Double Marker Test – Normal Range, Procedure & Results

The double marker test is a prenatal screening test that evaluates the risk of chromosomal abnormalities in the fetus, such as Down syndrome, Edward’s syndrome, and Patau syndrome. These conditions arise due to an extra chromosome in the DNA, leading to developmental delays and physical deformities. The test is usually recommended during the first trimester of pregnancy, typically between the 11th and 14th week. It is a predictive rather than diagnostic test, meaning it identifies the probability of an abnormality rather than providing a definitive diagnosis.

Purpose of the Double Marker Test

The dual marker test in pregnancy evaluates two specific markers in the mother’s blood: beta-human chorionic gonadotropin (beta-hCG) and pregnancy-associated plasma protein A (PAPP-A). Elevated or decreased levels of these markers could indicate potential chromosomal issues. This screening is particularly important for women over the age of 35, those with a history of chromosomal conditions in the family, or those who have had previous pregnancies with abnormalities. Early detection allows for better decision-making and management during the pregnancy.

How is the Double Marker Test Performed?

The double marker test procedure is a test that checks your blood and does an ultrasound. It looks for two things:

• Free beta-h CG: This is a hormone that the placenta makes. If it’s too high, it might mean your baby has Down syndrome or Trisomy-18.
• PAPP-A: This is a protein that helps your body work. If it’s too low, it might mean your baby has Down syndrome.

The test results can be positive, high-risk, or negative.

Women over 35 or with a family history of birth defects are more likely to have a problem with their baby’s chromosomes. So, doctors recommend this test for them.

What Are the Results of the Double Marker Test?

The double marker test results are presented as ratios or probabilities. These indicate whether the risk of chromosomal abnormalities is high or low. The results are usually categorised into three levels: low risk (screen negative), moderate risk, and high risk (screen positive).

For example:

• Screen Negative (Low Risk): Indicates that the fetus is at low risk of chromosomal abnormalities.
• Screen Positive (High Risk): Suggest a higher risk, and further diagnostic tests such as amniocentesis or chorionic villus sampling (CVS) may be recommended.

Understanding Test Results

Understanding the double marker blood test results is crucial in determining the next steps:

• 1:1000 or Higher Ratio: Low risk of chromosomal abnormalities; no further tests are usually needed.
• 1:10 to 1:250 Ratio: High risk; additional tests may be advised.
• Hormone Levels: Abnormally high or low levels of beta-hCG or PAPP-A can indicate a higher likelihood of chromosomal issues.

Accuracy and Reliability of the Test

While the double marker test is a valuable screening tool, it’s important to note that it’s not definitive. The accuracy rate is approximately 70%, making it reliable but not infallible. This is why more invasive diagnostic tests are often recommended to confirm the results if the test indicates a high risk.

Potential Risks and Side Effects

The double marker test is non-invasive, meaning it poses minimal risk to both the mother and the fetus. However, there are a few considerations:

• False Positives: The test may sometimes indicate a high risk when no chromosomal abnormality is present.
• False Negatives: Conversely, there may be cases where abnormalities are not detected.

When Should the Double Marker Test be Done?

The ideal time to perform the double marker test in pregnancy is between the 11th and 14th week of gestation. This is when the levels of beta-hCG and PAPP-A are most indicative of chromosomal abnormalities. Early screening allows parents to prepare better and explore further diagnostic options if needed.

Alternatives to the Double Marker Test

While the double marker blood test is widely used, there are other screening options available:

1. Triple Marker Test: Conducted after the 13th week, it includes an additional marker (AFP) to assess the risk of neural tube defects.
2. Non-Invasive Prenatal Testing (NIPT): A more advanced test that screens for a wider range of chromosomal abnormalities.
3. Amniocentesis: A diagnostic procedure that involves taking a sample of amniotic fluid to check for chromosomal issues.
4. Chorionic Villus Sampling (CVS): A test involving a small placenta sample for more detailed genetic analysis.

Conclusion

The double marker test plays a critical role in prenatal screening, offering valuable insights into the potential risks of chromosomal abnormalities. While the test is not definitive, it provides expecting parents with essential information that can guide further medical decisions. With minimal risks involved and the ability to detect significant chromosomal issues early on, the dual marker test in pregnancy is a vital part of comprehensive prenatal care.

Opting for the right health insurance plan, such as one from Bajaj Allianz General Insurance Company, can ensure that these important tests are covered, giving you peace of mind during this crucial phase of your life. Remember, early detection and timely medical intervention can make a significant difference in ensuring the well-being of both mother and baby.

FAQs

1. What should I do if my double marker test results are abnormal?

If the results indicate a high risk, your doctor may recommend further diagnostic tests, such as amniocentesis or CVS, to confirm the findings.

2. What are the specific markers tested in the double marker test?

The test evaluates the levels of beta-hCG and PAPP-A in the blood.

3. Are there any special preparations required before taking the double marker test?

No special preparations are needed. The test is non-fasting, so you can eat and drink normally.

4. How does the double marker test compare to the triple marker test?

The double marker test is conducted earlier in the pregnancy, while the triple marker test is done later and includes an additional marker for better risk assessment.

5. Is the double marker test covered by insurance?

Yes, most health insurance plans, including those from Bajaj Allianz General Insurance Company, cover the cost of prenatal screening tests like the double marker test.

6. How often should the double marker test be repeated during pregnancy?

The double marker test is typically done once during the first trimester. Based on the results, further tests may be recommended.

7. What is the cost of a double marker test, and does it vary by location?

The cost usually ranges between INR 2500 and 3500, depending on the hospital and city.

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