Neural Tube Defect
Screening
Why should I consider being
tested for spina bifida?
Measuring alpha-fetoprotein (AFP) level by a blood
test checks for a birth defect known as spina
bifida (open spine deformity). One out of
every 1,000 babies in the United States is born
with this defect. About 80 percent of the time
when a woman is carrying a child with spina bifida,
her blood test will show a higher than normal
AFP level.
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Should I have this test
if there has never been anyone in our families
with spina bifida?
In 90 to 95 percent of the cases in which a child
is born with spina bifida, there has never been
anyone else in the family with this problem. We
are not able to predict which pregnant women,
who do not have a relative with spina bifida,
may give birth to a child with this defect.
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What if my partner or I
have a relative with spina bifida?
A family history of spina bifida or other spinal
cord problems may indicate a higher than expected
risk. Our genetic counselors can help determine
what your risk is and what type of test would
be best for your situation.
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If my blood test shows a
high level of AFP, does that mean that my child
will have spina bifida?
No, not necessarily. There are many other reasons
why the AFP level may be higher than normal in
a woman's blood. In fact, most women with a higher
than expected level of AFP will have normal babies.
Sometimes the AFP blood test may be repeated and
this result may show a normal level. An ultrasound
often explains why the AFP level is high. For
example, the pregnancy may be further along than
realized, or the woman may be carrying twins.
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What if my blood test
shows a high level of AFP and the ultrasound does
not show a reason for this: does this mean spina
bifida?
No, not necessarily. Once again, most women in
this situation have normal pregnancies. However,
an amniocentesis may be suggested, since this
is a very accurate way to determine if the fetus
has spina bifida. Amniocentesis is a test done
by taking a small amount of amniotic fluid (water
around the fetus) and measuring the AFP in the
fluid. Alternatively, patients with elevated blood
AFP levels that are unexplained have an increased
risk for complications later in pregnancy and
are watched more carefully by their doctors in
the third trimester.
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What if you find that
my baby has spina bifida or some other birth defect?
In cases such as this, our genetics staff will
help explain the results of the test as well as
discuss all possible options with you, including
delivery and raising a child with special needs.
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What if my blood test is
normal? Does that mean that the baby will be normal?
No, not necessarily. Most birth defects do not
cause a high AFP level. Even some women who are
carrying a child with spina bifida have a normal
level of AFP. However, a normal result implies
that you are not at an increased risk for an open
spine deformity and a variety of other fetal problems.
Penn Ob/Gyn Care physicians and counselors provide
prenatal diagnosis, consultation and care at various
locations throughout the Philadelphia region.
Please call PennHealth at 1-800-789-PENN (7336)
for more information.
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