I was asked to fast from 6PM the night before. The only prep I did was to take a lot of fluids (to keep from dehydrating). I did chicken stock that my wife made (very tasty) and lime Jello. I knew everything was out when my bag filled with lime green fluid. That was more than a bit of a trip to see. I told my surgeon about that and said she was lucky because for a colonoscopy/endoscopy I had to have a couple of weeks prior to the takedown, I did the same prep, but went with lemon Jello instead. That was even trippier, as the bag turned a pretty bright yellow.