Diagnostic tests can be performed during pregnancy to test whether a fetus has spina bifida. The tests include the following:
- Blood tests
The American College of Obstetrics and Gynecology (ACOG) recommends that a blood test be offered between 15 to 20 weeks to all women who are pregnant who have not previously had a child with an open neural tube defect (ONTD) and who do not have a family history of ONTD. This blood test measures alpha-fetoprotein (AFP) levels and other biochemical markers in the mother’s blood to determine whether her pregnancy is at increased risk for an ONTD. AFP is a protein normally produced by the fetus that crosses the placenta into the mother’s blood. Generally, if a fetus has an ONTD, the alpha-fetoprotein level in the mother’s blood will be increased. Although this test does not tell for certain whether a fetus has an ONTD, it will determine which pregnancies are at greater risk, so that additional testing may be performed.
- Prenatal ultrasound
Ultrasound is a diagnostic imaging technique that uses high-frequency sound waves and a computer to create images of blood vessels, tissues and organs. Ultrasounds are used to view internal organs as they function and to assess blood flow through various vessels. Prenatal ultrasound may be able to detect an ONTD and to examine other organs and body systems of the fetus.
This procedure involves inserting a long, thin needle through the mother’s abdomen into the amniotic sac to withdraw a small sample of the amniotic fluid for examination. The fluid is then tested to determine the presence of alpha-fetoprotein, which occurs with an open neural tube defect. Small or closed defects may not be picked up by this test.
After birth, the signs and symptoms of spina bifida vary widely, depending on the form of the condition and its severity in the individual child. For example, at birth:
- Babies with spina bifida occulta may have no obvious signs or symptoms—just a small, hairy patch, dimple or birthmark.
- Babies with meningocele have a sac-like protrusion that is found along the back bone area.
- Babies with myelomeningocele have an exposure of the nerves and spinal cord.
In severe spina bifida, symptoms related to nerve damage in the lower spine include: