Contribution of the appendix sphericity index in predicting perforated acute appendicitis

The purpose of the present study was to investigate the diagnostic value of the appendiceal sphericity index (SI) and appendix diameters in cases of perforated and non-perforated acute appendicitis.

Eighty-one patients who underwent computed tomography (CT) in our clinic and who were diagnosed with acute appendicitis after histopathological assessment between January 2015 and August 2017 were included in the study. According to their histopathological findings, the patients were divided into two groups: perforated and non-perforated appendicitis. The patients' CT images were re-evaluated with respect to perforation. Long axis and short axis of the appendix and the SI obtained by their proportions were calculated from the appropriate plane on CT. Their parameters and other CT findings as defined in the current literature were analyzed for statistical significance in the detection of perforation.

The perforated and non-perforated appendicitis groups consisted of 20 and 61 patients, respectively. For wall defect, abscess, extraluminal air, free fluid, and appendicolith, the sensitivity values were 25%, 15%, 25%, 55%, and 50%, respectively, and the specificity values were 100%, 100%, 100%, 77%, and 70.5%, respectively. Sensitivity and specificity for the SI and long axis of the appendix were calculated as 85% and 90% and 85.2% and 73.8%, respectively (p<0.001).

Although there are many findings with high specificity in the diagnosis of perforation, their sensitivity is very low when evaluated separately. We consider that the measurement of long-axis length with high sensitivity and the evaluation of SI with high specificity and sensitivity will contribute significantly to the diagnosis of perforation.