Pregnancy: Should I Have the Maternal Serum Triple or Quadruple Test?

The maternal serum triple screen, sometimes called the triple test or MSAFP+ test, measures the amounts of three substances in a pregnant woman's blood:

• Alpha-fetoprotein (AFP)
• Human chorionic gonadotropin (hCG)
• Estriol (uE3)

The levels of these substances help your doctor estimate the chance that your fetus may have Down syndrome , neural tube defects , or certain rare genetic problems. Other things are considered along with the test results to estimate the chance of a problem. For example, your doctor will look at your age, weight, and race, and how far along your pregnancy is.

The quadruple (or quad) test combines the triple screen and a test for the hormone inhibin A, which is produced by the fetus and the placenta . The quad test is a little more accurate than the triple screen, but it might not be available everywhere.

The triple and quad tests are screening tests. They can't be used to diagnose a birth defect.

If your test result shows that your risk of having a fetus with Down syndrome is higher than average for your age, you can decide whether to have another test, such as amniocentesis , that can show for sure if there is a problem.

The American College of Obstetricians and Gynecologists recommends that all women be offered a screening test for Down syndrome. The risk of having a fetus with a genetic problem increases as a woman gets older. Many doctors use 35 and older as the age when risk increases.

The triple or quad screen finds 80 out of 100 fetuses with neural tube defects, such as spina bifida , and about 90 out of 100 with anencephaly . ¹ The test misses finding 20 out of 100 fetuses with spina bifida and 10 out of 100 with anencephaly.

The quad test finds Down syndrome almost 81 out of 100 times. It doesn't find it 19 out of 100 times. ² The quad test is more likely to find Down syndrome and may be less likely to be false-positive than the triple screen.

A triple or quad screen usually gives accurate results when it is done between 15 and 20 weeks of pregnancy. This is why your doctor might use a fetal ultrasound to find out for sure how far along your pregnancy is.

Normal results tell you that there is no need for more tests unless you have another concern, such as a known genetic disease in your family.

Positive results tell you that there is a higher-than-average chance of a birth defect. But if the average risk for your age is very low, or if your risk is above average but still very low, you may choose not to have more tests.

• If your screening test is positive (and your risk is above average) you may choose to have a fetal ultrasound as soon as possible to check the fetal age and number of fetuses. (The wrong fetal age or pregnancy with twins or more can lead to a false-positive result.) An ultrasound can find neural tube defects up to 99 out of 100 times. ¹ It won't find these problems 1 time out of 100. But ultrasound isn't as good at finding Down syndrome or genetic diseases.
• If your screening test is positive but the ultrasound shows no problems, you can have an amniocentesis . This test finds Down syndrome about 99 out of 100 times. ¹ The test doesn't find it about 1 time out of 100. In most cases, the amniocentesis results are normal.
• If your screening test is positive and the ultrasound suggests a possible genetic problem, you may choose to have an amniocentesis.

If a birth defect is found, you decide where to go from there. You may choose to learn all you can about raising a child with Down syndrome or a birth defect. Or you may decide to end the pregnancy.

A triple or quad test is a blood test, so there is little or no physical risk.

The most common risk of the tests is needless worry. There is a chance that the test could show that there's a problem when there isn't one. This is called a false-positive test result. The quad test is less likely than the triple test to show a problem when there isn't one.

But most women have normal test results. Even when the test is positive, most pregnancies turn out to have no problems.

If you don't have a triple or quad test or a test to diagnose a birth defect, your fetus could have a problem that you don't find out about until birth.

• The birth could be higher-risk for the baby if your doctor is not expecting a newborn with health problems.
• You could give birth in a hospital that does not have a neonatal intensive care unit (NICU) for sick newborns.
• A fetus with a rare, severe defect sometimes dies before delivery.
• You might not be emotionally ready for a sick baby or one with Down syndrome .

Your doctor might recommend a triple or quad test if:

• You have a family history of Down syndrome or birth defects.
• You want a test for birth defects, but you aren't sure if you want to have an amniocentesis .
• You might change your birth or parenting plans if you knew your fetus had a serious problem.