A colonoscopy is a visual examination - performed using an endoscope - which reveals possible abnormalities in the colon. The examination is performed under general anaesthesia in a public or private hospital gastroenterology department.
Colonoscopy is the reference examination that is used to visualise polyps or malignant lesions in screening for colorectal cancer. It can also identify the causes of intestinal bleeding, unexplained abdominal pain or chronic diarrhoea. In addition, it can be used for treatment such as the removal of polyps. It is a useful evaluation to monitor patients with clearly identified bowel diseases, or known risk factors such as cancer, past history of polyps or inflammatory bowel diseases, etc...
Colonoscopy is generally performed under short-term ‘comfort ‘ general anaesthesia, after faecal matter has been removed from the colon by a low-residue diet for three days before the examination and then by taking a specific solution intended to empty the colon. All raw and cooked fruits, whole-grain cereals and meats containing fibre or tendons should therefore be avoided. No food can be taken for 4 to 6 hours before the investigation. Not smoking is also strongly recommended. The colonoscope is introduced through the anus and advanced to the proximal end of the colon, the caecum, at its junction with the small intestine: the ileo-caecal valve. Air is gradually introduced as it is advanced to separate the walls.
Possible risks of colonoscopy
Colonoscopy is a very commonly performed examination and complications are rare. Cases of perforation of the wall of the colon and bleeding have been reported. The gastroenterologist should be informed if abnormal abdominal pain, red blood, black stools, temperature or rigours develop or persist after the examination. The possible risks of any anaesthesia must also be considered.
Source: Société française d'endoscopie digestive (French Society of Digestive Endoscopy), website accessed on 25 January 2011
Colonoscopy involves the colon. © Sebastian Kaulitzki, Fotolia