What factors determine the compatibility of blood types for transfusion?
Blood type compatibility for transfusion is determined by several factors based on the presence or absence of specific antigens and antibodies in the blood. The two main factors involved in blood compatibility are the ABO blood group system and the Rh (Rhesus) factor.
1. ABO Blood Group System:
- The ABO blood group system is determined by the presence or absence of two antigens on the surface of red blood cells: antigen A and antigen B. Each individual can have type A, type B, type AB, or type O blood based on the combination of these antigens.
- Antibodies against the missing antigens are naturally present in a person's plasma. For example, a person with type A blood will have anti-B antibodies in their plasma and a person with type B blood will have anti-A antibodies.
- During a blood transfusion, if a person receives blood with incompatible antigens, their antibodies will bind to these antigens, causing the transfused red blood cells to be destroyed, leading to a transfusion reaction.
2. Rh Factor:
- The Rh factor is another antigen present on red blood cells. Individuals who have this antigen are Rh-positive, while those who lack it are Rh-negative.
- A person with Rh-negative blood can receive blood from either Rh-positive or Rh-negative individuals. However, a person with Rh-positive blood should only receive Rh-positive blood transfusions to avoid developing anti-Rh antibodies and potential complications in future transfusions.
Compatibility Guidelines:
- A person with type O blood (universal donor) can donate to individuals with any blood type since type O red blood cells lack both A and B antigens.
- A person with type AB blood (universal recipient) can receive blood from any blood type since their plasma does not contain antibodies against A or B antigens.
- Transfusions with blood of the same ABO group and Rh type are always considered compatible.
It's important to note that additional factors such as minor blood group antigens, irregular antibodies, and immune system reactions can also influence blood compatibility. Pre-transfusion compatibility testing is performed to ensure that donated blood is compatible with the recipient's blood to prevent transfusion-related complications.