Question

Why is it important to know a person's blood type before giving him or she her a transfusion?

Answer 1

It is important to know a person's blood type before transfusing blood into the body to whether the blood which is going to be transfused into the person is compatible or incompatible. Only the compatible blood can be transfused. If incompatible blood is transfused to the person, it may cause death due to the clumping of blood.

Answer 2

Because if you give them the wrong kind of blood, then their body will react to the different blood cells like they were bacteria or a virus.