ABSTRACT
The rare cause of lower gastrointestinal bleeding is angiodysplasia. Angiolysplasia is most common in the right colon, but it can be found throughout the whole gastrointestinal tract. The main lesion of angiodysplasia is located at the submucosal layer. So, it is sometimes very difficult to search for the focus of bleeding via laparotomy or colonoscopy. We recently experienced a case of rectal arteriovenous malformation that was misdiagnosed as intussusception. A 57-year-old man visited the emergency room because of abrupt anal bleeding and low abdominal pain, and this was the third episode he'd experienced during the past 20 years. Sigmoidoscopy and abdominal CT revealed that his rectum was obstructed with a dark black colotuberant mass, which was suggestive of ischemic intussusception. We performed emergency laparotomy and we found an extremely swollen rectum with surrounding hematoma instead of intussusception. We performed low anterior resection and colo-anal anastomosis with ileostomy. The final pathologic diagnosis showed that the protuberant mass was a hematoma in the submucosal layer, and this developed by bleeding from an arteriovenous malformation in the rectum.