Everyone's anatomy is different, sometimes they can't get into the TI at all. I doubt that any scope can get 40 cm into the ileum - I think it is more like a few inches (10 cm??). It is best to ask your GI about
how far s/he got with the scope than to rely on what a nurse told you.
I don't know how good the CT is at identifying specific locations in your bowel. Sorry that this has become more complicated!