Prenatal Testing Basics: AFP and Multiple Marker Screening
What it is, who has it, when, why, and what it tells you.
When and why is the test taken?
The maternal serum alpha-fetoprotein (MSAFP, or, more commonly, AFP) test and the multiple marker screening test (sometimes called the "triple screen" or "triple test") are two different but similar tests offered to pregnant women, usually between weeks 16 and 18.
Who needs to take the test, and why?
Both the AFP and the multiple marker tests are used to determine a baby's chances of having neural tube defects and chromosomal abnormalities such as Down syndrome. The multiple marker test offers more comprehensive results and is often favored by practitioners. But neither AFP nor multiple marker screening is conclusive: they can simply tell you if your baby has a higher risk of abnormalities, and they may indicate a need for further testing. If you are over 35, your healthcare provider may suggest that you proceed directly to amniocentesis or CVS, which are more accurate in pinpointing the risk of fetal abnormalities.
Not all women opt to take these tests. If you're certain you would never terminate a pregnancy for any reason, or wouldn't want to know in advance that your baby might have special needs, you should discuss your feelings with your healthcare provider. He or she can help you decide if taking the test would be worthwhile.
Both tests require a blood sample, which means a quick needle stick, usually in your arm. Your blood is then analyzed to determine its level of alpha fetoprotein (a protein produced naturally by the fetus). The multiple marker test analyzes your levels of AFP and two hormones, human chorionic gonadotropin (hCG) and estriol, which are then interpreted on the basis of your age, weight, race, and other factors, to see if they fall within a "normal" range.
When are test results available, and how are they interpreted?
Both the AFP test and the multiple marker test are useful screening tools and are less invasive than the more accurate tests. If your test yields "abnormal" results, it certainly doesn't mean that your child will be born with birth defects. About 3 to 5 percent of women who have the multiple marker test will have an abnormal reading, but only about 10 percent of those women will have a child with a genetic problem. If your results are not reassuring, your practitioner will probably suggest an amniocentesis and an ultrasound to follow up.
All content here, including advice from doctors and other health professionals, should be considered as opinion only. Always seek the direct advice of your own doctor in connection with any questions or issues you may have regarding your own health or the health of others.