I think it depends on whether or not the therapist thinks you are in immediate danger. (I'm guessing that therapist is what you mean, forgive me if it isn't).
If the self harm has been relatively shallow, and in the past, they might just want to find out why and decide with you how to avoid further harm.

If you have started again, it probably depends on the severity of the wound and how well the therapist knows you. If they feel that you might be a danger, then they may want you in for a short in patient therapy. That isn't always bad. Its only temporary, and will give them the opportunity to work with you more frequently as well as keep you safe.

If there is self harm involved, the main thing is to get help and do it as soon as you can. Self harm can escalate without warning, or simply by mistake. Be honest with a therapist. That is the best way for you to get help.

Sam2