(899) Impact of Prenatal Surgical-to-Delivery Interval on Early Urologic Outcomes after Fetal Myelomeningocele Repair

To evaluate the association between the interval from prenatal fetal myelomeningocele (fMMC) repair to delivery and early childhood urologic outcomes in the Management of Myelomeningocele Study (MOMS) cohort.

Study Design:

This was an unplanned secondary analysis of the prenatal fMMC repair arm of the MOMS using de-identified data provided by the National Institutes of Health (NIH). The primary exposure was surgery-to-delivery interval, dichotomized as ≤58.2 days (lowest quartile) vs. >58.2–110 days. Primary outcomes included urologic surgery, clean intermittent catheterization (CIC), vesicoureteral reflux (VUR), and hydronephrosis by 30 months. Bivariate analyses used Fisher’s exact and Wilcoxon tests. Linear regression assessed associations between interval and urologic outcomes, adjusting for covariates significant at p< 0.05.

Results:

90 participants were eligible for inclusion, 23 (25.5%) in the shortest quartile and 67 (74.5%) in the longer quartiles. Preoperative ventricular size was larger in the shorter surgery-to-delivery interval (14.1 v. 10.8 mm, p < 0.001). Rates of urologic surgery, CIC use at 30 months, and CIC use at the latest follow-up were similar between groups. However, vesicoureteral reflux development or worsening demonstrated a trend toward increased risk in the shortest interval group (20% vs. 2.6%, p=0.06). Hydronephrosis at 12 months was notably more frequent in the shortest interval group (relative risk: 0.38, 95% CI: 0.15–0.98), approaching statistical significance (p=0.10). Hydronephrosis at 12 months was significantly associated with shorter prenatal surgical-to-delivery interval in adjusted analyses accounting for collinearity between the surgery-to-delivery interval and gestational age at delivery through residual analysis and preoperative ventricular size (adjusted OR: 0.94 [95% CI: 0.89, 0.99], p=0.04).

Conclusion:
A shorter interval between prenatal fMMC repair and delivery is associated with an increased risk of hydronephrosis in early childhood. This finding suggests that prolonging pregnancy post-surgery may independently improve early urologic outcomes.