The multiple marker test, also known as the triple or quad screen, is a prenatal blood test that screens for certain birth defects and chromosomal conditions in a developing baby. Typically performed between the 15th and 20th weeks of pregnancy, the test measures the levels of several substances in the mother’s blood, including alpha-fetoprotein (AFP), human chorionic gonadotropin (hCG), estriol, and, in the case of the quad screen, inhibin-A.
The results can help assess the risk of conditions such as Down syndrome, trisomy 18, and neural tube defects like spina bifida. While the multiple marker test provides valuable information, it does not diagnose these conditions, but rather indicates the likelihood of their occurrence. If the test results show an increased risk, further diagnostic testing, such as amniocentesis or chorionic villus sampling (CVS), may be recommended for a more definitive diagnosis.
What Is the Multiple Marker Test?
The multiple marker test is a blood test offered to all pregnant women. It screens for potential chromosomal disorders and neural tube defects in the developing baby. When combined with first trimester screening tests, it can provide more accurate results, known as an integrated screening test.
It’s important to note that this is a screening test, not a diagnostic test. If the results indicate a possible issue, further testing is required to confirm or rule out a diagnosis.
Why Is the Multiple Marker Test Done?
The test is typically performed between weeks 15 and 20 of pregnancy to screen for conditions like neural tube defects (e.g., spina bifida) and chromosomal disorders (e.g., Down syndrome and trisomy 18).
Depending on the substances measured, the test can be called:
- Triple Screen or Triple Marker: Measures the protein alpha-fetoprotein (AFP) and two pregnancy hormones, estriol and human chorionic gonadotropin (hCG).
- Quadruple Screen (Quad Screen) or Quadruple Marker (Quad Marker): Also measures inhibin-A, in addition to AFP, estriol, and hCG.
The screening calculates a woman’s individual risk by considering the levels of these substances along with factors like:
- Age
- Weight
- Race
- Whether she has diabetes requiring insulin
- Whether she’s carrying one or more fetuses
The more markers included, the more accurate the screening is at identifying the possibility of a problem. In some cases, doctors combine this test with first trimester screening results for a more comprehensive assessment of the baby’s risk for Down syndrome and neural tube defects.
Should I Have the Multiple Marker Test?
This test is offered to all pregnant women, though some health care providers may include different parts of it. Remember, it is a screening tool, not a diagnostic test. It’s not foolproof—a problem might not be detected, and some women with abnormal results may still carry a healthy baby. If the test indicates a potential issue, further testing is recommended to confirm the result.
When Is the Multiple Marker Test Done?
The test is usually done between the 15th and 20th weeks of pregnancy.
What Happens During the Multiple Marker Test?
A blood sample is taken from the mother for analysis.
When Are the Results Available?
Results are typically available within a week but can take up to two weeks.