The Witnesses accept both cell salvage and hemodilution. The following quotes are from the November 2006 Kingdom Ministry.
"Cell Salvage-Reduces blood loss. Blood is recovered during surgery from a wound or body cavity. It is washed or filtered and then, perhaps in a continuous process, returned to the patient." Note the words-"perhaps in a continuous process." It is often not completed until hours after the surgery. It also is hung up in a bag just like all other transfusions, after collecting during the surgery. If you saw the procedure, you could tell it was no different than receiving your own blood back after surgery. The only difference would be possibly in the amount of time it was outside the body, but we are not talking about minutes. There is a window of six hours to reinfuse the blood.
"Hemodilution-Reduces blood loss. During surgery, blood is diverted to bags and replaced with a nonblood volume expander. Thus, the blood remaining in the patient during surgery is diluted, containing fewer red blood cells. During or after the surgery, the diverted blood is returned to the patient." Once again, there is a six hour window to reinfuse the blood and it is hung in a bag as any other blood transfusion would be.
Witnesses may accept either of these procedures. However, they may not donate their own blood days ahead of surgery. The only difference is in the amount of time the blood is out of your body.
Explain to me what the difference is between these "acceptable " procedures and just removing the blood earlier? I do not see an ethical difference.