Quadruple Marker Test – There are many tests carried out during the time of pregnancy that can help one check up on maternal and foetal wellbeing. Marker tests help in detecting congenital and genetic disorders in the foetus. Most of the time, marker tests are carried out to see if the foetus could potentially have Down’s syndrome, a chromosomal abnormality affecting the physiological and psychological development of the child. For this reason, these tests are of utmost importance in the first and second trimester.
Dual Marker Test
The dual marker test is a screening test, or a blood test conducted during the first trimester, anytime between the 11th and 13th week of pregnancy. This test is often accompanied by a Nuchal Translucency scan, better known as an NT scan. The blood test is intended on measuring two markers called the human chorionic gonadotrophin, hCG, and the pregnancy-associated plasma protein or PAPP-A, while the NT scan gauges the fluid under the skin at the back of the foetus’ neck. The results of these tests can determine whether the child would have Down syndrome. If the results present unusual levels of hCG and PAPP-A, along with a high NT scan value, then it is highly likely that the child is at risk for Down Syndrome. These results will also show if the mother falls in the screen positive AKA high risk or screen negative or low risk category. One out of 350 expecting mothers in India carries a down syndrome baby, and depending on the results, the mother would be advised for more invasive tests such as Screening for Down Syndrome, amniocentesis, or CVS sampling.
Triple and Quadruple Marker Test
Unlike the dual marker test, a triple or quadruple screening test is carried out during the second trimester of pregnancy. The 15th to 20th week period is ideal for conducting these tests. Normally, a quadruple marker test is comparatively more sensitive than the triple marker test. For both of these tests, the expecting mother is advised to take these tests to check if the foetus will inherit any genetic disorders.
For the quadruple marker test, beta subunit of human chorionic gonadotrophin or b-hCG, serum alpha-fetoprotein or AFP, unconjugated estriol uEst, and Inhibin A, are the four hormones that are checked.
If the expecting mother is at risk of carrying a child who will have Down syndrome, then there are chances of hCG being high, while AFP and uEst would be lower than usual. Similar to the dual marker test, the doctors will go on to suggest other invasive tests based on the results of aforementioned tests.
Note: These screening tests have 99.9% accuracy, and hence any major decisions should be taken only once you consult the doctor.