Fetoscopic insufflation modeled in the extrauterine environment for neonatal development (EXTEND): Fetoscopic...

Minimally invasive fetal surgery, or fetoscopy, is an alternative to open fetal surgery to repair common birth defects like myelomeningocele. Although this hysterotomy-sparing approach reduces maternal morbidity, the effects of in utero insufflation on the fetus are poorly understood. Our purpose was to determine the optimal fetal insufflation conditions.

Fetal sheep at gestational age 104 to 107 days were studied under insufflation conditions in utero and ex utero. The ex utero fetuses were cannulated via their umbilical vessels into a support device, the EXTra-uterine Environment for Neonatal Development (EXTEND). EXTEND fetuses were exposed to four different insufflation conditions for four hours: untreated carbon dioxide (CO₂) (n=5), warm humidified (whCO₂) (n=4), whCO₂ with the umbilical cord exposed (n=3), and whCO₂ without amniotic fluid (skin and cord exposed) (n=3).

In utero insufflation led to significant increases in fetal CO₂ and reductions in fetal pH. Ex utero insufflation with whCO₂ did not lead to changes in fetal blood gas measurements or cerebral perfusion parameters. Insufflation with whCO₂ with an exposed umbilical cord led to reduced umbilical blood flow.

Insufflation with warm humidified CO₂ with an amniotic fluid covered umbilical cord is well tolerated by the fetus without significant changes in hemodynamics or cerebral perfusion parameters.

Basic science LEVEL OF EVIDENCE: N/A.