RESUMO
Objective To evaluate the value of the periportal free air(PPFA) sign at computed tomography(CT) in distinguishing between upper and lower gastrointestinal(GI) tract perforation. Methods CT images of 62 patients with surgically proven GI tract perforation were retrospectively analyzed. 62 cases included upper and lower GI tract perforation in 35 cases and 27 cases,respective-ly. When there was free air in the periportal area,it was defined as positive periportal free air(PPFA) sign. The difference of PPFA sign in upper and lower GI tract perforation, and the sensitivity, specificity, positive predictive value, negative predictive value and ac-curacy of PPFA sign in diagnosing gastrointestinal perforation were analysed respectively. Results The PPFA sign was seen in 33 of 35(94%) patients with upper GI tract perforation,but only in 10 of 27 (37%) patients with lower GI tract perforation,there was sig-nificant difference between them(P<0.05). For diagnosis of super GI perforation with PPFA sign, the sensitivity, specificity, positive predictive value,negative predictive value and accuracy were 94% (33/35), 63%(17/27), 770%(33/43), 89%(17/19) and 81% (50/ 62), respectively. Conclusion The PPFA sign is a useful finding in distinguishing between upper and lower GI tract perforation.