Colonoscopy

Colonoscopy is the endoscopic examination of the large bowel and the lower part of the small bowel, using a camera mounted on a flexible tube that is passed through the anus so a doctor can inspect the lining of the colon wall, detect ulceration or precancerous polyps, and take a biopsy or remove a suspected colorectal cancer lesion. In the United States it is a commonly recommended cancer screening test, often beginning at age 45 or 50 depending on risk factors and professional guidelines, though other countries more often rely on alternatives such as fecal occult blood testing or sigmoidoscopy. Beyond screening, colonoscopy is also used to evaluate gastrointestinal bleeding, unexplained changes in bowel habits, and to help diagnose inflammatory bowel disease or colon polyps.