Quad Marker test With Graph
What is Quad Marker test With Graph?
Quad marker with graph test is also known as the Quadruple test. This test measures the levels of four important substances in the placenta namely alpha fetoprotein, human chorionic gonadotropin, estriol, and inhibin A. This test is advised to women who are 15 to 20 weeks pregnant. It analyses the probability of the unborn baby to have certain genetic disorders like Down’s, Edward’s syndrome, neural tube defects, and sometimes multiple pregnancies.
Why is Quad Marker test With Graph done?
To diagnose Down syndrome
To diagnose neural tube defects
To diagnose the failure of closure of the abdomen in the fetus.
To diagnose multiple pregnancies
To diagnose miscarriage or ectopic pregnancy
What does Quad Marker test With Graph Measure?
This test measures four markers which include AFP, HCG, estriol, and inhibin A in the blood. As there are four markers involved, it is known as the Quad Marker test.
AFP is a protein which is produced by the fetus. If the levels of AFP are high, it indicates neural tube defects in the fetus or any case of incomplete closure of the fetus abdomen.
HCG hormone is produced by cells of the placenta. If the levels of HCG are low, it indicates a miscarriage or ectopic pregnancy. Whereas, if the levels of HCG are high this indicates multiple pregnancies.
Estriol is a form of the hormone estrogen which is present in both fetus and placenta. If the levels of estriol are low, it indicates the risk of the baby getting delivered with Down syndrome, especially when the levels of AFP are low and HCG are high.
Inhibin A is a hormone which is produced by the placenta. It is a dimer which means it has two parts. It is also sometimes referred to as DIA or dimeric inhibin A. In the 14 to 17 weeks of gestation (pregnancy), the levels of inhibin A in maternal blood slightly decrease and then rise again. Increased levels of Inhibin A indicates fetus with Down syndrome. Inhibin A enhances the sensitivity as well as the specificity in order to correctly identify cases of Down syndrome.
If the levels of all these four markers are abnormal, there can be the presence of neural tube defects like spina bifida (spinal cord fails to develop properly), anencephaly (absence of brain, skull, and scalp), and multiple pregnancies (twins or triplets).
Females who are 35 years or more, have a family history of birth defects, or have diabetes or are using insulin have a higher risk of getting abnormal values of these markers. Exposure to high levels of radiation or having the viral infection during pregnancy can also be considered as possible risk factors associated with these high levels. This test is also helpful to indicate any complications in the fetus after birth.
Interpreting Quad Marker test With Graph results
Neural tube defects
≥ 2.5 MoM (Multiples of median)
Down Syndrome (Trisomy 21)
75 -80 %
Edwards Syndrome (Trisomy 18)
Reference range may vary from lab to lab*
The base of screening tests is a statistical analysis of patient’s data which includes the demographic (statistical study of populations) and biochemical (laboratory) data.
Confirmation is mandatory by amniocentesis.
The results are illustrated in the form of a graph in the test report.
Positive quadruple marker test usually indicates that the unborn child has a high risk of neural tube defects and chromosomal disorders like Down's syndrome, Patau syndrome, etc. More specific tests like amniocentesis are then advised to make a definitive diagnosis
High levels of inhibin A usually indicate Down's syndrome whereas low levels might be associated with Edward's syndrome or trisomy 18. Sometimes, variable levels of inhibin A may also be present, and they are usually associated with trisomy 13 or Patau syndrome