maybe not for "hours" but you will definitely be spending more time than usual. the colon must be flushed out so depending on the prep you are given you will be having a lot of watery stools (until it is just water). get some good reading materials and bring in the phone. don't plan on doing anything else during this time so you will be in close proximity to the toilet.
will i be in the bathroom for hours after the prep starts for a colonoscopy?