Anesthetic management and obstetric outcome for open fetal myelomeningocele repair at a Japanese center: a retrospective cohort study.

BACKGROUND

Open fetal surgery for myelomeningocele (MMC) is an established treatment internationally, but remains new and rarely performed in Asia. This study aimed to describe our anesthetic management and obstetric outcomes of this procedure in Japanese patients, with a particular focus on preterm birth (PTB).

METHODS

We retrospectively reviewed 10 cases of open fetal MMC repair at our institution between April 2021 and April 2025. Anesthetic management, intraoperative uterine relaxation, maternal hemodynamic control, and perinatal outcome were descriptively analyzed.

RESULTS

PTB occurred in 5 cases (50%): 4 due to preterm labor and 1 due to preterm premature rupture of membranes. One case was delivered before 30 weeks, none between 30 and 34 weeks, and 4 between 34 and 37 weeks. Uterine relaxation was achieved using desflurane at a mean of 2.3 minimum alveolar concentration (MAC). Hypotension was managed with norepinephrine equivalent (NEE) scale (median maximum dose 0.13 µg/kg/min). Magnesium sulfate was reduced from 6 g to 4 g in the latter half of cases after high serum levels (up to 9.1 mg/dL) were observed. The PTB rate decreased from 60% in the first five cases to 40% in the latter five.

CONCLUSIONS

Open fetal MMC repair was feasible in this population under a standardized anesthetic approach, with acceptable maternal and obstetric outcomes. Individualized drug dosing and objective assessment of uterine relaxation may further improve safety. Our findings may serve as a reference for institutions introducing fetal surgery in Japan; however, they should be interpreted with caution due to the small sample size.