Editing Virtual colonoscopy (section)

==Procedure==
[[File:Vc3.theora.ogv|thumb|right|This video shows a virtual colonoscopy of the rectosigmoid colon performed in a retrograde fashion. There is a 10-mm colonoscopically-proven polyp in the sigmoid colon seen at the top of the frame at the midpoint of the movie. The movie concludes at the tip of the rectal tube which was used to insufflate the colon.]]
While preparations for VC vary, the patient will usually be asked to take [[laxative]]s or other oral agents at home the day before the procedure to clear [[feces|stool]] from the colon. A [[suppository]] is also used to cleanse the rectum of any remaining fecal matter.  The patient may also be given a solution designed to coat any residual faeces which may not have been cleared by the laxative, called 'faecal tagging'. This allows the physician (usually a [[Radiologist|consultant radiologist]]), viewing the 3D images to effectively subtract the left-over faeces, which may otherwise give false positive results.{{cn|date=January 2022}}

VC takes place in the [[radiology]] department of a [[hospital]] or medical center. The examination takes about 10 minutes and does not require [[sedatives]].{{cn|date=January 2022}}

During the procedure:{{cn|date=January 2022}}
* The patient is placed in a [[supine position]] on the examination table
* The patient may be given a dosage of [[Butylscopolamine]] intravenously to minimize muscle activity in the area.
* A thin tube is inserted into the rectum, so that air can be pumped through the tube in order to inflate the colon for better viewing.
* The table moves through the scanner to produce a series of two-dimensional cross-sections along the length of the colon. A [[computer program]] puts these images together to create a three-dimensional picture that can be viewed on the [[Electronic visual display|video screen]].
* The patient is asked to hold his/her breath during the scan to avoid distortion on the images.
* The scan is then repeated with the patient lying in a [[prone position]].

After the examination, the images produced by the scanner must be processed into a 3D image, +/- a fly through (a cine program which allows the user move through the bowel as if performing a normal colonoscopy). A radiologist evaluates the results to identify any abnormalities.

The patient may resume normal activity after the procedure, but if abnormalities are found and the patient needs conventional [[colonoscopy]], it may be performed the same day.<ref>[http://digestive.niddk.nih.gov/ddiseases/pubs/virtualcolonoscopy/ "Virtual Colonoscopy"] {{Webarchive|url=https://web.archive.org/web/20141009020407/http://digestive.niddk.nih.gov/ddiseases/pubs/virtualcolonoscopy/ |date=2014-10-09 }} - National Digestive Diseases Information Clearinghouse - NIH</ref>