A single centre evaluation of risk prediction models and imaging modalities in acute appendicitis

Patients with suspected appendicitis remain a diagnostic challenge. The aim of this study was to validate risk prediction models, and to investigate diagnostic accuracy of ultrasonography and computed tomography (CT) in adults undergoing appendicectomy.

A retrospective case review was performed of patients aged 16-45 years having an appendicectomy between January 2019 and January 2020 at a tertiary referral centre. Primary outcomes were the accuracy of a high risk appendicitis risk score and ultrasonography and CT imaging modalities compared with histological reports following appendicectomy.

A total of 206 patients (52% female) were included in the study. Removal of a histologically normal appendix was equally likely in men and women (13.1% vs 11.2% respectively, relative risk: 1.17, 95% confidence interval: 0.56-2.44, p=0.674). A high risk appendicitis score correctly identified 84.0% (79/94) of cases in men and 85.9% (67/78) of cases in women. Ultrasonography was reported as equivocal in 85.7% (18/21) of low risk women and 59.0% (23/39) of high risk women. CT correctly detected or excluded appendicitis in 75.0% (6/8) of low risk women and 88.5% (23/26) of high risk women.

This study suggests that risk prediction models may be useful in both women and men to identify appendicitis. Ultrasonography gave high rates of equivocal results and should not be relied on for the diagnosis of appendicitis. CT is a highly accurate diagnostic tool and could be considered in those at low risk where clinical suspicion remains to reduce negative appendicectomy rates.