Maximum outer appendiceal diameter as a criterion of acute appendicitis: Evaluation at computerized tomography

Objective: The goal of this study was to assess the optimum diagnostic cutoff value of maximum outer appendiceal diameter on computed tomography (CT) images in patients with suspected acute appendicitis in the emergency department. Methods: A total of 328 patients with clinical suspicion of appendicitis were retrospectively reviewed. Evaluation of CT images, and chart review for clinical, laboratory, surgical, and pathologic findings were performed. Logistic regression was used to identify possible predictive factors influencing diagnosis of acute appendicitis. The receiver operating characteristic (ROC) curve was applied to determine the most suitable diagnostic cutoff value of appendiceal diameter for acute appendicitis. Results: In a total of 136 patients (41.5%) the diagnosis of acute appendicitis was made; 192 patients (58.5%) had nonacute appendicitis. Mean appendiceal diameter was 12.68±3.31mm in patients with acute appendicitis and 6.01±1.50mm in patients without. The appendiceal diameter had a significantly statistical difference to differentiate the presence from the absence of acute appendicitis with an area under the ROC curve of 0.985 (95% confidence interval, 0.973-0.996). An appendiceal diameter cutoff value of 8.15mm had a sensitivity of 97%, a specificity of 93.2%, and an accuracy of 94.8%. Appendiceal wall enhancement with intravenous contrast medium also had a significantly statistical difference for discriminating patients with acute appendicitis from those without by logistic regression. Conclusion: Detection of maximum outer appendiceal diameter and appendiceal wall enhancement with intravenous contrast medium on CT could help differentiate patients with acute appendicitis from those without. An appendiceal diameter greater than 8.15mm is particularly useful for diagnosis of acute appendicitis.