Double Marker Test: Purpose, Procedure, and Results

During pregnancy, a series of tests are conducted to monitor the health of the baby and the mother to rule out any severe medical conditions in the fetus. One such test is the double marker or dual marker test, which ensures the fetus does not have any chromosomal diseases. 

Let’s understand the purpose of the double marker test, its procedure, and its results. 

What is a Double Marker Test?

Double marker test or maternal serum screening is performed in the first trimester of the pregnancy to assess the risks of chromosomal abnormalities in the fetus.  

The test measures the level of Beta-hCG (beta-human chorionic gonadotropin) and PAPP-A (Pregnancy-Associated Plasma Protein A). The altered presence of these markers in the blood of pregnant women may indicate the risk of chromosomal abnormalities like Down Syndrome and Edward’s Syndrome. 

Dual marker test in pregnancy is not mandatory, but it is essential in pregnant women over the age of 35 or in couples who have a family history of chromosomal diseases.  

The test is only predictive and does not confirm the chromosomal diseases in the developing foetus. The healthcare provider will order a diagnostic test after the screening tests are positive to confirm the abnormalities. 

What are Chromosomal Abnormalities?

Chromosomal disabilities that are detected in the double marker tests occur due to irregularities in the number of chromosomes in the foetus’ DNA. Normally, a female foetus will have 22 pairs of autosomes and a pair of XX chromosomes, and a male foetus will have 22 pairs of autosomes and a pair of XY chromosomes. In the case of chromosomal disabilities, this division differs in the following way:

• Down Syndrome: It occurs in the foetus when there is a duplication of the 21st chromosome. It is also known as trisomy 21. 

• Edward’s Syndrome: This happens when there is an extra copy of chromosome 18 and is also known as trisomy 18. 

• Patau’s Syndrome: It occurs when there is an extra copy of chromosome 13. It is also referred to as trisomy 13. 

What is the Procedure for the Double Marker Test? 

A double marker test is usually performed anywhere between weeks 11 and 14 in the first trimester. The test measures beta-hCG and PAPP-A in the blood. Beta hCG is a glycoprotein hormone secreted by the placenta. If the hormone is present in high levels, it can indicate the risk of Down Syndrome. PAPP-A is a plasma protein, and low levels of it are also associated with Down Syndrome.  

Double marker test involves a blood test and an ultrasound called nuchal translucency (NT) scan.  

NT scan uses sound waves to collect real-time images of the foetus and is particularly used to estimate the size of the clear area at the back of the foetus’ neck. It examines the fluid collection at the back of the neck. The presence of more fluid is associated with Down Syndrome. 

Together, these tests provide a much clearer understanding of the potential risks of chromosomal abnormalities in the development of a foetus. 

What are the Results of a Double Marker Tests?  

The results of the dual marker test can fall into any of three categories: low-risk, moderate-risk, and high-risk. Low risk means there are very low chances of chromosomal abnormalities in the baby.  

If the screening results in moderate or high risk of abnormalities, healthcare providers may perform more invasive tests such as non-invasive prenatal testing, amniocentesis, or chorionic villous sampling. These are diagnostic tests that can confirm the presence of chromosomal abnormalities in the fetus. 

After the test is conducted, the turnaround time or the expected time of the result can vary between three and seven days. 

Although the double marker test is not mandatory, it offers crucial insights into the fetus’s health. Pregnant mothers must consider taking the test to ensure the overall well-being of the fetus and to avoid any future complications. 

If someone is considering taking the double marker test, they must consult their healthcare providers for proper guidance and book a double marker test at Dr. Lal PathLabs for accurate screening. 

FAQs

1. What is double marker test in pregnancy?

Double marker test is a screening test conducted in the first trimester of pregnancy to detect the risk of chromosomal disabilities such as Down Syndrome, Edward’s Syndrome, and Patau’s Syndrome in the developing foetus. 

2. How to check the pregnancy kit?

Pregnancy kits are used to detect the presence of human chorionic gonadotropin (hCG) in the urine. The chemical on the strip changes colour when it comes in contact with hCG. The colour change depends on the test used, for which the instructions on the kit should be read carefully.   

3. How much does a double marker test cost?

Double marker test prices can vary based on the location and insurance coverage. It’s advisable to consult the labs performing the test to confirm the price and any prerequisites for the test.