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Alpha-Fetoprotein (Amniotic Fluid)

Does this test have other names?

Amniotic fluid alpha-fetoprotein, AFAFP test

What is this test?

This test checks a sample of amniotic fluid. The sample can confirm that your fetus has a birth defect called an open neural tube defect. Spina bifida is an example of a neural tube defect.

Amniotic fluid is the liquid that protects and feeds your fetus during pregnancy. When a developing baby has open neural tube defect, it often causes a high level of alpha-fetoprotein (AFP).

Why do I need this test?

You may have this test if you had an abnormal result from a blood test. You may also have had an ultrasound that showed the possibility of this defect. This test helps confirm whether the fetus does have a birth defect.

What other tests might I have along with this test?

Your health care provider may also order another test called amniotic fluid acetylcholinesterase (AChE). This test also helps find a neural tube defect. AChE is an enzyme found in blood, muscle, and nerve tissue.

What do my test results mean?

Many things may affect your lab test results. These include the method each lab uses to do the test. Even if your test results are different from the normal value, you may not have a problem. To learn what the results mean for you, talk with your health care provider.

High levels of both AFP and AChE mean your fetus may have an open neural tube defect.

How is this test done?

This test requires a sample of amniotic fluid. The sample is collected during a test called amniocentesis. It is usually done in a medical office.

In this test you lie down on an exam table. A health care professional uses an ultrasound machine to show an image of your unborn baby on a monitor. These images show where to take the fluid sample without touching the fetus.

A health care provider puts pain medicine on your abdomen. He or she then injects a needle to draw out a small sample of amniotic fluid. Collecting the sample of fluid usually only takes about 5 minutes. But you may be at the facility for 45 minutes or longer.

Does this test pose any risks?

Amniocentesis is considered a safe procedure. But you have a 1 in 300 to 500 chance that you may miscarry. Miscarriages can happen if you get an infection in your uterus, if your water breaks before it should, or if you go into early labor.

It's extremely rare for the baby to come into contact with the needle. The health care providers watch the monitor very closely.

After the procedure, you may feel cramping, leak a little fluid or blood from your vagina, or feel discomfort around the puncture site. If any of these symptoms continue or get worse, or if you develop a fever, call your health care provider right away. Ask your provider if you should avoid certain activities after the test.

What might affect my test results?

Other factors aren't likely to affect your results.

How do I get ready for this test?

You don't need to prepare for this test. But be sure your health care provider knows about all medicines, herbs, vitamins, and supplements you are taking. This includes medicines that don't need a prescription and any illicit drugs you may use. 

Medical Reviewers:

  • Larson, Kim, APRN, FNP
  • Sather, Rita, RN