A quad screen checks for the following components in your blood:
Alpha-fetoprotein (AFP): AFP is a protein that is produced in a developing fetus. Higher levels of this protein can indicate neural tube defects or seen in twin pregnancy and lower than normal levels can indicate a high risk of having Down syndrome in the baby.
Unconjugated estriol (UE): The Fetus and placenta produce this hormone. The lower levels might mean a high risk for having a baby with Down syndrome.
Human chorionic gonadotropin (hCG): The placenta makes a hormone called hCG. Levels that are higher than expected could mean an increased risk of a baby having Down syndrome.
Inhibin-A: The placenta and ovaries produce this protein. A higher level of this means having a baby with Down syndrome.