Alpha-fetoprotein Also known as Fetal alpha globulin or AFP. This is a substance that is naturally produced by the liver of a fetus. It is also a type of blood test. Often used as a prenatal test to determine the risk of neural tube defects, such as spina bifida, as well as the risk of Down’s syndrome. It is done 15-20 weeks into pregnancy. Low levels of this can normally be found in pregnant women. None to almost undetectable levels can usually be found in healthy non-pregnant, and men. These levels can be used to indicate certain conditions or diseases. The results of this test can often be used in combination with two other tests: estriol and human chorionic gonadotropin (hCG), to detect Down's Syndrome. The three tests together are called the triple test. In some states the triple test is required for all pregnant women.

To perform this test the medical professional draws blood from a vein on the back of the hand or on the inside of the elbow, like most blood tests. Before drawing the blood the site is cleaned with antiseptic and an elastic band is placed around the upper arm to apply pressure and to restrict blood flow through the vein, causing the veins below the band to fill with blood. An air-tight vial or syringe is used to collect the blood that is withdrawn with a needle that is inserted into the vein. The needle is removed, and the puncture site covered to stop any bleeding as soon as the blood has been collected.

Women’s Encyclopedia of Health and Emotional Healing