Actually, it gets weirder. Taking a blood transfusion (and not begging for forgiveness afterwards) became a disfellowshipping offence in 1961.
However, since the Bulgaria agreement it has become WBTS policy NOT to disfellowship. BUT this is not written down in any society literature - a letter was sent to COs and read to the elders (I think you can find a copy on http://www.ajwrb.org/basics/breaking.shtml).
So you will no longer be disfellowshipped for having a blood transfusion but the rank and file have not been told!!!!!
However, the punishment is that you will have disassociated yourself. And we all know there is really no difference except to say that, technically, the Society has not applied any sanctions! You have removed yourself! Sneaky eh?