Predicting Differential Renal Function in Children With Vesicoureteral Reflux Using Ultrasound

To evaluate whether relative renal volume (RRV) measured by ultrasound predicts differential renal function measured by dimercaptosuccinic acid scintigraphy in children with vesicoureteral reflux.

We retrospectively reviewed pediatric patients with vesicoureteral reflux followed at a single tertiary center between January 2008 and May 2023. Collected variables included sex, reflux grade, laterality, comorbidities, renal volume by ultrasound, RRV, and differential renal function by scintigraphy. Patients with bilateral reflux or urological comorbidities were excluded. Agreement between RRV and differential renal function was analyzed.

Among 921 patients reviewed, 147 had unilateral primary reflux without comorbidities (83 female, 64 male): 81 had grades I to III and 66 had grades IV or V. The median differential function was 33% (IQR: 22%-44%) and the median RRV was 36% (IQR: 25%-44%). The agreement was strong (intraclass correlation coefficient 0.94; 95% CI: 0.92-0.96; P < .001). RRV overestimated function by 2% (95% CI: -13% to 10%). A cutoff of 40% predicted a differential function below 40% with 89% sensitivity and 89% specificity (AUC 0.94; 95% CI: 0.90-0.97).

In children with unilateral primary vesicoureteral reflux, RRV by ultrasound accurately predicts differential renal function. This noninvasive alternative may reduce the need for scintigraphy, limiting radiation exposure and health care costs.