As technology improves so do medical procedures. It used to be that the body was opened up for most operations on the bodies organs. Nowdays keyhole surgery is used, as the patient recovers much quicker and with much less scarring after the op. More now is known about blood. Transfusing and transplants have always been a problem, but as technology has improved, the use of blood transfusion has become less necessary. Nowdays it is often just blood componants that are used, for that is better for the patient. Every doctor has always known that there is a potential from ablood transfusion going wrong, which is why they do not give one unless they feel it is necessary.
Before modern technology, transfusion was given as there was nothing else and so some diedxand some others lived. Nowdays if a transfusion can be avoided, it will not be given. However there are still some situations where the choice is either a transfusion or certain death.
JWs have the right to accept death if they want to.