[Use of multidetector computed tomography for locating the site of gastrointestinal tract perforations]

The purpose of this study was to evaluate the accuracy of multidetector computed tomography (MDCT) for locating the site of gastrointestinal tract perforations and to determine the most predictive signs in this diagnosis.

A total of 98 patients with pneumoperitoneum on MDCT were retrospectively analysed. Two experienced radiologists reviewed the presence or absence of direct signs (extravasation of oral contrast, focal defect in the bowel wall, focal defect with multiplanar reformations images) and indirect signs (free air in supramesocolic, inframesocolic, supramesocolic and inframesocolic compartments, concentration of extraluminal air bubbles adjacent to the bowel wall, extraluminal fluid, segmental bowel-wall thickening, perivisceral fat stranding, abscess) to identify the site of the perforation. The Kappa index was evaluated between radiologists to determine the site of perforation and for each predictive sign, as well as Kappa index between the site of perforation detected with MDCT and the site proven at surgery. The frequency, sensitivity, specificity and positive and negative predictive value (PPV and NPV, respectively) were calculated.

The perforation site was identified correctly in 80.4% of cases. Kappa index between radiologists to identify the site was excellent (0.919), varying between 0.5-1.0 for each radiological sign. The most frequent site of perforation at surgery (33.7%) and in MDCT (40.82%) was the sigmoid colon/rectum. Concentration of extraluminal air bubbles adjacent to the bowel wall was the most sensitive (91%) sign and "segmental bowel-wall thickening" had the highest PPV (90%).

MDCT is useful for locating the site of GI perforation, with a high sensitivity (80%) and an excellent agreement between radiologists.