Quad mark test

The quad marker screening test (quad screen) is a blood test usually done between the 16th and 18th weeks of gestation. It provides information about whether there is an increased risk for certain birth defects in the baby, like Down Syndrome and neural tube defects. The test involves taking a blood sample from the mummy, and checking the levels of 4 substances that are normally found in the baby's blood, brain, spinal fluid, and amniotic fluid. Do note that, quad marker is a screening test, meaning that it gives information about risk, and not a diagnosis. As with any screening test, an abnormal result does not mean that the foetus definitely has a birth defect or genetic condition. It only means that the blood levels of these four substances suggest that a woman's risk is increased of having a baby with certain conditions. Women who have a result suggesting increased risk are usually offered further testing.