The Indian Society of Pediatric Nephrology (ISPN) guidelines recommend only renal ultrasound for children > 2 years with febrile urinary tract infection (UTI), but its accuracy in predicting vesicoureteral reflux (VUR) is limited. We audited a modified top-down approach (MTDA) using late-phase Tc99m-dimercaptosuccinic acid (DMSA) scintigraphy to select patients for undergoing voiding cystourethrography (VCUG).

This is a retrospective audit of consecutive children > 2 years with febrile UTI who completed the index test (late-phase DMSA for the presence/absence of cortical scarring) and the reference standard (VCUG for the absence/presence of VUR). The main outcome measures were sensitivity, specificity, positive and negative predictive values of DMSA scan and US for detecting VUR and the number needed to diagnose (NND).

A total of 224 children (mean age 3.5 years) were included. Late DMSA showed sensitivity 95.45% (95% CI 84.5–99.4%) and specificity 91.11% (95% CI 86.0–94.8%) for predicting VUR (NND 1.16). The sensitivity and specificity of renal ultrasound were 18.18% (95% CI 8.2–32.7%) and 98.89% (95% CI 96.0–99.9%); NND was 6.25. MTDA avoids 5/6 VCUGs.

In children > 2 years with febrile UTI, late-phase DMSA had a high diagnostic accuracy and could be used to selectively perform VCUG, reducing invasive testing.