Dual Marker Test

Also known as Maternal Double Marker

This test is for

Female

Test Preparation

Provide maternal Date of birth (dd/mm/yy); Last date of your menstrual cycle, Ultrasound; Number of Fetuses (Single/Twins); Diabetic status and Body Weight in Kg, IVF, Smoking & Previous history of Trisomy 21 pregnancy at the time of sample collection. It is mandatory to fill a Maternal Serum Screen requisition form at the time of sample collection.
No special preparation required
Test is valid between 9-13 weeks of gestation (Ideal for combined risk assessment 11-13 weeks). Please keep the hard copy of your latest pregnancy ultrasound report(CRL, NT/NB or Level 1) and Maternal Screen details (LMP , DOB , Body Weight, Diabetic status & IVF) ready at the time of your test.

Understanding Dual Marker Test

What is Dual Marker Test?

Dual marker test is a first trimester screening test advised to all pregnant women, for assessing the risk of certain genetic abnormalities in the fetus. It can be conducted between the 9th-13th week of pregnancy, but the ideal sampling time is between 11-13^th week. The term “Dual Marker” means two markers are tested -Free beta human chorionic gonadotropin ( fβ-HCG ) & Pregnancy-Associated Plasma Protein (PAPP-A ). It helps in evaluating the risk of a fetus developing Trisomy 21 (Down syndrome) and Trisomy 13/18 syndrome. As these genetic conditions lead to mental retardation and other medical illnesses which might impact the vital organs of the fetus, it is extremely crucial for all pregnant women to undergo this investigation.

Dual Marker is a screening test, not a diagnostic test. This test is based on a predictive and statistical approach, further testing is always needed to confirm a diagnosis.

*The accuracy of the results is subjective to the information provided in the screening form(Annexure - CR 02) and this information is mandatory for combined risk assessment

* For combined risk assessment, it is always advisable to get tested in 11-13 weeks of pregnancy.

What does Dual Marker Test measure?

This test measures the levels of b-hCG and PAPP-A in blood with the ultrasound test. b-hCG is a hormone which is produced by the cells in the developing placenta during pregnancy. The levels of b-hCG increases in early pregnancy. The role of b-hCG in early pregnancy is to maintain the function of corpus luteum (the hormone-secreting structure that develops in an ovary). During the first three weeks production of b-hCG increases reaching to peak levels at 10th week (from the last menstrual cycle). After that, the levels of b-hCG start to fall to negligible within a few weeks after delivery.

PAPP-A is secreted by the placenta and its levels increase with duration of pregnancy. Variety of tissues express PAPP-A at very lower levels. Plaques which are not stable in coronary arteries also express PAPP-A in high levels.

Dual marker test is done along with Nuchal Translucency test to confirm the diagnosis of any genetic abnormality.

Nuchal Translucency (NT) is a measurement of the fluid beneath the skin along the back of the baby's neck. NT is measured by ultrasonography.

Interpreting Dual Marker Test results

Interpretations

All women should be screened for dual marker test in pregnancy for any pre-birth abnormalities irrespective of age. The ideal duration of this test is between 10-13 weeks of pregnancy. But it can be done between 9-13 weeks of pregnancy.

Answers to Patient Concerns & Frequently Asked Questions (FAQs) about Dual Marker Test

Frequently Asked Questions about Dual Marker Test

Q. Is there any risk associated with this test?

There is no risk associated with the test. However, since this test involves a needle prick to withdraw the blood sample, in very rare cases, a patient may experience increased bleeding, hematoma formation (blood collection under the skin), bruising or infection at the site of needle prick.

Q. Is Dual marker test especially for pregnant ladies above the age of 35 years?

No, it is advised to younger women as well. It helps in screening any birth abnormalities in the fetus before birth. As after the age of 35 years, the risk of Down’s syndrome increases especially in those women who have a family history of any birth defects or the women who have given birth to a child with any birth defects previously or there is a history of insulin-dependent type 1 diabetes.

Q. What is the importance of ultrasound in Dual marker test?

The doctor usually advises ultrasound before advising the Dual marker test. Based on the results of ultrasound test, Dual marker test is advised.

Q. What are the advantages of Dual marker test?

Dual Marker test helps you to go for other diagnostic tests if it comes positive. If the test is done earlier in pregnancy and it comes positive, early decisions can be taken.

Q. What is Down's syndrome?

It is a genetic disorder in which extra genetic material from chromosome 21 gets transferred to the fetus. This transfer affects the development of the fetus leading to abnormal development both physically and mentally. The affected baby will have a small head and short neck, obliquely positioned eyes looking in an upward direction, large tongue coming out of the mouth, flat face, wide hands with short fingers, and lack of muscle tone.

Q. What is Trisomy 18?

It is also known as Edwards Syndrome which is caused by the development of an extra chromosome 18. Because of this, the normal pattern of development in the baby gets disturbed even before its birth. The effects caused by Trisomy 18 are very complicated as compared to Down syndrome. The effects are so severe that it can cause stillbirth (death at the time of birth) of the child.

Q. What is b-hCG?

b-hCG refers to Beta human chorionic gonadotropin. b-hCG is a hormone which is produced by the cells in the developing placenta during pregnancy. The levels of b-hCG increases in early pregnancy. The role of b-hCG in early pregnancy is to maintain the function of corpus luteum (the hormone-secreting structure that develops in an ovary).

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