And Poppy, a thought from an ICU nurse:
Can't tell you how many blood transfusions we give. It's very routine, and saves many lives. If you're hesitant, tell your doc, but let them know that you'll definetly accept if needed. Maybe theyll let your hemoglobin drop a liittle more before giving blood. Some doctors give blood before others would. When your body is in need of blood, you are at risk for, among other things, a heart attack. The lower your hemoglobin gets (sort of like the lower your blood level is) the more at risk for a heart attack you are.
I have seen a man have a heart attack, right there on the monitor before my eyes. (This is different from funny heart rhythms or no heart rate at all. It was just so unusual for me to see the actual heart attack, and the only time. They call them tombstone rhythms, or something, because the wave looks like the shape of a tombstone.) We were frantically giving blood, but he needed the blood, like three days ago, and had refused to go to the hospital. I'm just saying, yeah, yeah you can get diseases from blood, but it's really used as a lifesaving technique. I wouldn't worry too much about it unless you're someone who gets sick all the time. If you're in some kind of sudden car accident or such thing, just accept the blood, you probably really need it.