Objective: Prenatal open neural tube defect (ONTD) repair is performed to decrease the risk of needing treatment for hydrocephalus after birth and to preserve motor function. Some centers may not consider patients to be candidates for surgery if severe ventriculomegaly is present and there is no expected benefit in risk for hydrocephalus treatment. This study sought to compare the postnatal outcome of fetuses with ONTD and severe ventriculomegaly (ventricular width ≥ 15 mm) that underwent prenatal repair with the outcome of fetuses with severe ventriculomegaly that underwent postnatal repair and fetuses without severe ventriculomegaly (< 15 mm) that underwent prenatal repair.

Methods: This was a retrospective study of fetuses with ONTD that underwent prenatal or postnatal repair between 2012 and 2021 at a single institution. The cohort was divided into two groups based on preoperative fetal ventricular size: those with severe ventriculomegaly (ventricular width ≥ 15 mm) and those without severe ventriculomegaly (< 15 mm). Fetal ventricular size was measured by magnetic resonance imaging before surgery using the standardized approach and the mean size of the left and right ventricles was used for analysis. Motor function of the lower extremities was assessed at the time of referral by ultrasound and if flexion-extension movements of the ankle were seen it was considered as preserved S1 motor function. Postnatal outcomes, including motor function of the lower extremities at birth and the need for a diversion procedure for hydrocephalus treatment during the first year after birth, were collected and compared between groups. Multivariate regression analysis was used to adjust for potential confounders.

Results: In this study, 154 patients were included: 145 underwent fetal surgery (101 fetoscopic and 44 open hysterotomy) and nine with severe ventriculomegaly underwent postnatal repair. Among the 145 patients who underwent fetal surgery, 22 presented with severe ventriculomegaly. Fetuses with severe ventriculomegaly at referral that underwent prenatal repair were significantly more likely to need hydrocephalus treatment by 12 months after birth than those without severe ventriculomegaly (61.9% vs 28.9%, P < 0.01). However, motor function assessment at birth was similar between both prenatal repair groups (odds ratio, 0.92 (95% CI, 0.33-2.59), P = 0.88), adjusted for the anatomical level of the lesion. The prenatal repair group with severe ventriculomegaly had better preserved motor function at birth compared to the postnatal repair group with severe ventriculomegaly (median level, S1 vs L3, P < 0.01; proportion with S1 motor function, 68.2% vs 11.1%, P < 0.01). Fetuses with severe ventriculomegaly that underwent prenatal repair had an 18.9 (95% CI, 1.2-290.1)-times higher chance of having intact motor function at birth, adjusted for ethnicity, presence of club foot at referral and gestational age at delivery, compared with the postnatal repair group. There was no significant difference in the need for hydrocephalus treatment in the first year after birth between prenatal and postnatal repair groups with severe ventriculomegaly (61.9% vs 87.5%, P = 0.18).

Conclusions: Although fetuses with ONTD and severe ventriculomegaly do not seem to benefit from fetal surgery in terms of postnatal hydrocephalus treatment, there is an increased chance of preserved motor function at birth. Results from this study highlight the benefit of prenatal ONTD repair for cases with severe ventriculomegaly at referral to preserve motor function. © 2024 International Society of Ultrasound in Obstetrics and Gynecology.