Introduction:
- A maternal serum marker test is a blood test that measures the levels of certain substances in the blood of a pregnant woman. These substances, called “markers,” can indicate the presence of certain conditions or disorders in the developing fetus.
- Maternal serum marker tests are typically performed during the second trimester of pregnancy, between the 15th and 20th weeks. The test is usually done in a laboratory and involves taking a blood sample from the pregnant woman’s arm.
- Maternal serum marker tests are used to screen for a range of conditions, including chromosomal abnormalities, such as Down syndrome, and neural tube defects, such as spina bifida. The test can also be used to monitor the health of the fetus and identify any potential problems that may require further evaluation or treatment.
- It’s important to note that maternal serum marker tests are screening tests and are not diagnostic. If the test results are abnormal, it does not necessarily mean that there is a problem with the fetus. Further testing, such as amniocentesis or chorionic villus sampling, may be needed to confirm a diagnosis.
Types of Serum marker:
Maternal serum marker tests are blood tests that are used to screen for certain chromosomal abnormalities or birth defects in a developing fetus. The tests measure the levels of specific substances, known as markers, in the blood of the pregnant woman. Elevated levels of certain markers can indicate an increased risk of certain chromosomal abnormalities or birth defects.
It’s important to note that maternal serum marker tests are only used to screen for certain conditions and are not diagnostic tests. If an increased risk is detected through a maternal serum marker test, further testing, such as amniocentesis or chorionic villus sampling, may be recommended to confirm the diagnosis. There are several different maternal serum marker tests that can be performed during pregnancy, including:
Pregnancy-associated plasma protein-A (PAPP-A): This test measures the level of PAPP-A in the mother’s blood. Low levels of PAPP-A can indicate an increased risk of Down syndrome or other chromosomal abnormalities.
Human chorionic gonadotropin (hCG): This test measures the level of hCG in the mother’s blood. Elevated levels of hCG can indicate an increased risk of Down syndrome or other chromosomal abnormalities.
Alpha-fetoprotein (AFP): This test measures the level of AFP in the mother’s blood. Elevated levels of AFP can indicate an increased risk of neural tube defects, such as spina bifida.
Inhibin-A: This test measures the level of inhibin-A in the mother’s blood. Elevated levels of inhibin-A can indicate an increased risk of Down syndrome or other chromosomal abnormalities.
First trimester Marker screening tests:
First trimester screening tests are used to screen for certain chromosomal abnormalities or birth defects in a developing fetus. The tests are usually performed during the first trimester of pregnancy, between 11 and 14 weeks.
First trimester screening tests are not diagnostic tests, and a positive result does not necessarily mean that the baby has a chromosomal abnormality or birth defect. If an increased risk is detected through first trimester screening, further testing, such as amniocentesis or chorionic villus sampling, may be recommended to confirm the diagnosis.
There are two main types of first trimester screening tests:
Nuchal translucency (NT) ultrasound
This test uses ultrasound to measure the thickness of the nuchal fold, a fold of skin at the back of the fetus’s neck. A thicker nuchal fold can indicate an increased risk of chromosomal abnormalities, such as Down syndrome.
Double marker test
The test measures the levels of two specific markers in the mother’s blood: human chorionic gonadotropin (hCG) and pregnancy-associated plasma protein A (PAPP-A). These markers are produced by the placenta and can be detected in the mother’s blood as early as the first trimester of pregnancy.
High levels of hCG and low levels of PAPP-A may indicate an increased risk of certain birth defects, such as Down syndrome, while low levels of hCG and high levels of PAPP-A may indicate an increased risk of other chromosomal abnormalities, such as trisomy 18.
The double marker serum test is usually done in conjunction with an ultrasound examination to get a more complete picture of the developing fetus. It is important to note that the test is not diagnostic and is only intended to assess the risk of certain birth defects. If the test results suggest an increased risk, further testing, such as amniocentesis or chorionic villus sampling, may be recommended to confirm the diagnosis.
Second trimester Marker screening tests:
Second trimester marker screening tests are blood tests and ultrasound examinations that are used to assess the risk of certain birth defects or chromosomal abnormalities in a developing fetus. These tests are typically performed during the second trimester of pregnancy, which is defined as the 13th to 27th weeks of pregnancy.
It’s important to note that these tests are not diagnostic, meaning they cannot definitively confirm or rule out the presence of a birth defect or chromosomal abnormality. They are simply used to assess the risk of certain conditions and inform further testing or monitoring. It’s also important to discuss the potential risks and benefits of these tests with a healthcare provider before deciding whether to undergo them.
Some common second trimester marker screening tests include:
Ultrasound
During the second trimester, an ultrasound can be used to examine the fetus’s organs and structures to check for any abnormalities. The ultrasound may also be used to determine the baby’s size and position, as well as the amount of amniotic fluid surrounding the baby.
Quadruple Test (Quad Marker) Test
The quadruple test, also known as the quad marker test, is a screening test that is used to assess the risk of certain birth defects or chromosomal abnormalities in a developing fetus. The test is typically performed during the second trimester of pregnancy, between the 15th and 20th weeks.
During the quad marker test, a healthcare provider takes a blood sample from the mother and sends it to a laboratory to measure the levels of four substances: alpha-fetoprotein (AFP), human chorionic gonadotropin (hCG), estriol, and inhibin-A. These substances are produced by the developing fetus and the placenta and are found in the mother’s blood.
Risks:
These tests are generally considered to be safe for the mother and the baby, with minimal risks involved.
It’s important to discuss the potential risks and limitations of maternal serum marker tests with a healthcare provider before deciding whether to undergo one. However, as with any medical procedure, there are some potential risks and limitations to consider when undergoing a maternal serum marker test. These may include:
False-positive or false-negative results: Maternal serum marker tests are not diagnostic, meaning they cannot definitively confirm or rule out the presence of a birth defect or chromosomal abnormality. As a result, the test may produce false-positive or false-negative results, which can cause unnecessary anxiety or false reassurance for the mother.
Risk of infection: There is a small risk of infection associated with any blood draw, as there is a possibility of the needle puncturing the skin and coming into contact with bacteria.
Limited accuracy: Maternal serum marker tests are generally less accurate than diagnostic tests, such as amniocentesis or chorionic villus sampling.
Stress and anxiety: The process of undergoing a maternal serum marker test and waiting for the results may cause stress and anxiety for the mother.
Benefits:
Maternal serum marker tests are blood tests that are used to assess the risk of certain birth defects or chromosomal abnormalities in a developing fetus. These tests may offer several potential benefits, including:
Early detection: Maternal serum marker tests can be performed early in pregnancy, allowing for early detection and intervention if necessary. This can be especially important for conditions that require prompt treatment, such as neural tube defects.
Risk assessment: Maternal serum marker tests can help to assess the risk of certain birth defects or chromosomal abnormalities, which can inform further testing or monitoring. This can help parents to make informed decisions about their pregnancy and plan for the future.
Non-invasive: Maternal serum marker tests are non-invasive, meaning they do not involve any procedures that involve inserting a needle or other instrument into the uterus. This can be appealing to some women who wish to avoid more invasive procedures, such as amniocentesis or chorionic villus sampling.
Convenience: Maternal serum marker tests can be performed in a healthcare provider’s office and do not require a hospital stay. This can be convenient for mothers who have busy schedules or who live far from a hospital.
References:
- Cuckle H. Prenatal Screening Using Maternal Markers. J Clin Med. 2014 May 9;3(2):504-20.
- Chitayat D, Langlois S, Douglas Wilson R; SOGC GENETICS COMMITTEE; CCMG PRENATAL DIAGNOSIS COMMITTEE. Prenatal screening for fetal aneuploidy in singleton pregnancies. J Obstet Gynaecol Can. 2011 Jul;33(7):736-750
- Audibert F, Gagnon A; Genetics Committee of the Society of Obstetricians and Gynaecologists of Canada; Prenatal Diagnosis Committee of the Canadian College of Medical Geneticists. Prenatal screening for and diagnosis of aneuploidy in twin pregnancies. J Obstet Gynaecol Can. 2011 Jul;33(7):754-67.