What is a triple screen?
A triple screen is a blood test that measures three things called alpha-fetoprotein, human chorionic gonadotropin and unconjugated estriol. The results of the blood test can help your doctor see if your baby may be at higher risk for certain birth defects such as Down syndrome and neural tube defects.
Why is it called a "screen"?
These test results can only show that there may be a problem, but they cannot prove that there definitely is one. An abnormal test result doesn't necessarily mean that your baby has a birth defect. Most often, the blood test results are abnormal because the baby is younger or older than your doctor initially thought. And some birth defects will not be detected by this test. Remember, this test does not screen for all birth defects.
When should the test be done?
Triple screens are most accurate when done between the 16th and 18th weeks of pregnancy. They may also be done between the 15th and 22nd weeks of pregnancy.
What happens if the test results of the triple screen are abnormal?
Your doctor will probably want you to have some other tests or see a doctor that specializes in high-risk pregnancy. The first step is often to have an ultrasound exam. This test can check on the age of the baby and look for problems in the baby's brain, spinal cord, kidneys and heart. Another test that you might have is called amniocentesis (say: am-nee-oh-cen-tea-sis). This test checks the fluid around the baby. The results of these tests will help your doctor decide if your baby might have a defect.
Maternal Serum Triple Analyte Screening in Pregnancy by J. Christopher Graves, M.D., Karl E. Miller, M.D., and Angela D. Sellers, M.D. (American Family Physician March 01, 2002, http://www.aafp.org/afp/20020301/915.html)
Written by familydoctor.org editorial staff