Spina Bifida Diagnosis
Most cases of spina bifida are diagnosed before birth. Tests that are used in making a diagnosis include second-trimester maternal serum alpha-fetoprotein screening, fetal ultrasound, multiple-marker screens, and amniocentesis. Mild cases, however, may not be detected until after the baby is born.
In most cases, a diagnosis of spina bifida is made before birth. However, mild cases may go unnoticed until after birth. Very mild cases, in which there are no symptoms of spina bifida, may never be detected.
Tests that are used to make a spina bifida diagnosis include:
- Second-trimester maternal serum alpha-fetoprotein screening
- Fetal ultrasound
- Multiple-marker screens
Maternal Serum Alpha-Fetoprotein Screening
The maternal serum alpha-fetoprotein screening measures the level of a protein called alpha-fetoprotein (AFP), which is made naturally by the fetus and placenta. During pregnancy, a small amount of AFP normally crosses the placenta and enters the mother's bloodstream. However, if abnormally high levels of this protein appear in the mother's bloodstream, it may indicate that the fetus has a neural tube defect. The AFP test is not specific for spina bifida, and the test cannot definitively determine that there is a problem with the fetus. If a high level of AFP is detected, the doctor may request additional testing, such as an ultrasound or amniocentesis, to help determine the cause.
The second-trimester maternal serum alpha-fetoprotein screening may be performed alone or as part of a larger, multiple-marker screen. Multiple-marker screens look for neural tube defects as well as other birth defects, including Down syndrome and other chromosomal abnormalities.