Alpha-Fetoprotein Test

MSAFP is a screening test that examines the level of alpha-fetoprotein in the mother's blood during pregnancy. Because it is measuring the level of alpha-fetoprotein, it is often referred to as an AFP test. This is not a diagnostic test. It is often part of the triple test screening that assesses whether further diagnostic testing may be needed.

Question: How is the MSAFP performed?

Answer: Blood is drawn from veins in the mother's arm and sent off to a laboratory for analysis. Results are usually returned between one and two weeks.

Question: When is MSAFP performed?

Answer: MSAFP may be performed between the 15th and 20th weeks of pregnancy, however it is most accurate during the 16th to 18th week. Your levels of AFP vary during pregnancy so accurate pregnancy dating is imperative for more reliable screening results.

Question: All pregnant women should be offered MSAFP screening, but it is recommended for:

Answer:
•Women who have a family history of birth defects
•Women who are 35 years or older
•Women who used possible harmful medications or drugs during pregnancy
•Women who have diabetes

Question: What does the MSAFP test look for?

The MSAFP test is measuring high and low levels of alpha-fetoprotein (AFP), which is a protein produced by the unborn baby's liver. The results are combined with the mother's age and ethnicity in order to assess probabilities of potential genetic disorders.

High levels of AFP may suggest that the developing baby has a neural tube defect. The most common neural tube defects are spina bifida or anencephaly. High levels of AFP may also suggest defects with the esophagus or a failure of your baby's abdomen to close.

Low levels of AFP may indicate that the developing baby has Down syndrome (Trisomy 21).

Abnormal levels may also be a result of one or more of the following:

  • Presence of more than one baby
  • An incorrect due date estimate
  • Potential sign of miscarriage, preeclampsia, or premature birth
  • Placental abruption
  • A baby smaller than normal
  • An overweight mother (especially for African Americans)
  • Diabetes
  • Defects in the ventral wall of the baby
  • Defects in the digestive system of the baby
  • Pregnancies that are more or less advanced than thought

Question: What do MSAFP results mean?

Answer: It is important to remember that the MSAFP is a screening test and not a diagnostic test. This test only notes that a mother is at risk of carrying a baby with a genetic disorder. There are between 50 and 100 abnormal test results for every 1,000 pregnancies tested; only 1 or 2 of the babies with high AFP levels have actual problems. The benefit of screening is that 90% of babies with anencephaly and 75% with spina bifida are discovered.

Abnormal test results warrant additional testing for making a diagnosis. A more conservative approach involves performing a second MSAFP or complete triple test followed by a high definition ultrasound. If the testing still maintains abnormal results, the more invasive procedures such as amniocentesis or CVS, may be performed.

These invasive procedures should be discussed thoroughly with your healthcare provider. It is also important to talk through further testing with you partner. Additional counseling and discussions with a counselor, social worker or minister may prove helpful.

Question: What are the risks and side effects of MSAFP to the mother or baby?

Except for the discomfort of drawing blood, there are no risks or side effects associated with the MSAFP.

Question: What about further testing?

MSAFP is a routine test that is not an invasive procedure and poses no risks to the mother or baby. The MSAFP results may warrant additional testing. The reasons to pursue further testing or not may vary from person to person and couple to couple. Performing further testing allows you to confirm a diagnosis and then provides you with certain opportunities: