Kleihauer Betke Test: What You Need to Know
The Kleihauer Betke (KB) test, also known as the acid elution test, is a medical test used to determine the amount of fetal blood that has entered the maternal bloodstream. This test is typically performed in cases of maternal trauma, placenta previa, and other conditions that may cause bleeding during pregnancy. It is also used to calculate the dose of Rh immune globulin (RhIg) that is needed to prevent Rh sensitization in Rh-negative mothers.
What is Rh Sensitization?
Rh sensitization occurs when an Rh-negative mother is exposed to Rh-positive fetal blood during pregnancy or delivery. This exposure can cause the mother's immune system to produce antibodies that attack and destroy Rh-positive blood cells. This can lead to hemolytic disease of the newborn (HDN), which can cause anemia, jaundice, and other complications.
Rh sensitization can be prevented by administering RhIg to the mother after exposure to Rh-positive fetal blood. RhIg works by binding to and neutralizing any Rh-positive fetal cells that may have entered the mother's bloodstream, preventing the mother's immune system from producing antibodies.
Why is Kleihauer Betke Test Preformed?
The Kleihauer Betke test is a medical test used to determine the amount of fetal red blood cells in the mother's bloodstream. This test is performed on pregnant women who have experienced bleeding during pregnancy or have a high risk of fetal-maternal hemorrhage due to trauma, placental abruption, or other conditions.
The test is particularly important for Rh-negative mothers who carry an Rh-positive fetus. If fetal-maternal hemorrhage occurs, the mother's immune system can develop antibodies against the Rh factor, which can lead to hemolytic disease of the newborn (HDN) in subsequent pregnancies. HDN can cause severe anemia, jaundice, and other complications in the newborn.
The Kleihauer Betke test allows healthcare providers to determine the amount of fetal blood that has entered the mother's bloodstream and to calculate the appropriate dose of Rh immune globulin (RhoGAM) to prevent the mother's immune system from attacking the Rh-positive fetus. This can help to prevent HDN and other complications in subsequent pregnancies.
How is the Kleihauer Betke Test Performed?
The Kleihauer Betke Test is a simple blood test that can be performed in a laboratory or hospital. A small amount of maternal blood is drawn from the mother's arm and mixed with a special solution that causes the mother's blood cells to lyse, or break open. The fetal cells, which are resistant to this solution, remain intact and can be visualized under a microscope.
The number of fetal cells is counted, and the percentage of fetal blood that has entered the maternal bloodstream is calculated. This percentage is used to determine the dose of RhIg that is needed to prevent Rh sensitization. The Kleihauer-Betke test is very accurate and can detect as little as 0.1% of fetal blood in the maternal bloodstream.
If the Kleihauer-Betke test shows that a significant amount of fetal hemoglobin has entered the mother's bloodstream, it may indicate that the mother has experienced a fetal-maternal hemorrhage. This can be a serious condition that requires immediate medical attention to prevent complications such as anemia or fetal death.
What are the risks and complications of the Kleihauer Betke Test?
The KB test is generally considered a safe and non-invasive procedure, but as with any medical test, there are some potential risks and complications to be aware of. These include:
1.) False positive or false negative results: The KB test has been known to produce inaccurate results due to several factors such as improper collection, handling, or processing of the blood sample. False-positive results may occur if there are residual fetal RBCs from a previous pregnancy, and false-negative results may occur if the fetal-maternal hemorrhage is small.
2.) Infection: There is a small risk of infection at the site where the blood sample is collected. However, this is rare and can usually be prevented with proper sterilization techniques.
3.) Bleeding or hematoma formation: There may be slight bleeding or hematoma formation at the site where the blood sample is collected. This is usually minor and resolves on its own.
4.) Allergic reaction: In rare cases, a person may have an allergic reaction to the needle or the antiseptic used to clean the skin before the blood sample is taken.
5.) Psychological distress: In some cases, undergoing a KB test may cause psychological distress or anxiety for the patient, particularly if they are anxious about the health of their unborn baby.
It's important to note that the KB test is typically only performed when there is a specific medical indication, such as a suspected fetal-maternal hemorrhage. Your doctor or healthcare provider can help you understand the benefits and risks of this test and address any concerns you may have.
