Nationwide survey of fetal myelomeningocele in Japan: Background for fetal surgery.

Background: Fetal surgery for myelomeningocele (MMC) has yet not been performed in Japan, and the clinical background of fetal MMC in Japan remains poorly described. We examined the prenatal characteristics and perinatal outcomes of fetal MMC to prepare for the introduction of fetal surgery.
Methods: A nationwide questionnaire survey was conducted with regard to fetuses with MMC between January 2012 and December 2014 at perinatal centers in Japan.
Results: In 50 tertiary centers, 188 cases of MMC were identified, of which 126 (67%) were isolated cases. Only half of the cases involved referral to tertiary centers with a diagnosis of MMC. The median time point for a prenatal diagnosis was 26 weeks' gestation (range, 12-38 weeks); in 54% of cases the diagnosis occurred after 26 gestational weeks, which is over the limit for fetal surgery for MMC. Furthermore, in 22% of cases the diagnosis was made before 22 gestational weeks, and in three-quarters of these cases termination of pregnancy was selected. No fetal or neonatal deaths were observed in the isolated MMC group. MMC repair, ventriculoperitoneal shunt and clean intermittent catheterization were required after birth in 100%, 73% and 55% of isolated MMC cases, respectively. In total, 96% of the tertiary centers cared for <5 cases of fetal MMC per year.
Conclusions: Gestational age at MMC diagnosis was late mid-gestation, therefore earlier detection is essential when considering fetal treatment of MMC in Japan. Although the survival rate was excellent, in three-quarters of isolated MMC cases ventriculoperitoneal shunt was required. Early detection and centralization of MMC cases at specialized centers should be considered.
(© 2019 Japan Pediatric Society.)