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Triple screen is a screening
test performed in the second trimester of pregnancy that helps
determine the mother’s risk of carrying a baby with open neural
tube defects, Down syndrome or trisomy 18. Triple screen is a blood test
done between
15 to 20 weeks of pregnancy.
From mother’s blood, triple screen measures the levels of three
chemicals that are naturally produced during pregnancy. The three
chemicals measured in the triple screen are alpha-fetoprotein (AFP),
human chorionic
gonadotropin (HCG) and unconjugated estriol (UE3). Triple screen
looks for certain patterns of these chemical levels that are associated
with
risks of open neural tube defects, Down syndrome or trisomy 18.
The
three chemical measurements and several other factors are entered
into the
computer program and the risks are calculated. The results are
available in 3 to 5 days. Triple screen has no risk to the baby
or the pregnancy.
Triple screen detects 80% of babies with open neural tube defects and
60% to 80% of babies with Down syndrome or trisomy 18.
If the test results indicate that your pregnancy is at increased risk
for open neural tube defects, Down syndrome, or trisomy 18, your doctor
will discuss with you further testing options such as level II ultrasound
and amniocentesis.
It is important to keep in mind that women who had UltraScreen™ done
in the first trimester may have a maternal serum alpha-fetoprotein (AFP)
test in the second trimester, but not a triple screen.
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