MODEL RELEASED. Colonoscopy procedure. View of a surgeon examining the colon (large intestine) of a patient using a colonoscope. The legs of the patient are supported in stirrups. A colonoscope is a flexible endoscope with fibre-optic illumination used to see inside the interior of the large intestine. The endoscope is usually inserted through the rectum, as seen here. The device may also be fitted with forceps and cutting instruments to retrieve tissue samples for biopsy examination, or to remove polyps. Crohn's disease, ulcers and cancer of the bowel may be diagnosed in this way.