MDCT Reveals Site and Cause of GI Tract Perforations

February 2010

By Damian McNamara
Elsevier Global Medical News

CHICAGO -- Multidetector computed tomography can identify the site and etiology of gastrointestinal perforations correctly in a high percentage of patients with acute abdominal pain who present to an emergency department, according to a prospective study.

This imaging technique can help surgeons make crucial and timely decisions about surgery or other therapeutic options in these acute patients, Dr. Leopoldo D. Salvatierra Arrieta said during the annual clinical congress of the American College of Surgeons.

To assess the accuracy of multidetector computed tomography (MDCT) in this setting, Dr. Arrieta and his colleagues prospectively studied 121 patients presenting with acute abdominal pain between April 2007 and January 2009 at La Paz University Hospital in Madrid. The research was designated a Poster of Exceptional Merit at the meeting.

Two radiologists who were blinded to the subsequent surgical findings used MDCT independently of one another and reached a consensus on the perforation site in 96 of 121 cases (79%). Surgery later revealed that MCDT correctly predicted the site in 80 of these 96 cases (83%).

Of the remaining 25 patients, 12 had an indeterminate perforation site, 10 did not have a GI perforation (verified by surgery), and 3 declined surgery.

The large bowel, stomach, and small bowel were the most common sites for GI tract perforations identified with MDCT. The mean patient age was 63 years (range, 15-97 years), and the study included 58 men and 63 women.

The strongest predictors of the perforation site on MDCT were bowel wall defect, concentration of extraluminal air bubbles, and segmental bowel wall thickening, Dr. Arrieta said.

Surgeons identified more perforation sites, a total of 108, compared with the radiologists using preoperative MDCT. Surgeons found 30 perforations in the descending colon and sigmoid, 25 in the stomach or duodenum, 21 in the small bowel, 10 in the cecum or ascending colon, 5 in the rectum, and 1 transverse colon perforation; the series also included 16 patients with an acute perforated appendix.

The radiologists also evaluated MDCT scans for information on the etiology of the perforation and correctly identified the cause in 71 patients. Inflammation was the most common etiology, followed by tumor and peptic ulcer. Ischemia, foreign bodies, and trauma were other causes of the perforations.

The radiologists analyzed axial and multiplanar images. They specifically looked for contrast extravasation, bowel wall focal defects, extraluminal air-free fluid, and any inflammatory changes, including segmental bowel wall thickening, perivisceral fat stranding, or abscess. Segmental thickening of the bowel wall, fat stranding, and abscess were the most important MDCT signs in perforations associated with inflammatory causes. For patients with neoplastic perforations, segmental thickening and free air were the most frequent MDCT findings.

Dr. Arrieta and his associates chose MDCT because the modality has an overall accuracy of 82%-90% for predicting the site of GI tract perforation in published studies (Am. J. Roentgenol. 2006;187:1179-83). With sensitivities ranging from 69% to 95% and specificities of 95%-100% for diagnosis of bowel blunt trauma and mesenteric injuries, CT scanning and MDCT have emerged as the primary diagnostic imaging modalities for patients presenting with abdominal or pelvic pain, he added (Radiographics 2006;26:1119-31).

"We think accurate preoperative diagnosis [with MDCT] is helpful," Dr. Arrieta said. MDCT is "the most valuable technique for identifying the presence, site, and cause of GI tract perforation."

Dr. Arrieta had no conflicts of interest to disclose.
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