Double marker test is a type of test conducted during pregnancy to diagnose any chromosomal malformation in the fetus. Get to know what Double marker test is, who need this test, the importance of Double marker test, its advantages, and its disadvantages.
What is Double Marker Test?
This is a type of blood test conducted during pregnancy for determining if there are any abnormalities in the development of chromosomes of the fetus. This test helps to detect if the child has a risk of suffering any kind of the neurological disorders like Down’s syndrome or Edward’s syndrome. Chromosomal abnormalities in fetus result in serious developmental deformities and may cause various health problems after birth in the child. But the risk of getting such defects is very low. Chance of getting this kind of chromosomal disorders and probability of suffering conditions like Down’s syndrome (Trisomy 21), or Edward’s syndrome (Trisomy 18) is very rare.
How and when the Double Marker Test is done?
Generally, a gynecologist may suggest this test if the pregnant woman is aged above 35 years. The risk factors for developing abnormalities in the fetus are high if the mother’s age is higher. Double marker test is done between the 8th and 14th weeks of the pregnancy.
This test is dependent on the Nuchal translucency or Nuchal fold of the fetus. NT or Nuchal fold is the translucent part of the back of the neck of the fetus. The measurement of the NT is obtained in the ultrasound scan. Based on the NT measurements the blood sampling test is done. To keep it simple the Double marker test is a combination of an Ultrasound scan and Blood test. In the blood test, there are two markers that are checked for. They are:
Free Beta HCG:
If this is detected at a high level, it shows there is a risk of Down’s syndrome and if a low level is detected, that means the risk of getting Trisomy 18 is high.
PAPP-A (Pregnancy-Associated Plasma Protein):
The presence of low-level plasma protein in the blood shows the risk of Down’s syndrome in the unborn child.
About Chromosome abnormalities
Chromosomes are thread-like structures which hold the genes. Genes act like carriers of messages needed to form a baby and all body parts. Generally, humans have 46 chromosomes. The baby gets 23 chromosomes from the father and remaining 23 from the mother. If any of the parents have an extra number of the chromosome, then there is a chance the baby gets trisomy. This causes the conditions called Trisomy 18 or Trisomy 21.
About Down’s syndrome or Trisomy 21
Down’s syndrome is developed as a result of an abnormality in chromosomes. Normally a healthy human would have 46 chromosomes. But mostly a person with Down’s syndrome would have 47 chromosomes. In very rare cases other chromosomal problems may cause this condition. This extra chromosome causes brain and body developmental abnormalities in the fetus during pregnancy. The risk ratio is high in some conditions like:
- If women’s age is higher than 35 years at the time of pregnancy
- If you had another child with this Down’s syndrome
- If you have a sister or brother with this condition
Down’s syndrome is a combination of physical and neurological disabilities which form at the stage of development of the fetus in mother’s womb. Symptoms of this condition are like
- Flat face
- Short neck
- Small hands
- Low set ears
- Learning disability
- Less lifespan
- Prone to other diseases related to sight, hearing, digestive and heart diseases
About Edward’s syndrome or Trisomy 18
This is also caused by abnormal chromosomal pairs. This may result in abnormal formation of body parts in the child. Trisomy 18 is of 3 types. They are Full trisomy 18, Partial trisomy 18, and Mosaic trisomy 18. The probability is about one baby out of 5000 may have the chance of developing this condition. Symptoms of this condition are like:
- Cleft palate
- Small jaw
- Defects of the lungs, kidneys, and stomach or intestines
- Deformed feet
- Heart defects
- Low set ears
- Severe developmental delays
- Chest deformity
- Retarded growth
- Small head or Microcephaly
Double Marker Test – Advantages and Disadvantages
This test is helpful for finding if the baby has the risk of getting Down’s syndrome (Trisomy 21), or Edward’s syndrome (Trisomy 18). Based on the results you can take necessary decisions with the help of your doctor.
Disadvantages are accuracy depends on skill level and machine quality. Moreover, it may not be available in every town and hospital and also it is an expensive test.
Let your doctor know if you are using any other supplements or medicine to be on safer side. Consult your doctor to know if you need this test or not.
Dr. Kaleem Mohammed graduated as a Bachelor of Physiotherapy in 2014 from Deccan College of Physiotherapy, affiliated to Dr. N.T.R. University of Health Sciences, Vijayawada, India. Dr. Kaleem is an expert at handling physiotherapy needs of patients suffering from orthopedic and spinal conditions and post-surgery rehabilitation. Dr. Kaleem is associated with HealthClues since its inception where he facilitates diagnosis and advanced consultation with senior doctors. He is also a medical researcher and prolific writer who loves sharing insightful commentaries and useful tips to educate the patient community about fitness, treatment options, and post-treatment recovery.