I come back from a GC sabbatical to a topic right up my alley. I have Crohn's Disease, so I've been through about every poking and proding procedure involving the digestive tract. Pretty much everything has been covered, so you're definitely going in well-informed. Just be glad it's not a colonoscopy. Wanna talk about fun.... ha. Even better is the Small Bowel Follow-Through. If you end up having to have one of those, I can tell you everything you need to know. I don't know yet if that's something to be proud of...
Good luck!