Optimization of colonoscopy quality: Comprehensive review of the literature and future perspectives

Colonoscopy is crucial in preventing colorectal cancer (CRC) and reducing associated mortality. This comprehensive review examines the importance of high-quality colonoscopy and associated quality indicators, including bowel preparation, cecal intubation rate, withdrawal time, adenoma detection rate (ADR), complete resection, specimen retrieval, complication rates, and patient satisfaction, while also discussing other ADR-related metrics. Additionally, the review draws attention to often overlooked quality aspects, such as nonpolypoid lesion detection, as well as insertion and withdrawal skills. Moreover, it explores the potential of artificial intelligence in enhancing colonoscopy quality and highlights specific considerations for organized screening programs. The review also emphasizes the implications of organized screening programs and the need for continuous quality improvement. A high-quality colonoscopy is crucial for preventing postcolonoscopy CRC- and CRC-related deaths. Health-care professionals must develop a thorough understanding of colonoscopy quality components, including technical quality, patient safety, and patient experience. By prioritizing ongoing evaluation and refinement of these quality indicators, health-care providers can contribute to improved patient outcomes and develop more effective CRC screening programs.

Factors affecting the quality of bowel preparation for colonoscopy in hard-to-prepare patients: Evidence from the literature

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.

Key factors for improving adenoma detection rate

INTRODUCTION

Colonoscopy is a fundamental tool in colorectal cancer (CRC) prevention. Nevertheless, one-fourth of colorectal neoplasms are still missed during colonoscopy, potentially being the main reason for post-colonoscopy colorectal cancer (PCCRC). Adenoma detection rate (ADR) is currently known as the best quality indicator correlating with PCCRC incidence.

AREAS COVERED

We performed a literature review in order to summarize evidences investigating key factors affecting ADR: endoscopists education and training, patient management, endoscopic techniques, improved navigation (exposition defect), and enhanced lesions recognition (vision defect) were considered.

EXPERT OPINION

'Traditional' factors, such as split dose bowel preparation, adequate withdrawal time, and right colon second view, held a significant impact on ADR. Several devices and technologies have been developed to promote high-quality colonoscopy, however artificial intelligence may be considered the most promising tool for ADR improvement, provided that endoscopists education and recording are guaranteed.

From advanced diagnosis to advanced resection in early neoplastic colorectal lesions: Never-ending and trending topics in the 2020s

Colonoscopy represents the most widespread and effective tool for the prevention and treatment of early stage preneoplastic and neoplastic lesions in the panorama of cancer screening. In the world there are different approaches to the topic of colorectal cancer prevention and screening: different starting ages (45-50 years); different initial screening tools such as fecal occult blood with immunohistochemical or immune-enzymatic tests; recto-sigmoidoscopy; and colonoscopy. The key aspects of this scenario are composed of a proper bowel preparation that ensures a valid diagnostic examination, experienced endoscopist in detection of preneoplastic and early neoplastic lesions and open-minded to upcoming artificial intelligence-aided examination, knowledge in the field of resection of these lesions (from cold-snaring, through endoscopic mucosal resection and endoscopic submucosal dissection, up to advanced tools), and management of complications.

Efficacy and tolerability of a low-residue diet for bowel preparation: systematic review and meta-analysis

BACKGROUND

Colorectal cancer (CRC) contributes significantly to cancer mortality worldwide. In an effort to reduce the risk of death, detection of polyps through colonoscopy is crucial. The success of the colonoscopy depends on the diet administered the day before the test. Our aim was to evaluate the efficacy, tolerability, and adverse effects of bowel preparation when using a low-residual diet (LRD) compared to a clear-liquid diet (CLD) the day before a scheduled colonoscopy.

METHODS

PubMed/Medline, Embase, the Cochrane Central Register of Controlled Trials (CENTRAL) and Scopus databases were searched. We included studies of patients undergoing a scheduled colonoscopy for CRC screening and surveillance or for diagnostic purposes that compared a LRD with a CLD the day before the colonoscopy. Efficacy, the primary outcome, was evaluated as the rate of adequate bowel preparation. Secondary outcomes were tolerability and adverse effects of bowel preparation.

RESULTS

Thirteen RCTs (N = 2587) were included. Patients receiving a LRD compared to a CLD showed no difference in adequate bowel preparations (RR 1.02; 95% CI 0.99-1.05; I² = 60%). However, the LRD improved patient tolerability (RR 1.17; 95% CI 1.12-1.23; I² = 66%) and had fewer adverse effects (RR 0.89; 95% CI 0.84-0.94; I² = 73%) compared to the CLD. Groups using a LRD with 4L of polyethylene glycol in a single dose or a LRD with < 2000 kcal < 32 g of fibres/day had better tolerability.

CONCLUSION

Based on these findings, our recommendation is strong in favour of a LRD for bowel preparation of patients undergoing a scheduled colonoscopy. This diet could also be useful as a preoperative colonic preparation, but this requires further research.

Efficacy of ultra-low volume (≤1 L) bowel preparation fluids: Systematic review and meta-analysis

BACKGROUND AND AIMS

High-quality bowel preparation is paramount for the diagnostic accuracy and safety of colonoscopy; however, it is often difficult for patients to adhere to high-volume laxatives, which may contribute to poor bowel preparation. This review aims to assess the efficacy of bowel preparation fluids of 1 L or less (≤1 L).

METHODS

We performed a systematic review including all relevant randomized controlled trials on ultra-low volume (≤1 L) bowel preparation fluids for colonoscopy published since 2015. Primary endpoint was the percentage of adequately prepared patients. Secondary endpoints included adenoma detection rate (ADR) and safety.

RESULTS

Bowel preparation with sodium picosulfate/magnesium citrate (SPMC; 19 trials, n = 10,287), 1L-polyethylene glycol with ascorbate (PEGA; 10 trials, n = 1717), sodium phosphate (NaP; 2 trials, n = 621), and oral sulfate solution (OSS; 3 trials, n = 597) was adequate in 75.2%, 82.9%, 81.9%, and 92.1%, respectively, of patients; however, heterogeneity between studies was considerable (I² range: 86-98%). Pooled ADRs were 31.1% with SPMC, 32.3% with 1L-PEGA, 30.4% with NaP, and 40.9% with OSS. Temporary electrolyte changes were seen with all ultra-low volume bowel preparation fluid solutions but without sustained effects in most patients.

CONCLUSION

Ultra-low volume bowel preparation fluids do not always meet the 90% quality standard for adequate bowel preparation as defined by current guidelines. Nonetheless, they may be considered in patients intolerant for higher-volume laxatives and without risk factors for inadequate bowel preparation or dehydration-related complications.

Validation and Application of Predictive Models for Inadequate Bowel Preparation in Colonoscopies in a Tertiary Hospital Population

Background: Bowel preparation is a major quality criterion for colonoscopies. Models developed to identify patients with inadequate preparation have not been validated in external cohorts. We aim to validate these models and determine their applicability. Methods: Colonoscopies between April and November 2019 were retrospectively included. Boston Bowel Preparation Scale ≥2 per segment was considered adequate. Insufficient data, incomplete colonoscopies, and total colectomies were excluded. Two models were tested: model 1 (tricyclic antidepressants, opioids, diabetes, constipation, abdominal surgery, previous inadequate preparation, inpatient status, and American Society of Anesthesiology [ASA] score ≥3); model 2 (co-morbidities, tricyclic antidepressants, constipation, and abdominal surgery). Results: We included 514 patients (63% males; age 61.7 ± 15.6 years), 441 with adequate preparation. The main indications were inflammatory bowel disease (26.1%) and endoscopic treatment (24.9%). Previous surgery (36.2%) and ASA score ≥3 (23.7%) were the most common comorbidities. An ASA score ≥3 was the only identified predictor for inadequate preparation in this study (p < 0.001, OR 3.28). The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of model 1 were 60.3, 64.2, 21.8, and 90.7%, respectively. Model 2 had a sensitivity, specificity, PPV, and NPV of 57.5, 67.4, 22.6, and 90.5%, respectively. The AUC for the ROC curves was 0.62 for model 1, 0.62 for model 2, and 0.65 for the ASA score. Conclusions: Although both models accurately predict adequate bowel preparation, they are still unreliable in predicting inadequate preparation and, as such, new models, or further optimization of current ones, are needed. Utilizing the ASA score might be an appropriate approximation of the risk for inadequate bowel preparation in tertiary hospital populations.

Novel frontiers of agents for bowel cleansing for colonoscopy

The incidence of colorectal cancer (CRC) is characterized by rapid declines in the wake of widespread screening. Colonoscopy is the gold standard for CRC screening, but its accuracy is related to high quality of bowel preparation (BP). In this review, we aimed to summarized the current strategy to increase bowel cleansing before colonoscopy. Newly bowel cleansing agents were developed with the same efficacy of previous agent but requiring less amount of liquid to improve patients’ acceptability. The role of the diet before colonoscopy was also changed, as well the contribution of educational intervention and the use of adjunctive drugs to improve patients’ tolerance and/or quality of BP. The review also described BP in special situations, as lower gastrointestinal bleeding, elderly people, patients with chronic kidney disease, patients with inflammatory bowel disease, patients with congestive heart failure, inpatient, patient with previous bowel resection, pregnant/lactating patients. The review underlined the quality of BP should be described using a validate scale in colonoscopy report and it explored the available scales. Finally, the review explored the possible contribution of bowel cleansing in post-colonoscopy syndrome that can be related by a transient alteration of gut microbiota. Moreover, the study underlined several points needed to further investigations.

ESPEN guideline on hospital nutrition

In hospitals through Europe and worldwide, the practices regarding hospital diets are very heterogeneous. Hospital diets are rarely prescribed by physicians, and sometimes the choices of diets are based on arbitrary reasons. Often prescriptions are made independently from the evaluation of nutritional status, and without taking into account the nutritional status. Therapeutic diets (low salt, gluten-free, texture and consistency modified, …) are associated with decreased energy delivery (i.e. underfeeding) and increased risk of malnutrition. The European Society for Clinical Nutrition and Metabolism (ESPEN) proposes here evidence-based recommendations regarding the organization of food catering, the prescriptions and indications of diets, as well as monitoring of food intake at hospital, rehabilitation center, and nursing home, all of these by taking into account the patient perspectives. We propose a systematic approach to adapt the hospital food to the nutritional status and potential food allergy or intolerances. Particular conditions such as patients with dysphagia, older patients, gastrointestinal diseases, abdominal surgery, diabetes, and obesity, are discussed to guide the practitioner toward the best evidence based therapy. The terminology of the different useful diets is defined. The general objectives are to increase the awareness of physicians, dietitians, nurses, kitchen managers, and stakeholders towards the pivotal role of hospital food in hospital care, to contribute to patient safety within nutritional care, to improve coverage of nutritional needs by hospital food, and reduce the risk of malnutrition and its related complications.

The unmet needs for identifying the ideal bowel preparation

Colonoscopy, since it was first employed over 60 years ago, is now the gold standard method for visualizing the mucosa of the colon, but should be of good quality. Many factors affect quality, including the type of health service organization, type of facility, staff, equipment, patient characteristics, and bowel preparation (BP). The adequacy of bowel cleansing is critical, but, unfortunately, may be inadequate in up to one‐third of procedures. The current article will present and discuss the main BPs and their drawbacks, which include patient‐dependent and procedure‐dependent factors. Cleansing quality depends on the ease/complexity of solution preparation, volume, taste, and timing of consumption. Consequently, important positive factors include simple instructions, easy preparation of the solution, low volume, pleasant taste, short drinking time (e.g. <30 min), and splitting the dose between the evening before and the morning of the colonoscopy (or even better, only one dose in the early morning to avoid night‐time problems), and short onset of action. The BP solution must also be safe with negligible side effects. Furthermore, a positive experience supports patient willingness to repeat the procedure.

A Systematic Review and Meta-Analysis of Low-Residue Diet Versus Clear Liquid Diet: Which Is Better for Bowel Preparation Before Colonoscopy?

The goal of this systematic review was to compare the clear liquid diet and the low-residue diet to determine which is better for bowel preparation before colonoscopy. A literature search for randomized controlled trials on the effects of employing the clear liquid diet and low-residue diets before colonoscopy was conducted in major online English databases (PubMed, Web of Science, and Ovid EMBASE). After the systematic review of all 16 studies, the outcomes including quality of bowel preparation, tolerance, willingness to repeat, and adverse effects were analyzed through meta-analysis. The statistical analysis was performed by using RevMan 5.3 software. No statistically significant difference was observed between the low-residue diet and clear liquid diet groups (odds ratio [95% confidence interval] = 1.19 [0.79, 1.81]; p = .41). There was no statistically significant difference between the Boston Bowel Preparation Scale (standard mean difference [95% confidence interval] =-0.04 [-0.21, -0.14]; p = .68) Ottawa Bowel Preparation Scale (standard mean difference [95% confidence interval] =-0.04 [-0.19, 0.11]; p = .59) scores of the two groups. The quality indicators for colonoscopy of the two groups were not statistically significant. However, patient tolerance to the low-residue diet was higher (odds ratio [95% confidence interval] = 1.86 [1.47, 2.36]; p < .01). More patients in the low-residue diet group were willing to repeat the low-residue diet for bowel preparation (odds ratio [95% confidence interval] = 2.34 [1.72, 3.17]; p < .01). More patients in the clear liquid diet group experienced hunger, nausea, and vomiting. People who employed the low-residue diet before colonoscopy had the same quality of bowel preparation as those with clear liquid diet. Meanwhile, the tolerance of people with low-residue diet was better than people with clear liquid diet, and these people were more willing to repeat the colonoscopy with less adverse events.

Bowel Preparation for Pediatric Colonoscopy

Colonoscopy is an important diagnostic and therapeutic tool in evaluating and treating gastrointestinal tract pathologies. Adequate visualization of the intestinal lumen is necessary for detection of lesions, and thus bowel preparation is a key component of the process. It is estimated that over 25% percent of pediatric patients have sub-optimal bowel preparations, which can lead to longer procedure times, missed pathology, unsuccessful ileal intubation, and possibly repeat procedure/anesthesia. There is no universal protocol for bowel preparation in pediatrics and there is a wide variability of practices around the world. The purpose of this paper is to review the recent published literature regarding bowel preparations for pediatric colonoscopy with focus on published work in the last decade exploring a number of factors involved in bowel preparation including the role of patient education, types of bowel preparation, and their efficacy and safety.

Comparison of the effect of 1-day and 2-day low residue diets on the quality of bowel preparation before colonoscopy

BACKGROUND/AIM

Low residue diet (LRD) has a similar quality of bowel preparation with clear liquid diet before colonoscopy, but improved patient tolerance. However, the optimal LRD duration is still controversial. In this study, we have compared the effect of a 1-day LRD and 2-day LRD on the quality of bowel preparation and patient tolerance.

PATIENTS AND METHODS

Our prospective, randomized, single-blind trial, single-blind, trial compared two dietary regimens administered the day before colonoscopy. All patients were administered PEG-ES and simethicone for bowel preparation. The primary outcome measure was bowel preparation quality. The secondary outcome measures were insertion time, withdrawal time, polyp detection rate, patient tolerance, and willingness to use the same diet for bowel preparation again. Bowel preparation quality was evaluated using the Boston bowel preparation scale (BBPS). Patient tolerance was evaluated using a hunger-comfort scale.

RESULTS

There was no significant difference in bowel preparation quality between the 2 groups. The 1-day LRD group had a BBPS score of 6.48 ± 1.59 points, while the 2-day LRD group had a score of 6.42 ± 1.06 points (P > 0.05). The groups reported similar colonoscope insertion times, withdrawal times, polyp detection rates and patient tolerance scores (hunger-comfort scores). The numbers of patients who reported that compliance as easy or very easy were 126 (78.2%) in the 1-day group versus 88 (55.0%) in the 2 day group (P < 0.05) and the numbers who were willing to use the diet again in the future were 154 (95.7%) in the 1-day group versus 131 (81.9%) in the 2 day group (P < 0.05).

CONCLUSION

LRD duration (1 day or 2 days) had no significant effect on bowel preparation quality. Patients in the 1-day LRD group had higher tolerance and satisfaction levels than patients in the 2-day LRD group. However, overall satisfaction was higher with the 1-day LRD group than with the 2-day LRD group.

A Theory-based Educational Pamphlet With Low-residue Diet Improves Colonoscopy Attendance and Bowel Preparation Quality

GOALS/BACKGROUND

Patients who "no-show" for colonoscopy or present with poor bowel preparation waste endoscopic resources and do not receive adequate examinations for colorectal cancer (CRC) screening. Using the Health Belief Model, we modified an existing patient education pamphlet and evaluated its effect on nonattendance rates and bowel preparation quality.

STUDY

We implemented a color patient education pamphlet to target individual perceptions about CRC and changed bowel preparation instructions to include a low-residue diet instead of the previous clear liquid diet. We compared the nonattendance rate over a 2-month period before and after the introduction of the pamphlet, allowing for a washout period during which pamphlet use was inconsistent. We compared the Boston Bowel Preparation Scale (BBPS) in 100 consecutive patients who underwent colonoscopy during each of the 2 periods.

RESULTS

Baseline characteristics between the 2 groups were similar, although patients who received the pamphlet were younger (P=0.03). The nonattendance rate was significantly lower in patients who received the pamphlet (13% vs. 21%, P=0.01). The percentage of patients with adequate bowel preparation increased from 82% to 86% after introduction of the pamphlet, although this was not statistically significant (P=0.44). The proportion of patients with a BBPS score of 9 was significantly higher in the pamphlet group (41% vs. 27%, P=0.03). There was no difference in adenoma and sessile serrated adenoma detection rates before and after pamphlet implementation.

CONCLUSIONS

After implementing a theory-based patient education intervention with a low-residue diet, our absolute rate for colonoscopy nonattendance decreased by 8% and the proportion of patients with a BBPS score of 9 increased by 14%. The Health Belief Model appears to be a useful construct for CRC screening interventions.

Evaluation of the combined effect of factors influencing bowel preparation and adenoma detection rates in patients undergoing colonoscopy

Background

Colonoscopy is a commonly used modality for screening and surveillance of colorectal cancer (CRC). Therefore, it is essential to have adequate bowel preparation (prep) for the procedure which depends on type of bowel regimens, diet before colonoscopy and timing of the procedure.

Aims

The purpose of this study is to analyse the effect of multiple factors on adenoma detection rate (ADR) and prep quality of colonoscopy. This is the also the first study determining outcomes based on various combinations of diet, timing of the procedure and bowel prep regimens.

Methods

This is a retrospective single-centre observational study. Data about diet before procedure, bowel prepprep regimen and timing of the procedure was collected for patients coming for screening colonoscopy.

Results

Patients with split prep had higher good prep rates (73.8% vs 56.2%) and higher ADRs (34.2 % vs 29.9%) as compared with non-split prep. The good prep quality (65.8% vs 62.1%) and ADRs (31.9% vs 31.5%) were comparable in patients who received clear liquid diet as compared with low residue diet. The good results of bowel prep were obtained with split prep with either clear liquids or low residue diet irrespective of the timing of procedure. The poor prep was noticed in patients who underwent procedure in afternoon, with a low restrictive diet and non-split bowel regimen.

Conclusions

The current study adds to our knowledge about the combined effect of multiple variables affecting the bowel prep quality and ADR. It is imperative to opt for the best combination required for colonoscopy, as this will influence the effectiveness of colonoscopies regarding timely cancer detection and prevention.

Impact of diet restriction on bowel preparation for colonoscopy

Diet restriction is one of the difficult parts of bowel preparation for colonoscopy, and many patients do not follow instructions properly. Few studies have evaluated the impact of dietary restriction in real clinical setting. The aim of this study was to study the effect of diet control on bowel preparation with detailed investigation of unacceptable food list in order to reveal what kind of foods are most problematic in clinical practice.Prospective observational study was carried out at a university-affiliated hospital. Around 4 L polyethylene glycol solution was used for bowel preparation on the day of colonoscopy. Patients were allowed to have regular diet until lunch the day before colonoscopy and educated to control diet from 3 days before colonoscopy with information regarding an unacceptable foods list. Factors associated with inadequate bowel preparation were analyzed using univariate statistics and multivariate logistic regression analysis.Of the 245 patients included in the study, 68 patients (27.8%) followed the diet instructions. Fiber-rich vegetables were the most commonly taken unacceptable foods (N = 143, 58.4%). Inadequate bowel preparation (fair and poor by Aronchick scale) was 47.3%. In multivariate analysis, diabetes [odds ratio (OR) 2.878, 95% confidence interval (CI) 1.242-6.671], preparation to colonoscopy interval (OR 1.003, 95% CI 1.000-1.005) and consumption of foods disturbing bowel preparation (OR 2.142, 95% CI 1.108-4.140) were independent predictors of inadequate bowel preparation.We could identify substantially low compliance to diet instructions in real clinical practice. Consumption of any foods disturbing bowel preparation was significant factor predicting inadequate bowel preparation, even though we could not select specific food list compromising preparation significantly. Favorable bowel preparation was achieved in the subgroup compliant to diet restriction, suggesting that regular diet avoiding specific kinds of foods can be possible option for diet restriction before colonoscopy.

Research progress on patient comfort during bowel preparation

Bowel preparation is one of the key and necessary steps for preoperative preparations of multiple operations such as electronic colonoscopy, capsule endoscopy, barium X-ray, colorectal surgery, gynecology surgery, and urology surgery. Although better methods for bowel preparation have been explored continuously, patient intolerance still exists during the current bowel preparation process. Adverse reactions such as nausea and vomiting often occur, leading to poor comfort experience and affecting the patient's compliance and bowel preparation results. This article reviews the factors influencing patient comfort during bowel preparation and the corresponding interventions.