Private London Gastroenterologist

020 7616 7645


Dr Philip Woodland



Having a colonoscopy


What is a colonoscopy?

A colonoscopy is a camera test that allows direct visualisation

of the large bowel (colon), and often the end of the small

bowel (terminal ileum).


Why is a colonoscopy done?

A colonoscopy allows the endoscopist to see what the inside

of the bowel looks like. This makes it the best test to

diagnose and exclude bowel cancer, polyps and inflammation

within the bowel (including ulcerative colitis and most

Crohn’s disease).  It gives an opportunity to take small biopsy

samples through the camera that can be looked at

microscopically by a pathologist. It also allows the removal,

through the camera, of polyps (see below).


What preparation do I need?

Your bowel will need to be clean in order for the endoscopist to give the most accurate assessment of the bowel. This means adhering to specific dietary instructions and taking bowel cleansing medications before you arrive. You will receive the medications and instructions about how to use it and what to eat before you arrive


How is it done?

The colonoscopy is usually done after injection of a sedative and painkiller, but in some cases people choose to have no sedation at all.

When you have a colonoscopy you are lying down on your left side. There will usually be 2 nurses in the room (one to stay by you and guide you through the test, and the other to help the endoscopist). The endoscopist passes the camera through the back passage (anus), through to the junction between the small and large bowel. A careful inspection of the bowel is made as the camera is withdrawn. If biopsy samples are done, tiny (a couple of millimetre) samples of the lining of the bowel are taken using small forceps that are passed through the endoscope.

Sometimes polyps are seen inside the bowel. These are small wart-like growths that are found on the bowel lining. The importance of polyps is that they can grow and become cancerous (a process that takes many years). Because of this, if they are seen at colonoscopy they are usually removed. This is done by passing a snare (a metal loop) through the camera, placing it around the polyps and then closing it to cut the polyp away.

Usually the whole procedure is usually complete within about 20 - 35 minutes.


What are the risks of a colonoscopy?

A gastroscopy is a very safe test. There is a  very small risk (1 in 1000) of a serious problem such as causing a bleed, or a perforation (a tear caused by the endoscope).


When do I get the results?

Your endoscopist should be able to tell you how the test looked before you go home. If biopsy samples are taken the results of the these may take a couple of days.



Colonoscopy diagram

Private Office:

tel: 020 7616 7645, fax: 020 3219 3289


post: London Digestive Health, 41 Welbeck Street, Marylebone, London W1G 8DU