The colon must be free of solid matter for the test to be performed properly. For one to three days, the patient is required to follow a low fibre or clear-fluid only diet. Examples of clear fluids are apple juice, bouillon, artificially flavored lemon-lime soda or sports drink, and of course water. It is very important that the patient remains hydrated. As orange juice, prune juice, and milk contain fibre, they are banned from the list, as are liquids dyed red, orange, purple, or brown, such as cola. However, in most cases black coffee is allowed.
The day before the colonoscopy, the patient is either given a laxative preparation (such as Bisacodyl, phospho soda, sodium picosulfate, or sodium phosphate and/or magnesium citrate) and large quantities of fluid or whole bowel irrigation is performed using a solution of polyethylene glycol and electrolytes.
The patient may be asked to skip aspirin and aspirin-like products such as salicylate, ibuprofen, and similar medications for up to ten days before the procedure to avoid the risk of bleeding if a polypectomy is performed during the procedure. A blood test may be performed before the procedure.
http://en.wikipedia.org/wiki/Colonoscopy
I had one done about two years ago without anethestic, they really don't hurt much, just uncomfortable. I was clean as a whistle - knock on wood.
wil..