Triple check, quad screen, and alpha-feto protein (AFP) are all names used for a blood test offered to the mother around 16 weeks. Results can indicate an increased chance of certain types of fetal conditions, including Down Syndrome and spina bifida (a spine problem that can cause paralysis), or the likelihood of late pregnancy complications. Test results for normal and problem pregnancies overlap, so the results don't tell us for sure that a baby has a particular problem. These markers are just indicators of risk. From the doctor's perspective, the purpose of these tests is to sort patients into two groups: those who require more testing and those who don't. This can be hard to understand-you probably have heard from friends that their test results were "false positives" and that after they went through further testing (and lots of anxiety) the baby was actually fine. This happens frequently. Most mothers with abnormal test results are carrying normal healthy babies.

So why would anyone do this test? If you want to know if there is a problem, a quad screen is often the first step. Depending on the results of the test, further evaluation, with repeat blood testing, amniocentesis or detailed anatomical ultrasound can help identify if the fetus has a particular condition.

Abnormal values of the quad screen can indicate a twin pregnancy or inaccurate dates. These findings could also be identified on routine ultrasound; Spina bifida, a serious problem which can cause paralysis and brain damage, can often be hinted at by the quad screen, indicating the need for a detailed, "level two" ultrasound. If that sort of expert ultrasound will be done regardless of the test results, the quad screen has less value. Patients often ask me if the quad screen can detect anything fixable. Yes. If you are not automatically going to get an expert "level two" sonogram, the quad screen can lead to the detection of some major anatomical problems. Some of these problems require cesarean delivery, or surgery by a specialist immediately after birth.

Knowing what you would do with an abnormal result can help to guide your decisions. For instance, if you would terminate a pregnancy with Down Syndrome, you need to know if your fetus has Down Syndrome in order to make that decision. If you don't have the testing done and the fetus does have Down Syndrome, your life will be changed, since you won't have the opportunity to terminate. On the other hand, if you would continue a pregnancy with Down Syndrome, the value in testing is to be prepared when the baby comes, and your life won't be much different whether you get the quad screen or not. Many of my patients who wouldn't terminate under any circumstances and who are going to have a detailed ultrasound anyway don't get the quad screen test.

The bottom line in making the decision about getting a quad screen (or whatever the multiple marker test is called at your practitioner's office) is to think ahead about what you will do if the result isn't normal. If you want to know ahead of time about potential problems or if you want to have the option to terminate, the test can help you determine whether to have an amniocentesis, detailed anatomical ultrasound, or other testing. Talk to your practitioner about the pros and cons of getting multiple marker screening.