Triple Marker Test

The triple marker test, also called the triple screen or triple test, is a blood test performed during the second trimester of pregnancy to check for certain genetic conditions and birth defects in the baby. The test checks the amounts of three substances in the mother’s blood: alpha-foetoprotein (AFP), human chorionic gonadotropin (hCG), and unconjugated oestriol (uE3).

The test results are reviewed along with factors such as the mother’s age, the pregnancy stage, and sonography details to estimate the likelihood of genetic defects in the foetus. The triple marker test is mainly used to check for conditions such as Down syndrome and Edwards syndrome (genetic conditions caused by an extra chromosome) and birth defects that affect the brain and spinal cord, such as spina bifida (birth defect in the spinal column) and anencephaly (baby is born without major portions of the skull, brain and scalp).1,2,3 Screening tests cannot give a definitive answer as to whether a baby has such defects; however, they can provide critical information to help parents and doctors make an informed decision about whether further diagnostic tests should be performed.

The triple marker test in pregnancy is usually done during the second trimester, between 15 and 20 weeks. The best test results are obtained when the test is done between 15 and 18 weeks.

Who should consider the Triple Marker Test?

• Pregnant women who are having routine pregnancy check-ups during the second trimester.
• Women aged 35 years or older have a higher chance of having a baby with certain genetic conditions.
• Women with a family or previous pregnancy history may be at increased risk of genetic conditions.
• Pregnant women whose healthcare provider recommends additional tests based on earlier screening results or other findings.

The triple marker test is usually performed once during pregnancy as part of routine second-trimester prenatal screening, typically between weeks 15 and 18.

The test may help detect or support the diagnosis of the following conditions:

• Down syndrome (Trisomy 21): A genetic condition caused by having an extra copy of chromosome 21. Babies with Down syndrome may have typical physical features, grow more slowly, and have different levels of learning difficulties. The triple marker test helps estimate the likelihood of this condition.
• Edwards syndrome (Trisomy 18): A rare chromosomal disorder caused by an extra copy of chromosome 18. It is associated with severe birth defects and a high risk of miscarriage, stillbirth, or early infant death.
• Neural tube defects (NTDs): These include conditions such as spina bifida (affects the spine) and anencephaly (affects the brain). Increased levels of alpha-foetoprotein (AFP) in mothers may indicate an increased risk of these defects.

What to Expect Before the Triple Marker Test

No fasting is required for a standalone Triple Marker test. You can eat and drink normally. However, if it is part of a broader package that includes fasting tests, your doctor may advise fasting for 8-12 hours. Avoid strenuous exercise for 24 hours before the test, as intense physical activity can temporarily raise triple marker levels and affect interpretation. Always inform your doctor about any ongoing medications.

What to Expect During the Blood Collection

A phlebotomist cleans the skin with an antiseptic, then places an elastic band around your upper arm to make the veins easier to access. A small needle is inserted into the vein; you may feel a brief pinch. Blood is collected into a labelled tube in under a minute.

What to Expect After the Triple Marker Test

A small cotton swab and bandage are placed over the site to stop any minor bleeding. You can return to normal activities immediately. Minor bruising is normal and disappears quickly. If dizzy, sit and rest for a few minutes.

Whenever a patient’s sample is registered for the triple marker screening test, it is mandatory to send a serum sample (3 mL in a Thyrocare barcoded gel tube) with Prenatal Risk Factor Analysis Patient History Form and most recent ultrasound report.

The test includes the following parameters:

• AFP, a protein produced mainly by the foetal liver.
• Human Chorionic Gonadotropin (hCG), produced by the placenta during pregnancy.
• Unconjugated Oestriol (uE3): The placenta and the growing foetus produce the oestrogen hormone known as unconjugated oestriol.

The normal range of the markers is shown in the table below.

The results of the triple marker test may be interpreted as follows:

The triple marker test requires only a blood sample collected from a vein in your arm. It is generally considered safe. However, like any blood test, it has certain risks and limitations.

Potential Risks and Complications

You may experience:

• Mild pain or discomfort at the site where the blood sample is collected.
• Minor bruising or slight bleeding at the puncture site.
• Dizziness, fainting, or infection after blood collection (rare).

Understanding the Triple Marker Test

• The triple marker test is not a diagnostic test; rather, it is a screening test. It cannot confirm or rule out a problem, but it can predict the chance of certain chromosomal issues before birth.
• A screen-positive result does not always indicate that the infant has a birth defect or a chromosomal issue.
• It is important to estimate the pregnancy stage correctly for the test to be accurate. Inaccurate pregnancy dates could affect how the results are interpreted.

Depending on the results of the triple marker test, your doctor may recommend additional tests to identify the cause of infertility and plan further treatment.

• Detailed ultrasound examination
• Non-invasive prenatal testing (NIPT)
• Amniocentesis
• Genetic Counselling