Pregascreen Quadruple Marker Test

Quadruple marker is a blood test done during the second trimester of pregnancy to identify chromosomal abnormalities in foetus. 

As per ACOG all pregnant women should be offered a prenatal screening and diagnostic test.

This tests screening pregnant women with HCG-?, AFP, uE3 & Inhibin A to establish risk to genetic anomalies in foetus. To further improve the accuracy of the high-risk results, if obtained, either NIPT or Karyotyping reflex to FISH of amniotic fluid is offered at no additional cost. The tests is recommended for pregnant women at14 to 22.6 weeks of gestation.

This test measures four markers (AFP, HCG, estriol & Inhibin-A) in the maternal blood.  This screening test provides statistical examination of patient’s data which includes the biochemical (laboratory) and demographical (statistical study of populations) data. The results are shown in the form of a graph in the test report. The chances of having a baby with Down syndrome or Trisomy 18 depend on multiple factors such as age & body weight of pregnant women, diabetic status & ethnicity etc. The quadruple screen can have false-negative and false-positive results (although it is slightly more accurate than the triple screen). NIPT (Screening) or Karyotyping and FISH of amniotic fluid (Any one) is used for confirmation of screen positives with consent.

Quadruple marker test is done to screen genetic disorders and other abnormalities in the foetus. It is very important to know that this is a SCREENING test and a positive (high risk) result does not confirm a defect. Further confirmatory tests should be done to reach a conclusion. Quadruple marker screen can predict approximately 75%-80% of open neural tube defects and can predict approximately 75% of Down syndrome cases in women under age 35 and over 80% of Down syndrome cases in women age 35 years and older. To increase sensitivity NIPT can be offered to patients. This test is also advised if the pregnant women is diabetic or has a family history of congenital disabilities.   If screen is positive reflex confirmation Either NIPT or Karyotyping and FISH of amniotic fluid is performed. 

This test requires a blood sample. A tourniquet (elastic) band is placed tightly on the upper arm. The patient is then asked to make a fist. This helps in the build-up of blood filling the veins. The skin is disinfected before needle insertion and the blood sample is collected in vacutainer.

Abnormal test (high risk pregnancy) result does not always indicate a birth defect; it might be because of a variation in the estimated gestational age or other factors. A more specific screening test (NIPT)/ confirmatory test like karyotyping/ FISH are highly recommended.
High levels of AFP point to neural tube defects in the foetus or there can be incomplete closure of the foetus abdomen. 
Low levels of HCG indicate a miscarriage or ectopic pregnancy. Whereas, if the levels of HCG are high this indicates multiple pregnancies. 
Low levels of estriol indicates a high risk with Down syndrome especially when the levels of AFP are low and HCG & Inhibin A are high. A negative screen doesn't guarantee that the baby won't have a chromosomal abnormality, single-gene disorder or certain birth defects. It is always suggested to consult your gynaecologist for any queries.