Alpha-Fetoprotein Assessment

TRIPLE SCREEN; HUMAN CHORIONIC GONADOTROPIN; UNCONJUGATED ESTRIOL TEST
DESCRIPTION:

A relatively common screening of a blood sample taken from the mother usually during the 15th to 20th week of pregnancy. Many women find this prenatal testing useful with 40% of pregnant women having the test each year. The primary measurement on the triple screen is for maternal serum alpha-fetoprotein (MSAFP or AFP), a protein produced by the liver cells of every fetus and is present in both the amniotic fluid and the mother’s blood. Testing for the human chorionic gonadotropin (hCG) and unconjugated estriol (uE3) is combined with the AFP test to help improve the results.

REASONS FOR PROCEDURE

To help rule out possible fetal abnormalities. The triple test is for screening purposes only and further testing is always necessary for accurate diagnosis of any problem.

RISK INCREASES WITH

No expected risks with the blood test itself.

DESCRIPTION OF PROCEDURE

Blood is usually drawn by needle from the upper arm (sometimes from the finger, heel or earlobe). The sample is then sent to a laboratory for testing. Results are available in a few days.

PREVENTIVE MEASURES

  • Avoid having sex at all.
  • Have sex only with someone you know does not have genital warts and is having sex only with you.
  • Using condoms may help prevent transmission; however, condoms can’t always cover all affected skin.

EXPECTED OUTCOME

  • The majority of time (over 95%), the test results fall within the normal range.
  • About 3 to 5% of women tested will have AFP levels outside the normal range the first time and 3% of these women will still have abnormal levels on a repeat blood test. These women will be offered genetic counseling which may lead to further testing such as amniocentesis, ultrasound or other prenatal tests to help verify if a problem exists.
  • Higher concentrations of AFP levels may indicate:
    • A neural tube defect such as spina bifida (failure of the spinal column to close completely).
    • Other rare abnormalities.
    • Threatened abortion.
    • Twins (or triplets) are expected.
    • Abruptio placenta.
    • The pregnancy is inaccurately dated.
  • AFP levels can be normally low which may include:
    • The pregnancy is inaccurately dated.
    • Trisomy-21 (Down Syndrome).

POSSIBLE COMPLICATIONS

  • Some discoloration, soreness or swelling may develop at the puncture site.
  • False-positive results of the test which can cause anxiety and worry for the parents-to-be.