1115 The Role of Ultrasound and Computer Tomography Imaging in the Management of Suspected Acute Appendicitis at a District General Hospital: A Clinical Audit Evaluating Our Practice Against International Standards

Aim Definitive diagnosis of acute appendicitis (AA) continues to pose a clinical challenge. Computer tomography (CT) is the gold-standard imaging modality for diagnosis, but ultrasound (USS) remains first-line and recommended for paediatric and young patients given the absence of ionising radiation. We conducted an audit evaluating the use of imaging as a diagnostic adjunct in diagnosing AA and whether it reduced the negative appendicectomy rate in a large UK district general hospital. A high NAR has both a significant patient impact (complications, increased hospital length of stay) and healthcare resource burden. Method We performed a retrospective analysis of electronic health records for a pre-Covid cohort of 344 patients who underwent a coded diagnostic laparoscopy/laparoscopic appendicectomy between 1st January 2019 and 1st January 2020. Histological confirmation of appendicitis was utilised as the gold-standard. Results USS was performed in only 10% of patients, particularly young females (16-35), and had 44% sensitivity, 88% specificity, 57% positive predictive value (PPV) and 84% negative predictive value (NPV). CT was performed in 22% of patients with 99% sensitivity, 100% specificity, 100% PPV and 88% NVP. Use of imaging (versus DLA) was associated with greater length of stay and readmission rates. Conclusions Despite its widespread use, ultrasound’s low sensitivity and PPV render its clinical utility debatable, particularly in females. Additionally, by counting occasions whereby ultrasound fails to visualise the appendix as negative results, its specificity is inaccurately increased. Therefore, CT remains gold standard given its highest sensitivity and specificity for diagnosing AA and its association with a reduction in NAR.