Alpha Feto Protein (AFP) Test

An alpha-fetoprotein (AFP) test measures the amount of AFP in a blood sample. It is also known as the AFP maternal test, maternal serum AFP, and the MSAFP screen.

The developing baby’s liver produces most of the AFP, which then enters the pregnant mother’s bloodstream. Sometimes, abnormal amounts of AFP are produced, which can indicate a higher risk of neural tube defects (problems with the baby’s brain and spinal cord development), Down syndrome (a genetic disorder causing developmental and intellectual challenges), and Edwards syndrome (a genetic condition that results in an abnormal head shape and abnormalities in the brain, kidneys, and other internal organs).

Therefore, this test is included in prenatal screening to assess the risk of these serious conditions and determine whether additional diagnostic testing or follow-up care may be required.

The AFP test is a routine screening test conducted during pregnancy.

It is also highly recommended for women in the following groups who are at high risk of having a baby with birth defects:

• Women with a family history of birth defects: This is important, especially in the case of Down syndrome and Edwards syndrome, as both are genetic conditions that can be inherited.
• Women aged 35 years and above: Increased maternal age leads to an increased risk of birth defects.
• Women with diabetes: Diabetes during pregnancy increases the risk for defects such as sacral agenesis (spinal cord disorder), holoprosencephaly (brain disorder), and limb defects.
• Women taking medicines or drugs during pregnancy: Consuming herbs, supplements, or over-the-counter medicines can put the developing foetus at risk.

The test is also recommended for individuals who have a high risk of developing liver cancer. Risk factors for liver cancer include having hepatitis B or C (infection/inflammation of the liver caused by a virus), heavy alcohol consumption, cirrhosis of the liver (chronic liver disease leading to scarring of the liver tissue), obesity, and diabetes.

The AFP test cannot diagnose any conditions by itself, but it can be used with other prenatal tests to help identify certain conditions, such as:

• Down syndrome: This is a genetic condition in which a newborn has an extra chromosome that affects the baby's brain and internal organ development, along with causing intellectual disability.
• Edwards syndrome: This is a genetic condition characterised by an extra chromosome in the baby that causes problems in organ development and learning disabilities.
• Spina bifida: This is a birth defect in which the bones surrounding a baby’s spine do not completely close around the spinal cord.
• Anencephaly: This is a neural tube defect in which a major part of the baby’s brain and skull fail to form during development.
• Liver cancer: The AFP test can help diagnose cancer of the liver in non-pregnant individuals who are not pregnant.

What to Expect Before the AFP Test

No fasting is required for a standalone Alpha-Fetoprotein (AFP) 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 Alpha-Fetoprotein (AFP) 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 AFP 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.

In the AFP test, the primary parameter being measured is:

• The level of alpha-fetoprotein in a sample of blood.

The normal range for the AFP test is indicated in the table below. 

Note: The normal range may vary slightly depending on the laboratory and individual’s medical condition.

The table below provides a general interpretation of the AFP test results in pregnant women based on whether the levels are low or high.

Note: The results must always be interpreted with clinical findings, symptoms, and other diagnostic tests.

Like any other medical test, this test also has certain risks and limitations.

Risks:

• The AFP test is generally safe and involves minimal risk. You may experience slight pain when the needle is inserted into a vein in your arm for sample collection or mild bruising afterwards, which usually resolves spontaneously.

Limitations:

• AFP test results can be affected by an inaccurate last menstrual date, carrying multiple babies, and false-positive results.
• An AFP test result alone is not enough for diagnosis. Additional tests may be needed to clarify the suspected condition, as AFP levels increase in both benign and malignant liver conditions.

Depending on your symptoms and results, your doctor might recommend certain additional tests to better understand your condition:

• Carcinoembryonic antigen (CEA) test
• Abdominal ultrasound 
• Liver biopsy Endoscopic retrograde cholangiopancreatography (ERCP)
• Human chorionic gonadotropin (hCG) test
• Genetic testing such as chromosomal analysis or more advanced genetic testing 
• Amniocentesis Chorionic villus sampling (CVS)
• Percutaneous umbilical blood sampling (PUBS)