Double Marker Test in Pregnancy: Importance, Process, and Results

The double marker test is an important screening tool used during the first trimester of pregnancy. It helps assess the risk of chromosomal abnormalities, such as Down syndrome, in the developing baby. This non-invasive blood test equips parents and doctors with valuable insights into the unborn baby’s health, facilitating informed decisions regarding further diagnostic tests and prenatal care. As an integral component of comprehensive first trimester screening, the double marker test, in conjunction with an ultrasound, enables early identification of potential risks.

What is a Double Marker/Dual Marker Test in Pregnancy?

The double marker test, also referred to as the dual marker test or maternal serum screening, is a prenatal screening that involves measuring the levels of two specific markers in the mother’s blood: human chorionic gonadotropin (hCG) and pregnancy-associated plasma protein A (PAPP-A). By analysing these markers, doctors can estimate the risk of chromosomal abnormalities, such as Down syndrome (trisomy 21), Edward’s syndrome (trisomy 18), and Patau’s syndrome (trisomy 13). The double marker test is used alongside a nuchal translucency (NT) scan, an ultrasound examination, to enhance the accuracy of the risk assessment. The combination of these tests provides a more comprehensive evaluation of the foetus’s health.

What is the Need for a Double Marker Test During Pregnancy?

The double marker test is highly recommended for detecting the risk of chromosomal abnormalities early in pregnancy, particularly for women over 35 years old or those with a family history of such conditions. While the test provides a risk assessment rather than a definitive diagnosis, it empowers parents to make informed decisions regarding further invasive diagnostic tests, such as amniocentesis or chorionic villus sampling. By enabling early detection, the double marker test facilitates timely decision-making concerning additional testing and prenatal care. Moreover, it offers expectant parents peace of mind by assessing the risk of significant genetic conditions, allowing them to prepare emotionally and practically for the journey ahead.

When Should a Double Marker Test be Performed in Pregnancy?

The double marker test is an important screening tool that is typically recommended between 11 and 14 weeks of pregnancy, ideally within the first trimester. This specific timeframe is crucial for ensuring the test’s accuracy in detecting potential chromosomal abnormalities, such as Down syndrome, trisomy 13, and trisomy 18. If this window is missed, an alternative risk assessment, known as the quadruple marker test, can be performed between 15 and 21 weeks of pregnancy.

Double Marker Test: Normal Range and Cost

The normal range and cost of the double marker test are important factors to consider when planning for this screening.

• Normal Range:
  • Free beta-hCG: For women of all age groups, the normal range is between 25,700 to 288,000 mIU/ml.
  • PAPP-A: The normal range for PAPP-A is 1 MoM (multiple of the median) across all age groups.
• Cost:
  • The cost of the double marker test usually ranges between ₹2,500 and ₹4,000, depending on your location and healthcare provider.
  • This cost may vary based on your insurance coverage and the specific clinic or hospital you visit.

Understanding the normal range and cost of the double marker test can help you prepare for the procedure and interpret the results effectively.

Double Marker Test Procedure

The double marker test is a simple and non-invasive procedure that combines a blood test with an ultrasound examination.

• To begin, a blood sample will be drawn from the mother to measure the levels of two specific markers: hCG and PAPP-A. This blood test is usually non-fasting, which means you can eat and drink normally before the test unless otherwise instructed by your doctor.
• In addition to the blood test, an ultrasound, often referred to as a NT scan, will be performed to measure the size of the clear area on the back of your baby’s neck.
• The measurements obtained from both the blood test and ultrasound will be combined with other factors, such as your age, to estimate the risk of chromosomal abnormalities in your developing baby.

Understanding Chromosomal Abnormalities

Chromosomal abnormalities in pregnancy occur when the number or structure of the foetus’s chromosomes is abnormal. These conditions can lead to serious health issues for the baby. The likelihood of these abnormalities increases with the mother’s age, especially if she is over 35 years old. The double marker test is a crucial prenatal screening tool that helps assess the risk of these chromosomal abnormalities.

Double Marker Test Results

The double marker test results are categorised into low-risk, moderate-risk, or high-risk for chromosomal abnormalities.

• A low-risk result suggests that the likelihood of chromosomal abnormalities is low, as the markers are within the normal range.
• Moderate or high-risk results, on the other hand, indicate an increased likelihood of abnormalities. In such cases, further testing, such as non-invasive prenatal testing (NIPT), amniocentesis, or chorionic villous sampling, may be recommended to confirm the diagnosis.

Benefits of the Dual Marker Blood Test

The dual marker blood test offers numerous advantages for expectant parents. It enables the early detection of chromosomal abnormalities like Down syndrome and trisomy 13 or 18, empowering parents to make informed decisions about their pregnancy. This knowledge allows them to prepare for the arrival of a child with special needs and enables doctors to implement appropriate prenatal care plans.

Double Marker Test vs. NT Scan: What’s the Difference?

The double marker test and the NT scan are frequently conducted together as part of the first-trimester screening process. While the double marker test is a blood test that measures beta-hCG and PAPP-A levels, the NT scan is an ultrasound that assesses the thickness of the nuchal fold at the back of the baby’s neck. The combination of these tests provides a more accurate risk assessment for chromosomal abnormalities compared to the NT scan alone. The double marker test complements the NT scan, enhancing the overall effectiveness of the screening process.

In conclusion, the double marker test is an invaluable tool in prenatal care, offering expectant parents crucial information about their foetus’s health. By facilitating the early detection of chromosomal abnormalities, this test allows parents and doctors to make informed decisions regarding further testing and pregnancy management.

Frequently Asked Questions (FAQ)

References

1. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3547446/
2. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5926339/
3. https://www.ijogr.org/html-article/17097
4. https://academic.oup.com/clinchem/article/69/Supplement_1/hvad097.293/7283940