Blood transfusions save lives. If you need one, there's no question you should get one. But a lot of patients who get transfusions probably don't need them. Doctors now say they get better results by using donor blood less often in patients who are medically stable. There's growing consensus that transfusions can increase the risk of infection and do more harm than good. It's a big change in how some physicians practice medicine and it's led to some Minnesota hospitals tightening their transfusion guidelines.