Introduction
Blood is a complex fluid in our bodies that carries essential nutrients and oxygen to every cell. Blood has the same function, but not all blood is the same. Beyond its function, blood also carries distinct markers that determine the blood types of an individual, which play a crucial role in blood transfusions to check the compatibility between the recipient and the donor. The Blood Type Compatibility Chart helps healthcare professionals navigate the complexities of blood transfusions and organ donations, ensuring the safety and well-being of patients. This article briefly explains the different blood types and highlights the significance of the blood type compatibility chart to outline which blood types are compatible for transfusion.
What Are Blood Types?
Several blood group systems are used to determine blood types, ABO blood group system is the most important type. Blood comprises red blood cells, white blood cells, and platelets in a liquid called plasma. The presence and absence of specific antibodies and antigens in the blood determine the blood type.
Antibodies are proteins present in plasma. They are the inherent part of the body's natural defense mechanism. If a foreign substance gets into the body, antibodies recognize it and alert the immune system, which destroys it, whereas antigens are protein molecules present on the surface of red blood cells. ABO blood group system determines the blood type based on the presence or absence of antigens A and antigen B on the surface of red blood cells.
There are 4 main blood groups defined by the ABO system:
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A - This type of blood group has A-antigens on the RBCs ( red blood cells) with anti-B antibodies in the plasma.
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B - This type of blood group has B antigens with anti-A antibodies in the plasma.
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O - This type of blood group has no antigens but has both anti-A and anti-B antibodies in the plasma.
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AB - This type of blood group has both A and B antigens, but no antibodies in plasma.
An additional antigen, called the RhD antigen, can be present in red blood cells. Based on the presence or absence of RhD antigen, the above blood groups can be positive or negative. That leaves us with eight possible blood types:
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A RhD positive (A+).
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A RhD negative (A-).
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B RhD positive (B+).
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B RhD negative (B-).
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O RhD positive (O+).
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O RhD negative (O-).
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AB RhD positive (AB+).
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AB RhD negative (AB-).
What Is a Blood Type Compatibility Chart?
Checking compatibility is important before someone gets a blood transfusion. Every blood type is not the same. Different individuals can have different blood types. If one gets a transfusion with a different blood type, the immune system might attack the donated blood. This may result in a transfusion reaction that is severe or even life-threatening. So, before the transfusion of blood, the donor's and recipient's blood is always tested to know the blood types of both.
Patients should get blood and plasma from the same ABO and RhD group while receiving a blood transfusion. If the necessary blood type is not available, a patient can receive a product from a different but compatible blood group instead. The Blood Type Compatibility Chart outlines which blood types are compatible for transfusion. For example,
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For Blood Type A: Individuals with blood group A with A-antigens can make anti-B antibodies against B or AB blood because anti-B antibodies would attack the blood received from any donor with B-antigens. One can only get type A or O blood.
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For Blood Type B: Individuals with blood type B with B-antigens can make anti-A antibodies. So, one cannot get type A or AB blood, because these anti-A antibodies will attack any donor blood with A antigens. So, individuals with the type B blood group can only get type B or O blood.
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For Blood Type AB: Individuals with blood type AB have A and B antigens, such blood group types do not make anti-A or anti-B antibodies. Because of this individuals with type AB blood can receive transfusions from any blood group type. These people are called universal receivers.
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For Blood Type O: Individuals with blood type O have no A or B antigens, such individuals can make both anti-A and anti-B antibodies. Hence, individuals with type O blood can receive only type O blood, as any donor blood containing A or B antigens will be attacked by their anti-A and anti-B antibodies. However, type O blood can be given to anyone with any blood type because it contains no antigens. Those who have type O blood are sometimes referred to as universal donors for this reason.
In addition to matching ABO types, blood also needs to be matched by Rh antigen. Rh factor is another protein that some people have in their red blood cells.
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For Rh-Positive Blood: individuals with Rh antigen on blood cells do not make anti-Rh antibodies. So, one can receive Rh-positive or Rh-negative red blood cell transfusions.
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For Rh-Negative Blood: Rh-negative blood group individuals do not have the Rh antigen on red blood cells. Such individuals can make anti-Rh antibodies such individuals can only receive Rh-negative red blood cells.
What Happens if Blood Is Not Compatible?
If a patient receives blood that is even partially not compatible with his blood, the body starts to produce antibodies to destroy the donor's blood cells. Blood received during transfusion must be compatible with one's blood. The blood transfusion between compatible groups does not cause any problems. However, minor mismatches in blood factors can cause a reaction. It is usually mild. Blood transfusions between incompatible groups cause an immune response. This can cause a transfusion reaction, which sometimes can be life-threatening. In case of any reaction, transfusion is stopped immediately. Treatment includes medications (antihistamines) used to treat allergic reactions, medications (steroids) used to treat allergies and edema, fluid administration through a vein (intravenously), and drugs to increase blood pressure in case it falls too low.
Conclusion
The Blood Type Compatibility Chart ensures the safe passage of blood from donor to recipient. Its principles guide healthcare professionals in making informed decisions, minimizing the risk of transfusion reactions, and maximizing patient outcomes. Furthermore, the blood type compatibility chart is a valuable tool in emergency situations where quick transfusions are required to preserve life of patient.
