The Double Marker test is a biochemical marker test which is prescribed to a pregnant lady as a part of the routine antenatal screening. It is usually done between 11 to 13 weeks of pregnancy.
The double marker test is done with a blood sample. It checks for two markers- Free β-hCG (human chorionic gonadotrophin) and PAPP-A (pregnancy-associated plasma protein A). The NT scan is a uses ultrasound during pregnancy to assess the development of the growing fetus.
The Double marker test requires a venous blood sample taken from a vein in the upper arm of the patient, it is collected in a vacutainer and sent to laboratory for testing. The NT scan is done using an ultrasound machine and a trained radiologist assessing the parameters for the scan.