Following a colonoscopy prep diet leads to a successful colonoscopy. But how necessary is a clear-liquids only diet? How can you stay full? I've always followed a colonoscopy prep diet that erred on the side of caution. In fact, for my first colonoscopy, I misread the instructions and followed a strict. Prep for your prep. Refrigerate your medication before you drink it, and try drinking it from a straw. Many people think this improves the taste. Hydrate yourself. Drink clear liquids often—water, coconut water, electrolyte drinks. Follow the plan. Your. Reportable procedure and diagnoses include: G0121, colorectal cancer screening; colonoscopy on individual not meeting the criteria for high risk. Z12.11, encounter for screening for malignant neoplasm of colon. The HCPCS code is the correct code to use—not the CPT ® code—because the patient is a Medicare patient.