Sonographic diagnosis of perforation in patients with acute appendicitis.

The sonographic diagnosis of appendicitis can be challenging in patients with perforation. In order to detect the accuracy of specific sonographic features of appendiceal perforation, graded compression sonograms in 100 patients with surgically confirmed acute appendicitis were reviewed retrospectively. Twenty-two of these patients had perforation. A statistically significant association was found between three sonographic findings and perforation: loculated pericecal fluid, prominent pericecal fat, and circumferential loss of the submucosal layer of the appendix. No single finding had a specificity greater than 59%. By using a combination of one or more findings, the overall sensitivity of sonography for the diagnosis of perforation was 86%. The specificity, however, was only 60%. Our results suggest that in patients without a sonographically visible appendix, recognition of loculated pericecal fluid and prominent pericecal fat may be a useful indirect clue to the diagnosis of perforating appendicitis.