Not every woman will choose to have a maternal serum triple test (triple screen). Your decision about the triple screen will be best informed by looking at a number of factors. Consider the following when making your decision.

• The triple screen test has a high rate of false-positive results, which increases with the mother's age. This means you may have a lot of unnecessary anxiety if you have the test, if it comes back with positive results even though your baby is normal. Or, if your results show low risk, you may find them to be reassuring. (Quadruple screen test results are a little more dependable.)
• The triple screen test doesn't diagnose a birth defect-it estimates the possibility that your fetus has a birth defect. If your results indicated a higher-than-normal possibility, your next decision would be whether to have diagnostic testing, such as amniocentesis.
• Before you undergo testing for birth defects, discuss the possible outcomes with your partner and your doctor or nurse midwife. Consider whether knowing about a birth defect would change your medical, birthing, or parenting plans.
• If you are considering an amniocentesis, you may benefit from first having a triple or quadruple serum screen test. Serum screen tests do not often have false-negative results. If your serum screen result is normal, it suggests that you need no further testing, such as a fetal ultrasound or amniocentesis.
• If you are planning to have an amniocentesis because of known risk factors (such as being age 35 or older, or family history), you can skip the serum screening test. The amniocentesis offers solid diagnostic information; the serum screen does not.

What is a triple screen 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), and estriol (uE3). The levels of these substances help estimate the risk that a fetus may have certain defects. The test results are computed based on a woman's age, her weight, her race, and how far along her pregnancy is, among other factors.

The relatively new quadruple screen combines the triple screen and a test for the hormone inhibin A, which is produced by the fetus and the placenta. One large study of over 23,000 women has reported that the quadruple screen detects almost 86% of all Down syndrome cases. Based on this study, the quadruple test is more likely to pick up Down syndrome and may be less likely to be false-positive than the triple screen.¹

The triple screen is only reliable when it is done between 15 and 20 weeks' gestation. This is why your health professional might use a fetal ultrasound to confirm how many weeks pregnant you are.

The American College of Obstetricians and Gynecologists recommends that all women be offered Down syndrome screening, including the triple or quad screen.

What can the triple screen test tell me?

The triple screen estimates the risk that a fetus may have certain birth defects, including Down syndrome, neural tube defects, and certain rare genetic problems. For more information, see:

• Triple or quadruple serum screen and Down syndrome.
• Triple or quadruple screen and neural tube and other birth defects.

What do I do if I have a positive triple or quadruple serum screen test result?

Normal results tell you that there is no need for further testing unless you have a separate concern, such as a known genetic disease in your family. Positive results tell you that there is a greater than average chance of a birth defect. However, if the average risk for your age is very low or your risk is above average but still very low, you may choose not to have any additional diagnostic tests.

If your serum screen results suggest that your fetus might have a birth defect, including Down syndrome or a neural tube defect, a fetal ultrasound will be done as soon as possible. If your test results are abnormal, a fetal ultrasound can confirm the fetal age and number of fetuses. (An incorrect fetal age or pregnancy with twins or more can lead to a false positive result.) An ultrasound can also be up to 99% accurate in detecting cases of neural tube defects.² However, ultrasound isn't a very dependable test for signs of Down syndrome or for genetic diseases.

If your serum screen is positive and the fetal ultrasound shows no problems, you can have an amniocentesis to check for genetic problems. Amniocentesis is accurate in helping diagnose genetic problems. For example, the test is more than 99% accurate when used to diagnose Down syndrome.² In most cases, the amniocentesis results are normal.

• If your serum screen is positive and the fetal ultrasound suggests a possible genetic fetal problem, an amniocentesis can be used to test for specific genetic markers and other substances in the amniotic fluid.

If a birth defect is found, you can learn what to expect and make plans for having a child with Down syndrome or a birth defect, or you can decide to terminate the pregnancy.

What are the risks of NOT having a triple or quadruple serum screen test?

The most common risk of having a triple or quadruple screen test is unnecessary worry. Most women have normal serum screen results. Of women who have positive results, most turn out to have no problems. This tendency toward false-positive triple screen results increases as you age. (The quadruple screen may be slightly less likely to give you a false-positive result.¹)

If you don't have the triple or quadruple screen or other diagnostic tests, you could potentially give birth to a baby with an undiagnosed birth defect or Down syndrome.

• Such a birth can be more complicated and risky for the baby when a doctor is not expecting newborn 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.
• Without advance knowledge, you might not be emotionally prepared for a Down syndrome or sick newborn.

For general information about the triple test, see the medical tests Alpha-Fetoprotein in Blood, Human Chorionic Gonadotropin (hCG), Estrogens, and Hormone Inhibin A.

Your choices are:

• Have the triple screen test (or the quadruple screen, if it's available in your area).
• Do not have the triple or quadruple screen test.

The decision about whether to have the triple or quadruple screen test takes into account your personal feelings and the medical facts.

These personal stories may help you make your decision.

Use this worksheet to help you make your decision. After completing it, you should have a better idea of how you feel about having the triple or quadruple screen test. Discuss the worksheet with your doctor or nurse-midwife.

Circle the answer that best applies to you.

Use the following space to list any other important concerns you have about this decision.

What is your overall impression?

Your answers in the above worksheet are meant to give you a general idea of where you stand on this decision. You may have one overriding reason to have or not have the triple or quadruple screen test.

Check the box below that represents your overall impression about your decision.

• Down Syndrome
• Pregnancy
• Spina Bifida

Return to the medical test:

• Alpha-Fetoprotein (AFP) in Blood
• Estrogens (Estriol)
• Human Chorionic Gonadotropin (hCG)
• Hormone Inhibin A

Citations

1. Benn PA, et al. (2003). Incorporation of inhibin-A in second trimester screening for Down syndrome. Obstetrics and Gynecology, 101(3): 451–454.

2. Cunningham FG, et al. (2005). Prenatal diagnosis and fetal therapy. In Williams Obstetrics, 22nd ed., pp. 313–339. New York: McGraw-Hill.