What is this test?

The double marker test helps to detect chromosomal abnormalities in the growing fetus. It screens for diseases like Down's Syndrome, Patau Syndrome and Edwards Syndrome. These are all conditions in which the baby has 3 chromosomes instead of the normal 2 at different positions.

Who should do the double marker test?

The test should be done by all mother's during the first trimester (1st 3 months of pregnancy). It is even more important in mothers who fit the following criteria.

• Mother's age more than 35 : Women older than 35 years, should definitely get the double marker test, as their children are at a higher risk of chromosomal abnormalities.
• Family History : There is a family history of chromosomal abnormalities or complicated pregnancies.
• IVF Pregnancies : If you are having an assisted pregnancy, it is more important to have a double marker test
• Routine screening : The test is recommended in all pregnancies, between week 11-13.
• Mother is smoker : If the mother is a smoker, there is higher risk for chromosomal abnormalities in the baby and so this test is essential

When to do the Double Marker Test?

This test should be done during 11-13 weeks of pregnancy.

What does double marker test measure?

Double marker test measures levels of two hormones in the mother's blood. PPAP-A and free beta-hcg. Based on these levels, and data from recent USG report, it can predict the risk of chromosomal abnormalities in the fetus.

What are chromosomal abnormalities?

Normally, humans have 23 pairs of chromosomes. In conditions tike Down's syndrome, there are 3 chromosomes, instead of 2 at some positions. This leads to many diseases in later life. Double marker test can predict whether a fetus will have these diseases.

Which genetic disease can double marker test predict?

Double Marker Test can predict the risk of various trisomies - disorders in which there are 3 chromosomes at a given position, instead of two. Disease include :

• Down's Syndrome - 3 chromosomes at position 21, babies have poor immunity, low IQ, heart defects, abnormal face and poor long term survival.
• Edwards's Syndrome - 3 chromosomes at position 18, babies have many physical abnormalities
• Patau Syndrome - 3 chromosomes at position 13, babies have physical abnormalities.

How is the test done?

This is a simple blood test and requires no special preparation. You do not need to be fasting for this test.

To perform this test, a sample of blood will be drawn from your vein, by inserting a sterile needle. The blood sample will then be analyzed in the lab.

The test uses some data from USG or ultrasound report. For this purpose you are required to have a USG done before giving your blood sample and get the report of the USG with you while coming for this test.

What will be included in the report?

The report includes the levels of PPAP-A, free beta-hcg, together with risk estimates for Down's Syndrome and other trisomies. The following table describes each parameter in the double marker report:

Parameter	Meaning
Free Beta-HCG	Level of hormone, seen in pregnancy
PAPP-A	Pregnancy Associated Plasma Protein
Risk of Trisomy 13-18	Chances of fetus having chromosomal abnormalities at chromosomes number 13 or 18. Normal Range is less than 1%
Risk of Trisomy 21	Chances of fetus having chromosomal abnormalities at chromosome 21 (Down's Syndrome). Normal Range is less than 0.25%
Mother's Weight	Weight of mother
LMP Date	Date of last menstrual period of mother

How to read the double marker test report?

There are only two entries in the report that you need to focus on. The value of Trisomy 21 Risk - If this value is less than 1:250 (for eg : 1:1000 or 1:10000 ..), then there is nothing to worry. The other value you need to focus on is the value of Trisomy 13/18 Risk - As long as this value is less than 1:100 (for eg 1:250, 1:800, 1:1000 ..), there is nothing to worry.

What is the normal range of double marker test report?

Normal Ranges for Double Marker Test
Disease Name	Risk Cutoff
The normal range for Trisomy 21 (Down's syndrome)	less than 1/250
The normal range for Trisomy 18	less than 1/100

Summary

Sample Type	Blood
Time to Get Report	Upto 2 days
Test Method	CMIA
Normal Range	Down's Syndrome Risk : less than 0.25%, Trisomy 13/18 risk : less than 1%
Purpose of test	Detecting chromosomal abnormalities in fetus
Intended for	Adult pregnancy females
Fasting Required	No
Total Tests	4
Doctor's Prescription Required	Yes
Other requirements	Recent Ultrasound Report
Reports Available By	PDF available through Watsapp,Email and Hardcopy(on request)
Other Names	Dual Marker, Prenatal Screening Test, 1st trimester test