Alpha-Fetoprotein (AFP) Blood Test

An Alpha-Fetoprotein test is a routine screening given to expectant mothers between the 14th and 22nd weeks of their pregnancy. It is most accurate between the 16th and 18th week and so it is important to know exactly when you became pregnant.

• AFP testing is usually part of a quad screen. This screening exam also tests your human chorionic gonadotrophin (HCG)
• Estriol – a hormone produced by your placenta and your baby’s liver
• Inhibin A – a hormone produced by your placenta

Doctors use your quad screen results, age, and ethnicity to help determine the chances that your unborn baby has a genetic birth defect. Defects detected by this type of screening can include neural tube defects like spina bifida and chromosomal abnormalities like Down syndrome. The results of the AFP test will help the doctor determine if further tests would be needed. A positive test does not necessarily mean your unborn baby will have a birth defect.

AFP test is especially important in:

• Women who are 35 or older
• Women with a family history of birth defects
• Women who used harmful medications or drugs during their pregnancies
• Women who have diabetes

If you are not pregnant, the AFP test can help to diagnose and monitor certain liver conditions such as liver cancer, cirrhosis and hepatitis. It can also help detect several other cancers including cancers of the testes, ovaries, biliary tract, stomach and pancreas

There is very little risk of having a blood test. You may have slight bruising or pain at the spot where the needle was injected.

A healthcare professional, after taking informed consent, will use a small needle to withdraw blood from a vein, usually in your arm or hand.  It is an outpatient procedure and you usually have results typically available within one or two weeks.

For women who are not pregnant as well as men, the normal amount is usually less than 10mg/ml of blood.

If your Alpha-Fetoprotein levels are higher than normal and you are pregnant, it can indicate a neural tube defect in your unborn child. However, the most common cause of elevated AFP levels is inaccurate dating of pregnancy. AFP levels vary widely during pregnancy. The test will be inaccurate if you have been pregnant for a longer or shorter period of time than you thought.

If you are pregnant and your AFP level is unusually low, it could indicate that your unborn baby has a chromosomal abnormality, such as Down syndrome or Edward’s syndrome.

An abnormal AFP may also mean multiple pregnancy such as having twins or triplets. An abnormal AFP reading can also be due to fetal death.

If you have abnormal test results, it does not necessarily mean that your child will have a birth defect. It only indicates that more tests are necessary for your doctor to make a diagnosis. Your doctor may perform another AFP test followed by an ultrasound to record images of your unborn child.

Your doctor may order a more invasive test, such as amniocentesis, if your results are still abnormal.