This is a very common question and very understandable! We ask that you drink the preparation so that the colon is completely cleansed of all fecal material. This will result in the best test for you, since polyps can sometimes be tricky and hide behind folds in the colon or underneath small amounts of feces. The prep that we give is the safest one as there have been reports of kidney damage with some of the alternatives. As long as the stool looks like urine (yellow, rather than clear) with no brown particles, this degree of cleansing is adequate for colonoscopy.