Predictors of Inaccurate Ultrasound Results in Pediatric Appendicitis

High body-mass index and low clinical suspicion predict inaccurate ultrasound results.


Investigators prospectively assessed accuracy of ultrasound for diagnosing appendicitis in 263 children (age range, 4–17 years) who presented to an emergency department in Canada with clinically suspected appendicitis from 2007 through 2008. Ultrasound exams were ordered by treating emergency physicians and performed by sonographers or radiology fellows. Patients with nondiagnostic ultrasound findings received a brief clinical reassessment followed by a second ultrasound, computed tomography (CT), or both, at the discretion of the consulting surgeon.

Ninety-five screening ultrasounds were interpreted as positive, 76 as negative, and 92 as nondiagnostic; 99 patients (37%) had surgically proven appendicitis. Overall, 162 screening ultrasound scans were accurate and 101 were inaccurate for assessment of appendicitis (87% sensitivity, 46% specificity, 49% positive predictive value, 85% negative predictive value, 62% accuracy). Independent predictors of inaccurate ultrasound scan results were body-mass index ?85th percentile (adjusted odds ratio, 2.0) and estimated clinical probability of appendicitis ?50% (AOR, 2.4). Accuracy of the screening ultrasound followed by either a second ultrasound or clinical reassessment was significantly higher in lean children than in obese children (93% vs. 83%).


Citation(s):

Schuh S et al. Predictors of non-diagnostic ultrasound scanning in children with suspected appendicitis. J Pediatr 2011 Jan; 158:112.