Adjunct technologies

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ColonoscopyAn examination of the large bowel using a camera on a flexible tube, which is passed through the anus.

Overview of evidence (non-systematic literature review)

No systematic reviews were undertaken for this topic. Practice points were based on selected evidence and guidelines (see Guideline development process).

'Add-on’ devices

Inspection on withdrawal could contribute to polyps being missed, as visualisation of the proximal surface of haustral folds may be limited. Several back-to-back colonoscopy trials have reported adenoma miss rates of up to 25%.[1][2] Sessile serrated adenomas or non-polypoid lesions have limited contrast in relation to the surrounding mucosa and can be overlooked.[3] This may contribute to the relatively high risk of interval cancers in the proximal colon.[3][4] As a result, 'add-on' technologies have been developed to improve visualisation, especially in areas behind haustral folds. These include:

  • Transparent Cap (TC)
  • EndoRing
  • Endocuff
  • G-EYE endoscope
  • Third Eye Panoramic device
  • Third Eye Retroscope.

The TC is the most studied add-on device. The cap is attached to the tip of a colonoscope prior to the examination. Although adding to the cost of colonoscopy, it has been proposed as a method for shortening withdrawal time in addition to improving adenoma detection rates (ADR).[5] When used by more experienced colonoscopists, the TC does not improve either the caecal intubation rate or the ADR, but does shorten the caecal intubation time. It may have utility for difficult cases, especially when initial caecal intubation fails.[6] A meta-analysis of 16 studies examining the role of the TC revealed a marginal benefit for polyp detection rate (relative risk 1.08) and no difference in ADR.[7] However, the TC has been shown to improve detection of serrated lesions (12.8% vs 6.6%).[8]

Brand et al recently published the results of a pooled analysis of three technologies (the Third Eye Retroscope, the Full Spectrum Endoscope, and the EndoRing), concluding that these adjunct technologies may enhance detection of small (<10mm) adenomas.[9]

In a multicentre back-to-back study involving 116 patients comparing colonoscopy with and without the EndoRing reported, adenoma miss rates of 10% versus 48% and polyp miss rates of 9% versus 53%.[10]

The Endocuff is a similar device, which appears to increase the detection of diminutive polyps and improve ADR.[11] However, a larger randomised control trial involving 1063 patients showed no change in the ADR.[12]

Shirin et al recently conducted a study over >1000 patients using a balloon based device, the G‐EYE colonoscope.[13] Significantly more adenomas were detected when this technology was used compared with conventional colonoscopy.

With all of these devices the additional cost is a factor that must be considered before incorporation into practice, considering the modest gains reported.

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Chromoendoscopy (dye spray) has been introduced to enhance the detection of polyps, particularly diminutive flat lesions that may be otherwise difficult to detect.[14] When combined with high magnification, chromoendoscopy was found to be highly efficient in differentiating adenomatous from non-adenomatous polyps.[15][16][17] It has also been strongly advocated in patients undergoing surveillance for IBDinflammatory bowel disease (IBDInflammatory bowel disease).[18][19][20] However, in a more recent non inferiority trial, high-definition white-light endoscopy was as effective as chromoendoscopy[21] (see also Colonoscopic surveillance and management of dysplasia in inflammatory bowel disease (IBD)).

Based on results from their studies, Lapalus[22] and Le Rhun[23] could not recommend the systematic use of chromoendoscopy for overall adenoma detection, although there was improvement seen in detecting small adenomas in the proximal colon. Other studies reported that chromoendoscopy detected more polyps compared with standard colonoscopy,[24][25] particularly in patients with Lynch syndrome.[26][27]

Despite being advocated for close to two decades, chromoendoscopy struggles to be accepted in mainstream clinical practice and as a result appears to have been superseded by electronic image enhanced technologies for characterisation of colorectal polyps.

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Carbon dioxide (CO2) insufflation

A recent meta-analysis has confirmed that, when compared to air insufflation, CO2 insufflation clearly reduces post-colonoscopy pain and distension and allows more rapid caecal intubation, but does not improve completion rates or adenoma detection.[28] It appears to be safe even in patients with airway disease.[29]

Barriers to implementation include the lack of incorporation of CO2 insufflation into standard endoscopy systems, the resulting cost of retrofitting CO2 insufflation, and the ongoing cost of the gas itself, estimated at US$3 per procedure.[30]Back to top

Practice pointA recommendation on a subject that is outside the scope of the search strategy for the systematic review, based on expert opinion and formulated by a consensus process.Question mark transparent.png

Chromoendoscopy should be considered for routine colonoscopy to improve the detection and characterisation of colorectal polyps.

Practice pointA recommendation on a subject that is outside the scope of the search strategy for the systematic review, based on expert opinion and formulated by a consensus process.Question mark transparent.png

Chromoendoscopy should be considered for patients undergoing surveillance for inflammatory bowel disease, although a recent study has shown equivalence with high resolution white-light endoscopy.

Practice pointA recommendation on a subject that is outside the scope of the search strategy for the systematic review, based on expert opinion and formulated by a consensus process.Question mark transparent.png

CO2 insufflation should be used routinely to improve patient tolerability of colonoscopy.

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  1. van Rijn JC, Reitsma JB, Stoker J, Bossuyt PM, van Deventer SJ, Dekker E. Polyp miss rate determined by tandem colonoscopy: a systematic review. Am J Gastroenterol 2006 Feb;101(2):343-50 Abstract available at
  2. Heresbach D, Barrioz T, Lapalus MG, Coumaros D, Bauret P, Potier P, et al. Miss rate for colorectal neoplastic polyps: a prospective multicenter study of back-to-back video colonoscopies. Endoscopy 2008 Apr;40(4):284-90 Abstract available at
  3. 3.03.1 Burgess NG, Tutticci NJ, Pellise M, Bourke MJ. Sessile serrated adenomas/polyps with cytologic dysplasia: a triple threat for interval cancer. Gastrointest Endosc 2014 Aug;80(2):307-10 Abstract available at
  4. Singh R, Cheng Tao Pu LZ, Koay D, Burt A. Sessile serrated adenoma/polyps: Where are we at in 2016? World J Gastroenterol 2016 Sep 14;22(34): 7754–7759.
  5. Horiuchi A, Nakayama Y. Improved colorectal adenoma detection with a transparent retractable extension device. Am J Gastroenterol 2008 Feb;103(2):341-5 Abstract available at
  6. Lee YT, Lai LH, Hui AJ, Wong VW, Ching JY, Wong GL, et al. Efficacy of cap-assisted colonoscopy in comparison with regular colonoscopy: a randomized controlled trial. Am J Gastroenterol 2009 Jan;104(1):41-6 Abstract available at
  7. Ng SC, Tsoi KK, Hirai HW, Lee YT, Wu JC, Sung JJ, et al. The efficacy of cap-assisted colonoscopy in polyp detection and cecal intubation: a meta-analysis of randomized controlled trials. American Journal of Gastroenterology 2012;107(8): 1165-1173.
  8. Rzouq F, Gupta N, Wani S, Sharma P, Bansal A, Rastogi A. Cap assisted colonoscopy for the detection of serrated polyps: a post-hoc analysis. BMC Gastroenterol 2015 Feb 5;15:11 Abstract available at
  9. Brand EC, Dik VK, van Oijen MGH, Siersema PD. Missed adenomas with behind-folds visualizing colonoscopy technologies compared with standard colonoscopy: a pooled analysis of 3 randomized back-to-back tandem colonoscopy studies. Gastrointest Endosc 2017 Aug;86(2):376-385.e2 Abstract available at
  10. Dik VK, Gralnek IM, Segol O, Suissa A, Belderbos TD, Moons LM, et al. Multicenter, randomized, tandem evaluation of EndoRings colonoscopy--results of the CLEVER study. Endoscopy 2015 Dec;47(12):1151-8 Abstract available at
  11. De Palma GD, Giglio MC, Bruzzese D, Gennarelli N, Maione F, Siciliano S, et al. Cap cuff-assisted colonoscopy versus standard colonoscopy for adenoma detection: a randomized back-to-back study. Gastrointest Endosc 2018 Jan;87(1):232-240 Abstract available at
  12. van Doorn SC, van der Vlugt M, Depla A, Wientjes CAConventional adenoma, Mallant-Hent RC, Siersema PD, et al. Adenoma detection with Endocuff colonoscopy versus conventional colonoscopy: a multicentre randomised controlled trial. Gut 2017 Mar;66(3):438-445 Abstract available at
  13. Shirin Haim, Shpal Beni, Epshtein Julia, Vilmann Peter, et al. Comparison of Adenoma Detection Rate by a High Definition Colonoscopy versus Standard High Definition Colonoscopy- A Prospective Randomized Multicenter Trial. Gastrointestinal Endoscopy 2016 May [cited 2018 Feb 7];83(5):AB192 Abstract available at
  14. Sonwalkar S, Rotimi O, Rembacken BJ. Characterization of colonic polyps at conventional (nonmagnifying) colonoscopy after spraying with 0.2 % indigo carmine dye. Endoscopy 2006 Dec;38(12):1218-23 Abstract available at
  15. Kudo S, Hirota S, Nakajima T, Hosobe S, Kusaka H, Kobayashi T, et al. Colorectal tumours and pit pattern. J Clin Pathol 1994 Oct;47(10):880-5 Abstract available at
  16. Eisen GM, Kim CY, Fleischer DE, Kozarek RA, Carr-Locke DL, Li TC, et al. High-resolution chromoendoscopy for classifying colonic polyps: a multicenter study. Gastrointest Endosc 2002 May;55(6):687-94 Abstract available at
  17. Singh R, Owen V, Shonde A, Kaye P, Hawkey C, Ragunath K. White light endoscopy, narrow band imaging and chromoendoscopy with magnification in diagnosing colorectal neoplasia. World J Gastrointest Endosc 2009 Oct 15;1(1):45-50 Abstract available at
  18. Kiesslich R, Neurath MF. Surveillance colonoscopy in ulcerative colitis: magnifying chromoendoscopy in the spotlight. Gut 2004 Feb;53(2):165-7 Abstract available at
  19. Marion JF, Waye JD, Present DH, Israel Y, Bodian C, Harpaz N, et al. Chromoendoscopy-targeted biopsies are superior to standard colonoscopic surveillance for detecting dysplasia in inflammatory bowel disease patients: a prospective endoscopic trial. Am J Gastroenterol 2008 Sep;103(9):2342-9 Abstract available at
  20. Laine L, Kaltenbach T, Barkun A, McQuaid KR, Subramanian V, Soetikno R, et al. SCENIC international consensus statement on surveillance and management of dysplasia in inflammatory bowel disease. Gastroenterology 2015 Mar;148(3):639-651.e28 Abstract available at
  21. Iacucci M, Kaplan GG, Panaccione R, Akinola O, Lethebe BC, Lowerison M, et al. A Randomized Trial Comparing High Definition Colonoscopy Alone With High Definition Dye Spraying and Electronic Virtual Chromoendoscopy for Detection of Colonic Neoplastic Lesions During IBD Surveillance Colonoscopy. Am J Gastroenterol 2017 Nov 14 Abstract available at
  22. Société Française d'Endoscopie Digestive, Lapalus MG, Helbert T, Napoleon B, Rey JF, Houcke P, et al. Does chromoendoscopy with structure enhancement improve the colonoscopic adenoma detection rate? Endoscopy 2006 May;38(5):444-8 Abstract available at
  23. Le Rhun M, Coron E, Parlier D, Nguyen JM, Canard JM, Alamdari A, et al. High resolution colonoscopy with chromoscopy versus standard colonoscopy for the detection of colonic neoplasia: a randomized study. Clin Gastroenterol Hepatol 2006 Mar;4(3):349-54 Abstract available at
  24. Park SY, Lee SK, Kim BC, Han J, Kim JH, Cheon JH, et al. Efficacy of chromoendoscopy with indigocarmine for the detection of ascending colon and cecum lesions. Scand J Gastroenterol 2008;43(7):878-85 Abstract available at
  25. Stoffel EM, Turgeon DK, Stockwell DH, Zhao L, Normolle DP, Tuck MK, et al. Missed adenomas during colonoscopic surveillance in individuals with Lynch Syndrome (hereditary nonpolyposis colorectal cancer). Cancer Prev Res (Phila) 2008 Nov;1(6):470-5 Abstract available at
  26. Lecomte T, Cellier C, Meatchi T, Barbier JP, Cugnenc PH, Jian R, et al. Chromoendoscopic colonoscopy for detecting preneoplastic lesions in hereditary nonpolyposis colorectal cancer syndrome. Clin Gastroenterol Hepatol 2005 Sep;3(9):897-902 Abstract available at
  27. Stoffel EM, Turgeon DK, Stockwell DH, Normolle DP, Tuck MK, Marcon NE, et al. Chromoendoscopy detects more adenomas than colonoscopy using intensive inspection without dye spraying. Cancer Prev Res (Phila) 2008 Dec;1(7):507-13 Abstract available at
  28. Sajid MS, Caswell J, Bhatti MI, Sains P, Baig MK, Miles WF. Carbon dioxide insufflation vs conventional air insufflation for colonoscopy: a systematic review and meta-analysis of published randomized controlled trials. ColorectalReferring to the large bowel, comprising the colon and rectum. Dis 2015 Feb;17(2):111-23 Abstract available at
  29. Yoshida M, Imai K, Hotta K, Yamaguchi Y, Tanaka M, Kakushima N, et al. Carbon dioxide insufflation during colorectal endoscopic submucosal dissection for patients with obstructive ventilatory disturbance. Int J ColorectalReferring to the large bowel, comprising the colon and rectum. Dis 2014 Mar;29(3):365-71 Abstract available at
  30. Lo SK, Fujii-Lau LL, Enestvedt BK, Hwang JH, Konda V, Manfredi MAMetachronous adenoma, et al. The use of carbon dioxide in gastrointestinal endoscopy. Gastrointest Endosc 2016 May;83(5):857-65 Abstract available at

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