Most of mine I didn't have to tell them. the therapist before them included incidences in the file, so when seeing new therapists they read it in my file. Sometimes they knew from things like my wearing long sleaves in summer - dead giveaway "something" is going on. When I have physicals my physicians sometimes would write in my charts scarring. So that too tells therapists. Those that I chose to tell I did so because the question came up for example I use the courage to heal text and workbook by Laura Davis as an active part of my therapy. I share my work in these books with my therapist so when we hit those questions about self harm and learning new ways to take care of things instead of self harm I just answer the questions head on and right out. I think there was only one time that I outright hid my self harm from my therapist. That was wback years ago when I was seeing a crisis center counselor and I was experiencing flashbacks and I didn't know thats what they were so when I would "wake up" cut I went to the crisis center and I was hospitalized- free cop car ride and full body search in the ER included. I didn't know what was going one but I knew one thing These cuts were not intentional and I was not suicidal. I got ticked off at everyone and when I got out I hid my cutting. other then that I have always been honest if the question ever came up didn't offer on my own but answered truthfully if they asked.