Prenatal Ultrasound Grading in Prognostication of Neonates with Posterior Urethral Valves

Posterior urethral valves (PUVs) are a major cause of congenital lower urinary tract obstruction and long-term chronic kidney disease (CKD). This study was aimed to evaluate the utility of a simplified prenatal ultrasound grading (PUG) system to assess CKD progression.

This retrospective case series included inborn neonates with antenatally diagnosed PUV managed at a tertiary center between 2010 and 2020. Postnatally detected or referred cases and those without complete follow-up were excluded. PUG was assigned at 32 weeks' gestation using prenatal ultrasound findings (no fetal urine sampling): PUG-1 (normal amniotic fluid index and renal echogenicity), PUG-2 (oligohydramnios with normal echogenicity), and PUG-3 (anhydramnios and/or increased echogenicity). Postnatal management included primary valve ablation or urinary diversion based on gestation and PUG category. The primary outcome was CKD stage ≥3 as per KDIGO criteria.

Fifty-eight neonates (42 term and 16 preterm) had complete follow-up (median: 7 years). Among all neonates, CKD occurred in 1/28 with PUG-1, in 5/21 with PUG-2, and in 8/9 with PUG-3 (P = 0.001). There was no significant difference (P = 0.46) in CKD progression between preterm (5/16) and term neonates (9/42). On multivariable logistic regression, higher PUG was independently associated with increased odds of CKD (odds ratio: 3.5, 95% confidence interval: 1.5-8.2, P = 0.004). Kaplan-Meier survival analysis revealed increasing CKD risk (Log-Rank Mantel-Cox χ² = 94.132; P = .0001) as the PUG grade progressed.

Primary valve ablation is safe in low-/intermediate-risk preterm neonates with PUV. CKD risk increases as PUG progresses. PUG shows promising prognostic application; larger validation studies are warranted.