Pregnancy blood screening can feel confusing because many names sound similar. The double marker, triple marker, and quadruple marker tests are all screening tests used to estimate the risk of certain chromosomal or developmental conditions.
They do not diagnose a condition. Instead, they help decide whether more detailed counselling, ultrasound, NIPT, or diagnostic testing is needed.
Double marker test
The double marker test is usually done in the first trimester, often along with the NT scan. It measures two blood markers and combines them with other clinical factors to estimate risk. It is commonly part of first trimester screening.
Triple marker test
The triple marker test is usually done in the second trimester, often between 15 and 20 weeks. It measures three substances in the mother’s blood and can provide risk information when first trimester screening was missed or when a second trimester screen is clinically appropriate.
Quadruple marker test
The quadruple marker test adds a fourth marker, inhibin-A, which can improve screening performance for some conditions. It is also a second-trimester screening test and may be used depending on availability, timing, and local protocol.
How are these different from NIPT?
NIPT uses cell-free DNA in the mother’s blood and is generally more accurate for common trisomies than traditional serum screening. However, NIPT is still a screening test. A high-risk result should be discussed with a specialist and may require confirmatory testing.
Can you do multiple screening tests?
Doing several screening tests independently can sometimes create confusing or conflicting results. The better approach is to choose a planned pathway with your doctor rather than adding tests randomly.
What should parents remember?
Screening tests estimate risk. Diagnostic tests such as CVS and amniocentesis analyze fetal or placental cells and can provide clearer answers for specific questions. Your doctor will recommend the next step based on the screening result, scan findings, gestational age, and family history.
If you receive a high-risk marker test result, do not panic. Book a fetal medicine or genetic counselling appointment so the result can be interpreted correctly.