If the quadruple marker test is abnormal, it means the screening results show a higher or lower estimated risk of certain chromosomal conditions or neural tube defects in the developing baby. An abnormal result does not confirm that the baby has a health condition. Your doctor may recommend a detailed ultrasound, genetic counselling, or additional tests to understand the result.
What Is the Quadruple Marker Test?
The quadruple marker test, also called the quad screen, is a prenatal blood test usually performed between 15 and 22 weeks of pregnancy, often around 16–18 weeks.
It measures four substances in the mother's blood:
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AFP (Alpha-fetoprotein): A protein produced by the developing baby.
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hCG (Human chorionic gonadotropin): A hormone produced during pregnancy.
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Unconjugated estriol (uE3): A hormone produced by the placenta and developing baby.
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Inhibin A: A hormone associated with the placenta.
The results are combined with factors such as maternal age and gestational age to estimate the risk of certain conditions.
What Does an Abnormal Quadruple Marker Test Mean?
An abnormal quadruple marker test may indicate an increased estimated risk of conditions such as:
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Down syndrome (Trisomy 21): A chromosomal condition associated with an additional copy of chromosome 21.
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Edwards syndrome (Trisomy 18): A chromosomal condition associated with an additional copy of chromosome 18.
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Neural tube defects: Conditions such as spina bifida, which affect the development of the brain, spine, or spinal cord.
Abnormal marker levels can also occur because of incorrect pregnancy dating, multiple pregnancy, or other factors. The pattern of all four markers matters, so individual values should not be interpreted alone.
What Happens If the Quadruple Marker Test Is Abnormal?
If your result is abnormal, your doctor may recommend the following steps based on your report and pregnancy history.
1. Review the Test Report
Your doctor will check the marker levels, estimated risk, gestational age, and other relevant details to understand the result.
2. Confirm the Pregnancy Dates
The levels of these markers change during pregnancy. An incorrect estimate of gestational age can affect the screening result.
3. Get a Detailed Ultrasound
A detailed ultrasound may be recommended to assess the baby's development and check for findings associated with the screening result.
4. Consider Further Testing
Depending on the estimated risk, your doctor may discuss cell-free DNA screening for certain chromosomal conditions or diagnostic testing, such as amniocentesis. Amniocentesis is an invasive procedure and has risks that should be discussed with your healthcare provider.
5. Consult a Specialist if Needed
Genetic counselling or consultation with a maternal-fetal medicine specialist may help you understand the results and available options.
Can an Abnormal Quadruple Marker Test Be Wrong?
Yes. The quadruple marker test is a screening test, not a diagnostic test. Some pregnancies with abnormal results do not have the condition being screened for. Similarly, a low-risk result cannot rule out every chromosomal or developmental condition.
The chance of a false-positive result depends on the condition being screened for and individual factors. Further assessment helps clarify what the result means for your pregnancy.
Frequently Asked Questions
1. Is an abnormal quadruple marker test dangerous?
Not necessarily. It indicates a change in the estimated risk, not a confirmed health problem. Your doctor can explain whether additional testing is appropriate.
2. Does an abnormal quad screen mean my baby has Down syndrome?
No. It means the screening test has estimated an increased risk. Further screening or diagnostic testing may be offered to clarify the result.
3. What should I do after an abnormal quadruple marker test?
Discuss the report with your obstetrician. Depending on the findings, you may need a detailed ultrasound, genetic counselling, or additional testing.
4. Can an abnormal quadruple marker test become normal later?
The original screening result does not change, but further assessment may provide more information and change the understanding of the estimated risk.
5. When is the quadruple marker test performed?
It is generally performed between 15 and 22 weeks of pregnancy, with timing determined by your healthcare provider.
6. Is the quadruple marker test accurate?
It helps estimate risk but cannot diagnose a condition. Its performance varies by the condition screened for and individual circumstances.
7. Is further testing always required after an abnormal result?
Not always. The next step depends on the specific result, estimated risk, ultrasound findings, and your preferences after discussing options with your doctor.
Conclusion
An abnormal quadruple marker test means the screening has identified a potentially increased risk that needs careful interpretation. It does not confirm that the baby has a chromosomal condition or neural tube defect. Review the report with your obstetrician, who can recommend appropriate follow-up tests and explain the next steps for your pregnancy.




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