Colonoscopy is a test that looks at the inner lining of the large intestine, which is also called the colon. The procedure allows your doctor to check for polyps or for cancer in the colon or rectum.
Polyps are growths in the colon that might turn into cancer over time. If you have polyps, these can usually be taken out during colonoscopy. Removing polyps lowers your chances of developing colon cancer. Cancer that is found early often can be cured or treated easily. There are 4 to 5 other tests to look for colon cancer, but most doctors believe that colonoscopy is the best test.
Colonoscopy is also used to look for causes of unexplained anemia, weight loss, rectal bleeding, abdominal or rectal pain, changes in bowel habits, and abnormal results from other colon tests.