How Often Does Medicare Allow Colonoscopy? 
Medicare will cover a colononscopy every 24 months -LRB- 2 years -RRB- if the patient is at high risk for colorectal cancer . If the patient is not high risk for colorectal cancer , Medicare will cover a colonoscopy every 120 months -LRB- 10 years -RRB- or 48 months after a flexible sigmoidoscopy . 