It is useful but may miss smaller polyps. As a screening test, it is covered by insurance every 5 to 10 years for those 50 and older. Flexible sigmoidoscopy is an examination of the rectum and lower portion of the colon with a flexible, lighted tube. As a screening test, it is covered by insurance starting at age 50 and every five years thereafter, which is the recommended frequency. But surprisingly few doctors offer the test to patients.
Colonoscopy is a visual exam of the entire colon, via a flexible scope monitored on a video screen.
It must be performed by a specially trained physician. You must take laxatives and eat no solid foods the day before, and you usually need sedation, as well as a few hours to recover. A highly accurate and valuable tool, colonoscopy can remove polyps that it detects. Complications, including perforation of the colon and hemorrhage, are rare but not unknown. Something called virtual colonoscopy is on the horizon.