Myelomeningocele (pronounced “my-ello-meningo-seel”), or MMC, is the most severe form of spina bifida. MMC occurs when the protective tube (neural tube) around the spinal cord does not close all the way. The bones and tissue do not form normally. Part of the spinal cord and surrounding nerves stick out through an opening in the skin, exposing them to amniotic fluid.
Myelomeningocele occurs in about one in every 2,500 live births in the U.S. The exact cause is unknown. Some research suggests that genes, certain medicines and nutrition may play a role. A baby may be at higher risk if the mother has diabetes while pregnant.
Myelomeningocele is typically found during a routine prenatal ultrasound between 18 and 22 weeks of pregnancy. A blood test can find the condition as early as 16 weeks. This test screens for maternal alpha-fetoprotein (AFP). AFP in the mother’s blood can show if the baby may have problems.
If doctors are concerned about what they see on the ultrasound or if AFP levels are high, the mother can have more testing to confirm the diagnosis. If the mother decides to have fetal surgery, the doctors will need to perform an “amniocentesis.”
An amniocentesis allows the doctor to take a fluid sample from the sac that surrounds the baby. They can test this fluid for certain “markers” such as AFP. This tells the doctors if spina bifida is present. It can also help determine which kind of defect it is.
The most serious complications of MMC include:
In general, the higher the defect is on the spine, the more severe the problems may be. Depending on where the defect is on the spinal cord, the baby may have the following problems after birth:
Until about 25 years ago, there was no way to treat MMC before a baby was born. The only option was to perform surgery after the birth to close the opening in the spine.
In 2011, doctors began offering a new and exciting alternative: fetal repair surgery. This surgery can significantly lessen spina bifida’s long-term effects.
Fetal repair surgery occurs between 19 and 26 weeks of pregnancy. During surgery, the team:
After the procedure, the surgeon closes the mother’s uterus and abdomen. The mother recovers in the hospital for four to five days. Weekly follow-up appointments and ultrasound tests take place to monitor the mother’s and baby’s conditions.
In 2011, a landmark research study called the “Management of Myelomeningocele Study (MOMS)” showed that babies who received open fetal repair surgery benefited significantly.
Fetal repair surgery is not a cure. But results from MOMS showed that, compared to surgery after the baby’s birth, fetal repair:
A follow-up study in 2020 showed significant physical and emotional benefits in school-age children who received fetal MMC repair surgery.
MOMS also found that fetal MMC repair comes with risks, including the risk of:
With these risks in mind, fetal surgeons began to consider alternatives to the “open” approach. A few hospitals, including Cincinnati Children’s, now provide a less invasive in-utero surgery called fetoscopic MMC repair. Cincinnati Children’s began offering this option in 2016.
Fetoscopic repair involves making tiny incisions in the mother’s uterus and inserting three small tubes. The surgical team puts a camera and surgical tools through these tubes to correct the defect.
Fetoscopic MMC repair surgery gives children the same benefits as “open” repair. It has fewer risks and complications for their mothers. In addition, it gives the mother the possibility to have a vaginal delivery with this child and with future pregnancies. Women who have open fetal repair require a cesarean section for delivering all their babies.
Fetal surgeons continue to develop new techniques and technologies to make the surgery even more safe and effective.
Patients may be eligible for open or fetoscopic MMC repair during pregnancy if they meet the following criteria.
Patients are not good candidates if the:
How well a child with MMC does depends on many factors. Some children will require minimal ongoing care. Others will require medical and educational support for many years. Outcomes are usually better for babies who:
Children who receive high-quality care from a team of specialists tend to have a better quality of life. They also reach a higher level of independence than those who don’t. All babies who have fetal surgery at Cincinnati Children’s get rigorous follow-up at our Center for Spina Bifida Care.
It’s essential to seek treatment from specialists who are familiar with myelomeningocele. The Fetal Care Center team at Cincinnati Children’s regularly cares for babies with this condition. Cincinnati Children’s does more fetal MMC repair surgeries each year than most other hospitals in the US. In fact, we’re one of the top five hospitals nationally.
Highlights* include:
* Data is based on patients cared for by the Cincinnati Children’s Fetal Care Center from Feb. 1, 2004, through June 30, 2024.
We treat patients with even the most complex fetal anomalies. Our multidisciplinary team collaborates to offer the most sophisticated, effective therapies to improve the health and quality of life for your baby.
Last Updated 07/2023
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