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Background and study aims Single-center studies, which were retrospective and/or involved unblinded colonoscopists, have suggested that water exchange, but not water immersion, compared with air insufflation significantly increases the adenoma detection rate (ADR), particularly in the proximal and right colon. Head-to-head comparison of the three techniques with ADR as primary outcome and blinded colonoscopists has not been reported to date. In a randomized controlled trial with blinded colonoscopists, we aimed to evaluate the impact of the three insertion techniques on ADR. Patients and methods A total of 1224 patients aged 50 – 70 years (672 males) and undergoing screening colonoscopy were randomized 1:1:1 to water exchange, water immersion, or air insufflation. Split-dose bowel preparation was adopted to optimize colon cleansing. After the cecum had been reached, a second colonoscopist who was blinded to the insertion technique performed the withdrawal. The primary outcome was overall ADR according to the three insertion techniques (water exchange, water immersion, and air insufflation). Secondary outcomes were other pertinent overall and right colon procedure-related measures. Results Baseline characteristics of the three groups were comparable. Compared with air insufflation, water exchange achieved a significantly higher overall ADR (49.3 %, 95 % confidence interval [CI] 44.3 % – 54.2 % vs. 40.4 % 95 %CI 35.6 % – 45.3 %; P = 0.03); water exchange showed comparable overall ADR vs. water immersion (43.4 %, 95 %CI 38.5 % – 48.3 %; P = 0.28). In the right colon, water exchange achieved a higher ADR than air insufflation (24.0 %, 95 %CI 20.0 % – 28.5 % vs. 16.9 %, 95 %CI 13.4 % – 20.9 %; P = 0.04) and a higher advanced ADR (6.1 %, 95 %CI 4.0 % – 9.0 % vs. 2.5 %, 95 %CI 1.2 % – 4.6 %; P = 0.03). Compared with air insufflation, the mean number of adenomas per procedure was significantly higher with water exchange (P = 0.04). Water exchange achieved the highest cleanliness scores (overall and in the right colon). These variables were comparable between water immersion and air insufflation. Conclusions The design with blinded observers strengthens the validity of the observation that water exchange, but not water immersion, can achieve significantly higher adenoma detection than air insufflation. Based on this evidence, the use of water exchange should be encouraged. Trial registered at ClinicalTrials.gov (NCT02041507).

Background Single site studies in male Veterans in the U.S. reported increased detection of presumptive cancer precursors (adenomas, hyperplastic polyps) in the proximal colon (cecum-splenic flexure) by water exchange. Aims Assess the reproducibility of the observation. Methods Analysis of secondary outcomes collected prospectively in 3 similarly designed randomized controlled trials using water exchange, water immersion and insufflation (air or carbon dioxide). Main outcome: detection rates of adenomas and hyperplastic polyps in proximal, transverse and right colon (cecum-ascending). Results 704 males (173 screening) were evaluated. In the proximal colon, WE showed increased detection of small adenomas ( p = 0.009) and adenomas plus hyperplastic polyps ( p = 0.015) (vs insufflation); increased detection of adenomas plus hyperplastic polyps of any size ( p = 0.045) and of small size ( p = 0.04) (vs water immersion). In the right colon water exchange increased detection of small adenomas (19% vs 12.1%, p = 0.04) (vs insufflation); small adenomas (19% vs 12%, p = 0.038), adenomas plus hyperplastic polyps of any size (25% vs 16.7%, p = 0.028) and of small size (23.7% vs 14.6%, p = 0.012) (vs water immersion). Water exchange significantly improved bowel cleanliness. Sedation had no impact on lesion detection. Conclusions Water exchange is a superior insertion technique for detection of adenomas and hyperplastic polyps primarily in the right colon, especially those of small size.

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 (P0.001). WE showed significantly higher detection rate (vs. AI) of the10 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 P0.001; 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.

Background: Water-aided colonoscope insertion reduces patients′ discomfort and need for sedation in unsedated and minimally sedated patients. However, water-aided technique has never been studied in inflammatory bowel disease patients, characterised by younger age, structural changes of the colon and need for repeated colonoscopies. Our trial was designed to evaluate discomfort associated with water-aided colonoscopy compared with air insufflation in on-demand sedated patients with known inflammatory bowel disease. Methods: In a randomised, single-centre study, 92 patients were randomised to either water-aided insertion and air insufflation during withdrawal [Water] or air insufflation during both insertion and withdrawal [Air]. The main outcome measured was success rate of unsedated colonoscopy, defined as reaching the caecum without requiring sedation and with discomfort during insertion of less than or equal to 5 using 0–10 continuous scale [0 = none, 10 = maximum pain]. Results: Success rate of caecal intubation without sedation or invoking a discomfort score greater than 5 was significantly higher in the Water arm compared with the Air arm [73.9 vs 45.7%, p = 0.01]. Discomfort score during insertion [mean ± SD] was significantly lower in the Water than in the Air arm [3.8±2.4 vs 5.4±1.9, p < 0.001]. Other outcomes including procedural times, success rate of terminal ileum intubation, need for abdominal compression, and repositioning were comparable. There were no complications recorded in the study. Conclusions: Compared with air insufflation, water-aided colonoscopy significantly reduces discomfort in on-demand sedated patients with inflammatory bowel disease, achieving comparable procedural outcomes.

Aim Water-aided insertion as an alternative colonoscopy technique reduces patient discomfort. Warm water has been used in most published trials, but the use of cool water is easier and, if equally effective, could support the use of the water-aided technique in routine practice. Method A double-blind, randomized, single-centre study was performed in which 201 patients were randomized to either cool (20–24°C) or warm (37°C) water immersion insertion. The primary outcome was caecal intubation time. The success rate of minimal sedation and patient discomfort were also assessed. Results The caecal intubation time for cool and warm water was similar (6.9 ± 3.5 vs 7.0 ± 3.4 min, P = 0.64). The respective success rates of minimal sedation colonoscopy (89.1% vs 90%, P = 1.00) and discomfort (P = 0.51) were no different. All other outcomes except a greater need for abdominal compression in the cool water arm (P = 0.04) were similar including the total procedure time, terminal ileum intubation rate, adenoma detection, length of the inserted scope, water volume, non-standard position rate, difficulty of the procedure and the patient's temperature sensation. Conclusion The use of cool water did not modify the caecal intubation time compared with warm water. Exception for abdominal compression, all other end-points were no different. Cool water immersion is an alternative to the technically more demanding warm water immersion colonoscopy.

OBJECTIVE Bowel distension by insufflated air causes abdominal discomfort after colonoscopy. Carbon dioxide (CO2) instead of air insufflation during colonoscopy can reduce postprocedural discomfort in diagnostic and screening cases. Discomfort after colonoscopy and CO2 insufflation have never been studied in inflammatory bowel disease (IBD) patients, characterized by younger age, structural changes of the colon, and need for repeated and frequently uncomfortable colonoscopies. Our trial was designed to evaluate postprocedural discomfort associated with CO2 compared with air insufflation in unsedated or minimally sedated patients with known IBD. METHODS In a double-blind, randomized, single-center study, 64 patients were randomized to either CO2 insufflation (CO2) or air insufflation colonoscopy (Air). Abdominal pain, bloating, and flatulence scores during 24 h after colonoscopy were recorded using a continuous scale of 0-10 (0=none, 10=maximum discomfort). The primary endpoint used for power calculation was bloating score at 1 h after colonoscopy. RESULTS Pain, bloating, and flatulence scores at end, 1, and 3 h after colonoscopy were significantly lower in CO2 than in Air arm (P

To determine whether observations were reproducible among investigators.From March 2013 through June 2014, 18-85-year-old diagnostic and 50-70-year-old screening patients were enrolled at each center to on-demand sedation colonoscopy with water exchange (WE), water immersion (WI) and insufflation with air or CO2 for insertion and withdrawal [air or carbon dioxide (AICD)]. Data were aggregated for analysis.Variations in real-time maximum insertion pain (0 = none, 1-2 = discomfort, 10 = worst).One thousand and ninety-one cases analyzed: WE (n = 371); WI (n = 338); AICD (n = 382). Demographics and indications were comparable. The WE group had the lowest real-time maximum insertion pain score, mean (95%CI): WE 2.8 (2.6-3.0), WI 3.8 (3.5-4.1) and AICD 4.4 (4.1-4.7), P0.0005. Ninety percent of the colonoscopists were able to use water exchange to significantly decrease maximum insertion pain scores. One investigator had high insertion pain in all groups, nonetheless WE achieved the lowest real-time maximum insertion pain score. WE had the highest proportions of patients with painless unsedated colonoscopy (vs WI, P = 0.013; vs AICD, P0.0005); unsedated colonoscopy with only minor discomfort (vs AICD, P0.0005), and completion without sedation (vs AICD, P0.0005).Aggregate data confirm superiority of WE in lowering colonoscopy real-time maximum insertion pain and need for sedation. Ninety percent of investigators were able to use water exchange to significantly decrease maximum insertion pain scores. Our results suggest that the technique deserves consideration in a broader scale.

Background and Aim Water immersion insertion is able to reduce discomfort and need for sedation during colonoscopy. A cap attached to the colonoscope tip may improve insertion during air insufflation colonoscopy. According to several reports, both techniques alone may result in higher detection of neoplastic lesions. Our study was designed to evaluate the efficacy of cap-assisted water immersion compared to water immersion colonoscopy in minimally sedated patients. Methods A total of 208 consecutive outpatients were randomized to either cap-assisted water immersion (Cap Water) or water immersion colonoscopy (Water). The primary endpoint was cecal intubation time. Results Cecal intubation time was 6.9 ± 2.9 min in Cap Water and 7.4 ± 4.2 min in the Water arm (P = 0.73). Success rate of minimal sedation colonoscopy was equal in both groups (92.9%, P = 1.00). From the endoscopist's point of view, there were non-significant trends towards lower discomfort (P = 0.06), less need for abdominal compression (P = 0.06) and lower difficulty score (P = 0.05) during Cap Water colonoscopy. Adenoma detection rate was similar in both arms (44% in Cap Water vs 45% in the Water group, P = 0.88). There were no complications recorded in the present study. Conclusions In comparison with water immersion without cap, cap-assisted water immersion colonoscopy was not able to shorten the cecal intubation time. However, it has the possibility of reducing patient discomfort and difficulty of colonoscope insertion. Potential impact on improved detection of neoplastic lesions has to be evaluated by further studies.

Low adenoma detection rate (ADR) predicts development of interval cancers, found mainly in the right (cecum-ascending) colon, where poor bowel preparation is an associated factor. Single-site studies reported increased detection of adenomas in the proximal colon segments by water exchange (WE). Data about colon cleansing revealed that WE had the greatest impact in the right colon.To test the hypothesis that WE had the greatest impact on ADR in colon segments with the most favorable bowel cleanliness scores, namely the right colon.We pooled right colon and overall ADR data of three similarly designed colonoscopy trials that compared WE, water immersion (WI) and insufflation of air or carbon dioxide (AICD) in a mixed gender European population.In this study, 1200 (704 males) subjects and were included. 288 were screening cases. Demographic and procedural data were comparable. Water exchange achieved significantly higher right colon10 mm ADR (11.9 %, vs WI 6.9 %, p = 0.016; vs AICD 7.2 %, p = 0.025). Water exchange achieved the lowest proportions of poor bowel preparation and the highest right colon and overall Boston bowel preparation scale scores (p range 0.003,0.0005). In patients with right colon excellent bowel cleanliness, water exchange was the only method significantly associated with right colon adenoma detection. One of the limitations is unblinded colonoscopists.In a mixed gender European population, water exchange is confirmed to be a superior insertion technique showing a significant increase in10 mm right colon adenoma detection, achieving the cleanest colon and lowest proportions of poor bowel preparation requiring repeat procedures. CLINICALTRIALS.NCT01781650, 01954862, 01780818.

Background and Aims Water exchange (WE) is the least painful insertion method during colonoscopy. Its impact on postcolonoscopy discomfort has not been well-described. Carbon dioxide (CO 2 ) insufflation consistently reduced postcolonoscopy discomfort. We compared postcolonoscopy outcomes of various combinations of insertion and withdrawal techniques (insertion-withdrawal modality): WE-CO 2 , WE-air insufflation (WE-AI), and CO 2 -CO 2 . Methods A total of 240 patients undergoing on-demand sedation diagnostic colonoscopy were randomized to WE-CO 2 (n = 79), WE-AI (n = 80), CO 2 -CO 2 (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. Results Demographic and procedural data were comparable. Compared with WE-AI, WE-CO 2 and CO 2 -CO 2 resulted in significantly less bloating (all P P values ranged from .008 to P values ranged from .003 to 2 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 Conclusions The combination WE-CO 2 appears to be the optimal choice to decrease pain during the examination and to reduce bloating and other undesired procedural outcomes afterward. If a CO 2 insufflator is already available, it seems advisable to adopt the combination WE-CO 2 . In the absence of a CO 2 insufflator, the cost effectiveness of the addition of withdrawal CO 2 to WE in diagnostic and nondiagnostic settings needs to be critically assessed. (Clinical trial registration number: NCT02409979.)

Water immersion insertion and carbon dioxide (CO2) insufflation, as alternative colonoscopic techniques, are able to reduce patient discomfort during and after the procedure. We assessed whether the combination of water immersion and CO2 insufflation is superior in efficacy and patient comfort to other colonoscopic techniques.In a prospective, randomized study, a total of 420 patients were randomized to either water immersion insertion and CO2 insufflation during withdrawal (water/CO2), water insertion and air insufflation during withdrawal (water/air), CO2 insufflation during both insertion and withdrawal (CO2/CO2), or air insufflation during both insertion and withdrawal (air/air). The main outcome was the success of minimal sedation colonoscopy, which was defined as reaching the cecum without switching to another insertion method and without additional sedation beyond the initial 2 mg of midazolam. Patient comfort during and after the procedure was assessed.A total of 404 patients were analyzed. The success rate of minimal sedation colonoscopy in the water insertion arm (water/CO2 and water/air) was 97% compared with 83.3% in the gas insertion arm (CO2/CO2 and air/air; P0.0001). Intraprocedural pain and bloating were significantly lower in the water/CO2 group than in all other groups. Patient discomfort in the water/CO2 group during 24 h after the procedure was comparable with that in the CO2/CO2 group and significantly lower than that in the air groups (water/air and air/air). No complications were recorded during the study.The combination of water immersion and CO2 insufflation appears to be an effective and safe method for minimal sedation colonoscopy. Overall patient discomfort was significantly reduced compared with that in other techniques.

Background & Aims Unsedated colonoscopy is acceptable for diagnostic, surveillance, and screening indications worldwide. However, insertion of the colonoscope can be painful; it is not clear which technique is least painful and thereby increases the likelihood of colonoscopy completion. We performed a head-to-head comparison of air insufflation (AI), carbon dioxide (CO 2 ) insufflation, water immersion (WI), and water exchange (WE) to determine which combination of insertion techniques produces the least amount of pain. Methods In a patient-blinded prospective trial, 624 subjects were assigned randomly to groups that underwent colonoscopy with AI–AI, CO 2 –CO 2 , WI–AI, WE–AI, WI–CO 2 , or WE–CO 2 insertion and withdrawal techniques, including on-demand sedation, at the St. Barbara Hospital (Iglesias, Italy) or the Vitkovice Hospital (Ostrava, Czech Republic), from October 2013 through June 2014. The primary outcome was real-time maximum insertion pain (0 = none, 10 = worst), recorded by an unblinded nurse assistant. At discharge, a blinded observer recorded the recalled maximum insertion pain and patients' and investigators' guesses about method or gas used. Results Patients and investigators correctly guessed the method used for fewer than 44% of procedures, confirming adequate blinding. The correlation between real-time and recalled maximum insertion pain (r = 0.9; P 2 –CO 2 (95% CI, 4.3–5.4), 4.3 for WI–CO 2 (95% CI, 3.8−4.9), 4.0 for WI–AI (95% CI, 3.5–4.5), 3.1 for WE–CO 2 (95% CI, 2.7−3.4), and 3.1 for WE–AI (95% CI, 2.7–3.6) ( P P Conclusions In a prospective study of colonoscopy insertion methods, CO 2 insufflation did not reduce real-time maximum insertion pain. Compared with AI or CO 2 , WI and WE reduced insertion pain. The least painful technique was WE, which significantly increased completion of unsedated colonoscopy and bowel cleanliness without prolonging insertion time. ClinicalTrials.gov number: NCT01954862.