The Expanded Alpha Fetoprotein (XAFP) screening test is a voluntary blood test available to all pregnant women between 15 and 20 weeks of pregnancy. The goal of the Expanded AFP Screening Program is to provide an opportunity for all pregnant women in California to have prenatal screening for Down syndrome, trisomy 18, open neural tube defects (spina bifida/anencephaly), abdominal wall defects, and Smith-Lemli-Opitz syndrome (SLOS.). You can learn more about these conditions below. It is important to remember that this screening test cannot look for all types of birth defects.

The XAFP test also known as the "quadruple marker" test, or quad test. This test measures maternal serum (blood) levels of four substances which are normally found in a woman's bloodstream when she is pregnant. These four substances are: AFP (alphafetoprotein), hCG (human chorionic gonadotropin), uE3 (unconjugated estriol), and inhibin-A.

The XAFP screening test is administered by the Genetic Disease Screening Program of the California Department of Health Services and is coordinated for Northern California Kaiser Permanente members by the Regional Prenatal Screening office located at the Kaiser Permanente Oakland Medical Center.

The blood test is done by taking a small amount of blood from a pregnant woman’s arm. Her blood is tested for the amounts of AFP, hCG, uE3, and inhibin-A. These substances are made by the mother’s placenta and the fetus (developing baby). The amount of each substance in the blood sample is affected by many factors including:

• The number of weeks pregnant a woman is on the day the blood test is performed.
• Her weight, race, and whether she is an insulin-dependent diabetic.
• Whether she has a single or a multiple pregnancy.
• Whether she has smoked one or more cigarettes in the week prior to having the blood test.

The XAFP Screening Program was established by the California Department of Health Services to provide prenatal screening for all pregnant women in California. Kaiser Permanente has a Northern California Regional Prenatal Screening Office in Oakland that is set up to coordinate all aspects of the program for our members. Our region covers the 43 Northern California Kaiser facilities, including clinics, laboratories and Prenatal Diagnosis Centers. The Prenatal Screening Office staff work to ensure complete, accurate results and that appropriate follow up is initiated when necessary.

References

Regional Prenatal Screening Coordinators: Peggy Fehlen-Quizon, M.S., Robyn Krieger, M.S., Carol Norem, M.S, Elise Obolensky, M.S., and Monica Wohlferd, M.S.S.W.