Use and accuracy of computed tomography scan in diagnosing perforated appendicitis

Perforated appendicitis has major implications on patient care. The ability of computed tomography (CT) scan to distinguish perforation in the absence of phlegmon or abscess is unknown. The purpose of this study is to assess the use and accuracy of CT scans in diagnosing perforated appendicitis without phlegmon or abscess. A retrospective chart review of 102 patients who underwent appendectomy from 2011 to 2013 was performed. Patient demographics and operative and postoperative course were recorded. Two radiologists were then blinded to operative findings and CT scans reread and results correlated. Findings on CT scan were also analyzed for correlation with perforation. Univariate and multivariate statistical analysis was performed. Of the 102 patients, 49 were perforated and 53 nonperforated. Analysis of patient populations demonstrated patients with perforation were significantly older (45 vs 34 years, P = 0.002), had longer operative times (132 vs 81 minutes, P = 0.001), and longer length of stay (8.2 vs 1.5 days, P < 0.001). Nineteen perforations (37%) were correctly diagnosed by CT scan. The sensitivity of CT scan to detect perforation was 38 per cent, specificity 96 per cent, and positive predictive value of 90 per cent. After multivariate analysis of significant variables, three were demonstrated to significantly correlate with presence of perforation: presence of extraluminal air (odds ratio [OR], 28.9; P = 0.02); presence of intraluminal fecalith (OR, 5.7; P = 0.03); and wall thickness greater than 3 mm (OR, 3.2; P = 0.02). CT scan has a low sensitivity for diagnosing perforated appendicitis without abscess or phlegmon. Presence of extraluminal air bubbles, increased wall thickness, and intraluminal fecalith should increase suspicion for perforation and are highly correlated with outcomes after appendectomy.