Key points

Introduction

Patients with inflammatory bowel disease (IBD) are at increased risk of developing colorectal cancer. Compared with sporadic cases, IBD-related colorectal cancers occur at a younger age, are more likely multifocal or synchronous, and have a more aggressive phenotype with worsened mortality. In light of the increased risk of colorectal cancer, regular colonoscopy is advised every 1 to 3 years in patients for surveillance of colorectal neoplasia. Candidates for surveillance are those with disease duration of 8 years or more who have either ulcerative colitis extending beyond the rectum or Crohn’s disease involving one-third or more of the colon. Strong, albeit indirect, data suggest a benefit to colonoscopic surveillance. It is therefore recommended by numerous professional guidelines and has become widely adopted in standard practice.

Introduction

Patients with inflammatory bowel disease (IBD) are at increased risk of developing colorectal cancer. Compared with sporadic cases, IBD-related colorectal cancers occur at a younger age, are more likely multifocal or synchronous, and have a more aggressive phenotype with worsened mortality. In light of the increased risk of colorectal cancer, regular colonoscopy is advised every 1 to 3 years in patients for surveillance of colorectal neoplasia. Candidates for surveillance are those with disease duration of 8 years or more who have either ulcerative colitis extending beyond the rectum or Crohn’s disease involving one-third or more of the colon. Strong, albeit indirect, data suggest a benefit to colonoscopic surveillance. It is therefore recommended by numerous professional guidelines and has become widely adopted in standard practice.

Importance of bowel preparation

The purpose of surveillance colonoscopy in IBD is to detect neoplasia (ie, cancer or precancerous dysplasia). Until recently, common surveillance technique has entailed a combination of targeted and random biopsies. All visible lesions receive targeted biopsy or resection (via polypectomy or endoscopic mucosal resection) to determine the histology and, most especially, the presence of dysplasia or cancer. In addition, by US guidelines, at least 33 additional random biopsies are taken throughout the colon to detect the presence of flat, endoscopically invisible dysplasia. However, with the advent of enhanced endoscopic imaging, it is increasingly recognized that most IBD-related dysplasia is visible with careful mucosal inspection using high-definition endoscopes and chromoendoscopy. In chromoendoscopy, a solution containing dilute indigo carmine or methylene blue is applied to the mucosal surface via the forward wash jet or biopsy channel to enhance lesion detection ( Fig. 1 ). Augmented lesion recognition via chromoendoscopy may supplant the need for random biopsy. A meta-analysis by Soetikno and colleagues confirmed that chromoendoscopy with targeted biopsies of visualized lesions resulted in increased dysplasia detection rates compared with standard white light endoscopy and random biopsies. Several guidelines now endorse the routine use of chromoendoscopy and question any incremental benefit of random biopsies to detect invisible dysplasia.

( A ) Poor bowel preparation preventing mucosal visualization. ( B ) Concealed lesion shown after irrigation and suctioning. ( C ) Lesion visualization enhanced by chromoendoscopy dye application.

( Courtesy of Silvia Sanduleanu, MD, PhD, Maastricht University, Maastricht, The Netherlands.)

This shift in surveillance practice toward targeted lesion biopsy (with endoscopic resection if possible) relies on the premise that even subtle dysplastic lesions are detectable with enhanced imaging techniques. Consequently, a meticulous bowel preparation is critical to facilitate detection of nonpolypoid (flat, slightly raised, or depressed) lesions, which may be extremely obscure and easily hidden by residual fecal matter, succus, or purgative solution ( Fig. 2 ). Although studies have not specifically examined the impact of inadequate bowel preparation on IBD surveillance outcomes, there is clear evidence in the general population that inadequate preparation negatively affects outcomes of screening or surveillance colonoscopy and increases resource use. Bowel preparation is inadequate in nearly 1 of 4 colonoscopies. Furthermore, suboptimal preparation results in aborted or incomplete examinations in up to 7% of cases and leads to early recall for surveillance in 12.5% to 20% of cases. Suboptimal preparation also negatively affects colonoscopy efficiency, being associated with prolonged cecal intubation times, decreased cecal intubation rates, increased withdrawal time, and increased perceived procedural difficulty.

Feculent material obscuring visualization of nonpolypoid lesions in ( A, B ) Crohn’s colitis and ( C, D ) ulcerative colitis.

( Courtesy of Roy Soetikno, MD, Veterans Affairs, Palo Alto, CA.)

Most importantly, suboptimal bowel preparation is associated with lower polyp detection rates, affecting detection of flat (nonpolypoid) lesions and small polyps, as well as large polyps (>10 mm). Among patients undergoing colonoscopy less than 3 years after a previous examination with suboptimal bowel preparation, 42% of all adenomas and 27% of advanced adenomas were found only after the repeat examination. Among examinations performed within 1 year of the initial suboptimal examination, the advanced adenoma miss rate was 36%, suggesting these lesions were truly missed. In another series of 133 patients undergoing repeat colonoscopy after previous suboptimal preparation, missed adenomas were found in 34%. A high-risk state was present in 18% of patients (ie, the presence of ≥3 adenomas, 1 adenoma >1 cm, or adenomas with high-grade dysplasia or villous features). Similarly, Sagi and colleagues reported that among patients undergoing early examination as a result of initial suboptimal bowel preparation, 6.5% had high-risk adenomas and 1.9% had high-grade dysplasia or cancer.

It is evident from the literature that inadequate preparation negatively affects the performance of colonoscopy in patients who do not have IBD. Although not directly studied in patients with IBD undergoing surveillance, a meticulous bowel preparation facilitates detection of IBD-related neoplasia, particularly nonpolypoid lesions. Flat dysplasia detection in patients with IBD has been shown to be directly correlated with procedure duration. Although the underlying reason for this association is unproven, prolonged withdrawal may reflect careful mucosal inspection. Poor preparation requiring lengthy irrigation may lessen total inspection time.

An impeccable bowel preparation is especially important for chromoendoscopy surveillance techniques. Personal and anecdotal shared experiences affirm the negative impact of suboptimal bowel preparation on the efficient application of chromoendoscopy. The admixture of chromoendoscopy dye with retained colonic soilage results in flocculent, green debris, which can obscure subtle lesions and require copious irrigation to achieve an acceptable mucosal inspection ( Fig. 3 ).

Poor preparation interferes with chromoendoscopy. Admixture of stool, dye, and mucus interferes with mucosal visualization.

( Courtesy of Roy Soetikno, MD, Veterans Affairs, Palo Alto, CA.)

Predictors of suboptimal bowel preparation

In patients without IBD, the known predictors of poor bowel preparation include advanced age, male gender, diabetes, obesity, multiple comorbidities, tricyclic antidepressant or opiate use, inpatient status, immobility, and lower education level. Most studies examining risk factors for poor colonic preparation do not assess the impact of IBD. When specifically evaluated, no significant difference in bowel preparation quality was detected between patients with IBD and those who did not have IBD, as rated by the Boston Bowel Preparation Scale. Nor did an association exist between IBD disease activity and preparation quality. Thus, there is no definitive proof that patients with IBD have an increased likelihood of inadequate bowel preparation.

Notwithstanding this limited published experience, personal and anecdotal experience suggests increased difficulty with bowel preparation in some patients with IBD. Bowel preparation is of poorer quality in patients with previous colonic resections, including patients with and without IBD, possibly because of disturbances in intestinal motility. Furthermore, some patients with IBD have increased nausea, bloating, cramping, or vomiting as a result of previous surgery, intestinal stenosis, altered motility, anxiety, or heightened visceral sensitivity. In a case control study by Bessissow and colleagues, patients with IBD did not experience increased levels of nausea or pain during bowel preparation overall, but patients with active Crohn’s disease did experience higher levels of abdominal pain. A higher level of anxiety was also associated with increased symptoms during bowel preparation, and patients with IBD experience significantly more embarrassment and burden (defined as feelings of worry, hardship, or distress) during preparation when compared with patients undergoing colonoscopy for other indications. Furthermore, in a study assessing factors affecting adherence with surveillance recommendations, patients with IBD most commonly cited difficulty with bowel preparation as the most important reason for failed compliance. Thus, although limited clinical studies do not convincingly show a higher incidence of suboptimal bowel preparations in patients with IBD, ample data confirm a reduced tolerance of the bowel preparation, which may negatively affect bowel preparation quality and compliance with surveillance protocols.

Optimization of bowel preparation

Bowel Preparation in Patients Undergoing Surveillance

In contrast, a meticulous bowel preparation is important in patients undergoing routine, elective colonoscopy for dysplasia surveillance. Whenever possible, the disease should be in remission at the time of surveillance colonoscopy, because active inflammation interferes with visual detection of nonpolypoid dysplasia and causes cytologic changes, which can be difficult to distinguish from true dysplasia. Complications of active inflammation therefore are of lesser concern, and preparation decisions focus on achieving maximum bowel cleanliness.

The best preparation regimen consists of an appropriate preprocedure diet, a suitable choice of laxative agent, and an optimal dosing of laxative administration. It is vitally important that physicians and nursing staff educate patients about the importance of the bowel preparation, carefully reviewing recommended dietary restrictions and counseling strict adherence to bowel preparation instructions. The remainder of this article emphasizes recommended, established preparation techniques for the purpose of nonurgent surveillance in patients with controlled disease.

Prepreparation dietary restriction

There are several uncertainties regarding the best preprocedure diet. In the days leading up to colonoscopy, many centers advise patients to avoid foods containing small seeds (eg, tomatoes and cucumbers) based on concern that colonoscopy efficiency can be diminished by clogging of the endoscope suction channel. This problem does arise, especially among patients with diverticulosis, although there is no literature studying the degree of encumbrance. Other routine advice includes several days of avoidance of high-fiber food or supplements, especially iron-containing supplements, which cause blackening of stool with increased adhesion of remnant stool to the bowel wall.

On the day preceding colonoscopy, patients are routinely instructed to consume only clear liquids. Many centers also advise patients to forego red-colored food products such as red gelatin, red juices, or red soft drinks to avoid confusion regarding the presence of possible blood. However, the rate of false alarm caused by these products has not been studied, and anecdotal experience suggests that their consumption is unlikely to create diagnostic uncertainty with the use of proven high-quality bowel preparation regimens.

Several recent studies have suggested that rigid adherence to a clear liquid diet on the day preceding the procedure may also be unnecessary ( Table 1 ). Dietary liberalization may allow for improved tolerance and better adherence without compromise of bowel preparation quality. In some studies, a less restrictive diet increases bowel preparation quality.

Table 1

Effect of less restrictive prepreparation diet on bowel preparation quality and tolerability

Study	N	Prepreparation Diet		Bowel Preparation	Dosing	Bowel Preparation Quality	Better Patient Tolerability
		Diets Compared	Duration of Dietary Liberalization a
Soweid et al, 2010	200	Fiber free vs clear liquid	Entire day	4 L PEG-ELS	Single	Fiber free > clear liquid	Fiber free
Park et al, 2009	214	Low residue vs clear liquid	Entire day	4 L PEG-ELS	Single	Low residue > clear liquid	Low residue
Melicharkova et al, 2013	213	Low residue vs clear liquid	Breakfast	Na picosulfate/magnesium citrate	Single	No difference	Low residue
Sipe et al, 2013	196	Low residue vs clear liquid	Breakfast + lunch + snack	Sulfate solution	Split	No difference	Low residue
Jung et al, 2013	801	Regular b vs clear liquid	Entire day	4 L PEG-ELS	Single	No difference	No difference

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