Abstract
Benign pneumoperitoneum can happen after colonoscopy, which shows itself as free air in the abdomen without symptoms or pneumoperitoneum without peritonitis. In this case, we reported a rare case of an elderly man who had acute abdominal stiffness after colonoscopy and observation of free air under the diaphragm that no perforation was observed in the intestine during laparoscopy and only one tiny intestinal tumor was randomly reported. There is no consensus on the treatment of pneumoperitoneum after colonoscopy. Patients with peritonitis benefit from laparoscopy but patients with micro perforation and asymptomatic patients benefit from intravenous antibiotic treatment and bowel rest.