From Citizendium
Jump to navigation Jump to search
This article is developing and not approved.
Main Article
Related Articles  [?]
Bibliography  [?]
External Links  [?]
Citable Version  [?]
This editable Main Article is under development and subject to a disclaimer.

In medicine, colonoscopy is a "endoscopic examination, therapy or surgery of the luminal surface of the colon."[1]



The most effective bowel preparation is split dose.[2][3]

Direct viewing

In the most common method, a direct-viewing fiber optic colonoscope is inserted in the anus, under conscious sedation or general anesthesia, and threaded into the colon. The operator sees the magnified surface on a color television monitor, and is able to insert instruments to take biopsies, or remove or cauterize suspicious areas.

Virtual colonoscopy

One method of virtual colonoscopy reconstructs the view from multiple computed tomography scans of the area. It is noninvasive, but does not allow biopsy or interventions.

Autonomous camera

Another method involves having the patient swallow a capsule containing a miniaturized camera and light source, which transmits to radio antennas around the patient's body. Like the CT method, it is noninvasive and does not allow intervention. There is some concern that colon obstruction or motility problems might cause the capsule to become stuck.


Colonosopy is not perfect and may miss colonic polyps that could lead to colorectal cancer.[4] Several factors affect accuracy and these are part various quality indicators.[5][6]

Adenoma detection rate

A cohort study found "The adenoma detection rate was inversely associated with the risks of interval colorectal cancer, advanced-stage interval cancer."[7]

Operative experience

Colonoscopies performed by a primary care physician may be less accurate.[8] Colonoscopies performed by examiners who have performed a large volume of procedures are better(at least 200 per year)[9][10], perhaps especially if the prior experience was very recent[11] Non-gastroenterologists do not do as well.[12]

Bowel cleaning method

Administering the osmotic laxative the morning of the colonoscopy[13], of splitting the administration of the osmotic laxative into a dose the evening before colonoscopy followed by a second dose the morning of the colonoscopy helps[14]. A smaller 960-mL oral sulfate solution split between half the evening before and half the morning of the procedure may be an alternative.[15]

Cecal intubation rates

Operators should intubate 95% of cecums when screening healthy adults.[5]

Withdrawal time

Withdrawing the colonoscopy too fast (less than 6 minutes) may cause missing of important abnormalities.[16]

Adverse effects

Colonoscopy has infrequent severe adverse effects.[17][18] In a study of 2531 volunteers 50 years of age or older undergoing colonoscopy:[19]


  1. Anonymous (2023), Colonoscopy (English). Medical Subject Headings. U.S. National Library of Medicine.
  2. Kilgore TW, Abdinoor AA, Szary NM, Schowengerdt SW, Yust JB, Choudhary A et al. (2011). "Bowel preparation with split-dose polyethylene glycol before colonoscopy: a meta-analysis of randomized controlled trials.". Gastrointest Endosc 73 (6): 1240-5. DOI:10.1016/j.gie.2011.02.007. PMID 21628016. Research Blogging.
  3. American Society of Colon and Rectal Surgeons (ASCRS). American Society for Gastrointestinal Endoscopy (ASGE). Society of American Gastrointestinal and Endoscopic Surgeons (SAGES). Wexner SD, Beck DE, Baron TH et al. (2006). "A consensus document on bowel preparation before colonoscopy: prepared by a Task Force from the American Society of Colon and Rectal Surgeons (ASCRS), the American Society for Gastrointestinal Endoscopy (ASGE), and the Society of American Gastrointestinal and Endoscopic Surgeons (SAGES).". Surg Endosc 20 (7): 1161. DOI:10.1007/s00464-006-3037-1. PMID 16799744. Research Blogging.
  4. Rex DK, Cutler CS, Lemmel GT, et al (January 1997). "Colonoscopic miss rates of adenomas determined by back-to-back colonoscopies". Gastroenterology 112 (1): 24–8. PMID 8978338[e]
  5. 5.0 5.1 Rex DK, Petrini JL, Baron TH, et al (April 2006). "Quality indicators for colonoscopy". Gastrointest. Endosc. 63 (4 Suppl): S16–28. DOI:10.1016/j.gie.2006.02.021. PMID 16564908. Research Blogging.
  6. The Joint Advisory Group on GI Endoscopy. Standards for Training in Endoscopy. Accessed: March 4, 2009
  7. Corley DA, Jensen CD, Marks AR, Zhao WK, Lee JK, Doubeni CA et al. (2014). "Adenoma detection rate and risk of colorectal cancer and death.". N Engl J Med 370 (14): 1298-306. DOI:10.1056/NEJMoa1309086. PMID 24693890. Research Blogging.
  8. Bressler B, Paszat LF, Chen Z, Rothwell DM, Vinden C, Rabeneck L (January 2007). "Rates of new or missed colorectal cancers after colonoscopy and their risk factors: a population-based analysis". Gastroenterology 132 (1): 96–102. DOI:10.1053/j.gastro.2006.10.027. PMID 17241863. Research Blogging.
  9. Harewood GC (January 2005). "Relationship of colonoscopy completion rates and endoscopist features". Dig. Dis. Sci. 50 (1): 47–51. PMID 15712636[e]
  10. Bernstein C, Thorn M, Monsees K, Spell R, O'Connor JB (January 2005). "A prospective study of factors that determine cecal intubation time at colonoscopy". Gastrointest. Endosc. 61 (1): 72–5. PMID 15672059[e]
  11. Dafnis G, Granath F, Påhlman L, Hannuksela H, Ekbom A, Blomqvist P (June 2001). "The impact of endoscopists' experience and learning curves and interendoscopist variation on colonoscopy completion rates". Endoscopy 33 (6): 511–7. PMID 11437045[e]
  12. Rabeneck L, Paszat LF, Saskin R (2010). "Endoscopist specialty is associated with incident colorectal cancer after a negative colonoscopy.". Clin Gastroenterol Hepatol 8 (3): 275-9. DOI:10.1016/j.cgh.2009.10.022. PMID 19879970. Research Blogging.
  13. Gupta T, Mandot A, Desai D, Abraham P, Joshi A, Shah S (August 2007). "Comparison of two schedules (previous evening versus same morning) of bowel preparation for colonoscopy". Endoscopy 39 (8): 706–9. DOI:10.1055/s-2007-966375. PMID 17661245. Research Blogging.
  14. Park JS, Sohn CI, Hwang SJ, et al (July 2007). "Quality and effect of single dose versus split dose of polyethylene glycol bowel preparation for early-morning colonoscopy". Endoscopy 39 (7): 616–9. DOI:10.1055/s-2007-966434. PMID 17611916. Research Blogging.
  15. Di Palma JA, Rodriguez R, McGowan J, Cleveland MB (2009). "A randomized clinical study evaluating the safety and efficacy of a new, reduced-volume, oral sulfate colon-cleansing preparation for colonoscopy.". Am J Gastroenterol 104 (9): 2275-84. DOI:10.1038/ajg.2009.389. PMID 19584830. Research Blogging.
  16. Barclay RL, Vicari JJ, Doughty AS, Johanson JF, Greenlaw RL (December 2006). "Colonoscopic withdrawal times and adenoma detection during screening colonoscopy". The New England journal of medicine 355 (24): 2533–41. DOI:10.1056/NEJMoa055498. PMID 17167136. Research Blogging.
  17. Ko CW, Riffle S, Michaels L, Morris C, Holub J, Shapiro JA et al. (2010). "Serious complications within 30 days of screening and surveillance colonoscopy are uncommon.". Clin Gastroenterol Hepatol 8 (2): 166-73. DOI:10.1016/j.cgh.2009.10.007. PMID 19850154. PMC PMC2821994. Research Blogging.
  18. Rabeneck L, Paszat LF, Hilsden RJ, et al (December 2008). "Bleeding and perforation after outpatient colonoscopy and their risk factors in usual clinical practice". Gastroenterology 135 (6): 1899–1906, 1906.e1. DOI:10.1053/j.gastro.2008.08.058. PMID 18938166. Research Blogging.
  19. Johnson CD, Chen MH, Toledano AY, et al (September 2008). "Accuracy of CT colonography for detection of large adenomas and cancers". The New England journal of medicine 359 (12): 1207–17. DOI:10.1056/NEJMoa0800996. PMID 18799557. Research Blogging.