Water Exchange Colonoscopy Research Articles

Tu1322 Water Exchange Enhanced Cecal Intubation in Potentially Difficult Colonoscopy - Unsedated Patients With Prior Abdominal or Pelvic Surgery: a Prospective Randomized, Controlled Trial

A hypothesis paper suggested that water exchange colonoscopy (WEC) may be effective in potentially difficult colonoscopy in unsedated patients with a history of abdominal or pelvic surgery (Scand J Gastro 2011;46:517).

Mo1563 Water Exchange and Suction Removal of All Residual Air in the Colonic Lumen Both Contribute to Attenuation of Insertion Pain in a Learning Curve Study

Water exchange (WE) colonoscopy with suction removal of infused water predominantly during insertion significantly reduces insertion pain, suggesting it is worth learning in settings where patients are either not sedated or receive only minimal sedation. Albeit simple, compared with air insufflation, WE entails an entirely novel set of skills which require practice to master. The mechanism(s) of pain alleviation is not fully known.

Tu1320 Water Exchange Colonoscopy in a Non-Veteran Female Population

Tu1320 Water Exchange Colonoscopy in a Non-Veteran Female Population

Water exchange enhanced cecal intubation in potentially difficult colonoscopy. Unsedated patients with prior abdominal or pelvic surgery: a prospective, randomized, controlled trial

Colonoscopy is widely used for management of colorectal diseases. A history of abdominal or pelvic surgery is a well-recognized factor associated with difficult colonoscopy. Although water exchange colonoscopy (WEC) was effective in small groups of male U.S. veterans with such a history, its application in other cultural settings is uncertain. To investigate the application of WEC in such patients. Prospective, randomized, controlled, patient-blinded study. Tertiary-care referral center in China. Outpatients with prior abdominal or pelvic surgery undergoing unsedated diagnostic, screening, or surveillance colonoscopy. Patients were randomized to examination by either WEC or conventional air colonoscopy (AC). Cecal intubation rate. A total of 110 patients were randomized to the WEC (n = 55) or AC (n = 55) group. WEC significantly increased the cecal intubation rate (92.7% vs 76.4%; P = .033). The maximum pain scores (± standard deviation) were 2.1 ± 1.8 (WEC) and 4.6 ± 1.7 (AC), respectively (P < .001). Multivariate analysis showed that the colonoscopy method was the only independent predictor of failed colonoscopy (odds ratio 11.44, 95% confidence interval, 1.35-97.09). A higher proportion of patients examined by WEC would be willing to have a repeat unsedated colonoscopy (90.9% vs 72.7%, P = .013). Single center; unblinded but experienced endoscopists. This randomized, controlled trial confirms that the water exchange method significantly enhanced cecal intubation in potentially difficult colonoscopy in unsedated patients with prior abdominal or pelvic surgery. The lower pain scores and higher proportion accepting repeat of the unsedated option suggest that WEC is promising. It may enhances compliance with colonoscopy in specific populations. ( NCT01485133.).

Underwater hot and cold snare polypectomy can be safely executed during water exchange colonoscopy

Underwater hot and cold snare polypectomy can be safely executed during water exchange colonoscopy

Vital signs and serum electrolyte levels are well preserved after large volume water exchange in the colonic lumen used with the water exchange method

Background: Reports of water exchange (We) colonoscopy did not describe complications, but the safety of the We method has not been critically evaluated. Aim: We report the vital signs, cardiac rhythm and serum electrolyte levels before and after large volume water exchange. Unsedated patients are chosen for evaluation to avoid the confounding effects of sedation medications. Patient and method: patients in two randomized controlled trials (RcT) comparing the use of air insufflations (AI) vs. We method for unsedated colonoscopy without missing data of interest were identified. Study 1: patients’ vital signs and cardiac rhythm before (immediately before insertion of the colonoscope into the rectum) and after (immediately after removal of the colonoscope from the rectum) colonoscopy were tabulated. Study 2: In patients who agreed to have pre and post colonoscopy electrolyte evaluation, blood samples (2 mL each) were drawn within 5 to 10 min before and after colonoscopy for measuring the serum Na+ and K+ levels. Results: Study 1: There were no significant differences in vital signs before and after colonoscopy in either the AI or We group. All patients were in normal sinus rhythm before and after the colonoscopy. Study 2: There were no significant differences between the serum Na+ and K+ before and after colonoscopy in either the AI or We group. Conclusion: Vital signs, cardiac rhythm and serum electrolyte levels are well preserved after large volume We in the colonic lumen. The We method is a safe modality in these regards.

Magnetic Endoscope Imaging (ScopeGuide®) Elucidates the Mechanism of Action of the Pain-alleviating Impact of Water Exchange Colonoscopy - Attenuation of Loop Formation

Purpose: Water exchange colonoscopy produces a significant reduction of pain (scheduled unsedated patients), a lower patient-controlled medication requirement (scheduled sedated patients) and a higher proportion of patients completing unsedated colonoscopy (on-demand sedated patients). The method entails omission of air insufflation and removal of residual air to minimize lumen distension and flexure angulation. Less need for abdominal pressure and position change indirectly suggest less looping may account for pain alleviation. No objective evidence currently exists to substantiate the claim. A recent editorial on magnetic endoscope imaging (MEI) recommended its use in water exchange colonoscopy to elucidate the mechanism of pain alleviation / avoidance of loop formation. Aim: To show that MEI documents less frequent loop formation when water exchange is used. Methods: The MEI equipment (ScopeGuide®, Olympus) with built-in magnetic sensors displays the configuration of the colonoscope inside the patient. Colonoscopy using air or water exchange method was performed as previously described (Endoscopy 2011;43:816-21). During colonoscopy, the endoscopist was blinded to the ScopeGuide images which were recorded. Subsequent review of the recordings was performed. Loop formation was scored based on a visual guide provided by Olympus. Loop formation was defined as full (scope crossing itself); partial (exaggeration of the curvature) and none (a smooth and straight configuration of the scope). Results: Recordings were collected prospectively in routine cases not enrolled in clinical trials (Table). There were 41 and 32 non consecutive cases in the water exchange and air group, respectively. Review of the MEI recording showed that the sigmoid N loop was most common, followed by the sigmoid alpha loop, and exaggeration of scope curvature at the splenic flexure/transverse colon. Of these, 20/32 vs 9/41 patients (p=0.0007) had sigmoid looping, and 17/32 vs 9/41 patients (p=0.0007) had sigmoid/splenic looping when the scope tip was in the transverse colon, in the air and water exchange group, respectively. Limitation: Single center, small number, observational study.Table: Comparison of air vs. water exchange colonoscopyConclusion: For the first time, recorded MEI data objectively demonstrated significantly less loop formation during water exchange colonoscopy, elucidating the mechanism of pain alleviation by water exchange / attenuation of loop formation. Coupled with the emerging RCT data that MEI feedback enhances cecal intubation by trainees, the role of MEI combined water exchange in speeding up trainee learning curves deserves further evaluations. Disclosure: Dr. Joseph Leung: Olympus America. Research and Education support, on loan of MEI for study purposes. Other authors have no conflict of interests to disclose related to this study. This research was supported by an industry grant from Olympus America: on loan of MEI for study purposes.

Underwater Snare Cautery Polypectomy Can Be Safely Executed During Water Exchange Colonoscopy

Purpose: Worries over inability to re-identify polyps seen on insertion during scope withdrawal has led to recommendations to remove them when first encountered. In water exchange colonoscopy, water is used to lavage and clean the bowel while dirty water is suctioned from the colon during insertion. Concerns have been expressed that polypectomy may be difficult under water. Here we report a case of underwater polypectomy and retrieval during water exchange colonoscopy. Case: A 77-year-old man underwent diagnostic colonoscopy for FIT positive stool test. The patient was fully sedated for the supervised trainee. Using the water exchange method, the scope was advanced to the cecum. In the cecum, two pedunculated polyps (1 cm and 1.5 cm) were encountered (A). With the cecum still distended with water, underwater snare cautery polypectomy was successfully carried out on these two polyps (B). The polyps were successfully recovered via the suction channel (C, D). The patient experienced no pain. Upon withdrawal of the scope back through the colon, an additional 12 polyps were removed. At a follow-up appointment, the patient had no signs or symptoms of serositis or post-polypectomy syndrome. Discussion: This patient received full sedation dictated by the conventional approach in our training program. Whereas traditional colonoscopy uses air insufflation to dilate the colon, this patient was examined by the trainee using the water exchange method supervised by an attending experienced in this method as a learning exercise. To date, routine polypectomy under water with successful retrieval of the resected polyp has not been reported. The current case details how successful polypectomy and retrieval can occur even with the cecum filled with water. Conclusion: Underwater polypectomy in conjunction with the water exchange method is safe. Proficiency in the water exchange method improves the ability to recover polyps underwater, should the need arise, e.g., removal of polyps encountered during insertion.Figure: [1339] Figure A: Polyp encountered with cecum filled with water. B: Underwater snare cautery polypectomy. C: Retrieval of polyp. D: Following underwater polypectomy.

Failed Colonoscopies Referred by Community Colonoscopists for Double-balloon Enteroscopy - Successful Completion by Water Exchange Colonoscopy

Purpose: To describe the use of water exchange method for the successful cecal intubation of patients referred for prior incomplete “difficult” colonoscopy performed by community gastroenterologists. Current guidelines recommend a cecal intubation rate >90% for all and 95% for screening cases. Incomplete cases occur in up to 10-17%. Single (GIE 2010;71:1319) and double (Endoscopy 2012;44:38) balloon-assisted examinations have been reported to salvage cecal intubation in these difficult cases. Water exchange method has been proposed as an inexpensive but effective technique for improving cecal intubation rates in difficult colonoscopies (Scand J Gastro 2011;46:517, JIG 2011;1:172). Methods: From Jan 2011 to Mar 2012, 10 patients with prior failed cecal intubation were referred to the UC Davis Medical Center GI Lab for double balloon enteroscopy by community physicians. Water exchange colonoscopy was performed on these patients by a single endoscopist. At the outset, the air pump was turned off. Water was infused through the colonoscope to expand the lumen. Residual air was suctioned as the scope was advanced through the colon. Water containing fecal debris was suctioned and replaced with clean water predominantly during insertion. When the cecum was reached, the air pump was turned on and lumen fully distended to allow for optimal visualization. Patient characteristics and procedural outcomes were reviewed and tabulated retrospectively. Results: (See Table) Ten patients (F/M: 7/3), age 60.3±14.7 yrs (range 37-82) were included. Indication for procedure was surveillance (4), screening (4) and diagnostic (2). Each patient underwent successful completed colonoscopy using the water exchange method. Cecal intubation time was 16.6±8.4 (range 6-28) min. Total procedure time was 28.4±8.5 (range 19- 43) min. Eight of the procedures were completed under conscious sedation (versed, fentanyl, Demerol, Benadryl, phenergan). Two patients had sedation given by anesthesiologist using moderate conscious sedation (versed, fentanyl). One patient was given remifentanyl. Average BMI was 26.4±5.5 (range 19.2-36.3). The polyp detection rate was 60%; adenoma detection rate was 50% in these patients. There were no complications.Table: Table. Reasons for prior failed cecal intubation based on referral documentsConclusion: The results provide proof-of-principle confirmation that water exchange method is effective for completing difficult colonoscopies. Patients with risk factors for difficult colonoscopy such as female sex, low and high BMI, prior abdominal surgery, young or advanced age, unsatisfactory bowel preparation, history of irritable bowel syndrome, or poor pain tolerance should be considered for this technique when undergoing colonoscopy.

Water Exchange Method in Scheduled Unsedated Colonoscopy Significantly Enhanced Patient-Centered Outcomes Without Prolonging Procedural Times - A RCT

Purpose: A proof-of-principle U.S. RCT in scheduled unsedated patients was conducted with deliberate procedural caution to obviate avoidable discomfort due to the evaluation of a novel but non time-tested water exchange method. Despite significant attenuation of insertion pain, enhancement of cecal intubation and willingness to repeat the unsedated option (GIE 2010;72:693) the prolonged insertion time was deemed a hurdle to widespread adoption in private practice models (GIE 2010;72:710). Aim: Using the subsequently time-tested method we reassessed the impacts of water exchange in a RCT (NCT01383252). Methods: Veterans who requested (scheduled) unsedated colonoscopy were randomized to water exchange or air method used as described (Endoscopy 2011;43:816-821). Outcomes included demographic, patient and procedure-related variables. Results: (Table). 90 of 100 randomized patients requested scheduled unsedated colonoscopy due to lack of escort. Intention-to-treat (ITT) cecal intubation rate was 98% (water) vs. 88% (air), p=0.2687. Fewer patients in the water exchange group required abdominal pressure (13 vs. 27, p=0.0076). During insertion there was a significantly lower maximum pain score 3 (2.8) vs. 5 (3.0) (p=0.0008) in the water exchange group. Willingness to repeat: 76% vs. 48% (p<0.0007, Fisher's exact test) was superior with water exchange. Overall (54% vs. 48%) and proximal (40% vs. 28%) and proximal <10 mm (36% vs. 28%) ADR were in favor of water exchange. Limitations: Single site, unblinded, small number of elderly male veterans.Table: Patients demographics and outcomeConclusion: The results confirm that water exchange produces significantly lower maximum pain scores during insertion, greater willingness to repeat unsedated colonoscopy, and less assistant burden to provide abdominal pressure. Although numerically superior, this study is underpowered to reconfirm a significant improvement (by water exchange) of an already high ITT cecal intubation rate (due to accumulated experience in unsedated patients), and overall and proximal ADR already far exceeding quality standards. However, for individuals without escorts, with a preference for no sedation, or screened by flexible sigmoidoscopy (no escort requirement), scheduled unsedated water exchange colonoscopy (akin to extended flexible sigmoidoscopy) may be relevant. It can examine the entire colon or offer an extended view beyond the splenic flexure without the costs and potential side-effects of sedation. More germane to concerns in private practice models, when the established and time-tested method is used, the favorable impacts on patient-centered outcomes are no longer at the expense of excessively prolonged procedural times. Disclosure: Olympus America - research and educational grant support. Cook Endoscopy - educational grant support.

Magnetic endoscope imaging (ScopeGuide) elucidates the mechanism of action of the pain-alleviating impact of water exchange colonoscopy - attenuation of loop formation

The explanation why water exchange colonoscopy produces a significant reduction of pain during colonoscopy is unknown. A recent editorial recommended use of magnetic endoscope imaging (MEI) to elucidate the explanation. In unselected patients to show that MEI documents less frequent loop formation when water exchange is used. Observational, performance improvement. Veterans Affairs outpatient endoscopy. Routine colonoscopy cases. Colonoscopy using air or water exchange method was performed as previously described. The MEI equipment (ScopeGuide, Olympus) with built-in magnetic sensors displays the configuration of the colonoscope inside the patient. During sedated colonoscopy the endoscopist was blinded to the ScopeGuide images which were recorded and subsequently reviewed. Loop formation based on a visual guide provided by Olympus. There were 41 and 32 cases in the water exchange and air group, respectively. The sigmoid N loop was most common, followed by the sigmoid alpha loop, and exaggeration of scope curvature at the splenic flexure/transverse colon. Of these, 20/32 vs. 9/41 patients (p=0.0007) had sigmoid looping, and 17/32 vs. 9/41 patients (p=0.0007) had sigmoid/splenic looping when the scope tip was in the transverse colon, in the air and water exchange group, respectively. Colonoscopy method was not blinded and non randomized. MEI data objectively demonstrated significantly fewer loops during water exchange colonoscopy, elucidating its mechanism of pain alleviation - attenuation of loop formation. Since MEI feedback enhances cecal intubation by trainees, the role of MEI combined water exchange in speeding up trainee learning curves deserves further evaluations.

Water exchange method for colonoscopy: Learning curve of an experienced colonoscopist in a U.S. community practice setting

Water exchange colonoscopy has been reported to reduce examination discomfort and to provide salvage cleansing in unsedated or minimally sedated patients. The prolonged insertion time and perceived difficulty of insertion associated with water exchange have been cited as a barrier to its widespread use. To assess the feasibility of learning and using the water exchange method of colonoscopy in a U.S. community practice setting. Quality improvement program in nonacademic community endoscopy centers. Patients undergoing sedated diagnostic, surveillance, or screening colonoscopy. After direct coaching by a knowledgeable trainer, an experienced colonoscopist initiated colonoscopy using the water method. Whenever >5 min elapsed without advancing the colonoscope, conversion to air insufflation was made to ensure timely completion of the examination. Water Method Intention-to-treat (ITT) cecal intubation rate (CIR). Female patients had a significantly higher rate of past abdominal surgery and a significantly lower ITTCIR. The ITTCIR showed a progressive increase over time in both males and females to 85-90%. Mean insertion time was maintained at 9 to 10 min. The overall CIR was 99%. Use of water exchange did not preclude cecal intubation upon conversion to usual air insufflation in sedated patients examined by an experienced colonoscopist. With practice ITTCIR increased over time in both male and female patients. Larger volumes of water exchanged were associated with higher ITTCIR and better quality scores of bowel preparation. The data suggest that learning water exchange by a busy colonoscopist in a community practice setting is feasible and outcomes conform to accepted quality standards.

Right Colon Polyp Miss Rates of Water Exchange and Carbon Dioxide Insufflation Colonoscopy

Right Colon Polyp Miss Rates of Water Exchange and Carbon Dioxide Insufflation Colonoscopy