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Myelomeningocele (MMC)

Myelomeningocele (MMC) Care at Cincinnati Children’s

Our Fetal Care Center specialists treat many fetal conditions once considered life-threatening or only treatable after birth. While many conditions can be managed through noninvasive therapies, some fetal conditions require surgery.

The Fetal Care Center is one of only a few fetal surgery centers in the U.S. with the expertise to perform the full range of fetal surgical interventions, including fetoscopic surgery.

Why Choose Us

Top-Ranked Center: Our neonatology program is ranked in the top 10 in the nation by U.S. News & World Report.

Deep Expertise and Experience: Our team specializes in treating complex and rare fetal conditions and is at the forefront of the innovation in fetal diagnosis and intervention therapies. We are one of the highest-volume centers in the nation for Myelomeningocele (MMC) with more than 500 evaluations and 140 prenatal repairs for MMC.

One-on-One Support: Through our family-centered approach to care, our nurse coordinators create a personalized program to support you and your baby at every turn. Throughout your time with us, you will be followed by a nurse coordinator who specializes in fetal care. Your nurse coordinator will be available to answer questions, as well as provide education and support for you and your family.

What Is Myelomeningocele?

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 (MMC), the most severe form of spina bifida.

What Causes Myelomeningocele?

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.

How Is Myelomeningocele Diagnosed?

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.

Complications of Myelomeningocele

The most serious complications of MMC include:

  • Chiari malformation—This is a structural defect in the back of the skull. It allows the back of the brain to settle into the upper portion of the neck. Severe Chiari malformation can cause the baby to have breathing and swallowing problems after birth.
  • Hydrocephalus—Our brains have fluid spaces called ventricles. Spina bifida can cause a backup of fluid into these spaces. This condition is called hydrocephalus. It can require more surgeries after birth to drain the fluid.
  • Damage to the nerves of the spinal cord—The nerve injury is permanent and irreversible. It can also get worse as the pregnancy progresses.
  • Tethered cord—This is scarring of the spinal cord.

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:

  • Bladder and bowel problems
  • Cognitive / learning problems
  • Difficulty breathing and swallowing
  • Hydrocephalus (buildup of fluid in the brain)
  • Inability to walk without help
  • Orthopaedic issues, such as club feet
  • Sexual dysfunction
  • Weakness and loss of feeling below the defect

How is Myelomeningocele Treated?

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.

Fetal Myelomeningocele Repair

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:

  • Makes an incision across the mother’s abdomen and exposes the uterus.
  • Makes an incision through the uterus into the sac around the baby.
  • Releases the attachment of the exposed spinal cord.
  • Removes the MMC sac if one is present.
  • Repairs the spinal defect.
  • Covers the spinal cord with a waterproof, protective patch. This protects the spinal cord from exposure to amniotic fluid.

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.

What Are the Potential Benefits of Fetal Myelomeningocele Repair?

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:

  • Cut the risk of hydrocephalus in half
  • Increased a child’s chances of walking on their own
  • Reversed hindbrain herniation in nine out of 10 patients

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:

  • Premature birth (birth earlier than 37 weeks gestation)
  • Problems with future pregnancies (more so for patients who undergo the open fetal surgery approach)
  • Damage due to the uterus rupturing

Fetoscopic Myelomeningocele Repair: A Less Invasive Option

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.

Who Is Eligible for Fetoscopic Myelomeningocele Repair?

Patients may be eligible for open or fetoscopic MMC repair during pregnancy if they meet the following criteria.

  • Mother is 18 years or older
  • Gestational age of between 19 and 25 weeks, six days at the time of surgery
  • Normal fetal echocardiogram and amniocentesis
  • Singleton pregnancy (one baby)

Patients are not good candidates if the:

  • Baby is having significant medical problems not related to spina bifida.
  • Mother has medical issues that prevent abdominal surgery or general anesthesia.

What Is the Outlook for Children with Myelomeningocele?

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:

  • Receive prenatal surgery
  • Are delivered close to their due date

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.

Spina Bifida Annual Outcomes at Cincinnati Children’s

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 three hospitals nationally.

Highlights* include:

  • Total number of evaluations for spina bifida: 433
  • Prenatal MMC repairs: 121
  • Fetoscopic prenatal MMC repairs (2016+): 62
  • Fetoscopic prenatal MMC repairs delivered vaginally (2016+): 40%

* Data is based on patients cared for by the Cincinnati Children’s Fetal Care Center from Feb. 1, 2004, through April 20, 2022.

Last Updated 07/2023

Reviewed By Erinn Goetz, BSN, RNIII, RNC-OB

For More Information

For more information or to request an appointment, contact the Cincinnati Children's Fetal Care Center at 1-888-338-2559 or use our online form.

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