I'm not sure what kind of work your wife does; but, if restraining violent/delirious patients is a possibility, just about any on-body carry method has a good risk of exposing the weapon and/or allowing the patient access to it...not a good situation (and one reason I can't carry in my line of work).
I'll second Wheelgun Dunn's suggestion for some type of off-body carry....esp. one that can be placed in a secured area while at work (locked locker, etc). Although the fanny pack carry has been overdone, it's still pretty popular in the health-care field...and there are still plenty of makers (I like Uncle Mike's). You can even get them in different colors...perhaps one to match her scrubs and be less obvious.