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Usually done between weeks 15 and 20 of your pregnancy, the quadruple serum screening test — often referred to as the quad screen — can help determine if your baby is at higher risk for certain birth defects.
The quad screen can evaluate the chances that your baby might be carrying certain chromosomal disorders like Down syndrome or Edwards syndrome, neural tube defects like Spina bifida, or abdominal wall defects.
Performing a quad serum test
The quad screen is a simple blood test. Your clinician will take a small sample of blood and have it examined for four substances:
- Alpha-fetoprotein (AFP), a protein made in the baby’s liver.
- Human chorionic gonadotropin (hCG), a hormone made in the placenta.
- Unconjugated estriol (uE3), a hormone made in the placenta and the baby’s liver.
- Inhibin A, a hormone made in the placenta.
Keep in mind that a positive test result doesn’t automatically mean your baby has a birth defect. It does mean, however, that there’s a higher chance. If you have a positive result, your clinician will offer other diagnostic tests.
If your results are negative, it means your baby has less of a chance of developing these birth defects.
Further diagnostic testing
A diagnostic test that is common after a positive quad screen is called an amniocentesis. An amniocentesis involves using a small, thin needle with ultrasound guidance to take a small amount of the amniotic fluid that surrounds your baby in the uterus. The fluid is tested for chromosomal defects, like Down Syndrome, and neural tube defects like spina bifida, and is 99% accurate.
For most people, this diagnostic test is very safe. Your clinician can help you learn more if you have any concerns.