Fetal myelomeningocele surgery: Only treating the tip of the iceberg

Abstract

Objective Fetal myelomeningocele (fMMC) surgery improves infant outcomes when compared with postnatal surgery. Surgical selection criteria and the option of pregnancy termination, however, limit the number of cases that are eligible for prenatal surgery. We aimed to quantify what proportion of cases could ultimately benefit from fetal therapy. Methods We retrospectively reviewed all cases of fMMC referred to a large tertiary care center over a 10‐year period and assessed their eligibility for fetal surgery, pregnancy termination rates, and actual uptake of the surgery. Results Of 158 cases, 67 (42%) were ineligible for fetal surgery based on surgical exclusion criteria. Eleven fetuses (7%) had chromosomal anomalies, 10 of which (91%) had other anomalies on ultrasound. Thirty‐four patients had a combination of maternal and fetal contraindications. Of the remaining 91 eligible cases (58%), 45 (49%) pregnancies were terminated, leaving only 46 (29% of initial 158 cases) as potential candidates for fetal repair. Actual uptake of fetal surgery was 15% (n = 14 of 91), but this increased after a national program was started. Conclusion Only a minority of fMMC cases will ultimately undergo fetal surgery. These numbers support the centralization of care in expert centers.

Update on prenatal diagnosis and fetal surgery for myelomeningocele

“…41,56 Recent series described that 40-60 % of cases with a prenatal diagnosis of spina bifida would be candidates for fetal surgery. 57,58…”

Fetal spina bifida: What we tell the parents

“…15 In less than 10% of cases, spina bifida is due to genetic syndromes or chromosomal anomalies, including the common trisomies 13 and 18, triploidy and microdeletions or duplications. [16][17][18] Most of these fetuses would present with anomalies in different organ systems 19 What's already known about this topic?…”

“…In less than 10% of cases, spina bifida is due to genetic syndromes or chromosomal anomalies, including the common trisomies 13 and 18, triploidy and microdeletions or duplications 16‐18 . Most of these fetuses would present with anomalies in different organ systems 19 in addition to the spina bifida. Variants in genes involved in folate metabolism (such as the MTHFR and DHFR genes) have also been identified as potentially causative 20 …”

Fetal surgical intervention for myelomeningocele: lessons learned, outcomes, and future implications

“…Based on the original MOMS criteria, fMMC surgery is reserved for healthy mothers and singleton fetuses without any non‐MMC‐associated structural or genetic anomalies. The MOMS trial excluded patients with a body mass index (BMI) greater than 35 owing to the potential for increased maternal complications, and therefore potential fetal candidates are rendered ineligible based on maternal obesity . Recently this somewhat arbitrarily chosen BMI has been questioned as too limiting for two main reasons .…”

“…The MOMS trial excluded patients with a body mass index (BMI) greater than 35 owing to the potential for increased maternal complications, and therefore potential fetal candidates are rendered ineligible based on maternal obesity. 78 Recently this somewhat arbitrarily chosen BMI has been questioned as too limiting for two main reasons. 79 First, between 2011 and 2015 the rate of pre-pregnancy obesity in the USA has increased from 8% to nearly 26% of all pregnancies.…”