A 21-year-old male visited emergency room in our hospital with right abdominal pain. He had a fever and symptoms of upper respiratory infection. There were tenderness in the right abdominal region, but no signs of peritoneal irritation. Abdominal CT scan revealed an invagination of the ileocecal intestinal tract into the ascending colon, and intussusception was diagnosed. We attempted repositioning by colonoscopy. During colonoscopy, we confirmed that a reddened ileocecal region had invaginated into the ascending colon. The invaginated intestinal tract was gradually repositioned by air insufflation. The symptoms did not relapse, and the patient was discharged. One month after discharge, we found no obvious problems in colonoscopy. A majority of adult-onset intussusception cases are accompanied by neoplastic lesions ; however, in this case, no obvious problems were noted. Therefore, we report this patient as a rare case.
