A colonoscopy is a procedure whereby a flexible telescope is inserted into the anus (back passage) and manoeuvred through the large intestine (colon) to the caecum (where the large and small intestines join). It is usually possible to visualise the last portion of the small intestine as well. It can be performed under conscious sedation (light sedation) or deep sedation (like a general anaesthetic). A colonoscopy is the best way to visualise the inside of the bowel and all colon diseases can be diagnosed by looking and taking biopsies of the lining of the bowel. As well as a diagnostic procedure, a colonoscope can be used to remove all growths) that are the precursor of bowel cancer.
What to expect
The day before the colonoscopy, a clear liquid diet is required. A bowel preparation is prescribed, usually 3 sachets of picoprep. This is a very powerful laxative that produces bowel motions and cleans out the bowel in order for successful visualisation of the bowel. Specific information for your bowel preparation can be found here.
After the procedure, you may feel the effects of the sedation for 24 hours so you should not drive until the following day. It is important to have someone to pick you up after the procedure. You may feel a little bloated and ‘gaseous’ and sometimes it takes a few days for your bowel habits to return to normal.
Complications during and after colonoscopy are rare.
The most serious complication is a perforation of the bowel. This can occur while taking off a polyp or rarely from manipulating around a tight angle or simply from distending the bowel with gas. The risk of perforation is approximately 1 in 2000. Most perforations require surgery to fix, although some can be managed non-operatively.
Bleeding can occur after removing a polyp or taking a biopsy. The risk of bleeding is about 1 in 200. It usually occurs between 1 -2 weeks after the procedure.
Care is taken to find and remove all significant polyps during a colonoscopy. There is a missed rate of polyps. Significant polyps (>1cm) can be missed in up to 1% of cases. Smaller polyps are missed in a higher percent of cases.