Radiation-associated ischemic coloproctitis: report of two cases.

Radiation-associated ischemic coloproctitis is a rare clinical entity caused by vascular insufficiency to the rectosigmoid colon. It most commonly occurs after radiotherapy for gynecological cancer. We present herein the cases of two patients who developed radiation-associated coloproctitis with transmural necrosis and eventual perforation. Perforation of the rectosigmoid colon occurred 3.5 years after radiotherapy in case 1, a 46-year-old woman, and presented as a well-defined small area of transmural necrosis. Conversely, in case 2, a 55-year-old woman, it occurred 1.5 years after radiotherapy, and presented as segmental, diffuse transmural necrosis. The lesion in case 1 had been caused by intramural vascular obliteration due to marked fibrosis of the bowel wall, while that in case 2 had been caused by occlusion of the mesenteric artery with thrombosis. Both patients underwent Hartmann's resection without rectal excision, and survived the perforative event.