Back about the year 2000 Washington state mandated that all hospitals take a look at their safety programs (I've posted this info before but am unable to locate the thread at this time). What all of the hospitals did was to make themselves a weapons free zone., in essence a "feel good measure."
In short if you OC you will be asked to remove the weapon. If you CC and are doing it properly, no one is the wiser.
All they can do is ask you to leave or put it away if caught.
Somewhere on this site is a list I made up of Hospitals that have a No Weapons policy. I can tell you that Group Health has a policy of no weapons and in fact state that they can terminate coverage.