the back-bleeding internal iliac artery branches were oversewn. The rectum was closed primarily. He made an uneventful recovery. Conclusions: An iliorectal fistula is an extremely rare and unlikely complication of coil occlusion of an iliac aneurysm. A high index of suspicion for the diagnosis is of paramount importance. Periodic imaging in these patients is required to detect recanalization and continuing aneurysm expansion.