The American Gastroenterological Association (AGA) Institute Clinical Practice Update aims to review the current evidence and provide the best practice advice for improving the quality of colonoscopy screening and surveillance. The update consists of 15 best practice advice statements targeting the level of endoscopists or endoscopy units.

Colonoscopy is an effective and widely used screening modality for reducing the colorectal cancer incidence and mortality.^1,2 However, the efficacy of colonoscopy depends on the quality of the procedures and the rate of adenoma detection, which varies widely among the endoscopists.^1,3

The quality of colonoscopy screening and surveillance can be measured by 3 parameters, namely safety - in minimizing adverse events (AEs); effectiveness - in detecting colorectal cancer; and value - in avoiding unnecessary costs.¹

According to the AGA Institute Clinical Practice Update, the best practices for endoscopy should involve quality bowel preparation and AE monitoring for patients.¹ Prior to endoscopy, patients should be educated about the risks, possible AEs and warning symptoms.¹ Following endoscopy, systematic monitoring should be considered for delayed AEs such as bleeding, perforation hospital readmission and colorectal cases. Instructions and emergency contact information should also be given to patients who have conducted colonoscopy, in the event of worrisome symptoms.¹

Ensuring high-quality bowel preparation is paramount to the best practice, as suboptimal preparation may lead to failed detection of flat or subtle polyps.^1,4 The update suggests that endoscopy units should measure bowel preparation quality annually at a minimum.¹ Adequate bowel preparation, defined as a Boston Bowel Preparation Scale (BBPS) score of ≥6, with each segment scoring ≥2, should be achieved in at least 90% of colonoscopies.¹

As per the best practice advice, split-dose bowel preparation should be applied as a standard preparation strategy for endoscopy, where part of the purgative is taken in the evening before colonoscopy, then at 4-6 hours before starting the colonoscopy.^1,5 This is superior to single-dose bowel preparation as it reduces the lag time from the completion of bowel purgative to the start of colonoscopy, thus improving the bowel preparation quality.^1,6

The best practice on split-dose bowel also suggests that patient instructions should be written at a 6^th grade level in their native tongue to reduce the rates of inadequate preparation.¹

In the course of performing the procedures, high-definition colonoscopes should be used for screening and surveillance, as it is associated with higher polyp detection rate.1 The update also recommends a regular baseline measurement of endoscopist performance with 4 main parameters, including:

1. A cecal intubation rate of ≥90%¹
2. A mean withdrawal time of at least 6 minutes, which is linked to higher rates of adenoma detection and colonoscopy quality^1,7
3. An adenoma detection rate of ≥30%¹
4. A serrated lesion detection rate of ≥7%¹

The ADR should be measured annually or with every 250 screening colonoscopies performed in order to provide feedback and prompt efforts to improve the outcome.¹ Endoscopists not meeting these ADR thresholds are recommended to consider extending the withdrawal times, self-learning regarding mucosal inspection and other educational interventions.¹

If resources are limited, cecal intubation tubes, bowel preparation quality and ADR should be prioritized.¹ According to the update, a variety of strategies are advised:

1. A second look at the right colon to detect polyps, either in forward or retroflexed view, which can increase ADR by 5%-20%¹
2. Use of cold-snare polypectomy for non-pedunculated polyps of 3-9mm in size, as it reduces the risk of post-polypectomy bleeding and thermal injury¹
3. Avoid forceps for polyps >2mm in size due to the high risk of residual neoplasia¹
4. Evaluation by an expert of polypectomy for patients with complex polyps lacking overt malignant endoscopic features¹
5. Thorough documentation of all findings, including the extent of examination, intervention and follow-up plan¹

In order to prevent interval colorectal cancer, and to avoid under- or over-utilization of colonoscopy surveillance and spending unnecessary costs, practice adherence to this update guideline is very important. Since the technology for endoscopy screening and surveillance is evolving, with higher quality of performance, endoscopists and endoscopy units should commit more in terms of optimizing the colonoscopy quality in order to provide the best care for their patients.