Spina bifida is a congenital defect of the spine. It causes part of the spinal cord and its meninges to be exposed through a gap in the backbone. The end result is often a paralysis below the waist. Developmental disabilities are also fairly common when this health condition is diagnosed. Because it is considered to be a birth defect, the spina bifida blood test is usually part of a mother-to-be’s prenatal screening.
Even if all of the screening tests come back negative, there is still a small chance that the birth defect may be present.
The primary screening test to detect spina bifida is called the maternal serum alpha-fetoprotein test, or MSAFP for short. It is usually requested during the second trimester of the pregnancy.
My OB/GYN Recommended a “Quad Screen.” What Does that Mean?
Many doctors will perform multiple prenatal tests at once to determine the status of the developing fetus. In addition to the MSAFP test for spina bifida, there may be inhibin A testing, estriol testing, and HCG testing. Because there are four tests involved, many medical providers refer to this series of tests as a “quad screen.”
These tests help to determine if there are any genetic concerns with the developing fetus in addition to the risks of certain birth defects.
What Do My Test Results Mean?
According to the CDC, about 1,500 babies are born every year in the United States with spina bifida. Hispanic women have the highest rates of having a child with this condition.
The spina bifida blood test will measure the amount of alpha-fetoprotein [AFP] that is in the mother’s blood. Having a little AFP present is normal as it tends to cross the placenta and into the mother’s bloodstream. It is only when AFP levels are extremely high will a medical provider begin to suspect that spina bifida may be a possibility.
The normal range for the MSAFP test is generally between 0.5-2.0 MoM. When a cut-off result of 2.5 MoM is given, this blood test will detect 3 out of every 4 open spina bifida cases. About 2.5% of pregnancies in the United States will have test results at the 2.5 MoM cut-off range.
If the spina bifida blood test results are high, then a medical provider may recommend amniocentesis as a follow-up procedure. This test requires a needle to remove a sample of the fluid that is in the amniotic sac that surrounds the baby. If AFP is present in this test at an elevated rate as well, then spina bifida is likely because the AFP has leaked into the amniotic sac from the skin that surrounds the spine.
What Does It Mean if My Doctor Ordered an Ultrasound?
Because there are mothers who have had babies with spina bifida despite having normal test results, it is not uncommon for a medical provider to recommend an ultrasound in the second trimester. These high-frequency waves can establish a picture of the developing fetus to determine if spina bifida is occurring and at what severity.
Some medical providers may even order the ultrasound in lieu of the actual spina bifida blood test.
What Can Be Done to Prevent Spina Bifida?
Although spina bifida may occur in women who are healthy and have AFP levels that are normal, since 1992 the US Public Health Service has recommended that all women who are trying to become pregnant or are of a child-bearing age should consume 400mcg of folic acid every day. Since 1998, all enriched food products contain folic acid as an effort to reduce the instances of this birth defect.
Since this mandate has gone into effective, there has been a 35% reduction in spina bifida cases when mothers and their doctors are actively looking for this condition. This means that up to 1,300 fewer babies in the US each year have this condition then there would have been if the fortification recommendations had not been made.
What’s Next After a Diagnosis?
Many types of spina bifida require no treatment at all. This is especially true for spina bifida occulta.
Some babies may require a surgery that places their meninges back into position and then closes the opening in the vertebrae. This surgery usually takes place 1-2 days after birth. Early surgery reduces the risk of infection and could protect the spinal cord from future trauma.
Recent surgical innovations also allow for prenatal surgery.
Spina bifida is an ongoing condition which may require a lifetime of treatment. That is why the spina bifida blood test is such an important part of prenatal care. Talk to your doctor about it so that you can plan for your future and the future of your child.