Screening vs Surveillance Colonoscopy

Our office and facility need clarification on colonoscopy coding for polyp surveillance. Some are saying it should be a high risk screening due to polyps (CPT 45378, DX: Z12.11, Z86.010) and patient's insurance will pay 100%. The other opinion is that it should be a surveillance colonoscopy due to polyps (CPT 45378, DX: Z86.010) and patient's deductible/co-insurance would apply.

Cannot find specific CMS guidelines in regards to this. Any help would be appreciated!!

Melanie