<unk>  () or coloscopy () is the endoscopic examination of the large bowel and the distal part of the small bowel with a CCD camera or a fiber optic camera on a flexible tube passed through the anus. It can provide a visual diagnosis (e.g., ulceration, polyps) and grants the opportunity for biopsy or removal of suspected colorectal cancer lesions.<unk>  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 precancerous or not. It can take up to 15 years for a polyp to turn cancerous.<unk>  is similar to sigmoidoscopy—the difference being related to which parts of the colon each can examine. A<unk>  allows an examination of the entire colon (1200–1500mm in length). A sigmoidoscopy allows an examination of the distal portion (about 600mm) of the colon, which may be sufficient because benefits to cancer survival of<unk>  have been limited to the detection of lesions in the distal portion of the colon. A sigmoidoscopy is often used as a screening procedure for a full<unk> , often done in conjunction with a fecal occult blood test (FOBT). About 5% of these screened patients are referred to<unk> . Virtual<unk> , 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. Virtual<unk>  does not allow therapeutic maneuvers such as polyp and tumour removal or biopsy, nor visualization of lesions smaller than five millimeters; if a growth or polyp is detected using CT colonography, it would require removal during a standard<unk> . Surgeons have used the term pouchoscopy to refer to a<unk>  of the ileo-anal pouch.
Colonoscopy
Proctoscopy
Sigmoidoscopy
GI cocktail
Defecography
Capsule endoscopy
Chromoendoscopy
Colonic polypectomy