Postnatal imaging of prenatally detected hydronephrosis-when is voiding cystourethrogram necessary?

Area of Science:

• Pediatric Nephrology
• Medical Imaging
• Urology

Background:

• Antenatally detected hydronephrosis is common in infants.
• Vesicoureteral reflux (VUR) is a significant risk factor for urinary tract infections (UTIs) and renal scarring.
• Voiding cystourethrogram (VCUG) is the gold standard for VUR diagnosis but is invasive.

Purpose of the Study:

• To determine if renal ultrasound (RUS) findings can predict high-grade VUR (grades 4-5).
• To develop a risk stratification tool based on RUS findings.
• To reduce the number of unnecessary VCUGs performed on infants.

Main Methods:

• Retrospective analysis of RUS and VCUG images from infants with prenatally detected hydronephrosis.
• Exclusion of patients with complex urinary tract anomalies.
• Multivariate analysis to identify RUS predictors of high-grade VUR and UTIs.

Main Results:

• A visible ureter (OR 12.72) and shorter renal length (OR 2.67) on RUS were significant predictors of grade 4-5 VUR.
• A visible ureter also predicted UTIs (OR 5.75).
• A RUS-based risk score categorized patients into low (2.9% grade 4-5 VUR), intermediate (12.2%), and high-risk (52.2%) groups, with 79% sensitivity and 82% specificity for high-grade VUR.

Conclusions:

• Visible ureter and reduced renal length on RUS are key indicators for high-grade VUR in infants with antenatal hydronephrosis.
• A RUS-based risk scoring system can effectively identify high-risk infants.
• Implementing this scoring system may decrease the need for invasive VCUGs.