Hospitals were obligated to warn patients. They should have given them the option of not using these scopes, especially in cases where it was not already a life or death situation. The hospitals should be held accountable for all of the deaths and illnesses that occurred as a result of using the tainted scopes.
Yes, US hospitals should have warned patients about potentially tainted scopes. If the hospitals were aware that the problem may exist, patients should have been warned about the extent of the health threat so that they could take precautions or make other decisions about the treatment that they wanted. It is scary that they did not.
I believe that if a patient's samples are coming into contact with a tainted scope, those patients should know that there is a chance of their sample being tainted and thus invalid. If my sample were tainted and it had tested for something deadly, I would like to know if there were a chance that there was a possible breach of standard and therefore a chance that I did not have what I tested positive for.
It's up to the hospitals to either not use dangerously tainted scopes, or to revamp their cleaning processes to decrease the risk of infection. Announcing to patients that the scopes that were about to be used on them might be contaminated would have only led to ill-informed and possibly hysterical decisions to postpone necessary testing. It is worth remembering though, that everything in a hospital is potentially dangerous -- hospitals are where all the germs go to hang out.