What is an alpha-fetoprotein screening test for?

An AFP blood test is used to check a developing fetus for risk of birth defects and genetic disorders, such as neural tube defects or Down syndrome.

What is FP blood test?

An alpha-fetoprotein (AFP) test is a blood test that measures the amount of AFP present in blood. It’s usually part of what’s called a triple screen or quad screen in the second trimester of pregnancy.

How accurate is AFP test for Down syndrome?

For years, women were screened for AFP alone in a test called the maternal serum AFP or MSAFP, but now most labs check for all four substances because the accuracy is better. The detection rate for Down syndrome is between 67 and 76 percent in women younger than 35.

How accurate is the AFP blood test?

This means it is not 100% accurate. It is only a screening test to see who might need more tests for their pregnancy. There can be false-positive results. These results show a problem when the baby is actually healthy.

What causes high levels of alpha fetoprotein?

Increased AFP levels may indicate the presence of cancer, most commonly liver cancer, cancer of the ovary, or germ cell tumor of the testicles. However, not every liver, ovarian, or testicular cancer will produce significant quantities of AFP.

How common is a false-positive AFP test?

AFP by Presence or Absence of Neural Tube Defect. The specificity is 0.97, indicating that there are 3% false-positives. NTDs are rare complications of pregnancy; the false-positives greatly outnumber the true positives, and the PVP is about 0.09.

How common are false-positive AFP tests?

How often is AFP wrong?

There are approximately 25 to 50 abnormal test AFP results for every 1,000 pregnancies tested. Of these abnormal results, only 1 in 16 to 1 in 33 will actually have a baby that has been affected by a neural tube defect or other condition.