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What Is Double Marker Test In Pregnancy?
A double marker test in pregnancy is a predictive blood test part of your first-trimester prenatal screening.
Let us see why a double marker test in pregnancy is important.
This maternal blood test is used to study the level of two 2 serum markers,
- PAPP-A
- Beta-hCG
Human chorionic gonadotropin (hCG) is a hormone produced by a mother’s placenta once an embryo is implanted in her uterus.
PAPP – A is nothing but a pregnancy-associated plasma protein, a key regulator essential for normal fetal development.
In Which Week Is A Double Marker Test Done?
When combined with the nuchal translucency scan, the ideal time to take a double marker test is between 11 to 13 weeks of pregnancy.
Uses Of NT Scan And Double Marker Test?
A double marker test is often coupled with your first-trimester ultrasound screening, the NT scan, to rule out the possibilities of chromosomal disorders in your baby.
Abnormal chromosome disorder is a condition when your baby has an extra copy of a chromosome in its karyotype.
Nuchal translucency scan and double marker are used to screen three main chromosomal abnormalities: Down syndrome, Edward’s syndrome, and Patau’s syndrome.
NT scan, when done alone, has an accuracy rate of only 70-75%. This is why it is always combined with a double marker test to give an accuracy rate of 85%.
What If The Double Marker Test Is Missed?
If you miss the first-trimester blood test, you can take a blood test during the second trimester called the Quadruple test.
This test can be done between 14 to 20 weeks of gestation.
This prenatal blood test measures four substances in a mother’s blood.
Risk Factors Of A Double Marker Test
There is no risk factor associated with a double marker test. It is a non-invasive maternal blood test, and it is highly safe.
What Is The Normal Value Of The Double Marker Test?
A decreased PAPP-A level and an increased beta hCG level during the first trimester indicate that your baby has an increased possibility of chromosomal disorder.
Normal Values Fall Under The Below Levels:
A PAPP-A level equal to or more than 0.5 MOM during the first trimester is considered a low-risk pregnancy.
Standard Beta-hCG level during the 13th and 16weeks of gestation falls between 13,300 – 2,54,000 mIU/mL.
Abnormal Results After NT Scan And Double Marker Test
Please be clear that both NT scan and double marker test are the initial screening checks to detect the possibilities of chromosomal or birth anomalies in your baby.
An abnormal result does not necessarily mean your baby will be born with congenital disabilities.
Your doctor will suggest certain confirmatory or diagnostic tests that examine the placental tissues, amniotic fluid, or maternal blood for the same.
Confirmatory Tests After Abnormal Results:
- Amniocentesis
- Chorionic villus sampling (CVS)
- Non-invasive test (NIPT)
Takeaway:
It would be best to undergo all your prenatal scans and testing without missing any. Some tests cannot be replaced with another during the latter part of the pregnancy.
Early detection of any abnormalities is necessary to take the right step at the right time.