Prenatal Screening for Down Syndrome
A simple screening for Down syndrome examines a drop of the mother's blood to determine if markers for the condition are present. If the results suggest an increased likelihood of the disorder, the doctor may recommend certain diagnostic tests. These tests help the doctor determine whether or not the fetus has the condition based on the screening for Down syndrome.
Prenatal screening for Down syndrome is available. There is a relatively simple, noninvasive screening test that examines a drop of the mother's blood to determine if there is an increased likelihood for Down syndrome. This blood test goes by several names, including:
- Multiple marker screening test
- Maternal blood screening test
- Triple screen
- Quad screen.
The blood test measures markers for Down syndrome, including:
- Maternal serum alpha-fetoprotein (MSAFP)
- Chorionic gonadotropin (hCG)
- Unconjugated estriol (uE3).
While these measurements are not a definitive test for Down syndrome, a lower MSAFP value, a lower uE3 level, and an elevated hCG level, on average, suggest an increased likelihood of a Down syndrome baby.
If the prenatal screening blood test suggests an increased likelihood of Down syndrome, the doctor may recommend certain tests to see whether or not the fetus has the condition. These are called diagnostic tests.
(Click Down Syndrome Diagnosis for more information on these diagnostic tests used during pregnancy.)