COLONOSCOPY : Colonoscopy is the endoscopic examination of the large colon and the distal part of the small bowel with a CCD camera or a fibre optic camera on a flexible tube passed through the anus.
A colonoscopy may provide a visual diagnosis (e.g. ulceration, polyps) and grants the opportunity for biopsy or removal of the suspected lesions.
Virtual colonoscopy, which uses 2D and 3D imagery reconstructed from computed tomography (CT) scans or from nuclear magnetic resonance (MR) scans, is also possible, as a totally non-invasive medical test. However, virtual colonoscopy does not allow for therapeutic maneouvers such as polyp/tumour removal or biopsy nor visualization of lesions smaller than 5 millimeters. If a growth or polyp is detected using CT colonography, a standard colonoscopy would still need to be performed.
Colonoscopy can remove polyps smaller than one millimeter. Once polyps are removed, they can be studied with the aid of a microscope to determine if they are pre-cancerous or not.
Colonoscopy is similar to but not the same as sigmoidoscopy. The difference between colonoscopy and sigmoidoscopy is related to which parts of the colon each can examine. Sigmoidoscopy allows doctors to view only the final two feet of the colon, while colonoscopy allows an examination of the entire colon, which measures four to five feet in length. Often a sigmoidoscopy is used as a screening procedure for a full colonoscopy.
