Water-assisted colonoscopy (WAC) application in inflammatory bowel diseases (IBD) endoscopy offers significant technical opportunities. Traditional gas-aided insufflation colonoscopy increases patient discomfort, presenting challenges in the frequent and detailed mucosal assessments required for IBD endoscopy. WAC techniques, including water immersion and exchange, provide superior patient comfort and enhanced endoscopic visualisation. WAC effectively reduces procedural pain, enhances bowel cleanliness, and increases adenoma detection rates, which is crucial for colorectal cancer screening and disease-related evaluations in IBD patients. Additionally, underwater techniques facilitate basic and advanced endoscopic resections, such as polypectomy and endoscopic mucosal and submucosal resections, often required for resecting IBD-associated neoplasia.

Recently, the ENDOANGEL (EN) system, a computer-assisted detection technique, and water exchange (WE) assisted colonoscopy have both been shown to increase the colorectal adenoma detection rate (ADR).

The aim of this study was to compare the ADR between EN- and WE-assisted colonoscopy.

This was a retrospective study.

Data from patients who underwent either EN- or WE-assisted colonoscopy between October 2021 and August 2022 were analysed consecutively. The primary outcome measure was the ADR.

The ADR was found to be similar between the EN and WE groups, with 80 out of 199 (40.2%) patients in the EN group compared to 78 out of 174 (44.8%) patients in the WE group [1.21; 95% confidence interval (CI), 0.80-1.83]. In the analysis using stabilized inverse probability treatment weighting after adjustment for confounding factors, both colonoscopy methods had similar performance in terms of ADR (1.41; 95% CI, 0.88-2.27).

EN was found to be comparable to WE in terms of ADR during colonoscopy, and both methods may be effectively used in clinical practice.

Research demonstrates adenoma detection rate (ADR) and proximal sessile serrated polyp detection rate (pSSPDR) are associated with endoscopist characteristics including sex, specialty, and years in practice. However, many studies have not adjusted for other risk factors associated with colonic neoplasia.

To assess the association between endoscopist characteristics and polyp detection after adjusting the factors included in previous studies as well as other factors.

This cohort study was conducted in the Cleveland Clinic health system with data from individuals undergoing screening colonoscopies between January 2015 and June 2017. The study analyzed data using methods from previous studies that have demonstrated significant associations between endoscopist characteristics and ADR or pSSPDR. Multilevel mixed-effects logistic regression was performed to examine 7 endoscopist characteristics associated with ADRs and pSSPDRs after controlling for patient demographic, clinical, and colonoscopy-associated factors.

Seven characteristics of endoscopists performing colonoscopy.

The ADR and pSSPDR, with a hypothesis created after data collection began.

A total of 16 089 colonoscopies were performed in 16 089 patients by 56 clinicians. Of these, 8339 patients were male (51.8%), and the median (range) age of the cohort was 59 (52-66) years. Analyzing the data by the methods used in 4 previous studies yielded an association between endoscopist and polyp detection; surgeons (OR, 0.49 [95% CI, 0.28-0.83]) and nongastroenterologists (OR, 0.50 [95% CI 0.29-0.85]) had reduced odds of pSSPDR, which was similar to results in previous studies. In a multilevel mixed-effects logistic regression analysis, ADR was not significantly associated with any endoscopist characteristic, and pSSPDR was only associated with years in practice (odds ratio, 0.86 [95% CI, 0.83-0.89] per increment of 10 years; P < .001) and number of annual colonoscopies performed (odds ratio, 1.05 [95% CI, 1.01-1.09] per 50 colonoscopies/year; P = .02).

The differences in ADRs that were associated with 7 of 7 endoscopist characteristics and differences in pSSPDRs that were associated with 5 of 7 endoscopist characteristics in previous studies may have been associated with residual confounding, because they were not replicated in this analysis. Therefore, these characteristics should not influence the choice of endoscopist for colorectal cancer screening. However, clinicians further from their training and those with lower colonoscopy volumes have lower adjusted pSSPDRs and may need additional training to help increase pSSPDRs.

To test the hypothesis that water exchange (WE) significantly increases adenoma detection rates (ADR) compared with water immersion (WI).

Low ADR was linked to increased risk for interval colorectal cancers and related deaths. Two recent randomized controlled trials of head-to-head comparison of WE, WI, and traditional air insufflation (AI) each showed that WE achieved significantly higher ADR than AI, but not WI. The data were pooled from these 2 studies to test the above hypothesis.

Two trials (5 sites, 14 colonoscopists) that randomized 1875 patients 1:1:1 to AI, WI, or WE were pooled and analyzed with ADR as the primary outcome.

The ADR of AI (39.5%) and WI (42.4%) were comparable, significantly lower than that of WE (49.6%) (vs. AI P=0.001; vs. WI P=0.033). WE insertion time was 3 minutes longer than that of AI (P<0.001). WE showed significantly higher detection rate (vs. AI) of the >10 mm advanced adenomas. Right colon combined advanced and sessile serrated ADR of AI (3.4%) and WI (5%) were comparable and were significantly lower than that of WE (8.5%) (vs. AI P<0.001; vs. WI P=0.039).

Compared with AI and WI, the superior ADR of WE offsets the drawback of a significantly longer insertion time. For quality improvement focused on increasing adenoma detection, WE is preferred over WI. The hypothesis that WE could lower the risk of interval colorectal cancers and related deaths should be tested.

To determine the effect of carbon dioxide insufflation on the most important outcome measure of colonoscopic quality: adenoma detection rate (ADR).

Bowel cancer is the second most common cause of cancer deaths in males and females in Australia. Carbon dioxide has in recent times become the insufflation methodology of choice for screening colonoscopy for bowel cancer, as this has been shown to have significant advantages when compared with traditional air insufflation.

Endoscopies performed over a period of 9 months immediately before and after the implementation of carbon dioxide insufflation at endoscopy centers were eligible for inclusion.

The difference in ADR between the carbon dioxide and air insufflation methods was statistically significant, with an increased ADR in the carbon dioxide group. The superiority of carbon dioxide insufflation was sustained with a logistic regression model, which showed ADR was significantly impacted by insufflation method.

Carbon dioxide insufflation is known to reduce abdominal pain, postprocedural duration of abdominal pain, abdominal distension, and analgesic requirements. This study represents for the first time the beneficial effect of carbon dioxide insufflation upon the key quality colonoscopy indicator of ADR.

Water-aided colonoscopy techniques, such as water immersion (WI) and water exchange (WE), have shown different results regarding adenoma detection rate (ADR). We determined the impact of WI and WE on ADR and other procedural outcomes versus gas (air, AI; CO2) insufflation colonoscopy.

A systematic search of multiple databases for randomized controlled trials comparing WI and/or WE with AI and/or CO2 and reporting ADR was conducted. A network meta-analysis with mixed comparisons was performed. Primary outcome was ADR (overall, in the right side of the colon and by colonoscopy indication).

Seventeen randomized controlled trials (10,350 patients) were included. WE showed a significantly higher overall ADR versus WI (odds ratio [OR], 1.31; 95% credible interval [CrI], 1.12-1.55) versus AI (OR, 1.40; CrI, 1.22-1.62) versus CO2 (OR, 1.48; 95% CrI, 1.15-1.86). WE achieved the highest ADR also in the right side of the colon and in colorectal cancer screening cases (both significant vs AI and WI) as well as in patients taking a split-dose preparation (significant vs all the other techniques). The Boston Bowel Preparation Scale cleanliness score (vs AI and WI) was significantly higher for WE. Both WI and WE showed increased proportion of unsedated examinations and decreased real-time insertion pain, with WE being the least-painful insertion technique. Withdrawal time was comparable across techniques, but WE showed the longest insertion time (3-5 additional minutes).

WE significantly increases overall ADR, ADR in screening cases, and in the right side of the colon; it also improves colon cleanliness but requires a longer insertion time.

Recently, water exchange (WE) instead of water immersion (WI) for colonoscopy has been proposed to decrease pain and improve adenoma detection rate (ADR). This systematic review and meta-analysis is conducted to assess whether WE is superior to WI based on the published randomized controlled trials (RCTs).

We searched studies from PubMed, Cochrane Central Register of Controlled Trials, EMBASE, and MEDLINE. Only RCTs were eligible for our study. The pooled risk ratios (RRs), pooled mean difference (MD), and pooled 95% confidence intervals (CIs) were calculated by using the fixed-effects model or random-effects model based on heterogeneity.

Five RCTs consisting of 2229 colonoscopies were included in this study. WE was associated with a significantly higher ADR than WI (RR = 1.18; CI = 1.05-1.32; P = 0.004), especially in right colon (RR = 1.31; CI = 1.07-1.61; P = 0.01). Compared with WI, WE was confirmed with lower pain score, higher Boston Bowel Preparation Scale score, but more infused water during insertion. There was no statistical difference between WE and WI in cecal intubation rate and the number of patients who had willingness to repeat the examination. Furthermore, both total procedure time and cecal intubation time in WE were significantly longer than that in WI (MD = 2.66; CI = 1.42-3.90; P < 0.0001; vs MD = 4.58; CI = 4.01-5.15; P < 0.0001).

This meta-analysis supports the hypothesis that WE is superior to WI in improving ADR, attenuating insertion pain and providing better bowel cleansing, but inferior in time and consumption of infused water consumption during insertion.

Colonoscopy provides less protection from colorectal cancer in the right colon than the left. Areas covered: This review examines patient outcomes and colonoscopy success rates to identify factors that limit the protective effect of colonoscopy in the right colon. The MEDLINE and Embase databases were searched for literature from 2000 onwards, on the long-term outcomes and differences in screening practice between the right and left colon. In total, 12 systematic reviews (including nine meta-analyses) and 44 primary data records were included. Differences in patient outcomes and colonoscopy practice were identified between the right and left colon, suggesting that several factors, many of which disproportionally affect the right colon, impact lesion detection rates. Shorter withdrawal times reduce detection rates, while longer times significantly increase detection; mostly of adenomas in the right colon. Colonoscope attachments often only show a significant improvement in detection rates in the right colon, suggesting detection is more challenging due to visibility of the right colonic mucosa. Higher bowel cleansing grades significantly improve detection rates in the right colon compared to the left. Expert commentary: These findings confirm the need for continued improvement of colonoscopy effectiveness, and obligatory quality assessment, overall and especially in the right colon.

Colorectal cancer is the third most common cancer worldwide and the second most common cause of cancer-related death in Europe and North America. Colonoscopy is the gold standard investigation for the colon but is not perfect, and small or flat adenomas can be missed which increases the risk of patients subsequently developing colorectal cancer. Adenoma detection rate is the most widely used marker of quality, and low rates are associated with increased rates of post-colonoscopy colorectal cancer. Standards of colonoscopy and adenoma detection vary widely between different endoscopists. Interventions to improve adenoma detection rate are therefore required. Many devices have been purported to increase adenoma detection rate. This review looks at current available evidence for device technology to improve adenoma detection rate during colonoscopy.

The water exchange (WE) method can decrease the discomfort of the patients undergoing colonoscopy. It also provides salvage cleansing and improves adenoma detection, but a longer intubation time is required. Cap-assisted colonoscopy leads to a significant reduction in cecal intubation time compared with traditional colonoscopy with air insufflation. The aim of this study was to investigate whether combined cap-assisted colonoscopy and water exchange (CWE) could decrease the cecal intubation time compared with WE.

A total of 120 patients undergoing fully sedated colonoscopy at a regional hospital in southern Taiwan were randomized to colonoscopy with either CWE (n=59) or WE (n=61). The primary endpoint was cecal intubation time.

The mean cecal intubation time was significantly shorter in CWE (12.0 min) compared with WE (14.8 min) (P=0.004). The volume of infused water during insertion was lower in CWE (840 ml) compared with WE (1044 ml) (P=0.003). The adenoma detection rate was 50.8 and 47.5% for CWE and WE, respectively (P=0.472). The Boston Bowel Preparation Scale scores were comparable in the two groups. Results from the multiple linear regression analysis indicated that WE with a cap, a higher degree of endoscopist's experience, a higher Boston Bowel Preparation Scale score, and a lower volume of water infused during insertion, without abdominal compression, without change of position, and without chronic laxative use, were significantly associated with a shorter cecal intubation time.

In comparison with WE, CWE could shorten the cecal intubation time and required lower volume of water infusion during insertion without compromising the cleansing effect of WE.

Methods to improve polyp detection during colonoscopy have been investigated, with conflicting results for warm water irrigation. Carbon Dioxide (CO ₂₎ warmed to 37 °C may have similar or more pronounced effects on bowel motility. This study aimed to assess whether warmed CO ₂ would improve polyp detection compared to room temperature air insufflation.

 This was a double-blind, randomized controlled trial that enrolled 204 patients undergoing screening or surveillance outpatient colonoscopy. The primary outcome was polyp per patient detection rate. Secondary outcomes included adenoma per patient detection rates, bowel spasm, and patient comfort.

 The trial was terminated after an interim analysis determined futility. Between the warmed CO ₂ and room air groups, no significant differences were found in the per-colonoscopy polyp detection rate ( P  = 0.57); overall polyp detection rate ( P  = 0.69); or adenoma detection rates ( P  = 0.74). More patients in the room temperature group had lower spasm scores (p = 0.02); however, there was a trend towards greater patient comfort in the warmed CO ₂ group ( P  = 0.054). An ex-vivo study showed a significant difference between exiting CO ₂ temperature at the insufflator end vs. delivered CO ₂ temperature at the colonoscope tip end. The temperature of insufflation at the tip of the colonoscope was not different when using warmed vs. unwarmed insufflation ( P  = 0.62).

 When compared with room air insufflation, warmed CO ₂ insufflation did not affect polyp detection rates.

Adenoma detection rate (ADR), defined as the proportion of patients with at least one adenoma of any size, is a quality indicator. We tested the hypothesis that water exchange (WE) improves ADR but water immersion (WI) has no adverse effect on ADR compared with air insufflation (AI).

A prospective study was conducted at the Dalin Tzu Chi Hospital in southern Taiwan and the Hualien Tzu Chi Hospital in eastern Taiwan on patients randomly assigned to WE, WI, or AI with stratification by the 3 study colonoscopists. The primary outcome was ADR.

From July 2013 to December 2015, 651 patients were recruited and randomized into 3 groups with a 1:1:1 ratio (217 patients per group). Overall, ADR met quality standards: WE 49.8% (95% CI, 43.2%-56.4%), AI 37.8% (95% CI, 31.6%-44.4%), and WI 40.6% (95% CI, 34.2%-47.2%). Compared with AI, WE significantly increased ADR (P = .016). There was no difference between WI and WE. ADRs of WI and AI were comparable. Compared with AI, WE confirmed a longer insertion time, higher cleanliness score, but similar adenoma per positive colonoscopy (APPC) and withdrawal time with polypectomy. Subgroup analysis found WE significantly increased ADR in propofol-sedated patients. Multivariate generalized linear mixed model analysis revealed that age ≥50 years, WE (vs AI), colonoscopy indication, no previous history of colonoscopy, and withdrawal time >8 minutes were significant predictors of increased ADR.

Confirmation of prior reports showing WE, but not WI, increased ADR further strengthened the validity of our observations. WE significantly increased ADR in propofol-sedated patients. The outcome differences justify assessment of the role of WE in colorectal cancer prevention. Similar APPC and withdrawal times suggest that adequate inspection was performed on colonoscope withdrawal in each of the study arms. (Clinical trial registration number: NCT01894191.).

Adenoma detection rate (ADR) is a key colonoscopy quality indicator in Western clinical literature. Our low ADR prompted us to assess novel methods to improve performance. Western retrospective reports suggested that water exchange (WE) could increase ADR. However, most of these studies used pain score or intubation rate as the primary outcome. Here we test the hypothesis that WE significantly increases ADR among Chinese colonoscopists and design a prospective randomized controlled trial using ADR as our primary outcome.

This prospective, randomized controlled trial was performed at six centers in China. Screening, surveillance, and diagnostic cases were randomized to be examined by WE or traditional air insufflation (AI) method. The primary outcome was ADR.

From April 2014 to July 2015, 3,303 patients were randomized to WE (n=1,653) and AI (n=1,650). The baseline characteristics were comparable. Overall ADR was 18.3% (WE) and 13.4% (AI) (relative risk 1.45, 95% confidential interval: 1.20-1.75, P<0.001). ADR in screening patients using AI was 25.8% (male) and 15.7% (female). ADR in screening patients aged >50 years old was 29.4% (WE) and 22.9% (AI) (relative risk 1.09, 95% confidential interval: 1.00-1.19, P=0.040). The increase by WE was reproducibly observed in all indication categories, and significant in screening and diagnostic cases. The limitation imposed by the unblinded investigators was mitigated by comparable inspection times in cases without polyps, similar adenoma per positive colonoscopy, and reproducible enhancement of ADR and adenoma per colonoscopy by WE across all eight investigators.

This prospective study confirms Western retrospective data that WE significantly improves ADR among Chinese colonoscopists. WE may be superior to AI for screening colonoscopy in China. Colonoscopists elsewhere with low ADR might consider evaluating WE for performance improvement.

Water exchange (WE) is the least painful insertion method during colonoscopy. Its impact on postcolonoscopy discomfort has not been well-described. Carbon dioxide (CO₂) insufflation consistently reduced postcolonoscopy discomfort. We compared postcolonoscopy outcomes of various combinations of insertion and withdrawal techniques (insertion-withdrawal modality): WE-CO₂, WE-air insufflation (WE-AI), and CO₂-CO₂.

A total of 240 patients undergoing on-demand sedation diagnostic colonoscopy were randomized to WE-CO₂ (n = 79), WE-AI (n = 80), CO₂-CO₂ (n = 81), with postprocedural data collected up to 24 hours. The primary outcome was postcolonoscopy bloating. Other postcolonoscopy outcomes included pain scores, flatus and incontinence episodes, toilet use, interference with normal activities, patient satisfaction, and patient willingness to repeat the procedure.

Demographic and procedural data were comparable. Compared with WE-AI, WE-CO₂ and CO₂-CO₂ resulted in significantly less bloating (all P < .0005) and lower pain scores (P values ranged from .008 to < .0005) up to 3 hours and fewer flatus episodes up to 6 hours (P values ranged from .003 to < .0005). WE-CO₂ resulted in less interference with same-day activities compared with WE-AI (P = .043). The differences in postprocedural outcomes were significant, but the magnitude was small. Patient satisfaction and willingness to repeat the procedure were high and comparable among groups. WE was the least painful insertion technique (P < .0005).

The combination WE-CO₂ appears to be the optimal choice to decrease pain during the examination and to reduce bloating and other undesired procedural outcomes afterward. If a CO₂ insufflator is already available, it seems advisable to adopt the combination WE-CO₂. In the absence of a CO₂ insufflator, the cost effectiveness of the addition of withdrawal CO₂ to WE in diagnostic and nondiagnostic settings needs to be critically assessed. (Clinical trial registration number: NCT02409979.).

Adenoma detection rate (ADR) is the most robust colonoscopy quality metric and clinical studies have adopted it as the ideal method to assess the impact of technical interventions. Areas covered: We reviewed papers focusing on the impact of colonoscopy technical issues on ADR, including withdrawal time and technique, second evaluation of the right colon, patient positional changes, gastrointestinal assistant participation during colonoscopy, water-aided technique, optimization of bowel preparation and antispasmodic administration. Expert commentary: Overall, technical interventions are inexpensive, available worldwide and easy to implement. Some of them, such as the adoption of split dose regimen and slow scope withdrawal to allow a careful inspection, have been demonstrated to significantly improve ADR. Emerging data support the use of water-exchange colonoscopy. According to published studies, other technical interventions seem to provide only marginal benefit to ADR. Unfortunately, the available evidence has methodological limitations, such as small sample sizes, the inclusion of expert endoscopists only and the evaluation of single technical interventions. Additionally, larger studies are needed to clarify whether these interventions might have a higher benefit on low adenoma detectors and whether the implementation of a bundle of them, instead of a single technical maneuver, might have a greater impact on ADR.