Colonoscopy is a procedure that lets your doctor look inside your entire large intestine. It uses an instrument called a colonoscope, or scope for short. Scopes have a tiny camera attached to a long, thin tube. The procedure lets your doctor see things such as inflamed tissue, abnormal growths, and ulcers.
Your doctor may recommend a colonoscopy:
Your doctor can also remove polyps from your colon during a colonoscopy.
You need to be on a clear liquid diet for 1 to 3 days before the colonoscopy. During the procedure, you receive medicines to keep you relaxed.
NIH: National Institute of Diabetes and Digestive and Kidney Diseases