Appendicitis Computed Tomography Score: a Useful Tool for Predicting Perforation and Surgical Course of Acute Appendicitis

Full Article

BMH Lai, CY Chu, BST Leung, VKP Fung, DTF Lee, THT Sung, JLS Khoo

Hong Kong J Radiol 2015;18:267-76

DOI: 10.12809/hkjr1515310

Objective: To investigate the utility of the Appendicitis Computed Tomography (ACT) scoring system in the diagnosis of perforated appendicitis and prediction of surgical outcome.

Methods: A retrospective study was conducted on 102 subjects who underwent computed tomography (CT) scan and appendectomy for acute appendicitis between May 2011 and January 2012. Images were reviewed for five individual CT signs (appendiceal wall defect, phlegmon, abscess, extraluminal gas, and extraluminal appendicolith) and a score (ACT score) was assigned for each patient based on the number of detectable findings. Correlation of ACT score and individual CT signs with appendiceal perforation and surgical outcome was evaluated statistically. Diagnostic power was assessed using receiving operating characteristic (ROC) curve.

Results: A total of 84 subjects were included in the final study after exclusion. ACT score was significantly higher for the perforated group compared with the non-perforated group (2.52 vs. 0.40, p < 0.001) and also higher for the open surgery group than the laparoscopic surgery group (2.78 vs. 0.93, p < 0.001). ACT score was an independent predictor of perforation (odds ratio [OR] = 7.05, p < 0.001), need for open surgery (OR = 2.99, p = 0.002), and operating time (increase of 12.93 minutes, p < 0.001). On ROC curves, ACT score showed a higher discriminating power for both appendiceal perforation (area under the curve [AUC] = 0.939) and need for open surgery (AUC = 0.858) than individual CT signs. An ACT score of 0 was 100% sensitive for excluding appendiceal perforation and open surgery in our study, whereas an ACT score of >3 was diagnostic for perforated appendix.

Conclusions: The ACT score is a practical and accurate tool for diagnosis of appendiceal perforation and prediction of surgical outcome.