Alpha-Fetoprotein (AFP) in Blood
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Why It Is Done
The AFP test is done to:
- Check the developing baby (fetus) of a pregnant woman for brain or spinal problems (called neural tube defects). Such defects occur in about 2 out of every 1,000 pregnancies.1 The chance of a neural tube defect in a baby is not related to the mother's age. Most women whose babies have neural tube defects have no family history of these problems.
- Check the developing baby (fetus) of a pregnant woman for Down syndrome.
- Find certain cancers, especially cancer of the testicles, ovaries, or liver. But up to half of the people with liver cancer do not have high AFP levels.
- Check how well treatment for cancer is working.
- Check for liver cancer (called hepatoma) in people who have cirrhosis or chronic hepatitis B.
How To Prepare
You do not need to do anything before you have this test.
If you are pregnant, you will be weighed before the blood test, because the test results will be based on your weight. The test results are also based on race, age, and how many weeks you are in your pregnancy.
How It Is Done
The health professional drawing blood will:
- Wrap an elastic band around your upper arm to stop the flow of blood. This makes the veins below the band larger so it is easier to put a needle into the vein.
- Clean the needle site with alcohol.
- Put the needle into the vein. More than one needle stick may be needed.
- Attach a tube to the needle to fill it with blood.
- Remove the band from your arm when enough blood is collected.
- Put a gauze pad or cotton ball over the needle site as the needle is removed.
- Put pressure on the site and then a bandage.