Triple Marker Test – Procedure, When is it required and Results

Lab Test and Medical Investigation

Overview

Pregnancy is a beautiful phase in a woman’s life. Sometimes, certain genes are passed on from the parents to the child. Therefore, doctors recommend several tests and scans to ensure that the child has no chromosomal defect. One of the tests that can help detect chromosomal defects is the triple marker test. Read all about the triple marker test, associated benefits, and the reasons why it may be prescribed.

What is a triple marker test?

A triple marker test is a simple test to identify any genetic or chromosomal disorder, during the prenatal phase.

When is a triple marker test required?

A triple marker test is a blood test that is conducted on pregnant women between the gestational age of 15 to 20 weeks to assess for possible defects in the unborn baby. This test may be necessary if the results of the double marker test are inconclusive. If the expectant mother has any of the following signs and traits, then this test is highly advisable.

A family history of genetic problems
Above the age of 35 years or more
Diabetic and takes insulin
Suffering or experienced prenatal viral infection
Exposure to radiation
Consuming medication with significant side effects

The healthcare provider may recommend this test in the second trimester to analyse the serum levels of three hormones, namely:

Alpha-fetoprotein (AFP)
Unconjugated estriol
Human chorionic gonadotropin (beta-hCG)

What are the different types of hormones that are tested in the triple marker test?

As mentioned above, three hormones are analyzed in the triple marker test. Here is a detailed understanding of all three hormones.

1. Alpha-fetoprotein (AFP)

This is a protein produced by the foetus. High levels of this protein, if detected, 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.

Although the primary reason for conducting the test is to screen for genetic disorders, the results of the triple screen can also be used to identify:

A pregnancies
Pregnancies that are more or less advanced than thought

2. Estriol

Found in both the foetus and the placenta, low levels of estriol indicate the risk of the baby being born with Down syndrome. When coupled with low AFP levels and high hCG levels, the risk is even higher.

3. Human chorionic gonadotropin (hCG)

Produced in the placenta, low levels of hCG may indicate ectopic pregnancies or even miscarriages. On the contrary, high levels of hCG may denote molar pregnancies or multiple pregnancies.

When do you need to visit a doctor?

If the result of the triple marker test is inconclusive or indicates abnormal levels, then it is highly recommended that you visit your healthcare provider at the earliest.

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How should a pregnant woman prepare for the triple marker test?

Pregnant women do not need to carry out any preparations for the triple marker test and there are no fasting requirements for this test.

What happens during the procedure?

It is similar to a blood test. Once the skin is cleaned, the needle is inserted to draw blood. The blood is later sent to the lab for analysis. A rubber band may be placed to make the vein more accessible.

What are the complications of the triple marker test?

There are no complications associated with the triple marker test apart from the mild discomfort that comes with needles.

What are the benefits of the test?

A triple marker screen test can indicate potential complications that are associated with a pregnancy, and the presence of multiple pregnancies as well. This may assist the parents in being appropriately prepared for the birth.

What do the triple test results mean?

It is important to remember the triple test is a screening test and not a diagnostic test. This test only notes that a mother is at possible risk of carrying a baby with a genetic disorder. The triple screen test is known to have a high percentage of false-positive results.

Abnormal test results warrant additional testing for making a diagnosis.

Doctors frequently consider several other factors that might affect the test results including:

The mother’s weight, ethnicity, and age
Whether or not the mother is diabetic
Whether or not the mother is carrying multiple fetuses

What should be the next steps after receiving the results?

the triple marker test has a high rate of false-positive reports. A healthcare provider will know how to accurately read the report. Therefore, it is important to discuss the results with them.

A more conservative approach involves performing a second triple screen followed by a high definition ultrasound. If the testing still displays abnormal results, a more invasive procedure like amniocentesis may be performed. Invasive testing procedures should be discussed thoroughly with your healthcare provider and between you and your partner.

When the results show high levels of AFP, the doctor may order a detailed ultrasound to examine the fetal skull and spine for neural tube defects. Ultrasounds might also help determine the age of the foetus and the number of foetuses a woman is carrying.

Conclusion

Various pregnancy-related tests and scans are crucial to determine if a woman is expecting a healthy baby or not. If there is a risk of a defect in the baby, this test can help the parents be better prepared to handle the health issues that may arise from the expected condition.

Frequently Asked Questions

What are the disorders that can be screened with the help of the triple marker test?

The following are some of the disorders that can be screened via this test:

Down syndrome
Edward syndrome
Neural tube defects
Other chromosomal abnormalities

Is there any possibility of harm to the baby during the test?

The blood is drawn from the mother to be analysed in the laboratory and there is no procedure performed on the baby. Therefore, there is no harm to the baby during this test.