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Do you know that in time of emergency and in between life and death situation, when there is a massive need of blood and their blood type is not available in the blood bank.
In the table above it will tell you what are the possible blood types that can substitute if theres no available of the same patient blood type.
In medical,we used universal blood donor or recepient.In this case a particular person can recieve a type of blood that is different from his own blood type.
If you observed in the table ,the O- donor can be transfused to all types of types and with an AB+ can recieve with all types of blood.
Therefore:
Universal blood donor is A-
Universal blood recepient is AB+