Laws don't mandate this like they do for gunshot wounds. Doctors do have discretion, and if they feel that there is a danger to the public (i.e. a nutjob stabbi

Laws don't mandate this like they do for gunshot wounds. Doctors do have discretion, and if they feel that there is a danger to the public (i.e. a nutjob stabbing people) they are legally able to report it (it wouldn't be a HIPAA violation). That said, due to the litigious nature of the US some patients are still likely to sue and/or generate bad press. While it's unlikely that a court would find the doctor/hospital guilty of any HIPAA violations it's a giant headache the hospital and their lawyers don't want to deal with.