If you're coming in for a disembowlement, sure, but even then you're only really revealing the condition; your name, history, insurance details etc. are still private information. (The hospital would also still be forbidden from, say, publishing "amelius came in today with with a minor disembowlement" without your permission, no matter how public it was in the waiting room.)
In the waiting room they usually don't shout out "Geoff, who's here for the cock wart, the doctor will see you now"... they just say "Geoff, the doctor will see you now."
