Surgical Decisions: Prenatal and Postnatal Repair

If your child is diagnosed with myelomeningocele (the open form of spina bifida), one of the most significant decisions you will face is when to have the defect repaired. Historically, all repairs were done after the baby was born. However, a landmark clinical trial known as the MOMS trial (Management of Myelomeningocele Study) changed the standard of care by showing that operating while the baby is still in the womb can improve certain outcomes ^[1][2].

Comparing Prenatal and Postnatal Repair

Both surgical options aim to close the opening in the spine and protect the spinal cord from further damage.

Prenatal (In-Utero) Surgery

This surgery is performed between 19 and 26 weeks of pregnancy ^[1]. The goal is to protect the exposed spinal cord from amniotic fluid and stop the “leakage” of spinal fluid that can pull the brain downward ^[2].

• Benefits: The MOMS trial found that children who had prenatal surgery were half as likely to need a shunt (a tube to drain fluid from the brain) by age one ^[1]. They were also more likely to walk without crutches or braces and had better motor function scores at 30 months old ^[3][4].
• Risks: This is a major surgery for the mother and the fetus. The biggest risk is preterm birth; babies who have prenatal surgery are typically born earlier (average 34 weeks) than those who have postnatal surgery (average 37 weeks) ^[2][5].

Postnatal (After Birth) Surgery

If prenatal surgery is not chosen or is not an option, the baby is often delivered via a planned Cesarean section to protect the spinal sac, though some centers may support a vaginal delivery depending on the size of the lesion and obstetric factors ^[1]. The repair is then performed by a neurosurgeon within 24 to 48 hours after birth ^[1].

• Benefits: This approach avoids the significant maternal surgical risks and the high chance of a very premature birth ^[2].
• Risks: The spinal cord remains exposed to amniotic fluid throughout the rest of the pregnancy, and the risk of needing a shunt for hydrocephalus is higher ^[1][2].

Maternal Risks and Future Pregnancies

It is vital to consider the health of the mother, as prenatal surgery carries lifelong implications.

• Uterine Dehiscence: This is a thinning or partial tearing of the uterine scar where the surgery was performed ^[6]. Because of this risk, any woman who has had “open” fetal surgery must deliver all future children via Cesarean section before labor starts to prevent a full uterine rupture ^[6][7].
• Other Risks: Mothers may face risks like placental abruption (the placenta detaching from the womb), blood loss, or complications from anesthesia ^[6][8].

Am I a Candidate for Fetal Surgery?

Fetal surgery is not an option for every pregnancy. To be eligible based on the MOMS trial criteria, certain conditions must be met:

• Timing: The surgery must occur between 19 and 25 weeks and 6 days of gestation ^[1].
• Lesion Level: The defect must be located between the T1 and S1 vertebrae ^[1].
• Brain Findings: There must be evidence of a Chiari II malformation (hindbrain herniation) ^[1].
• Maternal Health: The mother must have a healthy BMI (typically under 35), no other major health issues, and no history of certain uterine surgeries ^[9][10].
• Fetal Health: The baby must not have other major birth defects or chromosomal abnormalities ^[10][1].

Newer Approaches: Fetoscopic Repair

Some centers now offer fetoscopic repair, a minimally invasive technique using small incisions and a camera ^[11]. This is designed to reduce the risk to the mother’s uterus and potentially allow for a vaginal delivery in the current or future pregnancies ^[12][13]. While promising, doctors are still studying how the long-term neurological outcomes for the baby compare to the traditional “open” surgery ^[14][15].