Quality of colonoscopy

From Clinical Guidelines Wiki


High-quality colonoscopy is dependent on patient-related factors, operator-related factors, system-related factors and equipment.[1]

Operator factors, which are arguably the most significant, include appropriate training and experience of the colonoscopist, proper risk assessment of the patient, complete examination to the caecum with adequate mucosal visualisation and bowel preparation, the ability to detect and remove polyps safely, adequate documentation, timely and appropriate management of adverse events, follow-up of histopathology, and appropriate screening and surveillance intervals based on published guidelines.[2] In Australia the Conjoint Committee for Recognition of Training in Gastrointestinal Endoscopy provides a framework to certify training of endoscopists. Recently recertification of colonoscopists has been introduced by the Gastroenterological Society of Australia (GESA). Requirements for recertification every 3 years include at least 150 logged procedures over the 3 years with a 95% completion rate, at least 25% adenoma detection rateThe proportion of individuals undergoing a complete screening colonoscopy who have one or more adenomas, or polyps, detected. (ADR) in eligible patients (intact colons, over age 50 years and without a diagnosis of inflammatory bowel disease) and completion of a cognitive review. The aim of recertification is to maintain colonoscopy expertise, continue to develop skills and to increase the safety standards and quality of care delivered to patients.

Quality assurance key performance indicators for the colonoscopy procedure include consent, indication, preparation, caecal intubation rates, polyp detection and removal, withdrawal time and complication rates.[3] Adequate documentation, through a comprehensive computer-generated report incorporating relevant images, is also critical.[4]Back to top

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).


Patients must provide informed consent to undergo any endoscopic procedure. The requirements for an adequate bowel preparation form part of the consent, along with a full explanation of the procedure, including any risks and potential complications, the indication and any alternative investigation options. Patients must be given the opportunity to ask questions and receive advice.[5]

Clinicians should also follow the Clinical Care Standards that apply to the preparation of patients for procedures, including informed consent (see Australian Commission on Safety and Quality in Health Care Colonoscopy Clinical Care Standards).


The National Bowel Cancer Screening Program Quality Working Group[5] recommends that, prior to colonoscopy, the colonoscopist should ensure that the indication for performing the colonoscopy is appropriate and documented. The indications for asymptomatic patients should conform to the national clinical practice guidelines[6] for the prevention, early detection and management of colorectal cancer (CRC) and include a significant family history of CRC, personal history of CRC or polyps, colitis surveillance or a positive faecal occult blood testA test that can detect microscopic amounts of blood in stools.. The use of colonoscopy for screening other asymptomatic patients is not supported by the Australian Government, unlike in other countries including the USA. Symptomatic patients should have relevant symptoms documented on the colonoscopy report.

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Effective bowel preparation is obligatory for high quality colonoscopy. See Bowel preparation.

Several societies suggest that poor preparation should be present in less than 10–15% of studies.[7][8] Several validated preparation scores exist but poor preparation is probably best defined clinically by the requirement to repeat the examination (i.e. ‘adequate’ versus ‘inadequate’), and should routinely be documented in the colonoscopy report.

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Caecal intubation rate

Caecal intubation is defined as deep intubation into the caecum with the tip of the colonoscope being able to touch the appendiceal orifice.[7] Caecal intubation demonstrates a complete examination of the colon, and is fundamental for colorectal cancer screening.[7] The intubation of the caecum should ideally be documented by an image of the appendiceal orifice and/or terminal ileum, if intubated.[7]

Lower caecal intubation rates correlate with higher rates of interval cancerA cancer whose presence is diagnosed in the time between scheduled screening tests or surveillance procedures. and lower case volume, with experienced operators achieving 95% or higher.[9] Performance indicators set by the National Bowel Cancer Screening Program Quality Working Group[5] include caecal intubation rates of 90% for general patients and 95% for patients undergoing screening colonoscopy (unadjusted rates including studies with poor preparation and obstructing cancer). Other societies suggest appropriate caecal intubation rates of between 90% and 95%.[10] The GESA recertification guideline suggests a caecal intubation rate of at least 95%.

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Withdrawal time

Longer withdrawal times are associated with increased adenoma detection.[11][12] The National Bowel Cancer Screening Program Quality Working Group[5] recommends that the mean colonoscopy withdrawal time from the caecum for each proceduralist should be 6 minutes or greater for procedures where no polypectomy is performed. This recommendation is similar to those in European Society for Gastroenterology (ESGE) guideline[7] and American Society for Gastrointestinal Endoscopy/American College of Gastroenterology[13] guidelines. However, as noted above, withdrawal time is likely to be a surrogate marker for ADR and, as such, should not be relied upon as an independent marker of quality.[14]Back to top

Polyp detection, removal and retrieval

The UK NHS Bowel Cancer Screening Programme defines ADR as the number of colonoscopies at which one or more histologically confirmed adenomas is removed, divided by the total number of colonoscopies performed.[7] It is the best validated key performance indicator for colonoscopy, with the total number of adenomas per colonoscopy a less well studied alternative.[15] Studies of ADR variability between endoscopists report a three-to six-fold difference in ADR.[11][16][17][18] Adenoma detection rateThe proportion of individuals undergoing a complete screening colonoscopy who have one or more adenomas, or polyps, detected. does not address detection of serrated polyps, which do not count toward ADR. Similarly, the detection of serrated polyps also differs between endoscopists.[19][20]

Adenoma detection rateThe proportion of individuals undergoing a complete screening colonoscopy who have one or more adenomas, or polyps, detected. correlates inversely with the incidence of interval colorectal cancer. Kaminski et al[21] demonstrated a significant increase in interval cancers in individual colonoscopists with an ADR below 20%. Corley et al demonstrated increasing benefit from higher ADRs.[22] The ESGE guidelines recognise that there is a difference between populations in whom screening colonoscopy is performed (e.g. the USA, where suggested ADRs are 15% for women and 25% for men) and for colonoscopy populations enriched with patients with positive faecal occult blood testing, in whom the ADR should be nearer to 35%.[7] The GESA recertification rate is for 25% in all patients over the age of 50 years, excluding those with IBD. Missed serrated polyps in the proximal colon do confer an increased risk of CRC and serrated detection targets have been suggested for screening colonoscopy (e.g. 5%). Australian colonoscopy cohorts have now regularly demonstrated serrated polyp detection rates above 10%.[23] European guidelines[7] recommend that a minimum of 90% of resected polyps should be retrieved.

Measurement of ADR often requires manual calculation and is time consuming to generate in endoscopy units without electronic linking between endoscopy reporting systems and histopathology reports. To overcome difficulties measuring ADR, a recent suggestion of using polypectomy rates as a surrogate for ADR has been studied and validated.[24][25] However, a study by Boroff et al warns that while the correlation with ADR is reliable in the right colon, it is not in the left colon.[26] Therefore, while measurement of polypectomy rate cannot be recommended as an alternative to measurement of ADR, for endoscopy units that have difficulty in measuring ADR, measurement of polypectomy rate is a reasonable first step.

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There is some evidence to suggest that an increased volume of colonoscopy performed by individual colonoscopists results in fewer complications.[27][28][29] As a result, the UK NHS Bowel Screening Program suggests a lifetime experience of 1000 colonoscopies and an annual number of 150 colonoscopies before becoming certified to perform bowel cancer screening program colonoscopy.[30]

The traditional complications of colonoscopy include pain, aspiration, perforation and bleeding (usually post polypectomy). However, this risk is offset by the fact that a missed cancer or advanced polyp is a bad outcome, which is mitigated by a high ADR. Perforation in screening colonoscopy approximates 1/1000[31] and could be used as a useful indicator of colonoscopy safety in large colonoscopy units or in national screening programs. This increases to around 1/500 post polypectomy.[31] The rates are higher when resecting larger polyps.[32] For screening populations enriched with those with positive faecal blood tests, the likelihood of adenomas and advanced adenomas is increased[7] and the overall colonoscopy complication rate is likely to be increased unless the quality of colonoscopy consistently high across colonoscopy services.

The British Joint Advisory Committee and the Australian Quality Working Group guidelines state colonoscopy perforation rates should be <1:1000,[5][33] while Rex et al[13] suggest perforation rates >1 in 500 for all colonoscopies or 1 in 1000 for screening colonoscopies require evaluation of practice.

Post polypectomy bleeding is defined as rectal blood loss that requires a blood transfusion and occurs up to 2 weeks post polypectomy.[7] Bleeding risk is affected by many factors including the definition of bleeding, use of antiplatelet and anti-thrombotic medication, lesion characteristics, colonoscopist volume and different diathermy settings.[32][34][35][36] Due to this wide range of variables that impact on post polypectomy bleeding, there is a large range of reported incidence in the literature, with rates ranging from 1:10 to 1:300 colonoscopies.[37][38]Back to top


A clear and comprehensive report is an essential part of quality endoscopy.[4] The key elements of a colonoscopy report include:[39]

  • patient demographics and history
  • assessment of patient risk and comorbidity
  • indication(s)
  • a technical description of the procedure (including bowel preparation quality and depth of insertion)
  • findings (abnormalities, including site, size)
  • interventions
  • unplanned events and complications
  • assessment
  • follow-up plan (including surveillance recommendations)
  • pathology samples sent.

Computer-generated reports enhance compliance, enable audit, and facilitate photo-documentation, particularly of landmarks of completion (e.g. ileal mucosa) and any pathology.[40] The report should be given to the patient, and routinely reach the relevant clinicians, including referring doctors and reporting pathologists.

However, compliance with quality colonoscopy reporting is poor, impairing communication, follow-up, audit and even remuneration.[41][42]Back to top

Practice Points

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Accurate and sufficient information about the procedure (and optimally consent) should be provided to patients prior to the commencement of bowel preparation for colonoscopy.

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Colonoscopy should be performed only for accepted indications, which should be clearly documented.

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Less than 10% of patients should require a repeat procedure due to poor bowel preparation, this should be offered within 12 months.

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Unadjusted rates for caecal intubation should be ≥90%.

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Photo-documentation, that terminal ileum or the base of the caecum (appendix orifice and ileocaecal valve) has been reached, should be performed to confirm completeness of the examination.

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Withdrawal times of >6 minutes for examinations without polypectomy are a surrogate marker for adenoma detection rates, but cannot be relied on as an independent quality indicator.

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Individual proceduralists should routinely document and maintain their adenoma detection rateThe proportion of individuals undergoing a complete screening colonoscopy who have one or more adenomas, or polyps, detected. at >25% in patients over the age of 50-years and without a diagnosis of inflammatory bowel disease.

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Serrated polyp detection rates are likely to be an equally valid marker of quality as adenoma detection rateThe proportion of individuals undergoing a complete screening colonoscopy who have one or more adenomas, or polyps, detected., and increasing evidence suggests that maintaining a rate of >10% in patients over age 50 years without a diagnosis of inflammatory bowel disease may prove to be an additional, useful quality indicator in the future.

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Perforation rates post colonoscopy should be <1/1000. This is more relevant for population programs and large endoscopy units rather than individual colonoscopists.

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All colonoscopists should have their training certified by the Conjoint Committee for the Recognition of Training in Gastrointestinal Endoscopy and undergo regular recertification through an endorsed program.

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Comprehensive computer-generated colonoscopy reports with embedded photo-documentation should be generated at the time of the procedure, and provided to patients and relevant clinicians.

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