If that were so, I doubt it is recent teachings. As already mentioned, the WTBTS is wriggling out of the no blood stance ever-so-slowly, and may be soon a 'conscience matter'.
I hope this happens soon. I think it would serve as a great catalyst to help my wife (and likely others) to wake up. If they make all blood transfusion a conscience matter, I'll ask my wife: "Now that it's OK to accept blood, how do you feel about the fact that you could have been made blood guilty by participating in the preaching work?" When she doesn't understand, I'll present the scenario of studying with someone who gets baptised and later dies because they refuse blood. Wouldn't you be, at least partially, responsible for their unneccesary death?
One of the things I'm most thankful for is that I was never actually "successful" in my ministry and none of my studies ever progressed.