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 for a substance called alpha-fetoprotein. It is made by the developing baby and passes into the amniotic fluid. The sample can help tell if your baby 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 surrounds your baby during pregnancy. When a developing baby has an open neural tube defect, it often causes a high level of alpha-fetoprotein (AFP) in the amniotic fluid.

Why do you 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 baby does have a birth defect.

What other tests might you have along with this test?

Your doctor 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 your test results mean?

Test results may vary depending on your age, sex, health history, and other things. Your test results may be different depending on the lab used. They may not mean you have a problem. Ask your doctor what your test results mean for you.

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

How is this test done?

This test needs 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. An ultrasound machine is used to show an image of your unborn baby on a monitor. These images show where to take the fluid sample without touching the baby.

A doctor cleans your belly and uses a local anesthetic to numb the area. They insert a needle to draw out a small sample of amniotic fluid. Collecting the sample of fluid usually takes only 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 doctor watches 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 doctor right away. Ask your doctor if you should stay away from certain activities after the test.

What might affect your test results?

Other factors aren't likely to affect your results.

How do you get ready for this test?

Be sure your doctor knows about all medicines, herbs, vitamins, and supplements you are taking. This includes medicines that don't need a prescription and any illegal drugs you may use. Your doctor will tell you if you need to have your bladder empty or full for the test.