I think it's amazing that your T offered, and I think you should go with your gut on this one - if you want her there, then say yes, if not, then say no.

If you do say yes, it might be helpful to have a conversation with her in advance of what kind of role you would like her to have when she is there; would you want her to talk to you and be supportive, talk about random things and be more of a distraction, or just sit and be present? I think knowing what you want/need from her and talking it over ahead of time would really help.

I don't have any experience with anything similar, so I don't have any personal advice to give you. I am one of those people who refuses to have anyone with me at medical things, especially if it is invasive or scary. I hate being vulnerable in front of people, so I won't even let my boyfriend come with me. (Plus I don't see that as something my T would ever offer, anyway )

I hope it goes well for you, and please keep us updated on how you are doing!

*hugs*