Retrospective audit of patients presenting for ultrasound with suspicion of appendicitis

Purpose: To assess the ultrasound performance on patients presenting to Waikato hospital ultrasound department with a clinical suspicion of appendicitis. Method: This was a retrospective audit of 309 patients presenting to our department within business hours with clinical suspicion of appendicitis between September 2012 and March 2014. The patients were evaluated by operators of mixed experience. The scan reports, surgical reports, histology and discharge summaries were reviewed. Results: The overall sensitivity of ultrasound on detecting appendicitis was 50%, the specificity was 98.5%. The positive predictive value and the negative predictive value were 84% and 92.6% respectively. The appendix was visualised in 14% of the true positive cases. When the appendix was visualised, the sensitivity and specificity of ultrasound was 95.2% and 69.2% respectively. Conclusion: The sensitivity of ultrasound to appendicitis was lower than that commonly reported in the literature, but on a par with a recent audit from another tertiary hospital in New Zealand.