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Colonoscopy and flexible sigmoidoscopy 

Colonoscopy and flexible sigmoidoscopy
Colonoscopy and flexible sigmoidoscopy

James E. East

, and Brian P. Saunders

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date: 25 February 2021

Colonoscopy involves full oral bowel preparation and planned examination of the whole large bowel, while flexible sigmoidoscopy is usually performed after a phosphate enema and visualizes only the rectum and left colon. In expert hands, after appropriate explanation to the patient (which increases the chances of the procedure being well tolerated), and (usually) some form of ‘conscious sedation’, total colonoscopy is possible in 98 to 99% of cases in the absence of obstruction, a severely ulcerated colon, or other contraindication. The indications for colonoscopy are wide and constantly expanding, and are likely to continue to do so until alternative less invasive techniques (‘virtual colonoscopy’ or genetic tests) are perfected. Common indications include patients with or requiring (1) bleeding, anaemia, or occult blood loss; (2) chronic diarrhoea or known inflammatory bowel disease, which is accurately and easily assessed by endoscopy and biopsy; (3) polyps that can be removed endoscopically; and (4) surveillance for cancer prevention. Therapeutic colonoscopy now allows resection of almost all benign colonic polyps and some very early cancers as well as dilatation of anastomotic or Crohn’s disease strictures and stenting of malignant strictures.

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