An 82-year-old man was admitted to our hospital because of abdominal distention and vomiting. He did not have a history of anticoagulant medication or trauma. We diagnosed large bowel obstruction on Xray film. Abdominal US, CT, and MRI showed a mass of 6 cm inside of the wall of descending colon. Gastrografin enema showed the stenotic colonic lumen occupied by the mass. Its surface was covered with normal colonic mucosa on colonoscopy, colored dark red. We diagnosed it as a colonic intramural hematoma. We thought of the possibility of avoiding laparotomy. For about 4 weeks, we performed conservative management with a transanal ileus tube. After removing the tube, he left hospital. The colonic intramural hematoma had disappeared on MRI and colonoscopy three months later. We present a rare case of large bowel obstruction by idiopathic colonic intramural hematoma. There is no report of such a case resolved with conservative management by a transanal ileus tube, within the visualization range.
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