RRV predicts differential renal function in children with vesicoureteral reflux

Relative renal volume (RRV) by ultrasound demonstrates accurate prediction of differential renal function in children with unilateral primary vesicoureteral reflux, reports a study.

"This noninvasive alternative may reduce the need for scintigraphy, limiting radiation exposure and healthcare costs,” said the researchers, who retrospectively reviewed paediatric patients with vesicoureteral reflux followed at a single tertiary centre between January 2008 and May 2023.

Variables collected were 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. Finally, the researchers analysed the agreement between RRV and differential renal function. 

A total of 921 patients were reviewed, of whom 147 had unilateral primary reflux without comorbidities (83 females, 64 males; 81 had grades 1 to III, 66 had grades IV of V).

The median differential function was 33 percent, while the median RRV was 36 percent. The agreement was robust, with intraclass correlation coefficient of 0.94 (95 percent confidence interval [CI], 0.92−0.96; p<0.001). RRV overestimated function by 2 percent (95 percent CI, −13 percent to 10 percent).

Using a cutoff of 40 percent predicted a differential function below 40 percent, with a sensitivity of 89 percent and specificity of 89 percent (AUC, 0.94, 95 percent CI, 0.90−0.97).