Anencephaly

Anencephaly is a severe birth defect in which a large portion of a baby’s brain, skull and scalp are missing.

The brain tissue the baby does have is often exposed, with no skin or bone protecting it.

Anencephaly is a type of neural tube defect (NTD), birth defects of the central nervous system (CNS). Neural tube defects occur in the first few weeks of fetal development when a structure known as the neural tube, which develops into the baby’s brain, skull, spine and spinal cord, does not close completely.

In a fetus with anencephaly, the upper end of the neural tube fails to close, leaving the developing brain and spinal cord exposed to the amniotic fluid. This exposure causes degeneration of the developing tissue, resulting in minimal brain development and missing bones around the baby’s head.

How does anencephaly affect my baby?

Babies with anencephaly are missing large parts of the cerebrum and cerebellum, regions of the brain required for thinking, seeing, hearing, touch, and movement.

The defect is so severe, these babies are unable to survive. The majority of pregnancies end in miscarriage or stillbirth.

Babies that do survive until birth typically live only a few hours or days.

Cause and Risk Factors

Anencephaly occurs in roughly 1 out of every 10,000 births in the United States.

The condition affects an estimated 1 in every 1,000 pregnancies in the U.S., but in most cases the pregnancy ends in miscarriage.

The exact cause of neural tube defects remains unknown. Suspected risk factors include:

• Genetics
• Insufficient folic acid before and during pregnancy
• Environmental factors
• Previous child born with anencephaly
• Certain medications taken during pregnancy

Diagnosis

Anencephaly is usually detected during pregnancy through a routine ultrasound or blood test.

A blood test known as a maternal serum alpha-fetoprotein (MSAFP) screening may detect high levels of alpha-fetoprotein in the mother’s blood, which can indicate the developing baby has a neural tube defect.

In some cases, the diagnosis is made at birth based on the presence of skull and brain abnormalities.

Specialized Evaluation and Additional Testing

If anencephaly is diagnosed during pregnancy, you may be referred to a fetal center for a comprehensive evaluation. At Texas Children’s Fetal Center, we arrange for a detailed assessment by a team of specialists experienced in diagnosing these rare neural tube defects, including maternal-fetal medicine (MFM) physicians, fetal imaging experts, genetic counselors, neonatologists, and pediatric neurologists.

Additional testing may include:

• High-resolution anatomy ultrasound to confirm the diagnosis, evaluate the defect and identify any other abnormalities
• Ultra-fast MRI for a more detailed view of the fetal brain and related structures
• Amniocentesis and chromosomal analysis to measure alpha-fetoprotein and acetylcholinesterase levels in the amniotic fluid, indicators of neural tube defects, and identify chromosomal anomalies

Following this thorough evaluation, our specialists will meet with you about your results, answer any questions your family has.

Delivery and Treatment

There is no treatment for anencephaly. Babies that survive until birth rarely live longer than a few hours or days.

Why Texas Children’s Fetal Center?

• A single location for expert maternal, fetal and pediatric care, including immediate access to Texas Children’s level IV NICU.
• A compassionate, experienced team of specialists dedicated to caring for pregnancies involving these rare neural tube defects
• Patient support services, including genetic counseling for future pregnancies, women’s mental health services for reproductive loss and grief, and referrals to local and national support groups as well as other families who have had similar experiences