Official policy now says taking a transfusion is not a DF'ing matter. Quite simply someone has "left the faith" (DA'd) by their choice (actions) if they are not repentant about caving in a moment of spiritual weakness when agreeing to accept a transfusion.
This way WTS can claim that they take no punitive action against one accept blood transfusions to save their life or the life of a loved one. Of course, we know that when they say that person has by their own choice disassociated themself, it means the same damn thing.