Forty-two patients with 10 cases of proximal GI perforation and 32 cases of distal GI perforation were evaluated based on the CT findings of extraluminal air (which was subdivided into the CT-falciform ligament sign crossing the midline and scattered pockets of air), bowel wall thickening (>8 mm in gastroduodenal wall,>3 mm in the small bowel wall,>6 mm in the caliber of the appendix and>5 mm in the colonic wall), associated abscess formation, ascites and adjacent fat stranding.