According to Wikipedia - let the reader use discernment -
Bloodless surgery is a term that was popularized at the beginning of the 20th century by the practice of an internationally famous orthopedic surgeon, Adolf Lorenz, who was known as "the bloodless surgeon of Vienna."
The above wiki quote references early 1900's as the time period of innovation in 'bloodless' surgery, however, it wasn't until the 1950's or 1960's that the witnesses made their stand against blood.
So who really was the 'pioneer' here.
Also, while the Jehovah's Witnesses may have advanced the cause, they are not the pioneers as it's doubtful that they did the actual scientific research. They took a stand, and humanitarian physician scientists took up the cause to find an effective way to treat the challenging patient.
The physicians who took on the challenge are the ones who pioneered the practice.
-Aude.