Colonoscopy

Colonoscopy is a medical procedure that allows direct examination of the interior lining of the colon and rectum using a long, flexible tube called a colonoscope, equipped with a camera and light. It is used for colorectal cancer screening, investigation of symptoms such as rectal bleeding, chronic abdominal pain, or changes in bowel habits, and surveillance in people with inflammatory bowel disease or a history of polyps. The procedure is typically performed by a gastroenterologist or an equipped surgical endoscopist.

Before colonoscopy, patients undergo bowel preparation to clear the colon, often involving laxatives and a clear liquid diet for 1 to 2 days. Sedation is commonly used; most patients receive conscious sedation, though some centers offer general anesthesia. During the procedure, the colonoscope is inserted through the anus and advanced through the colon to the cecum while air or carbon dioxide is insufflated to improve visibility. The clinician inspects the mucosa and can perform interventions such as polypectomy (removal of polyps), biopsy, or dilation if needed. The examination typically lasts 30 to 60 minutes. Afterward, patients recover from sedation and are advised to rest; common short-term effects include bloating or gas.

Risks include bleeding, perforation, and adverse reactions to sedation, which are uncommon. Colorectal polyps found during colonoscopy can be removed and sent for pathology, and findings guide future screening intervals. Alternatives include sigmoidoscopy (limited to the lower colon), CT colonography (virtual colonoscopy), and stool-based tests; some alternatives do not allow therapeutic intervention.

Contraindications include certain acute intestinal conditions, bowel obstruction, or unstable patients. If polyps or lesions are found, follow-up colonoscopy intervals are based on initial findings and prevailing guidelines.