[Obstructive colitis following the ingestion of laxatives during bowel preparation for colonoscopy: a report of two cases].

The first case of obstructive colitis (OC) was observed in a 71-year-old man who presented to our hospital complaining of frank blood in the stool. After receiving a laxative for bowel preparation, he complained of lower abdominal pain. Colonoscopy revealed a circumferential tumor at the rectosigmoid junction. Diffuse erythema with erosion and ulceration was observed 5cm proximal to the tumor. The second case of OC was observed in a 73-year-old man. He was admitted to our hospital for endoscopic resection of a colonic polyp. After receiving a laxative for bowel preparation, he complained of lower abdominal pain. Colonoscopy revealed that the rectum was filled with feces. Diffuse erythema with ulceration was observed in the part beyond the feces. In both cases, although the cause of the obstruction differed, the obstructing lesions were located at the rectum, and the OC appeared to be induced by laxative ingestion.