Final answer:
The quad screen is a prenatal test offered between the 15th and 22nd weeks of pregnancy to assess the risk for certain fetal conditions. It measures four substances in the mother’s blood to indicate potential risks for conditions like Down syndrome and neural tube defects. The test does not diagnose these conditions but suggests whether further diagnostic testing is needed.
Step-by-step explanation:
The quad screen is typically offered between the 15th and 22nd weeks of pregnancy. This prenatal test consists of measuring levels of four substances in a pregnant woman’s blood:
- Alpha-fetoprotein (AFP), which is produced by the fetus.
- Human chorionic gonadotropin (hCG), a hormone produced within the placenta.
- Estriol, an estrogen produced by both the fetus and the placenta.
- Inhibin A, a hormone produced by the ovaries and the placenta.
The results of the quad screen are used to assess whether the fetus is at an increased risk for certain conditions, such as Down syndrome, neural tube defects, and other chromosomal abnormalities. It's important to note that the quad screen does not diagnose these conditions; it only indicates potential risk levels, so further diagnostic testing would be required if the quad screen results suggest increased risk.