How bad is a urodynamic study?

I have a vaginal vault prolapse caused by my uterus & bladder coming down, and a rectal prolapse. It’s likely from my Ehlers-Danlos Syndrome. I have a urodynamic study tomorrow, because it’s required before I can get surgery. I’ve never had a urethral catheter and I’m really afraid of the pain it could cause. Both with insertion and triggering bladder spasms. When I get them, the spasms last about 2 hours and the pain is by far the worst thing I’ve ever felt (and I dislocate my shoulder in my sleep pretty often). I come close to fainting from the pain. I just really, really do not want to deal with that. I just want to get my surgery and leave this behind me. 😭