Maternal Serum Screening/Alpha-fetoprotein Test
Along with numerous other tests you will be offered as part of your prenatal care, your health care provider will likely ask you if you would like a maternal serum screening test or an alpha-fetoprotein (AFP) test. Like chorionic villous sampling and amniocentesis, maternal serum screening and AFP can offer you valuable information about your developing baby. However, it is up to you whether or not you want to have these tests done.
A protein produced by your baby’s liver, alpha-fetoprotein can be found in your blood. This simple blood test is used as a screening tool to check for neural tube defects, including spina bifida and ancephaly. However, this test can also alert you and your health care provider to the possibility of your baby having Down Syndrome or Turner Syndrome, placental problems, and kidney or urinary tract abnormalities among other issues. This test is optional and is very safe to perform without increased risk to you or your baby. It can be done between the 15th and 17th week of pregnancy.
What is Maternal Serum Screening?
Maternal serum screening is an optional blood test done on pregnant women to check for certain neural tube defects, such as spina bifida, or birth defects, like Down syndrome. Maternal serum screening is also known as a multiple marker screening test or triple screen because it measures levels of several substances in the blood. The test is usually conducted between 15 and 18 weeks into pregnancy.
What does the Test Assess?
In addition to measuring your levels of AFP, maternal serum screening also measures the hormones estriol and human chorionic gonadotropin (hCG), which are also produced by your baby and enter into your bloodstream. When AFP, estriol and hCG are measured together, the test is known as a triple screen. Because more hormones are measured, maternal serum screening is thought to be more accurate than measuring just the alpha-fetoprotein level. For this reason, it is used more often than the AFP test.
A quad screen is identical to the triple screen except that this test also measures the levels of inhibin-A in your system The quadruple test is used to give a more accurate assessment of your baby’s risk of having Down Syndrome. The test has about an 80% accuracy rate in indicating a baby’s risk of Down Syndrome. Amniocentesis can be used to confirm the diagnosis.