Screening flexible sigmoidoscopy

Has the rule changed as to when this can be done. I thought it was every 4 years unless a colonoscopy has been done then you have to wait 119 months.

re: Screening flexible sigmoidoscopy

Medicare covers the following screenings:

Fecal occult blood test - once a year (every 12 months) for persons age 50 or older
Flexible sigmoidoscopy - once every four years (48 months) for persons at high risk and less frequently for other persons
Colonoscopy - once every two years (24 months) if you are at high risk for colorectal cancer (e.g. have a family history of the disease or have had colorectal polyps or colorectal cancer, or have had inflammatory bowel disease). If you are not at high-risk, Medicare covers colonoscopies every 10 years (but not within 48 months of a screening flexible sigmoidoscopy).
Barium enema – once every two years for persons at high risk and once every four year for others (but not within 48 months of a screening flexible sigmoidoscopy).