The Quad Screen Test also known as the quadruple marker test or the second-trimester testing is a prenatal test that measures levels of four substances in pregnant women’s blood. The test is similar to that of Triple Screen Test where along with three substances another substance, Inhibin- A is evaluated. Inhibin-A is a protein produced by the placenta and ovaries. The test determines whether your pregnancy has an increased chance of being affected with certain conditions, such as Down syndrome or neural tube defects.
When is Quadruple Marker Screen Test performed?
The quad screen is done between weeks 15 and 18 of pregnancy, during the second trimester. However, the procedure can be done up to week 22. Every pregnant woman should be offered with a triple screen test, but it is recommended for women who:
- Have a family history of birth deficiencies
- Are 35 years or older
- Used possible harmful medications or drugs during pregnancy
- Have diabetes and use insulin
- Had a viral infection during pregnancy
- Have been exposed to high levels of radiation
How is the Quadruple Marker Screen Test administered?
The triple marker screen test is administrated in a hospital, clinic, doctor’s office, or lab. The process is similar to any other blood test. This involves drawing around 4-5 ml blood from mother which takes for 5- 10 minutes and will be sent to the laboratory for testing. The results usually take a few days after receiving the blood.
What does the Quadruple Marker Screen Test look for?
The quad screen measures high and low levels of AFP, abnormal levels of HCG and estriol, and high levels of Inhibin-A. The results are combined with the mother’s age and ethnicity in order to assess the probabilities of potential genetic disorders. High levels of AFP may suggest that the developing baby has a neural tube defect such as spina bifida or anencephaly.
However, the most common reason for elevated AFP levels is inaccurate dating of the pregnancy. Low levels of AFP and abnormal levels of HCG and estriol may indicate that the developing baby has Trisomy 21(Down syndrome), Trisomy 18 (Edwards Syndrome) or another type of chromosome abnormality.
What are the results of Quadruple Marker Screen Test?
Quad screen results give the level of risk of carrying a baby who has certain conditions compared with the general population’s risk. The positive quad screen simply means that levels of some or all of the substances measured in your blood were outside the normal range. If your test results are positive, your health care provider might recommend an ultrasound to verify the baby’s gestational age and confirm the number of babies you’re carrying.
Is there any risk associated with quadruple Marker Test?