With the triple or quad test, there is a chance of getting a
false-positive test result. This means that the test
could show a problem when the baby doesn't have the problem. A
false-positive result is more and more likely the closer a woman gets to age 40. A false positive may be more likely with the triple screening than the quad screening.
A false-positive result can cause stress and lead to unnecessary testing (such as
an amniocentesis). Many women who have a positive screening test result are actually carrying a healthy baby.
Sometimes negative test results can be wrong too. They may show that the baby is fine when he or she does have a birth defect. (This is a false-negative test result.)
large study of more than 23,000 women, the quad screening accurately predicted almost 86%
of all Down syndrome cases. Based on this study, the quad test is more
likely to pick up Down syndrome and less likely to be false-positive than the
Your doctor will use your age and your baby's age to interpret the test results. If your test results are
abnormal, your doctor may use a
fetal ultrasound to make sure of your baby's age.
What do the results mean?
A "positive" result means that there is a higher-than-average chance your baby has a birth defect. If
the result is "negative," or normal, it means that your baby probably
doesn't have a birth defect. But it doesn't guarantee that you will have a
normal pregnancy or baby.
Your doctor may tell you the result of your test as a set of numbers. Doctors often use a certain number as a cutoff for a positive result. For example, your doctor may say the cutoff is 1 out of 200. This means that if your result is 1 out of 200 or 1 out of a number less than 200 (such as 1 out of 100), you have a positive result and your baby has a higher chance of a birth defect. If your result is 1 out of 300, this means that you have a negative result and your baby has a lower chance of a birth defect.
What do you do with the results?
If you have a positive test result, your doctor may want you to have the diagnostic test amniocentesis to find out for sure if there is a
problem. But it's your choice whether to have another test.
If you have a negative result, you may choose not to have another test.
Should you have the triple or quad screening?
Deciding whether to have a test for birth defects is a personal decision. And it can be a hard choice. You need to think about what the results of a test would mean to you and how they might affect your choices about your pregnancy.