Background: Vesicoureteral reflux (VUR) affects 1-2% of healthy children and up to 30-50% of those with urinary tract infections. While voiding cystourethrogram (VCUG) remains the gold standard for VUR diagnosis, its invasive nature and radiation exposure have prompted investigation of ultrasound as an alternative screening tool. The study aims to determine the diagnostic accuracy of renal ultrasound compared to VCUG for detecting VUR in pediatric patients and evaluate its potential as a screening modality in resource-limited settings.

Methods: This prospective cross-sectional study was conducted at Central Child Teaching Hospital, Baghdad, from January to December 2024. Children aged 1 month to 12 years with clinical suspicion of VUR underwent both renal ultrasound and VCUG within 48 hours. Ultrasound examinations were performed by experienced pediatric radiologists blinded to VCUG results. VUR was graded according to International Reflux Study Committee classification. Diagnostic accuracy measures including sensitivity, specificity, positive and negative predictive values were calculated with 95% confidence intervals.

Results: Among 180 children (60% female, mean age 4.2±3.1 years), VCUG confirmed VUR in 98 patients (54.4%). Renal ultrasound demonstrated overall sensitivity of 76.5% (95% CI: 67.2-84.3%), specificity of 82.9% (95% CI: 73.9-90.0%), positive predictive value of 81.5%, and negative predictive value of 78.2%. The area under ROC curve was 0.807. Performance varied significantly by VUR grade, with sensitivity of 91.2% for high-grade VUR (grades IV-V) versus 65.8% for low-grade VUR (grades I-III). Inter-observer agreement was substantial (κ=0.78).