Thank you Ma'am, I want to know that double marker test is done for some specific purpose, so what is that?

An ultrasound scan is like a window in the womb. It works on sound rays and will show the doctor the fetus and other aspects of the pregnancy. First scan is done to establish gestational age, number of fetuses and placenta position. The double triple or quadruple marker test is a blood test and it's a hormonal test. It depends on which one your doctor prefers depending on the risk factor expected. These are standard tests prescribed for every pregnancy.