Perhaps of interest is how the Koran addresses this: Surah16,115
He has forbidden to you only carrion, and blood, and the flesh of swine, and that over which any name other than God's has been invoked; but if one is driven [to it] by necessity - neither coveting it nor exceeding his immediate need - verily, God is much-forgiving, a dispenser of grace.
Many conservative Muslims do interpret the prohibition of eating blood as relevant to transfusions. However, they also understand necessity for the preservation of life to be of greater importance. Shamefully, blood donations Muslims provide are to be given for other Muslims only and not sold to a commercial company.