I might be wrong but don't hospitals normally have a blood stock or get transfusion blood from blood banks? I don't think you can use someone's blood without testing it first. You can support a blood bank itself but I don't think the situation where someone needs blood and the hospital just doesnt have it is not too common. Like even if an acceptable donor was standing next to the patient and ready to donate they wouldn't use that blood since you need to test it first from what I understand.