Clinical correlation needed: what do emergency physicians do after an equivocal ultrasound for pediatric acute appendicitis?

Abstract

Background: Although follow-up CT is recommended for pediatric appendicitis if initial ultrasound (US) is equivocal, many physicians observe the patient at home. There are limited data to understand currently how common or safe this practice is. Our objectives are to assess prevalence of acute appendicitis and outcomes in patients with equivocal US with and without follow-up CT and to identify variables associated with ordering a follow-up CT.

Methods: Retrospective analysis of the prevalence of appendicitis and outcomes of patients 1-18 years old with an equivocal US at a pediatric emergency department from 2003 to 2008. Recursive partitioning analysis and multivariate logistic regression were used to identify variables associated with ordering follow-up CT.

Results: Fifty-five percent (340/620) of children with equivocal US did not receive CT, none of whom returned with a missed appendicitis. The prevalence of appendicitis in children with equivocal US was 12.5% (78/620). In children with follow-up CT, the prevalence was 22.1% (62/280); in those without follow-up CT, the prevalence was 4.7% (16/340). Recursive partitioning identified age >11 years, leukocytosis >15,000 cells/ml, and secondary signs predisposing toward acute appendicitis on US as significant predictors of CT.

Conclusions: We view our study as a fundamental part of the incremental progress to understand how best to use US and CT imaging to diagnose pediatric appendicitis while minimizing ionizing radiation. Children at low risk for appendicitis with equivocal US are amenable to observation and reassessment prior to reimaging with US or CT.

Keywords: abdominal/gastrointestinal; clinical guidelines; medical imaging; pediatrics; ultrasound.