Maternal Alpha Fetoprotein Test.A friend told me about a blood test she had that can detect problems with the baby. What is it?
You probably mean the maternal alpha-fetoprotein AFP test. It is a blood test done on you to determine abnormalities in your baby. Measurement of the amount of alpha-fetoprotein in your blood can help your doctor predict problems, such as Down syndrome and spina bifida.
Is the AFP test done on all pregnant women?
At this time, it is not performed on all pregnant women. However, it is required in some states, such as California and New York. If the test is not offered to you, discuss it with your doctor.
When is the test done?
It is usually performed between 16 and 20 weeks of pregnancy. Test results must be correlated with the mother-to-be's age and weight, and the gestational age of the fetus. If AFP detects some problem, additional, more definitive testing is usually ordered.
What kind of abnormalities can AFP detect?
The test is designed to detect babies with the following conditions:
- neural-tube defects
- severe kidney disease
- severe liver disease
- esophageal or intestinal blockage
- Down syndrome
- urinary obstruction
- osteogenesis imperfecta (fragility of the baby's bones)
I've heard that if I have an alpha-fetoprotein test, chances are rather high that it will be abnormal, even if there are no problems. Is this true?
Yes. The test is not specific enough. For example, if 1,000 women are tested, 40 tests will come back abnormal. Of those 40 tests, only 1 or 2 actually have a problem. So if you have AFP and your test result is abnormal, don't panic. Another AFP test will be done to correlate results, and an ultrasound will be performed. Be sure you understand what false-positive and false-negative test results mean. Ask your doctor to explain what each result can mean to you.
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