Diagnostic performance of computed tomography in differentiating appendiceal diverticulitis from acute appendicitis.

BACKGROUND: Appendiceal diverticulitis is a rare condition; however, it has a higher perforation rate than acute appendicitis and is more frequently associated with appendiceal malignancy. The aim of this study was to evaluate the diagnostic performance of computed tomography in differentiating appendiceal diverticulitis from acute appendicitis. METHODS: This study included 531 patients who underwent appendectomy for suspected acute appendicitis or appendiceal diverticulitis. The computed tomography diagnostic criterion for appendiceal diverticulitis was defined as a saccular structure protruding from the appendix. Three independent observers retrospectively reviewed axial, coronal, and multiplanar reconstruction images. Interobserver agreement was assessed using Fleiss' kappa, and a consensus computed tomography diagnosis of appendiceal diverticulitis was established. Diagnostic performance of computed tomography was evaluated by comparison with histopathological diagnosis. RESULTS: Histopathological analysis confirmed appendiceal diverticulitis in 31 (5.8%) patients and acute appendicitis in 500 (94.2%). Interobserver agreement was substantial (Fleiss' kappa = 0.767). The overall sensitivity and specificity of computed tomography for diagnosing appendiceal diverticulitis were 65% (95% confidence interval, 48%-79%) and 98% (95% confidence interval, 96%-99%), respectively. In patients without periappendiceal abscess (n = 433), sensitivity and specificity improved to 75% and 99%, respectively. Among patients without perforation (n = 396), sensitivity and specificity were 69% and 98%, respectively. CONCLUSION: Computed tomography demonstrated moderate sensitivity (65%) and high specificity (98%) for differentiating appendiceal diverticulitis from acute appendicitis. The diagnostic performance improved in cases without periappendiceal abscess or perforation, suggesting that computed tomography is a reliable tool for identifying appendiceal diverticulitis in patients with uncomplicated disease.