Roel Bogie

Chapter 7

Quality of bowel preparation is critical for optimizing the diagnostic and therapeutic yield of colonoscopy. 1-4, 7 Of course, cecal intubation is important in visualizing the entire colonic mucosa, 22, 23 albeit it is less modifiable. Insufficient bowel preparation prolongs insertion time and hinders detection and resection of colorectal neoplasms, especially subtle appearing flat and depressed adenomas and sessile serrated polyps. 24-28 It is a risk factor for the detection of advanced adenomas during follow-up. 16, 22, 29 Insufficient bowel preparation requires repeated examination, increasing the cost and risk of complications. 29, 30 Several issues need tobe clarified tooptimize the colonoscopy surveillance practice: For example: How to define adequate bowel cleansing?; When to stop and when to repeat colonoscopy in case of insufficient bowel preparation?; And how to record information regarding bowel preparation? Many colonoscopy practice guidelines 1, 2, 5, 23, 29 now recommend that bowel preparation should be considered sufficient if lesions ≥5mm in size can be detected. Furthermore, post-polypectomy surveillance guidelines 23, 29, 31-33 recommend a split dose of 2-4 L polyethylene glycol (or a same-day regimen for afternoon colonoscopies). Qualification of the degree of bowel cleansing using a valid and reliable scale is crucial, although not yet widely implemented in routine practice. 29 Table 7.2 summarizes the most common assessment scales: Aronchick Bowel Preparation Scale, Ottawa Scale and Boston Bowel Preparation Scale (BBPS). 34-37 The Aronchick Scale relies on a qualitative assessment, which seems easier to apply, albeit estimation of the percentage of colonic mucosa visualized can be difficult. 34 Given the lack of reliability data, the Aronchick scale is presently not recommended for clinical practice. The Ottawa scale evaluates cleanliness and quantity of fluid as separate items. 35 In contrast to the Ottawa and Aronchick scales which report the quality of bowel preparation before cleansing (washing and suctioning), the BBPS quantifies the degree of bowel preparation during withdrawal, after maximal cleansing of the mucosa and is preferable. 36 The BBPS correlates with the polyp detection rate (40% for BBPS ≥5 versus 24% for a BBPS <5). 36, 38 Furthermore, endoscopists seem to be more confident of not missing lesions >5mm when BBPS is rated 6 versus 5 (82% versus 33%). 39 To improve uniformity in reporting using the BBPS scale, the designers provided a set of images and a 15-minute web training module. The next confronting issue is when to stop and when to repeat colonoscopy in cases of insufficient bowel cleansing. Current guidelines recommend to already estimate the degree of bowel preparation in the rectosigmoid. 29 If a surveillance colonoscopy is carried out and the bowel preparation is inadequate to allow detection of polyps ≥5mm, then the procedure should be aborted and rescheduled. Alternatively, bowel cleansing can be continued and the procedure rescheduled later on the same day. 33 Inadequate bowel preparation is a risk factor for insufficient bowel preparation at repeat colonoscopy. 40, 41 A recent meta-analysis showed comparable adenoma detection rates in patients with moderate versus high quality bowel preparation. 37 However, endoscopists tend to schedule patients with ‘fair’ bowel preparation sooner than those with excellent preparation (65.9% ≤1 year). 42 In case the colonoscopy was complete but the degree of bowel preparation was inadequate, then a repeat colonoscopy should be recommended within 1 year (or earlier in cases of suspected advanced neoplasia), using a more intensive bowel preparation (combination of diet, medication and personalized patient instruction). 2, 27, 29 Of note, rescheduling of the procedure is frequently omitted or unnecessarily postponed in practice. A single-center retrospective study by Lebwohl et al. including 12,787 colonoscopies found that the quality of bowel preparation was poor or fair in 24% of cases. 43 However, only 17% of these patients were rescheduled for repeat examination within 3 years. Among patients receiving re-examination with optimal preparation, the miss rates of adenomas and advanced adenoma were 42% and 27%,

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