I want to share with you, that everyone who has ever had an IV administered has had a blood transfusion of their own blood (this is not blood salvaging), small but for those JWs who argue abstain means abstain...it shows they are already tainted. Yes I personally have informed the WBTS, since they remain silent I assume it means all is well.
Also consider that if you ask an Elder if there are bans on blood, they say YES
but
If you call up the WBTS on the phone, the Brother on the other end will only comment that all blood products are "a matter of conscience"
ANHs are often considered for surgeries of JWs because they can be modified to keep attached to the circulation system.
HOWEVER
please consider the below article link.
http://www.anesthesia-analgesia.org/cgi/content/full/91/2/497
Best Wishes
Y