Double Marker Test: Purpose, Procedure, Cost, and Results
A double marker test is an essential prenatal screening test that helps detect chromosomal abnormalities in an unborn baby. It is commonly recommended for pregnant women to assess the risk of genetic conditions such as Down syndrome, Edwards syndrome, and other abnormalities.
In this article, we will discuss everything you need to know about the double marker test, including its purpose, procedure, cost, and how to interpret the results.
What is a Double Marker Test?
The double marker test, also known as the dual marker test, is a blood test performed during pregnancy to assess the risk of chromosomal abnormalities in the fetus. This test is a part of prenatal screening and is usually done during the first trimester between 9 to 14 weeks of pregnancy.
The test measures two important biochemical markers in the mother’s blood:
- Free Beta-human Chorionic Gonadotropin (Free β-hCG) – A hormone produced by the placenta. Abnormal levels may indicate chromosomal defects.
- Pregnancy-Associated Plasma Protein-A (PAPP-A) – A protein produced by the placenta. Low levels may be associated with genetic abnormalities.
This test is often conducted along with an ultrasound nuchal translucency (NT) scan, which measures the thickness of the baby’s neck to assess the risk of Down syndrome.
Why is the Double Marker Test Important?
The double marker test is important because it helps:
- Identify the risk of chromosomal disorders such as Down syndrome (Trisomy 21) and Edwards syndrome (Trisomy 18).
- Assess the likelihood of genetic abnormalities early in pregnancy.
- Guide parents and doctors in making informed medical decisions.
- Determine if further diagnostic tests such as amniocentesis or chorionic villus sampling (CVS) are required.
It is important to note that the double marker test does not confirm a genetic disorder, but it helps evaluate the risk level and whether further testing is needed.
Who Should Take the Double Marker Test?
The double marker test is not mandatory for every pregnant woman. However, doctors often recommend it for:
- Women above the age of 35, as the risk of genetic abnormalities increases with maternal age.
- Pregnant women with a family history of genetic disorders.
- Women who had a previous pregnancy with chromosomal abnormalities.
- Those who have been advised by their doctor based on ultrasound findings.
Even if you do not fall into these categories, your doctor may still recommend this test as a precautionary measure.
When is the Double Marker Test Done?
The double marker test is conducted during the first trimester, typically between 9 to 14 weeks of pregnancy. It is often done along with the nuchal translucency (NT) scan, which is performed between 11 to 14 weeks.
The test is most effective when done during this period because it provides early insights into the baby’s health, allowing doctors to suggest further tests if necessary.
Procedure of the Double Marker Test
The double marker test is a simple blood test and follows these steps:
- Doctor’s Consultation – Your doctor will assess your medical history and suggest the test if necessary.
- Blood Sample Collection – A small amount of blood is drawn from your arm.
- Lab Analysis – The blood sample is sent to a laboratory where Free β-hCG and PAPP-A levels are measured.
- Report Generation – The results are analyzed along with the nuchal translucency (NT) scan findings.
- Doctor’s Interpretation – Your doctor will review the results and inform you about any potential risks.
The entire procedure is non-invasive and poses no risk to the mother or the baby.
How to Prepare for the Double Marker Test?
There are no special preparations required for the double marker test. However, here are a few things to keep in mind:
- Fasting is not required, so you can eat and drink normally before the test.
- Inform your doctor if you are taking any medications that might affect the test results.
- Ensure that the test is done within the recommended 9 to 14-week timeframe for accurate results.
Understanding the Double Marker Test Results
The results of the double marker test are usually presented as high risk or low risk.
1. Low-Risk Result
A low-risk result means that the baby has a lower chance of having chromosomal abnormalities. This is a reassuring outcome, and no further testing is usually required.
2. High-Risk Result
A high-risk result means that there is an increased likelihood of chromosomal abnormalities. However, this does not confirm that the baby has a genetic disorder. Your doctor may recommend further tests such as:
- Non-Invasive Prenatal Testing (NIPT) – A more advanced blood test to check fetal DNA.
- Amniocentesis – A procedure that tests amniotic fluid for chromosomal abnormalities.
- Chorionic Villus Sampling (CVS) – A test that examines placental tissue for genetic conditions.
Accuracy of the Double Marker Test
The double marker test is a screening test, not a diagnostic test. It has a high accuracy rate, but it cannot confirm genetic disorders. Instead, it helps doctors assess the risk level and decide whether further testing is needed.
The accuracy of the test improves when combined with the nuchal translucency (NT) scan. However, if the results are inconclusive or suggest a high risk, additional diagnostic tests are necessary.
Cost of Double Marker Test in India
The cost of the double marker test in India varies depending on the hospital or laboratory. On average, the price ranges between ₹2,500 to ₹5,000. In major cities like Delhi, Mumbai, Bangalore, and Chennai, the cost may be slightly higher.
Some factors that affect the price include:
- The location and reputation of the diagnostic center.
- Additional ultrasound scans (if required).
- Medical consultation fees.
It is advisable to check with multiple diagnostic centers for the best pricing and services.
Difference Between Double Marker Test and Triple Marker Test
| Feature | Double Marker Test | Triple Marker Test |
|---|---|---|
| Timing | 9 to 14 weeks | 15 to 20 weeks |
| Markers Measured | Free β-hCG, PAPP-A | AFP, hCG, Estriol |
| Purpose | First-trimester risk assessment | Second-trimester risk assessment |
| Accuracy | High when combined with NT scan | Helps in detecting neural tube defects |
Conclusion
The double marker test is an important prenatal screening test that helps assess the risk of chromosomal abnormalities in a developing baby. It is a simple, non-invasive, and highly recommended test, especially for women with a higher risk of genetic disorders.
Although the test does not confirm any disease, it helps in making informed decisions about further diagnostic tests. If your doctor suggests a double marker test, it is best to get it done within the recommended first-trimester window to ensure accurate results.
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