Influence of symptom duration and WBC profile on the negative predictive value of a non-diagnostic ultrasound in children with suspected appendicitis

Abstract Background The aim of this study was to explore the combined negative predictive value (NPV) of symptom duration and WBC profile in children with a nondiagnostic ultrasound (US) for appendicitis. Methods This was a retrospective analysis of children with suspected appendicitis at a single children's hospital from 1/2010 to 3/2018. NPVs based on WBC profile and symptom duration at presentation were calculated individually and combined for children with a nondiagnostic US. Results 2277 patients were included, of which 1018 (44.7%) had a nondiagnostic US. The NPV of a nondiagnostic US ranged from 83.7% with ≤ 24 h of symptoms to 94.5% with > 72 h of symptoms (p   72 h of symptoms and a normal WBC profile. Conclusions Incorporation of symptom duration and WBC profile significantly improves the accuracy and clinical utility of the negative predictive value associated with a nondiagnostic ultrasound. Level of evidence Study of diagnostic test level II: development of diagnostic criteria in a consecutive series of patients and a universally applied gold standard.