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Every thing you wanted to know about blood group classification​

Blood groups are classifications of blood based on the presence or absence of antigenic substances on the surface of red blood cells. These antigens can provoke an immune reaction and are determined by each individual's genetic make-up.

There are several blood group systems, but the most important are the ABO and Rhesus (Rh) systems.

The ABO system distinguishes four blood groups: A, B, AB and O. Each group has specific antigens on the surface of red blood cells and corresponding antibodies in plasma.

- Group A has A antigens and anti-B antibodies.

- Group B has B antigens and anti-A antibodies.

- Group AB has both A and B antigens, but no antibodies.

- Group O has no antigens, but anti-A and anti-B antibodies.

The Rhesus system distinguishes two blood groups: Rh+ and Rh-. Group Rh+ has an antigen called Rhesus factor on the surface of red blood cells, while group Rh- does not.

The combination of the ABO and Rhesus systems results in eight possible blood types: A+, A-, B+, B-, AB+, AB-, O+ and O-.

Each blood group is compatible with the others in the event of blood transfusion or pregnancy. Incompatibilities must be avoided, as they can lead to serious or even fatal immune reactions.

In the event of a blood transfusion, the following rules must be observed:

- The donor must have a blood group compatible with that of the recipient, i.e. he or she must not possess antigens that the recipient has as antibodies.

- The recipient can receive blood from his or her own blood group or from a universal blood group.

- The universal blood group for recipients is group AB+, as it has no antibodies and can therefore receive blood from any group.

- The universal blood group for donors is group O-, because it has no antigens and can therefore give blood to any group.

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