A colonoscopy is a test which allows me to look into your large bowel or colon and often, the end of the small bowel or terminal ileum. The last part of the colon leads into the rectum where faeces (stools or motions) are stored before being passed out from the anus. A colonoscope is a thin, flexible, telescope. It is about as thick as a little finger. It is passed through the anus and into the colon. The colonoscope contains fibre optic channels which allow light to shine down so the operator can see inside your colon. The colonoscope also has a ‘side channel’ which allows different devices to be passed. For example, I may take a small sample (biopsy) from the inside lining of the colon by using a thin ‘grabbing’ instrument (forceps).