What is the Serum Quadruple Marker Test?
The Serum Quadruple Marker Test, also known as the quadruple screen, is a maternal blood test performed between 15 and 20 weeks of pregnancy. It measures four biomarkers to assess the risk of chromosomal abnormalities and neural tube defects in the fetus.
Why is it done?
- Screen for chromosomal anomalies: Down syndrome (Trisomy 21) and Trisomy 18
- Detect risk of neural tube defects such as spina bifida and anencephaly
- Provide additional information when first trimester screening results are inconclusive
- Offer risk assessment for women who did not have first trimester combined screening
When should I get it?
The ideal time for the Serum Quadruple Marker Test is between 15 weeks and 20 weeks + 6 days of gestation. Testing outside this window may reduce accuracy.
How is it performed?
- A blood sample is drawn from the mother’s arm
- The sample is analyzed for four biomarkers: - Alpha-fetoprotein (AFP) - Human chorionic gonadotropin (hCG) - Estriol (uE3) - Inhibin A
- Results are reported as multiples of the median (MoM) and combined into an overall risk estimate
What does it show?
- High AFP levels may indicate neural tube defects or inaccurate dating
- Abnormal hCG, uE3, and inhibin A levels contribute to risk assessment for Down syndrome and Trisomy 18
- The overall risk estimate helps determine need for further diagnostic testing
Benefits and Limitations
Benefits:
- Non-invasive screening with a simple blood draw
- Provides risk assessment for both chromosomal anomalies and neural tube defects
Limitations:
- Not diagnostic; positive results require confirmation via CVS or amniocentesis
- False-positive rate can lead to anxiety and unnecessary invasive tests
- Accuracy depends on correct gestational dating and maternal factors (weight, diabetes, ethnicity)
Frequently Asked Questions (FAQs)
Is any preparation needed?
No special preparation; you can eat and drink normally before the test
Is the test safe?
Yes. It involves only a maternal blood draw with no risk to the fetus
When will I get the results?
Results are typically available within 7–10 business days
What if my result indicates high risk?
High-risk results should be followed by diagnostic tests like amniocentesis
Will insurance cover this test?
Coverage varies; check with your insurance provider