organization has given written guidance to JW's working in hospitals, med-labs and other occupations that involve the use and handling of blood that clearly contradict the idea that any action done would be prohibited.
Mishnaic law teaches that a servant's hand is an extension of his master's, and a JW doing his job can do his assigned job for his employer, ask for another job, or quit; if he was in control of the situation he must act accordingly: like if it involved stealing or participating in christmas. I am sure you are aware that JW doctors can administer blood to non JW. So, in the case of handling blood for an employer, he is acting in an extensional capacity.