Clinical and Inflammatory Predictors of False-Negative Ultrasound in Children With Suspected Appendicitis: A Prospective Cohort Study.

Abstract

Ultrasound (US) is the first-line imaging test for suspected pediatric acute appendicitis (AA), yet false-negative examinations remain a concern and may delay diagnosis. Clinical and inflammatory factors may influence this risk but have not been well defined. The aim of this study was to identify predictors of false-negative US in children with suspected AA. We conducted a prospective cohort study from 1 January 2022 to 31 October 2025 including children presenting with suspected AA whose initial abdominal US was negative. Multivariable logistic regression identified independent predictors of false-negative US. Among 1174 children evaluated, 610 had a negative US and were included in the analysis. Of these, 54 were ultimately diagnosed with AA (false-negative US). The median age was 10 years and males accounted for 51.3% of the cohort. On univariable analysis, male sex, symptom duration > 48 h, Pre-hospital antibiotic administration, admission temperature > 38°C, Alvarado score ≥ 5, white blood cell count > 10 × 10⁹/L, and C-reactive protein (CRP) ≥ 10 mg/L were significantly associated with false-negative findings. In multivariable analysis, three factors remained independently predictive: Alvarado score ≥ 5 (OR 10.53; 95% CI 4.49-24.70; p < 0.001), symptom duration > 48 h (OR 4.54; 95% CI 2.18-9.45; p < 0.001), and CRP ≥ 10 mg/L (OR 2.25; 95% CI 1.03-4.92; p = 0.042). False-negative US occurred in 8.9% of children with suspected AA. Higher Alvarado scores, prolonged symptoms, and elevated CRP were independently associated with missed AA despite negative imaging.