Every dr. is different; I was on a full liquids 2 days before, then clear liquids the day before w/ my prep-4 ducolax followed by 1 bottle of miralax mixed w/ 64 oz of gatorade. I also had to take 6000 mg of antibiotics in between. The actual day of my surgery I wasn't allowed anything and my surgery wasn't scheduled until 5pm so I went from Tuesday morning until Thursday evening for my "prep."
I'd do it all over again! It's the BEST thing I've EVER had done ! I've never felt better!
On another note, an ERCP is a pressure test of the ducts of the pancreas; they have to sedate you to do the test and you have a high risk of getting pancreatitis from it. I know because I've had pancreatitis 3 times and I got it once from that test. It is the WORST pain ever.
My thoughts and prayers are with you all, especially, Tom