AFP Test Pregnancy: What Is It And Why Is It Done?
When you are pregnant, there are a number of tests to do at different levels of your pregnancy. These tests are usually screening tests in comparison to diagnostic tests. The main difference between the two is that – screening tests are for a wide range of women to check for any genetic defect in the developing fetus. The AFP test pregnancy is one such test that is referred to every pregnant woman out there.
The AFP screening is one of the first tests that pregnant women need to go through with. The rest of her tests depend on the results of the alpha-fetoprotein test.
If you just got pregnant for the first time and are a little worried about this test, this article is just for you. Here, we will discuss everything there is about the AFP test pregnancy. And why there is nothing that should worry you about this initial test.
What Is Alpha-Fetoprotein?
Before you understand why this test takes place or what to anticipate, it is important that you know what alpha-fetoprotein actually is. The alpha-fetoprotein is a protein that encodes in humans by AFP genetics. This protein is also known as alpha fetoglobulin, alpha 1 fetoprotein, or alpha fetal protein. This particular gene is present in the q arm of chromosome four.
Maternal AFP levels are used to track any fetal abnormalities like neural tube defects, down syndrome, or any other chromosomal abnormalities.
AFP is a vital plasma protein in the yolk sac and the fetal liver that is produced during the development of the fetus.
The AFP is made up of a carbohydrate moiety and 591 amino acids.
Function Of AFP
The main function of the AFP in adult humans is still unknown to medical sciences. AFP is the highest concentration plasma protein available in a human fetus; both the yolk sac and the liver in the fetus contribute to the production of alpha-fetoprotein. It mainly acts as a career protein and helps transport elements like fatty acids to the cells.
Maternal plasma levels stay the highest at the end of the first trimester. The levels gradually drop throughout the pregnancy and rapidly decrease after birth. While its functions in humans remain unknown, in rodents, it helps in binding estradiol to be able to prevent the transportation of the hormone to the placenta of the fetus. The main job of this is to stop the virilization of the female fetus. As the AFP present in humans does not bind the estrogen, its function in the human race remains unclear to this date.
What Is The AFP Test Pregnancy?
The AFP test, or the Alpha Fetoprotein test, is a blood test that helps measure the level of alpha-fetoprotein in the blood of the mother at the time of pregnancy. AFP is a kind of protein that is generally produced by the liver of the fetus and is present in the amniotic fluid around the fetus. It further crosses the placenta to pass into the mother’s blood. While the test is done to check for the Alpha-fetoprotein levels in the blood, the test is known as an MSAFP or maternal serum AFP test.
The AFP count can also be measured through the amniotic fluid known as AFAFP.
What Does AFP Test Pregnancy Imply?
There are multiple reasons for which an AFP test is conducted during pregnancy. Any abnormality found in the AFP level might imply:
- Down syndrome
- Open neural tube defects like spina bifida
- Defects in the abdominal walls surrounding the uterus
- Any chromosomal abnormalities
- A miscalculation in the due date, as the levels tend to vary during pregnancy
- Twins, as more than one fetus contributes towards the protein count
AFP screening is just one part of a two-, three-, or four-part screening. It is often known as the multiple marker screen. The other parts of the test include the following tests:
hCG – a hormone produced by the placenta which is known as the human chorionic gonadotropin hormone.
Estriol – yet another hormone that is produced by the placenta.
Inhibin-A – a placenta-based hormone released during pregnancy.
Any abnormality available in the levels of AFO or any of the other markers might indicate the need to do some additional testing. Generally, an Ultrasound is done to confirm the date of pregnancy and to have a look at the spine of the fetus and its other body parts to check for any defects. An amniocentesis might be the best choice for an accurate diagnosis.
Why Do You Need To Get An AFP Test Done?
AFP is one of the routine tests that you need to get done during pregnancy. It is mainly done between the 14th and 22nd weeks of pregnancy. The results are usually most accurate within the 16th and 18th week of pregnancy. So, it is important to know exactly when you got pregnant.
AFP tests are generally a part of a quad screen. As mentioned in the previous section, this test is done to test for hCG, estriol, and inhibin A in the blood.
Doctors usually use your quad screen results, your ethnicity, and your age to help determine if there is any chance for the baby to be born with any genetic defects. Your AFP test pregnancy will help your doctor determine if you need any further tests to check for the abnormalities of the fetus.
If your result comes positive, it does not mean that your baby is going to be born with any birth defect.
An AFP test is particularly important for those who are at a higher risk of bearing children with birth defects. This mainly includes women:
- Who are beyond the age of 35
- Have a family history of birth defects
- Who have used any harmful drugs at the time of their pregnancy
- Who have diabetes
If you are not pregnant, the AFP test may also help in diagnosing and monitoring certain liver problems like cirrhosis, liver cancer, and hepatitis. It may also help in the detection of other cancers, which might include:
- Ovaries
- Testes
- Stomach
- Biliary tract
- Pancreas
How Is The AFP Test Pregnancy Performed?
There is nothing too complicated about performing the alpha-fetoprotein test. All you need to do is get your blood drawn for the AFP test. You can get your blood taken from any diagnostic lab. The process is simple and does not require you to maintain your food or diet before the test, like the glucose screening test.
The doctors at the lab will use a very small needle to withdraw some of your blood from a vein in your hand. Then, a laboratory professional will analyze the blood sample that you just gave.
The results generally arrive within one or two weeks after the tests.
What Do Your Test Results Mean?
Now, this is the part where things might get a little complicated. For men or women who are not pregnant, the usual amount of AFP stays less than ten nanograms for every milliliter of blood. If your alpha-fetoprotein levels are typically high but you are not pregnant, it might indicate the presence of liver diseases or certain cancers.
However, if you have a high level of alpha-fetoprotein in case of pregnancy, it might mean there is a neural tube defect in the developing baby. However, the most common cause of increased AFP levels is the wrong dating of pregnancy. The AFP levels go through major variations during pregnancy. The test results tend to come inaccurately if you have been pregnant for a longer or shorter time than what you thought.
If you are pregnant and yet the AFP level is certainly low, it might indicate that the fetus has a certain amount of chromosomal abnormalities, like Edwards syndrome or Down Syndrome.
There is also a chance of abnormal alpha-fetoprotein levels in the blood because of multiple pregnancies like having triplets or twins. An abnormal AFP reading might also be an indication of fetal death.
As per the American Pregnancy Association, “results are abnormal for 25 to 50 pregnant women out of every 1,000 pregnant women given an AFP test. However, only between 1 in 16 and 1 in 33 women who have abnormal results will actually have a baby with a birth defect.”
Just to make things clear, abnormalities in your test results do not mean that your baby will be born with any birth defects. It is only an indication that more tests are required for the doctors to come to a conclusion.
What Are The Risks Of An AFP Test Pregnancy?
There are absolutely zero risks when it comes to an alpha-fetoprotein test done in pregnant women. All that you might experience is a slight faintness or just a bit of soreness or pain where they injected the needle.
There is a very small chance of experiencing excessive bleeding or hematoma. It usually happens when the blood accumulates under the skin. There is also a very slight risk of an infection in the puncture area. However, all these side effects are only associated with puncture on your skin. And it is mainly on the hand. If you are concerned that anything wrong is happening to the baby at the time of the test, you can take a breath of relief. Other than the mentioned risks, there are no other risks associated with the alpha-fetoprotein test and your developing baby.
What Are The Benefits Of AFP Test Pregnancy?
The main purpose of the alpha-fetoprotein test is to detect if a woman is at a higher risk of delivering a baby with any birth defects. The AFP test also determines if a woman needs any additional tests while pregnant. Without doing the AFP test at first, women don’t go through with any additional tests to do during their pregnancy.
Follow-Up Tests After The AFP Test
If you test for an abnormal reading for your AFP test during pregnancy, your doctor will immediately suggest that you go for some other line of tests. These will just help the doctor come to a solid conclusion.
The tests that are done after conducting an AFP test may include:
Ultrasound test: This test is mainly done to produce images of the unborn baby
Amniocentesis: This test checks the amniotic fluid that surrounds your baby in the belly
Non-invasive prenatal screen: This blood test is done to confirm any genetic abnormality of the fetus.
Some other tests that might be performed in line with the AFP test include:
Liver function test: This test helps determine the working of the liver
Blood clotting test: This plays one of the major roles in your body’s ability to produce blood clotting factors. These tests will help monitor if there are any changes in how your liver is making any of those factors.
Complete blood count: This blood test takes a look at the multiple blood cells. It includes the red blood cells and the white blood cells too.
Viral hepatitis: This is a blood test that mainly checks for hepatitis B and C. These have a link with liver cancer.
Tissue biopsy: A very small piece of tissue gets taken from any organ or mass for atomic pathologists to further evaluate.
The Bottom Line
The AFP test pregnancy is done to decide if the unborn baby is at risk of having any abnormal conditions or birth defects. This screening test is one of the very initial tests done on pregnant women. It determines all the tests a woman needs to go through during her pregnancy. If any abnormality is detected in the AFP levels, the doctor will recommend other tests to reach an accurate conclusion.
However, this same test is also done on people who are not pregnant. It checks for the risks of liver cancer or testicular or ovarian tumors. The AFP test is an effective risk indicator, but it certainly cannot diagnose the condition or the disease. This is the reason why doctors suggest other tests to confirm the condition after doing an AFP test on women.
Lastly, the AFP test is nothing risky, and you certainly do not need to worry about it. It only is a simple blood test and is highly unlikely to cause any harm to your baby.
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