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Alpha-Fetoprotein (AFP) in Blood

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.

How It Feels

The blood sample is taken from a vein in your arm. An elastic band is wrapped around your upper arm. It may feel tight. You may feel nothing at all from the needle, or you may feel a quick sting or pinch.

You may feel anxious while awaiting results of an alpha-fetoprotein test done to determine the health of your unborn baby.

Risks

There is very little chance of a problem from having blood sample taken from a vein.

  • You may get a small bruise at the site. You can lower the chance of bruising by keeping pressure on the site for several minutes.
  • In rare cases, the vein may become swollen after the blood sample is taken. This problem is called phlebitis. A warm compress can be used several times a day to treat this.
  • Ongoing bleeding can be a problem for people with bleeding disorders. Aspirin, warfarin (Coumadin), and other blood-thinning medicines can make bleeding more likely. If you have bleeding or clotting problems, or if you take blood-thinning medicine, tell your doctor before your blood sample is taken.

Results

An alpha-fetoprotein (AFP) blood test checks the level of AFP in a pregnant woman's blood. AFP is a substance made in the liver of a developing baby (fetus). The amount of AFP in the blood of a pregnant woman can help find certain problems with her baby.

Normal

The normal values listed here—called a reference range—are just a guide. These ranges vary from lab to lab, and your lab may have a different range for what's normal. Your lab report should contain the range your lab uses. Also, normal values vary with the age of the baby. A high or low AFP may mean that the age of the baby has been recorded wrong or not calculated correctly. An ultrasound may be done to check the baby's age more accurately.

Alpha-fetoprotein in blood
Men and nonpregnant women:

0–40 nanograms per milliliter (ng/mL) or micrograms per liter (mcg/L)2

Women 15–18 weeks pregnant:

10-150 ng/mL or mcg/L3

WebMD Medical Reference from Healthwise

Last Updated: April 04, 2012
This information is not intended to replace the advice of a doctor. Healthwise disclaims any liability for the decisions you make based on this information.

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