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Blood groups |
• Blood groups are substances linked to the membrane of many of the cells in our bodies. These include red blood cells (erythrocytes). The presence of these substances determines blood group and compatibility for blood transfusions.
• There are many blood groups but the two most important of these are the ABO group and the Rh factor.
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The ABO group |
• This blood group is determined by sugars and comprises four groups based on their sugar composition: A, B, AB and O. The frequency of these groups is as follows:
| Blood group |
Frequency (%) |
| O |
45 |
| A |
40 |
| B |
11 |
| AB |
4 |
• As mentioned above, these blood groups determine our compatibility for blood transfusions:
A patient
in group: |
can receive blood from a donor in group: |
|
1st choice |
2st choice |
3st choice |
4st choice |
| AB |
AB |
A |
B |
O |
| A |
A |
O |
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| B |
B |
O |
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| O |
O |
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• This table illustrates that people with AB blood are universal recipients because they can receive blood from anybody, and those with O blood are universal donors because they can give blood to anybody.
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Rh factor |
• There are two types in this group: Rh positive and Rh negative. Rh positive people can only donate blood to Rh positive people, whereas Rh negative people can give blood to anybody, regardless of whether they are positive or negative.
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