Intraluminal Air within an Obstructed Appendix. A CT Sign of Perforated or Necrotic Appendicitis

Rationale and Objectives: The aim of this study was to evaluate the predictive value of intraluminal air for appendiceal necrosis and/or perforation when not apparent on imaging. Additional factors of intraluminal appendicoliths, age, and gender were also assessed. Materials and Methods: Patients with pathologically proven appendicitis who underwent multidetector computed tomographic imaging over a 3-year period (n = 487) were retrospectively reviewed. Those with imaging evidence for perforation were excluded to create a study population of apparent uncomplicated acute appendicitis (n = 374). Each scan was assessed for intraluminal appendiceal air and appendicoliths on multidetector computed tomography and compared against surgical and pathologic results for appendiceal necrosis and/or perforation. Results: Image-occult necrosis or perforation was present in 17.4% (65 or 374) of the study cohort. Intraluminal air and appendicoliths were predictive variables by univariate logistic regression (P = .001 and P ≤ .001, respectively), with odds ratios of 2.64 (95% confidence interval, 1.48-4.73) for intraluminal air and 2.67 (95% confidence interval, 1.55-4.61) for appendicoliths. Both remained independent variables on multivariate modeling despite multicollinearity. Increasing age was also predictive (odds ratio, 1.25; 95% confidence interval, 1.09-1.44; P = .002), whereas gender was not (P = .472). Conclusions: Intraluminal appendiceal air in the setting of acute appendicitis is a marker of perforated or necrotic appendicitis. Recognition of this finding in otherwise uncomplicated appendicitis at imaging should raise suspicion for image-occult perforation or necrosis.