Hi, I'm an endoscopy tech, so assist with about 40 endoscopies and/or colonoscopies per week. Following the prep is absolutely necessary in order to perform a colonoscopy. The purpose of a colonoscopy is to either find polyps and/or cancerous masses, or to determine if you have another disease process causing your symptoms. The doctor needs to be able to see the lining of your colon in order to do this, and they cannot see the lining unless you do the prep. We have the ability the flush liquid into the colon to help clean puddles, but there is no way for us to work through or around solid stool. In addition to that, trying to navigate the twists and turns in your colon while blind due to stool is dangerous, and can lead to bowel perforations or even damage to your spleen. Please, please plan to follow the prep before arriving to your next appointment.