What is the Urodynamic test like?

[RAS6]

I am going in for my test on Tuesday and while I have read and re-read all the info the Doctors gave me and everything the IC Survival guide had to say about this, I am curious as to how uncomfortable this is and whether other people felt good right away or not. I have only had a catheter once and it wasn't as horrible as I anticipated, but my Urethra is very inflamed right now and feels like it is on fire, so I am starting to worry about the upcoming urodynamic test.
Any thoughts or experiences are welcome!
Thanks!
-Rachel