The Quadruple Marker Test, also called the Quad Screen, or quad test is a blood test that measures the levels of four different biomarkers in a pregnant woman's bloodstream. The test is commonly done between the 15th and the 20th week of pregnancy to evaluate the possibility of chromosomal abnormalities and neural tube defects.

What is a Quadruple Marker Test?

The Quadruple Marker Test, also called the Quad Screen, or quad test is a blood test that measures the levels of four different biomarkers in a pregnant woman's bloodstream. The test is commonly done between the 15th and the 20th week of pregnancy to evaluate the possibility of chromosomal abnormalities and neural tube defects.

The four biomarkers evaluated in the quadruple marker test are:

1. Alpha-fetoprotein (AFP): AFP is a protein the fetus produces and is found in the amniotic fluid and maternal blood. Elevated levels could indicate a neural tube defect, such as spina bifida, or an issue with the baby's digestive tract.
2. Human chorionic gonadotropin (hCG): It is produced by the placenta. Higher levels could indicate chromosomal issues like Down syndrome or molar pregnancy.
3. Unconjugated Estriol (uE3): Estriol is a hormone formed by the placenta and baby's liver. Low levels indicate the possibility of developmental issues like Down’s syndrome.
4. Inhibin A: The hormone is produced by the placenta and used to evaluate the possibility of fetal chromosomal abnormalities.

The quadruple marker test is not typically used as a diagnostic tool but as an initial screening tool for chromosomal abnormalities or neural tube defects. This means that if the results show elevated levels, additional diagnostic testing would be required to confirm the diagnosis. There is a possibility of a false-positive or false-negative result, which is why a quadruple marker test is not considered a diagnostic tool.

What is the purpose of the Quadruple Marker Test?

A quadruple marker test may be recommended to ensure your baby's health. The quadruple marker test is a valuable tool for detecting potential health issues in the developing fetus and can provide important information to guide medical decisions throughout pregnancy. By combining the results of the quadruple marker test with other diagnostic tests, such as ultrasound and amniocentesis, healthcare providers can make informed decisions about the health of the fetus.

Your doctor may recommend a quadruple marker test:

• If you're pregnant and are 35 years or older.
• Have a family history of birth defects.
• Had a viral infection during your pregnancy
• Used harmful drugs or medications while pregnant.
• Have diabetes and use insulin.

It is important to note that the quadruple marker test is a screening test, not a diagnostic one. If the test indicates an increased risk of fetal abnormalities, further diagnostic tests, such as chorionic villus sampling (CVS) or amniocentesis, may be recommended.

What does Quadruple Marker Test Diagnose?

The Quadruple marker test helps doctors identify potential health issues in the developing fetus, such as:

• Down Syndrome: This genetic disorder causes developmental delays and physical abnormalities. The Quadruple test can detect Down Syndrome by measuring the levels of AFP, hCG, and estriol in the mother's blood.
• Neural Tube Defects: These are structural abnormalities of the spinal cord and brain, which can cause developmental delays, paralysis, and other serious complications. The Quadruple marker test can detect neural tube defects by measuring the level of AFP in the mother's blood.
• Abdominal Wall Defects: These are birth defects that affect the development of the abdomen and can lead to hernias, malformations, or other serious complications. The Quadruple marker test can detect abdominal wall defects by measuring the levels of AFP and estriol in the mother's blood.
• Other Congenital Disabilities: The Quad screen can also detect other congenital disabilities, such as Turner Syndrome and triploidy by measuring the levels of hCG and inhibin A in the mother's blood.

Preparation and procedure required for the Quadruple Marker Test:

The Quadruple marker test is a simple blood test that can be performed at your healthcare provider's office or a laboratory. There is no special preparation required for this test. You can eat, drink and take your medications as usual before the test. However, it's recommended that you wear comfortable clothing that allows easy access to your arm for the blood draw.

Procedure:

Here's what you can expect during the procedure:

• A healthcare provider will clean your arm with an antiseptic solution and then wrap a tight band around your upper arm to make your veins more visible.
• They will then insert a small needle into a vein in your arm and collect a small sample of blood into a tube.
• Once the blood is collected, the needle will be removed, and a bandage or cotton ball will be placed over the injection site to stop bleeding.
• The blood sample will be sent to a laboratory for analysis, and the results will be sent to your healthcare provider.

Feeling a slight pinch or prick during the blood draw is normal, but the procedure is generally painless and takes only a few minutes to complete. You may experience some mild bruising or soreness at the injection site, but this typically goes away within a few days.

Understanding the Quadruple Marker Test results:

Understanding the results of a Quadruple marker test can be overwhelming, especially for those with no medical background. Here are a few key points that can help make the results easier to understand:

• Normal range: Each of the four substances tested for in the Quadruple Marker Test has a normal range of values that are typically seen in healthy pregnancies. If the results fall within this normal range, it usually means that there is no cause for concern.
  
  Typically, the normal level of AFP in the mother's blood increases throughout pregnancy and peaks around 32 weeks, then begins to decrease. The normal level of hCG and inhibin-A increase throughout pregnancy, while the level of uE3 tends to decrease.
  
  
• Abnormal range: If any of the substances tested fall outside the normal range, it may indicate a potential issue with the pregnancy. However, an abnormal result does not necessarily mean that there is a problem with the baby, as there are many factors that can affect the test results. For example, a high level of AFP in the mother's blood may indicate a neural tube defect, while a low estriol level may suggest Down syndrome.