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Prevalence of High-Risk Bladder Categorization with Prenatal and Postnatal Myelomeningocele Repair Types
Jonathan Gerber, MD, Alexandra N. Borden, PA-C, Duong D. Tu, MD, Paul F. Austin, MD.
Texas Children's Hospital, Houston, TX, USA.

BACKGROUND: The evolution of myelomeningocele (MMC) repair types has offered improvement in patient outcomes. Prenatal open repair (PROM) outcomes have been well-described in the MOMs trial with urological outcomes focused on urinary continence. Fetoscopic MMC repair (FMR) is gaining traction due to added benefits to the mother, but urological outcomes have yet to be analyzed. Rather than focus on achievement of continence, we believe attainment of safe bladder pressures to protect the kidneys is the ultimate goal. We hypothesize that prenatal MMC repairs (PROM and/or FMR) offer better bladder risk categorization compared to postnatal repairs (PSTNR) of MMC. Furthermore, we hypothesize that FMR is non-inferior to POMR in regard to urological outcomes.
METHODS: Using an IRB-approved database, we performed a retrospective analysis of all patients undergoing different MMC repair types (PROM, FMR, and PSTNR) at a single institution. Inclusion required initial urodynamic studies (UDS), renal bladder ultrasound (RBUS) and voiding cystourethrogram (VCUG) within the first year of life and follow-up studies within 18 months thereafter. Outcome variables assessed included bladder categorization (high-risk, intermediate and safe), hydronephrosis (HN) and vesicoureteral reflux (VUR). A single reader evaluated each UDS.
RESULTS: 93 patients met initial inclusion criteria. 69 patients met criteria for follow up. Initial distribution of bladder categorization approached significance (p=0.0618) and showed more prevalence of high-risk in the PROM group (60%) compared to the other MMC repairs (PSTNR 36%; FMR 33%). Follow-up UDS showed only 7.7% of FMR were high-risk compared to 35% PROM and 36% PSTNR. When evaluating high-risk versus safe and intermediate combined, no difference was noted. Distribution changes of bladder risk category with follow-up approached significance (p=0.0659) with 10% PSTNR worsened to high-risk on follow-up, compared to none in either prenatal group. Sub-analysis of follow-up UDS in the FMR and PROM cohorts showed near significant difference after initial category distribution (p=0.055). Only 7.7% of FMR worsened or stayed high-risk compared to 35% in the PROM group (p=0.1). VCUG showed initial VUR in 18% PSTNR, 5% PROM, and 14% FMR cohorts and 44.6%, 50%, and 13%, respectively, at follow-up. Significant differences are noted for the presence of HN at initial and follow-up RBUS across the groups (31% PSTNR, 10% PROM, 0% FMR, p=0.0015 and 24% PSTNR, 0% PROM, 0% FMR, p=0.005, respectively).
CONCLUSIONS: Although continence is an important urological outcome, bladder risk categorization should be the primary outcome when examining the urological benefits from MMC repairs types. Our results demonstrate similar prevalence of initial, high-risk bladders with traditional PSTNR. Additionally, there is an increased likelihood of worse bladder categorization over time in the PSTNR and POMR groups. Presence of VUR and HN similarly correlates with the high-risk bladder categorization. FMR was shown to be non-inferior, and trended towards significant improvement compared to PROM in regard to all evaluated metrics in this study. Larger, prospective studies on MMC repair types are required to confirm these promising findings after FMR.


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