Radiological imaging to improve the emergency department diagnosis of acute appendicitis

Abstract

To determine the institution's current non-therapeutic (negative) appendicectomy rate; the frequency of clinical predictors for appendicitis in patients who underwent appendicectomy; and the utilization and accuracy of ultrasound scans (USS) and computed tomography (CT) in the diagnosis of appendicitis. A retrospective chart review was conducted in an adult, metropolitan teaching hospital. Patients who presented to the ED and underwent an appendicectomy over a 12-month period were analysed. Symptoms and signs predictive of appendicitis, results of USS and CT scans if performed, and histopathology findings were abstracted from patient records. Two hundred and forty patients had appendicectomies, 147 (61%) were male and the median age was 25 years (range 14-78 years). The negative appendicectomy rate was 14.3% (95% CI 9.1-21.0%) and 18.3% (95% CI 11.0-26.7%) in males and females, respectively. Abdominal pain shifting to the right iliac fossa (RIF), anorexia and RIF rebound tenderness were found more frequently in patients with positive than negative appendicectomies (P < 0.05). USS and CT scans were performed in 68 (28%) and 15 (9.5%) patients, respectively. The likelihood ratio for appendicitis in patients with a normal USS or a normal CT scan was 0.83 (95% CI 0.56-1.24) and 0.08 (95% CI 0.01-0.60), respectively. There were no false positive CT scan results. Computed tomoraphy scanning should play an increasing role in the ED management of suspected appendicitis. Our negative appendicectomy rate could potentially be halved by the introduction of CT scans in the diagnostic work up of these patients.