This systematic review aims to evaluate (1) the effectiveness of exercise therapy in bowel preparation for colonoscopy, and (2) the characteristics of exercise programs for bowel preparation. Systematic searches were done in PubMed, EMBASE, the Cochrane Library, Web of Science, and CINAHL from inception to November 2022. Randomized controlled trials and quasi-experimental studies assessing the efficacy of exercise during bowel preparation were included in this review. Two reviewers independently assessed the methodological quality using a modified Downs and Black checklist. A narrative synthesis was conducted. A total of five studies (1,109 participants) were included in this review. In all eligible studies, the characteristics of the exercise programs varied and included mainly two types of exercise (walking and yoga), various amount of exercise (3,000-10,000 steps or 0.5-1.9 hours), and two exercise timing (during and 1 hour after taking the laxative). Available evidence indicated that exercise therapy is effective in improving the quality of bowel preparation. However, there was insufficient high-quality evidence to conclude the effects on procedure-related indicators, adverse events, and willingness to repeat preparation. Exercise should be recommended as an important part of routine bowel preparation for patients undergoing colonoscopy to improve the quality of bowel preparation. More rigorous studies focusing on the effects on procedure-related indicators, adverse events, and willingness to repeat preparation are needed. To ensure the effectiveness and safety of the intervention, it is critical to establish a standard, well-structured exercise program for bowel preparation.

Adequate bowel cleansing is critical for a high-quality colonoscopy because it affects diagnostic accuracy and adenoma detection. Nevertheless, almost a quarter of procedures are still carried out with suboptimal preparation, resulting in longer procedure times, higher risk of complications, and higher likelihood of missing lesions. Current guidelines recommend high-volume or low-volume polyethylene glycol (PEG)/non-PEG-based split-dose regimens. In patients who have had insufficient bowel cleansing, the colonoscopy should be repeated the same day or the next day with additional bowel cleansing as a salvage option. A strategy that includes a prolonged low-fiber diet, a split preparation regimen, and a colonoscopy within 5 h of the end of preparation may increase cleansing success rates in the elderly. Furthermore, even though no specific product is specifically recommended in the other cases for difficult-to-prepare patients, clinical evidence suggests that 1-L PEG plus ascorbic acid preparation are associated with higher cleansing success in hospitalized and inflammatory bowel disease patients. Patients with severe renal insufficiency (creatinine clearance < 30 mL/min) should be prepared with isotonic high volume PEG solutions. Few data on cirrhotic patients are currently available, and no trials have been conducted in this population. An accurate characterization of procedural and patient variables may lead to a more personalized approach to bowel preparation, especially in patients undergoing resection of left colon lesions, where intestinal preparation has a poor outcome. The purpose of this review was to summarize the evidence on the risk factors influencing the quality of bowel cleansing in difficult-to-prepare patients, as well as strategies to improve colonoscopy preparation in these patients.

Background: Inadequate bowel preparation (IBP) has a critical influence on the colonoscopy procedure and is associated with significantly lower rates of detection of colorectal lesions. Constipation is an important risk factor of IBP, and some studies have attempted to address the bowel cleansing for constipated patients. However, there is still lack of consensus to guide the clinical work of bowel preparation (BP) for patients with constipation. Therefore, we aimed to perform a network meta-analysis to compare the overall efficacy of various regimens for BP in constipated patients. Methods: We performed a comprehensive search of PubMed, MEDLINE, EMBASE, Cochrane, and Web of science to identify randomized controlled trials (RCTs) of bowel preparation regimens in constipated patients, update to January 2021. Two investigators independently evaluated articles and extracted data. The odds ratio (OR) with a 95% confidence interval (CI) was used to combine dichotomous data of the primary outcome which was defined as adequate bowel preparation (ABP). Rank probability was used to exhibit the outcome of the network meta-analysis. Results: Eleven studies that included 1891 constipated patients were identified as suitable for inclusion. The proportion of ABP was associated with the administration of intensive regimen (OR 2.19, 95% CI 1.16-4.17, p = .02, I2 = 84%). Moreover, an intensive regimen had a significant efficacy and light heterogeneity when the same basic laxative program was used (OR 4.06, 95% CI 3.04-5.43, p < .0001, I2 = 0%). In the network meta-analysis, the protocol of a normal regimen + A (normal regimen plus advanced intestinal regulation) had a significant effect for bowel preparation compared with a normal regimen + IR (normal regimen plus irritating laxative regimen) (OR 5.21, 95% CI 1.18-24.55), H PEG (4L- polyethylene glycol) (OR 8.70, 95% CI 1.75-52.56), and normal regimen (NR) (OR 7.37, 95% CI 2.33-26.39). In the remaining protocols, no significant difference was observed in any comparison. No significant severe adverse events (AEs) associated with bowel preparation were reported in included studies. Conclusion: Intensive regimens could improve bowel cleansing quality for patients with constipation, and advanced intestinal regulation regimens may be superior to others.

We evaluated factors that can predict the adequacy of bowel preparation in patients with chronic constipation undergoing colonoscopy.

We identified patients with chronic constipation who underwent anorectal manometry and at least 1 colonoscopy at 2 tertiary referral centers from 2003 to 2019. We also identified a subgroup of patients who underwent colonic transit testing through radiopaque marker testing. We determined demographic, medical, and constipation-related factors associated with poor bowel preparation and their effect on standardized quality metrics using univariate and multivariate analyses.

We identified 274 patients with chronic constipation who underwent anorectal manometry testing. Both outlet dysfunction (prolonged balloon expulsion) and slow-transit constipation were associated with suboptimal bowel preparation. Outlet dysfunction was also associated with decreased cecal intubation rates, adenoma detection rates, and sessile serrated polyp detection rates. In multivariable analyses controlling for demographics and known factors associated with poor bowel preparation, outlet dysfunction was associated with an almost 3-fold odds of suboptimal bowel preparation [odds ratio (OR): 2.9; 95% confidence interval (CI): 1.6-5.1] and a 3-fold reduction in cecal intubation rates (OR: 0.3; 95% CI: 0.1-0.8). Among those with radiopaque marker colonic transit testing available, slow-transit constipation was associated with a >2-fold odds of suboptimal bowel preparation (OR: 2.2; 95% CI: 1.1-4.4).

Among a cohort of patients with chronic constipation undergoing colonoscopy, outlet dysfunction was associated with suboptimal bowel preparation and other quality metrics. Constipated patients with a rectal evacuation disorder may represent a subgroup of patients that could benefit from individualized strategies for better bowel preparation.

Appropriate bowel cleansing before colonoscopy is an important factor in increasing the detection rate of lesions. Low-volume polyethylene glycol (PEG) plus ascorbic acid (PEG-Asc) reduces the dosage of bowel preparation agent, but still presents discomfort to patients. The primary aim of the present study was to compare the efficacy of bowel cleansing between 2 L PEG-Asc (control) and 1 L PEG-Asc with bisacodyl suppository (suppository) groups, and the secondary aim was to investigate complications and tolerability between the two groups.

This was a single-center prospective randomized controlled study. We identified 168 patients scheduled for colonoscopy between August 2017 and January 2018 and randomly assigned them to the control or to the suppository groups. Efficacy of bowel cleansing was assessed using the Boston Bowel Preparation Scale (BBPS), and side-effects were surveyed using questionnaires.

No significant difference was detected in baseline characteristics including insertion and withdrawal times, and adenoma detection rates between the two groups. Total BBPS score was 7.93 ± 1.06 and 7.74 ± 1.02 in the control and suppository groups, respectively (P = 0.22). Incidence of abdominal pain and nausea was not statistically different, whereas that of sleep disturbance and anal discomfort was higher in the control group. (P = 0.00).

One liter PEG-Asc with bisacodyl suppository resulted in an equivalent bowel-cleansing outcome with reduced patient discomfort compared to 2 L PEG-Asc. Therefore, PEG-Asc with bisacodyl suppository represents a potential alternative and increases patient compliance with bowel preparation.

Radio-opaque markers have been widely used in the study of colon motility in patients with chronic functional constipation (FC). Here, we evaluate the relationship between the colon transit time (CTT) and the Boston Bowel Preparation Scale (BBPS) to determine whether CTT is a sufficient predictor of bowel preparation in patients with chronic functional constipation.

A total of fifty-six patients with constipation and fifty-two healthy controls (HC) were enrolled in this study. All subjects underwent the colonic transit study using radio-opaque markers and were given a follow-up colonoscopy examination on day 3 to 7 to determine BBPS. The correlation between total and segmental CTT and BBPS was evaluated, and risk factors for predicting inadequate bowel preparation were determined.

In our study, we found some distinct outcomes compared with previous studies. The mean total CTT (TCTT) was determined to be 43.37 ± 18.82 h in the FC group and 23.08 ± 10.18 h in the HC group. This difference was found to be significant for both the total and segmental CTTs between the two groups (P < 0.05). Further, TCTT was negatively correlated with BBPS both in the FC (r = -0.899, 95% CI -0.748 to -0.925, P < 0.001) and the HC (r = -0.978, 95% CI -0.854 to -1.003, P = 0.004) groups, as was segmental CTTs and segmental BBPS (P < 0.05). In the case of patients with slow transit constipation, multivariate logistic regression analysis indicated that prolonged TCTT (OR 0.722, 95% CI 0.589-0.885, P = 0.002) was independently associated with poor bowel preparation. The total and right to left CTTs were found to predict inadequate bowel preparation and exhibited the best sensitivity and specificity at 48.0 h, 15.5 h, 17.5 h, and 19.0 h, based on ROC curve analysis.

The CTT test represents a valuable method for predicting the level of bowel preparation prior to a colonoscopy examination. That is, both total and segmental CTTs can be considered an objective predictor of bowel preparation prior to colonoscopy. The present study demonstrates some distinct results relative to previous studies, including STC subtype proportion in FC, the proportion of inadequate bowel preparation in the STC subtype, and the cut-off value of TCTT for predicting inadequate bowel preparation.

Adequate bowel preparation is essential for an effective and safe colonoscopy. This study aimed to evaluate the quality of bowel preparation according to waiting times from education to colonoscopy.

A prospective, investigator-blinded, randomized study was performed from December 2016 to March 2017. Patients were divided into two groups: within 2 weeks (group A, n=64) or more than 2 weeks (group B, n=66) from education about bowel preparation to colonoscopy. The primary outcome was the quality of bowel preparation as assessed by the Boston Bowel Preparation Scale (BBPS). The secondary outcome was the polyp and adenoma detection rate.

A total of 130 patients were enrolled. The total BBPS score was significantly higher in group A (within 2 weeks from education to colonoscopy) than in group B (more than 2 weeks). Total BBPS scores were 8.25}0.97 in group A and 7.75}1.32 in group B (P=.017). The rate of good preparation (BBPS≥8) was higher in group A than in group B (78.1% vs. 59.1%, P=.020). The rates of polyp and adenoma detection were both slightly higher in group A (polyps, 42.2% vs. 38.5%, P=.667; adenoma, 31.2% vs. 22.7%, P=.275). A numerical trend was observed for the slightly superior polyp and adenoma detection rate in group A, but it was not statistically significant.

This study demonstrated that shorter waiting times from education to colonoscopy can improve the quality of bowel preparation. Ensuring sufficient staff and equipment for endoscopy is one approach to reducing waiting times to colonoscopy. If waiting times can not be reduced, more contact through telephone, e-mail, and text messaging could be used to remind patients about information regarding bowel preparation.

Effective bowel cleansing is crucial for high quality colonoscopy. A notable portion of patients still present with low quality bowel preparation prior to their colonoscopy, compromising the overall quality of their colonoscopy. Areas covered: This review focuses on the main strategies that can improve the cleansing quality with a special interest on those clinical conditions that have been associated with a poor bowel preparation quality, such as patients with chronic constipation, history of bowel resection, liver cirrhosis, diabetes mellitus and chronic kidney disease. The review provides a practical and evidence-based approach to help clinicians in the management of 'hard-to-prepare' patients. Expert commentary: In the past few years, the quality of colonoscopy has become a hot topic and bowel cleansing is a crucial part of it; however, the approach to patients with an increased risk of poor bowel preparation quality is still not always supported by high-quality evidence, since most of these patients are routinely excluded from the clinical studies. Trials focused on this subgroup of patients are recommended to provide tailored bowel preparation regimens and guarantee high-quality procedures.

To investigate whether there is a difference between acromegalic and non-acromegalic cases in terms of bowel preparation and colonoscopic intervention.

Patients with controlled and uncontrolled acromegaly and as a control group (CG) patients without acromegaly between January 2010 and March 2014 were included. Groups were compared regarding adequacy of bowel preparation, cecal insertion time (CIT) and colonoscopy results.

Fifty-nine patients with acromegaly (controlled n=30, uncontrolled n=29) and 73 age and gender matched volunteers without acromegaly were evaluated. CIT in cases with controlled, uncontrolled acromegaly cases and in CG was 5.33 [4.00-6.00], 7.00 [4.91-11.31], and 3.10 [2.35-4.65] minutes, respectively (p<0.001). Cases in CG had shorter CIT compared to controlled and uncontrolled acromegaly cases ( p=0.014 and p<0.001, respectively). There was no significant difference regarding CIT between controlled and uncontrolled acromegaly cases (p=0.247). Six (20%) of controlled acromegaly patients, 10 (35%) of uncontrolled acromegaly patients and three (4%) of CG had inadequate bowel cleansing (p<0.001). Although statistically insignificant, cases with inadequate bowel cleansing had tendency towards having prolonged CIT in comparison to cases with adequate bowel cleansing (6.00 [3.87-9.00] and 4.16 [2.95-5.70] minutes, respectively, p=0.07).

Inadequate bowel cleansing is one of the main problems encountered during colonoscopic investigation/surveillance in acromegalic patients. Therefore, a different protocol for colonoscopy preparation may be needed for these cases.

Bowel preparation for colonoscopy is a key quality indicator that impacts on all aspects of the procedure, such as patient comfort, diagnostic yield, and adverse events. Although most laxative regimens currently employed have been compared in a multitude of settings, the optimal preparation regimen still remains an open question.

Recent studies have focused on developing new regimens by modifying dosage, timing of administration or by combining laxatives with synergic mechanisms of action with the purpose of increasing patient tolerability while maximizing bowel cleansing. Several low-volume preparations and combinations of laxatives and adjunctive medication have shown promise in delivering both adequate preparation of the colon and good patient tolerability. Also, we have gained a better understanding of the influence of patient-related factors such as health literacy and education on the quality of bowel preparation.

Although several novel regimens have been tested in recent trials, it remains unclear which, if any, of these bowel preparations can replace the standard bowel cleansing regimens in clinical practice. Also, further data are required on how to improve bowel cleansing by choosing the appropriate regimen for the individual patient.