Evaluating Changes in Diagnostic Accuracy of Ultrasound for Appendicitis: Does Practice Make Perfect?

Ultrasound (US) is the preferred method of initial evaluation for appendicitis in pediatrics. However, limited accuracy of US for appendicitis is an obstacle to implementation of US-first protocols at facilities less experienced with US.

The primary objective was to demonstrate changes in diagnostic accuracy of US for appendicitis over time, after implementation of an US-first protocol. Secondary objectives included evaluating trends in utilization and factors associated with accuracy of US.

We reviewed 5 years of pediatric emergency department encounters that included US evaluations for appendicitis. The primary outcome was conclusive US (fully visualized normal appendix or unequivocal appendicitis) vs. equivocal US (partially visualized or nonvisualized appendix). We also analyzed rates of conclusive US over time; accuracy, sensitivity, and specificity of US for appendicitis; and associations of US accuracy with patient gender, body mass index, and ultrasonographer's experience.

A conclusive US report was found in 267 of 1058 encounters (25.2%); overall accuracy rate was 24.5%. Over 5 years, the diagnostic accuracy of US for appendicitis improved significantly from 13.9% to 31.5% (p = 0.001). Overall sensitivity was 80.7% and specificity was 77.6%. Male gender and dedicated US of the appendix were significantly associated with conclusive US (ps < 0.001). Higher body mass index was significantly associated with equivocal US (p < 0.001). Ultrasonographer experience was not significantly associated with conclusive US (p = 0.22).

An US-first imaging protocol for appendicitis in children shows chronologic improvement in diagnostic accuracy. This may provide encouragement to facilities using computed tomography-based diagnostic protocols to implement US-first protocols to reduce childhood radiation exposure.