The CPT definition of modifier 78 states, "Unplanned return to the operating/procedure room by the same physician following inital procedure for a related procedure during the postoperative period."

CMS gives a great definition of an operating room, but how exactly do you define a procedure room? Would this modifier be applicable to a physician's office? Let's say the patient had surgery done in a physician's office, but it was done in an exam room and not a procedure room, and then we had to do a related procedure again in the exam room. Would this be modifier 78? What exactly defines a procedure room?

I hope my question is clear here.

Thanks in advance.