The purpose of this study is to review the computed tomography (CT) appearance 
of gastrointestinal tract (GI) perforation. 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. The results 
were compared using Fisher's Exact Test. Detection of extraluminal air in the 
upright plain films and CT was analyzed by Z test. Our results showed that 
CT-falciform ligament sign was more frequent in the proximal GI perforation, 
while pockets of extraluminal air (excluding the cases accompanying CT-falciform 
ligament sign), bowel wall thickening and fat stranding were found in higher 
incidence in distal GI perforation (P<.05). CT detected extraluminal air in more 
cases than the upright plain films did (69% vs. 19%; Z=4.62>Z(0.01)=2.326). We 
concluded that CT is a good imaging tool to differentiate the various GI 
perforations.