Quad Screening For Birth Defects

Test Overview

The quad screening is a blood test that may be done at 15 to 22 weeks of pregnancy. It's used to look for possible problems with your baby. The quad screening measures the amounts of four things in a pregnant woman's blood. They are:

• Alpha-fetoprotein (AFP). AFP is made in the liver of an unborn baby (fetus).
• Human chorionic gonadotropin (hCG). This hormone is made by the placenta when a woman becomes pregnant.
• Estriol (uE3). This is a form of estrogen that increases during pregnancy. It's made in large amounts by the placenta.
• Hormone inhibin A. This hormone is produced by the baby and the placenta.

This test can't show for sure that your baby has a birth defect. You would need a diagnostic test called amniocentesis to find out for sure if there is a problem.