Role of progressive urethral dilation and primary valve ablation in the long-term renal outcomes of small, preterm infants with posterior urethral valve

Introduction: PUV patients managed with primary vesicostomy instead of primary valve ablation (PVA) historically are preterm, low-birth-weight (LBW) infants with inadequate urethral size. We previously described progressive urethral dilation (PUD) as an effective method of enhancing the likelihood of PVA in these infants, allowing equal access to PVA as an initial management method. Objective: We aim to characterize renal outcomes in patients managed with PUD + PVA and compare this to outcomes with PVA alone. We also re-examine the effect of LBW and gestational age on renal outcomes in PUV with a cohort treated uniformly by PVA. Methods: We performed retrospective review of 78 neonates with PUV treated with PVA prior to 10 weeks of age with >1 year of follow up. Before valve ablation, boys either underwent PUD (serial upsizing of a smaller bore urethral catheter to an 8Fr catheter; PUD + PVA) or non-dilation (smaller bore catheter was maintained; PVA-only). PUD + PVA versus PVA-only was compared using chi-square and t-test. Logistic regression was performed to assess the effect of PUD, preterm (<37 weeks), LBW (<2.5 kg), and other predictors on the final outcomes of CKD3+ and ESRD. Results: 31 of 78 patients underwent PUD + PVA. Mean follow up was 5.2 years (SD 3.4), with no significant difference between PUD + PVA and PVA-only. The PUD + PVA group included significantly lower gestational age infants with lower birth weight and ablation weight. There was no significant effect of PUD on final CKD3+ or ESRD outcome on univariable or multivariable analysis. When adjusted for other variables, only Cr nadir >0.5 remained an independent predictor of CKD3+ (OR 41.2; p < 0.001) and ESRD (OR 18.9; p = 0.015). Discussion: We previously demonstrated that PUD is an effective means to achieve PVA in small neonates who might otherwise require vesicostomy. The data herein demonstrates no significant effect of PUD on renal outcomes. In this unique cohort of newborns treated with PVA, only creatinine nadir and not gestational age or an independent predictor of outcomes. Conclusion: In small preterm infants who would have been excluded from PVA due to limited urethral size, PUD + PVA confers the same renal outcomes as PVA alone in larger infants. This novel data will assist in the risk-benefit analysis of using PUD before PVA in newborns diagnosed with PUV. When primary intervention is uniformly PVA, preterm birth and LBW are not independent predictors of renal outcomes.