[Sixty-one consecutive patients with gastrointestinal perforation: comparison of conventional radiology, ultrasonography, and computerized tomography, in terms of the timing of the study].
Plain abdominal radiography is the method of choice to diagnose gastrointestinal perforation because it shows the presence of free intraperitoneal air and of other associated radiologic signs. Recently, the modern methods of cross-section imaging, that is US and CT, have become useful tools for the accurate detection and depiction of free abdominal air, especially when plain films are normal or nonspecific. A series of 61 consecutive patients operated on for viscus perforation at Cardarelli Hospital, Neaples, was retrospectively reviewed: the authors report the site and cause of perforation and the diagnostic methods used preoperatively to recognize the radiographic sign of free air; examination time and the time passed between the first radiograph and surgery were also investigated. Of 61 patients, 53 underwent preoperative radiologic exams: plain abdominal radiographs were performed on 50 patients, abdominal US on 29 and CT on 15, while 8 patients were submitted to surgery with no previous diagnostic examination. Direct and indirect signs of perforation were assessed to compare the sensitivity of the methods and to suggest a possible diagnostic protocol. Combined radiography, US and CT showed signs of perforation in 71% of cases (direct signs in 57.5% and indirect signs, that is free intraperitoneal fluid and hypoperistalsis, in 14.5% of cases). When free air was absent (1/3 of cases), free intraperitoneal fluid was the only radiologic finding. The authors conclude that plain abdominal radiography, when correctly performed, is still the main tool permitting free air, if present, to be depicted in 100% of cases. When plain abdominal radiography is positive, other radiologic procedures are unnecessary while, when it is negative and symptoms persist, US and CT should be performed after at least 6 hours' interval to allow the radiologic picture to change markedly.