Quadruple marker test : When is it advised & Is it compulsory?-Dr. Beena Jeysingh

Quadruple marker test is a test performed on the mother who is pregnant, it is atleast assessed to test the risk of the fetus carrying any one of the chromosomal abnormalities such as trisomy 21, Down’s syndrome, or Trisomy 18 or the fetus having a risk of having an open neural defect, a defect of the brain and the spinal cord. In the Quadruple marker test there are 4 substances that are assayed. One is the alfa fetoprotein, a substance produced by the fetal liver, then beta human chorionic gonadotropin, which is a hormone secreted by the placenta, estriol and estrogen secreted by the fetal liver and inhibin A, a substance secreted by the placenta. This Quadruple marker blood test is not a confirmatory diagnosis. It helps us to assess the risk and gives us a pointer to whether we have to do further confirmatory tests to conform the diagnosis, so if a patient comes as screen positive for the test, it doesn’t mean 100% positive, the fetus has the abnormality. Likewise if the fetus is screen negative, does not 100% give the assurance that the baby does not have the defects that have been spoken earlier, so what is the accuracy of the test? This test have been known to be 80% accurate in detecting fetus with Down’s syndrome and 85% in detecting a fetus with open neural defect. If a lady has been tested positive, screen positive with Quadruple marker test, then what are the other tests that are available to conform the diagnosis? First is the level 3 scan. And see if there are any other chromosomal markers or abnormalities in the baby. The condomration comes from a an invasive test called as amniocentesis wherein a needle is generally passed in under ultrasound guidance water from around the baby is picked up and the cells that are floating in the water are picked up and send in for the chromosomal analysis . but being an invasive test, the incidence of miscarriage is about 1 in 300. There is another non invasive test called as the NIPP test hat is also used for the confirmatory test. It involves taking blood sample form the mother and the fetal cells that are circulating in the mother are then send in for chromosomal studies. It gives a sensitivity and accuracy not 100%, but 99%. This Quadruple marker test is usually performed between 15 and 20 weeks of pregnancy, we offer it as a routine and counsel every pregnant woman about this test, . But we find that there are not many who opt to do it because of the uncertainly that prevails around the test, but we do stress that it is good for certain women to go for the tests and who are they? Women at 35 years of age and above because there is an increase of incidence of Down’s syndrome, women who suffer form Type 1 diabetes, because they are at infrareds risk of having one neural tube defect, and women who have had previous pregnancies with chromosomally abnormal children namely Downs’ syndrome or those who have had children born with congenital heart disease or those who have a family history of chromosomal abnormality or congenital birth defects.