Blood grouping is the classification of individuals based on inherited features on the surface of the red blood cells. This classification is purely based on presence or absence of certain protein molecules called antigens and antibodies on the surface of the blood. The antigens are located on the surface of the Red Blood Cells and antibodies are in the blood plasma.
There are practically more than 20 genetically determined blood group systems known today, but the ABO and Rh systems are the most important ones used for blood transfusions.
Let’s discuss the ABO blood group system and Rh system only.
THE ABO BLOOD GROUPING SYSTEM.
There are four main blood groups:
- Blood Group A: This group has A antigens on the surface of the red blood cells and also has anti-B antibodies in the plasma.
- Blood Group B: This group has B antigens on the surface of the red blood cells and also has anti-A antibodies in the plasma.
- Blood Group O: This group has no antigens on the surface, but has both anti-A and anti-B antibodies in the plasma.
- Blood Group AB: This group has both A and B antigens with no antibodies in the plasma.
Blood Groups are very important to know, because receiving blood from the wrong ABO group can lead to death. Take for example, the anti-B antibodies in a recipient with group A blood will attack the group B cells if transfused to them.
- Group O blood cells do not have any A or B antigens and therefore are safe to be given to any other person
- Group AB does not have any antibodies. It van receive blood from any group.
THE RHESUS BLOOD GROUPING SYSTEM.
The Red Blood cells sometimes have another antigen, a protein known as the RhD antigens or Rhesus factor. If this is present, your blood group is RhD positive or
RhD negative if absent.
This means you can be one of these eight Blood Groups:
- A RhD Positive (A+)
- A RhD Negative (A-)
- B RhD Positive (B+)
- B RhD Negative (B-)
- O RhD Positive (O+)
- O RhD Negative (O-)
- AB RhD Positive (AB+)
- AB RhD Negative (AB-).
In most cases, O RhD Negative Blood (O-) can safely be given to anyone. It is often used in medical emergencies when the blood type is not immediately known.
Copied from Dr. Chudi Ufondu.