Introduction
The embryonic yolk sac and the fetal liver produce the plasma protein known as alpha-fetoprotein (AFP). AFP levels in serum, amniotic fluid, and urine serve as screening tests for congenital impairments, chromosomal abnormalities, and various other cancers and illnesses that can develop in adults. For example, the AFP gene on chromosome 4q25 produces a glycoprotein as a tumor marker. After the first trimester, prenatal levels in the growing human embryo start to rise and decline after 32 weeks of pregnancy. Therefore, the triple or quadruple screening tests for fetal abnormalities include maternal serum AFP.
What Is the Indication for Alpha-Fetoprotein Screening?
The indications for alpha-fetoprotein screening are as follows:
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To assess the effectiveness of cancer treatment.
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History of chromosomal or birth abnormalities in the family (e.g., Down’s syndrome, spina bifida)
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Advanced age for pregnancy.
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Detection of cancer (like liver, testicular, ovarian).
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Chromosomal or birth abnormalities from prior births (like neural tube defects).
How Is an Alpha-Fetoprotein (AFP) Sample Collected?
Blood is extracted from the vein using aseptic techniques and standard safety precautions for AFP blood tests. Serum alpha levels are measured in male and female patients who are not pregnant as part of a maternal triple or quadruple screening test or for other diagnostic purposes. Although they may be significantly lower than those in serum, alpha-fetoprotein levels in urine samples collected in straightforward or universal bottles can also be analyzed. The amount of alpha-fetoprotein in the amniotic fluid must be assessed during amniocentesis. During a diagnostic amniocentesis, amniotic fluid is extracted for an AFP immunoassay by inserting an ultrasound-guided hollow needle into the amniotic cavity within the mother.
How to Get Ready for the AFP Test?
A particular preparation is not necessary for an AFP blood test. In general, consuming lots of water to stay hydrated helps facilitate a quicker and more seamless blood draw. Staying hydrated lowers the likelihood of blood pressure swings and keeps the veins from contracting.
What Are the Phlebotomy Techniques for Collecting Blood for Alpha-Fetoprotein (AFP) Samples?
The steps involved in collecting blood samples for alpha-fetoprotein screening are as follows:
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Firstly, inform the patient of the procedure and the potential discomfort associated with the needle prick.
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The patient should be appropriately positioned so the upper arm may be seen.
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Wrap the upper arm in the tourniquet.
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Choose a noticeable vein, then wipe it with an alcohol swab.
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Introducing the vacutainer-mounted needle.
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After getting a sample, remove the tourniquet and the needle.
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Add pressure with a cotton ball to the needle site to halt bleeding.
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Sample bottles should be labeled appropriately.
What Is the Procedure for Amniocentesis?
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Amniocentesis is performed starting at week 15 of pregnancy.
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Confirm the patient's name and the pregnancy's gestational age.
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Counseling before the test. Typically, this also includes genetic counseling.
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Obtain consent after being told.
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The patient should be positioned appropriately.
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The abdomen's exposed area should be cleaned. If required, use a local anesthetic.
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Use caution when inserting the hollow, ultrasound-guided needle through the anterior abdominal wall and into the amniotic sac.
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15 to 20 cc of amniotic fluid should be aspirated for an AFP analysis.
What Are the Ranges of Alpha-Fetoprotein?
The blood's level of AFP is measured by doctors in nanograms per milliliter or ng/mL. Regardless of age or ethnicity, alpha-fetoprotein levels (AFP tumor marker normal range) in males and non-pregnant women typically range from 0 ng/ml to 40 ng/ml. Pregnant women will have different reference ranges. From the 14th week of gestation until roughly 32 weeks, maternal AFP levels begin to increase. Levels typically range from 10 ng/ml to 150 ng/ml between weeks 15 and 20. Hepatocellular carcinoma is strongly suggested in adults with liver cirrhosis whose blood levels are more significant than 200 ng/ml.
What Do the Results Imply?
Errors in predicting the due date are the most frequent cause of erroneous AFP test findings during pregnancy. However, an abnormal result could also indicate potential issues:
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Lesser-than-normal AFP levels may indicate that the baby has a genetic disease that includes Down syndrome, which causes cognitive challenges and health issues.
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Elevated AFP levels above normal could indicate that the child is more likely to suffer from a neural tube abnormality, like:
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A disorder known as spina bifida causes the spine's bones to fail to close around a portion of the spinal cord.
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Anencephaly is a disorder in which there is improper brain development.
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Elevated AFP levels could also indicate multiple pregnancies. Additionally, a false-positive result could occur. This indicates that although the baby's health is normal, the AFP findings are abnormal. More testing will probably be necessary to help with the diagnosis if the findings from the AFP test are abnormal.
What Is a Test for AFP Tumor Markers?
AFP testing is most frequently performed on pregnant patients by medical professionals. However, if not pregnant, the physician may occasionally request an AFP tumor marker test. The AFP test and the tumor marker test serve separate functions for pregnant individuals.
AFP levels are normally high in newborns and fall to low ranges by the time they are one year old. An adult's elevated AFP may indicate:
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Either hepatitis B, hepatitis C, or both.
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Carcinoma of the liver.
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Testicular or ovarian cancer.
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Hepatitis that is toxic or autoimmune-related.
Medical professionals can also use AFP tumor marker tests to schedule treatment for cancer. For instance, targeted therapy—drugs that specifically target cancer cells—might be an effective treatment if someone has liver cancer with elevated AFP levels. It is critical to realize that testing for AFP tumor markers is the only instrument for determining AFP levels. They can aid in the diagnosis of diseases like cancer. However, an unusual test result may not always indicate a problem. To find out more, the healthcare provider will typically request more testing.
Does Alpha-Fetoprotein Give False Positive Results?
Several conditions have been linked to false-positive outcomes:
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Two weeks following radiodiagnosis utilizing radioactive tracers.
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People who smoke cigarettes.
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Slightly higher levels in black women.
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Lower in women of Asian descent as compared to whites.
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Additionally, AFP levels are weight-adjusted.
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Multiple pregnancies.
What Are the Complications Associated With Alpha-Fetoprotein Screening?
Complications Related to Phlebotomy:
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People with clotting issues or blood thinners may experience phlebitis, abnormal bruising, and bleeding.
The Danger Connected to Amniocentesis:
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Miscarriage.
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Early birth.
What Is the Clinical Significance of Alpha-Fetoprotein Screening?
Alpha-fetoprotein levels in the blood of pregnant women are frequently measured as part of a triple (AFP, estriol, and human chorionic gonadotropin [hcg]) or quadruple (AFP, estriol, hCG, and inhibin A) screening test for birth abnormalities. Ordinarily, levels are interpreted regarding age, race, weight, and gestational age.
Since the levels are increased, there is a high possibility of having birth abnormalities; therefore, additional testing may be necessary to determine the risk. The risk of obstetric difficulties such as premature membrane rupture and placenta rupture may be increased in patients with excessive maternal AFP. In contrast, most of these patients do not have birth abnormalities.
Low maternal AFP levels could be a sign of a Down syndrome risk. In non-pregnant women and men, elevated levels are reported in malignancies, particularly liver cancer. Hepatocellular carcinoma is suspected in cirrhotic patients with levels over 200 ng/ml. Alpha-fetoprotein levels are also elevated in ovarian and testicular cancers. AFP levels can gauge a patient's response to cancer treatment.
Conclusion:
A screening test for alpha-fetoprotein may require additional tests to establish a diagnosis based on the results. A negative test does not always mean there is no risk because Down syndrome is more common when the level of alpha-fetoprotein in the mother's blood is very low. Therefore, a low alpha-fetoprotein level in the maternal blood must be considered. Amniocentesis patients must get adequate counseling regarding the procedure and any potential dangers. Following an amniocentesis, there is a chance of an obstetric accident; less than one percent of pregnancies end in miscarriage. Preterm labor, infection (amnionitis), iatrogenic trauma, or harm to the growing fetus or mother are highly uncommon amniocentesis side effects.
