Just to interject - I am/was a scratcher. It was my T who called it 'scratching'.

It's something I do when anxious but also (sounds like I'm contradicting myself), when in a dissociative state. It's hard to explain but I'm anxious & then I do it without conscious thought.

Generally it is just scratching, like an itch but there is no itch. Occasionally the scratching would cause scratch marks but they disappeared within a day. I only ever scratch the inside of my arm near my wrist.

My therapist puts it in the category of self harm (previously I had some limited & infrequent cutting).

When pointed out to me I generally will stop. Sometimes I will become aware of it myself & stop.

There doesn't appear to be in physical reason, and I haven't done it for some months now. It seemed to happen when my symptoms were at there worse & I was avoiding treatment/engaging in therapy.

I wouldn't consider it a big factor of my PTSD. I think actual self injury would be more prevalent in PTSD then scratching. But then I think you'd run the risk of making it about 'self harm' and not PTSD.