Evaluating Bladder Function and Safety in Prenatal Fetoscopic Versus Prenatal Open Myelomeningocele Repair
Jonathan Gerber, MD, Paul F. Austin, MD, Alexandra N. Borden, PA-C, William E. Whitehead, MD, Jonathan Castillo, MD, Heidi Castillo, MD, Michael A. Belfort, MD, Duong D. Tu, MD.
Texas Children's Hospital, Houston, TX, USA.
BACKGROUND: Myelomeningocele (MMC) is the most common permanently disabling birth defect in the United States. Neurosurgical management has shifted to antenatal MMC closure. With the advent of improved surgical techniques, minimally invasive, or fetoscopic, antenatal repair has emerged. Prior studies, limited to open antenatal closure, demonstrate significant improvement in motor and neurological function, in the absence of clear urologic benefit. Purported benefits of the fetoscopic approach include decreased risk for preterm labor and the allowance for vaginal delivery. The clinical impact, from a urologic perspective, remains unclear. We hypothesize that fetoscopic myelomeningocele (MMC) repair (FMR) is non-inferior to prenatal open hysterotomy MMC repair (POMR) in terms of urological outcomes.
METHODS: A Baylor College of Medicine, IRB approved, retrospective study of all patients having undergone any fetal repair of MMC at our institution was performed. POMR and FMR were compared. Inclusion criteria required renal ultrasound (US) and urodynamic studies (UDS) to be obtained within the first 9 months of life with a subsequent follow up study within 18 months thereafter. US were evaluated for the presence of hydronephrosis (HN). UDS were risk stratified into the categories of safe, intermediate, or high risk [Figure 1]. Intervention such as anticholinergics and/or clean intermittent catheterization was determined at each time point.
RESULTS: 13 FMR and 15 POMR patients met inclusion criteria. Demographics of the two groups are depicted in Table 1. Unilateral HN was initially noted in only two patients, both in the POMR group, and both resolved on follow-up US. On initial UDS, the majority (73%) of the POMR patients were high risk with a third (36%) of those improving to lower risk categories without intervention. In comparison, only half (54%) of the FMR patients were high risk with 43% improving without intervention on subsequent evaluation. At follow up, 40% of the POMR group had high-risk bladders compared to 7.7% of the FMR cohort [Figure 2].
CONCLUSIONS: Although there is an inherent bias present given the small cohort size, fetoscopic myelomeningocele repair not only demonstrates fewer initial high-risk bladder categorization (54% versus 73%), but also a much lower proportion with high-risk bladders on follow up UDS (7.7% versus 40%). Additionally, FMR had a higher likelihood of improvement in risk categorization without intervention (43% versus 36%). A multi-institutional, prospective study focusing on the urologic outcomes of fetoscopic repair is warranted based on these promising findings. 
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