Lets find out what is double marker test and why it is done in pregnancy and how accurate is double marker test in reality.
Double Marker Test
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| Learn Facts about Double Marker Test done in Pregnancy |
As you have a lot of question like what is double market test, why double market test is used for pregnancy, how accurate is the double market test, lets start with understanding what actually double market test is.
What is double market test?
In simple terms a Double Marker Test is a test which is mainly given to pregnant women to determine any kind of chromosomal malformation in the foetus. This test also a plays a huge and very vital role in the detection of any kind of neurological conditions in the foetus, such as founding the down’s syndrome or Edward’s Syndrome.
Chromosomal abnormalities found in foetus can result in very harmful and serious developmental deformities and lead to various health problems in the child post birth which no one wants, but such abnormalities are extremely rare.
The Double Marker Test is well made and only given to pregnant women above 35 years of age and those who have a very serious family history of birth defects and diabetic history insulin that is dependent type 1 diabetes.
Uses Of Double Marker Test
The different and main uses of the Double Marker Test are as follows;
- This test helps in assessing whether the unborn baby is at risk for any mental disorder
- This test is used primarily for the detection of Down syndrome
- Double Marker Test also in addition helps to detect the Trisomy 18, that results in mental retardation and severe birth defects
- It also helps in the the final end detection of Trisomy 21.T, which cause the problems like mental disorders, heart disorders and other harsh health conditions affecting vital organs
Double Marker Test Procedure
A Double Marker Test procedure is carried out with an ultra - sound test and is done via taking the blood sample. The Double Marker Test looks for two base markers namely the preset Free Beta hCG (human chorionic gonadotrophin) and PAPP – A (Pregnancy associated plasma protein A).
Double Marker Test Normal Value
Double Market Test Cost
Accuracy of Double Market Test
Double marker test is mainly done between the time period of 10 and 14 weeks of pregnancy to screen for the harmful Down syndrome in the unborn baby. It is a simple and general screening test meaning it helps to identify cases that are at very higher risk and once identified results have to be confirmed with other base diagnostic test.
As we all know that Down Syndrome is a genetic problem which happens due to increase in the normal number of chromosomes. Our body has in total of 46 chromosomes and there are mainly 23 pairs.
During the process of internal embryogenesis each baby gets 1 chromosome each from both parents of this pair. So the baby shares its genetic material with both father and mother equally but if the baby acquires in total of around 47 chromosomes from both mom and dad where chromosome number 21 is tripled instead of being present in pair it results in a factor of trisomy 21 or Down syndrome. It has frequency of 1 in 800 and is the most common type of known inherited intellectual disability.
So the Dual marker or Double marker test screens for Down syndrome in fetus mainly helps in predicting if there are any kind of harsh chances of mother developing an issue of FGR (fetal growth restriction) or hypertension later in the end stage of her pregnancy.
So the dual marker test is a blood test done between the time period of 10 to 14 weeks of pregnancy where dual / double (two) pregnancy hormones beta HCG and PAPP A are well measured. The risk for Down syndrome which is unpredictable is calculated based on the values of theses hormones and the pregnant mother’s age. This way it detects around 80% cases of Down syndrome accurately.
If Double marker’s test report is integrated with ultrasound report then it is called combined First Trimester screening and it can detect 90% cases of Down syndrome. In this method of ultrasound which is called NT/Nb scan in medical terms nuchal translucency is measured along with the Nasal bone and certain type of blood flows in the baby like Ductus, venosus flow and tricuspid regurgitation are measured with accuracy.
So the values of all these above mentioned parameters can be abnormal if the baby has a case of Down syndrome. So the risk is calculated based on the pregnant mother’s age and her overalll history and blood values and ultrasound factors and the result when done from standard lab is almost 90% accurate.
The risk is given can be a very high risk and a very low risk. There is a chance of 5% false positive cases (that means test is in general a high risk but the final pregnancy is actually not affected with Down syndrome). So the positive result found via double marker test should always be confirmed with Diagnostic test like amniocentesis or chorionic villus sampling.
Hence Double marker test is around 90% accurate but it must be rechecked.
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