Underwater Resection Research Articles

WEO Newsletter: Tips and tricks for underwater resection. How to swim without drowning in this technique.

WEO Newsletter: Tips and tricks for underwater resection. How to swim without drowning in this technique.

Endoscopic underwater detection and resection of anal squamous intraepithelial lesions in non-anesthetized patients – a feasibility study and comparison with standard surgical treatment

Background Anal squamous intraepithelial lesions (ASILs) correspond to premalignant changes preceding the development of anal squamous cell carcinoma. Objective To describe a new endoscopic technique to detect and remove ASILs in non-anesthetized patients and compare it with standard surgical treatment. Methods For endoscopic treatment, high resolution (HR) flexible endoscopes with a distal attachment were used. Underwater inspection of the anal canal was performed in near-focus mode with white light and narrow-band imaging. Detected lesions were resected with a diathermia snare after local injection of xylocaine/adrenaline. We did a retrospective comparison of all patients who underwent endoscopic or standard surgical treatment for ASILs at Ersta hospital in Stockholm between 2018 and 2020. Patient files were reviewed for number of lesions, treatments until macroscopic radicality, degree of dysplasia, bleeding, pain and other complications. Results Endoscopic (n = 37) and surgical (n = 43) treatment displayed comparable number of lesions per patient (p = .37). The number of procedures until macroscopic radicality was higher for endoscopy than surgery (p = .04). However, in endoscopic follow up of 12 of the surgically treated patients, residual ASIL was found in 10 cases. Post-procedural bleeding requiring healthcare occurred in two endoscopy patients and one surgically treated patient. Conclusions Underwater resection using a HR flexible endoscope in non-anesthetized is a new, feasible and well tolerated method for ASILs treatment. Its efficacy and risk of complications seem comparable to standard surgical treatment while avoiding general anesthesia. However, minor lesions might be overlooked at surgery.

Saline-immersion therapeutic endoscopy facilitated en bloc endoscopic submucosal-subserosal dissection of a sigmoid diverticulum containing a refractory adenomatous lesion.

Underwater resection has become a well-recognized alternative approach to standard endoscopic resection techniques [1]. Based on the same principles, saline-immersion therapeutic endoscopy (SITE) was introduced as an “evolution of the underwater technique” with several potential advantages [2]. SITE facilitates endoscopic submucosal dissection (ESD) through maintenance of the submucosal lift, intrinsic buoyancy (obviating the need for traction), enhanced dissection, and improved visibility [2] [3].

Water-assisted colonoscopy: an international modified Delphi review on definitions and practice recommendations

Since 2008, a plethora of research studies has compared the efficacy of water-assisted (aided) colonoscopy (WAC) and underwater resection (UWR) of colorectal lesions with standard colonoscopy. We reviewed and graded the research evidence with potential clinical application. We conducted a modified Delphi consensus among experienced colonoscopists on definitions and practice of water immersion (WI), water exchange (WE), and UWR. Major databases were searched to obtain research reports that could potentially shape clinical practice related to WAC and UWR. Pertinent references were graded (Grading of Recommendations, Assessment, Development and Evaluation). Extracted data supporting evidence-based statements were tabulated and provided to respondents. We received responses from 55 (85% surveyed) experienced colonoscopists (37 experts and 18 nonexperts in WAC) from 16 countries in 3 rounds. Voting was conducted anonymously in the second and third round, with≥80% agreement defined as consensus. We aimed to obtain consensus in all statements. In the first and the second modified Delphi rounds, 20 proposed statements were decreased to 14 and then 11 statements. After the third round, the combined responses from all respondents depicted the consensus in 11 statements (S): definitions of WI (S1) and WE (S2), procedural features (S3-S5), impact on bowel cleanliness (S6), adenoma detection (S7), pain score (S8), and UWR (S9-S11). The most important consensus statements are that WI and WE are not the same in implementation and outcomes. Because studies that could potentially shape clinical practice of WAC and UWR were chosen for review, this modified Delphi consensus supports recommendations for the use of WAC in clinical practice.

S2363 Underwater Full-Thickness Resection of a Colonic Polyp: A Novel Technique

INTRODUCTION: Underwater resection is an emerging technique in which the gastrointestinal lumen is distended with water instead of air, allowing the mucosal layer to float, facilitating lesion demarcation and resection. Underwater endoscopic mucosal resection (EMR) for colon polyps has been well-studied. Full-thickness resection device (FTRD, Ovesco Endoscopy AG, Tuebingen, Germany) is a dedicated system for single step full-thickness resection of colon lesions that are not amenable for resection by conventional methods. In this study, we combined both techniques to resect a recurrent adenomatous colonic polyp. CASE DESCRIPTION/METHODS: A 52-year-old female patient with no significant past medical history underwent screening colonoscopy which revealed a 2 cm polyp (Kudo IV) in the descending colon. The polyp was completely resected using underwater EMR. Histology report showed tubulovillous adenoma with low grade dysplasia. A follow-up colonoscopy was performed 3 months later and revealed a 2 cm sessile polyp at the previous resection site consistent with recurrent adenoma. Underwater full-thickness resection using FTRD was planned. A colonoscope was inserted and advanced to the lesion site. The FTRD grasper was used to grasp the lesion and pull it completely into the PRVE Cap. The lesion was determined to be amenable to full-thickness resection. The area surrounding the lesion was marked with the FTRD marking probe. The colon lumen was then distended with warm normal saline. The colonoscope was removed and the FTRD device was attached to the scope. The colonoscope with FTRD was then reinserted into the colon and advanced to the site of the lesion. The over-the-scope (OTS) clip was then deployed successfully and the FTRD snare was used to resect the lesion. The entire device and scope were withdrawn from the colon. A second colonoscope was then advanced into the colon to the site of resection with excellent visualization of the resected area. The resected lesion measured 2 cm × 2.5 cm. No complications were reported during or after the procedure. The patient was discharged on the same day. DISCUSSION: The use of FTRD in a water filled colon lumen can improve feasibility, efficacy, and safety of lesion resection via FTRD. Further research should be performed to determine whether the underwater technique enhances the FTRD procedure by possibly reducing procedure time and improving patient outcomes.

Effectiveness and safety of underwater techniques in gastrointestinal endoscopy: a comprehensive review of the literature

Conventional endoscopic resection techniques such as endoscopic mucosal resection (EMR) or endoscopic submucosal dissection (ESD), represent the standard of care for treatment of superficial gastrointestinal lesions. In 2012 a novel technique called underwater endoscopic mucosal resection (U-EMR) was described by Binmoeller and colleagues. This substantial variation from the standard procedure was afterwards applied at endoscopic submucosal dissection (U-ESD) and recently proposed also for peroral endoscopic myotomy (U-POEM) and endoscopic full-thickness resection (U-EFTR). This paper aims to perform a comprehensive review ofthe current literature related to supporting the underwater resection techniques with the aimto evaluate their safety and efficacy. Based on the current literature U-EMR appears to be feasible and safe. Comparison studies showed that U-EMR is associatedwithhigher "en-bloc" and R0 resection rates for colonic lesions, but lower "en-bloc" and R0 resection rates forduodenal non-ampullary lesions, compared to standard EMR. In contrast to U-EMR, little evidence supporting U-ESD are currently available. A single comparison study on gastric lesions showed that U-ESD had shorter procedural times and allowed a similar "en-bloc" resection rates compared to standard ESD. No comparison studies between U-ESD and ESD are available for colonic lesions. Finally, only some anecdotal experiences have been reported for U-POEM or U-EFTR, and the feasibility and effectiveness of these techniques need to be further investigated. Further prospective studies are necessary to better explore the advantages of underwater techniques compared to the respective standards of care, especially in the setting of U-ESD where consistent data are lacking and where standardization of the technique is needed.

Underwater versus conventional endoscopic resection of nondiminutive nonpedunculated colorectal lesions: a prospective randomized controlled trial (with video)

Incomplete resection of colorectal neoplasia decreases the efficacy of colonoscopy. Conventional resection (CR) of polyps, performed in a gas-distended colon, is the current standard, but incomplete resection rates of approximately 2% to 30% for nondiminutive (>5mm), nonpedunculated lesions are reported. Underwater resection (UR) is a novel technique. The aim of this study was to determine the incomplete resection rates of colorectal lesions removed by UR versus CR. In a randomized controlled trial, patients with small (6-9mm) and large (≥10mm) nonpedunculated lesions were assigned to CR (gas-distended lumen) or UR (water-filled, gas-excluded lumen). Small lesions in both arms were removed with a dedicated cold snare. For CR, large lesions were removed with a hot snare after submucosal injection. For UR, large lesions were removed with a hot snare without submucosal injection. Four-quadrant biopsy samples around the resection sites were used to evaluate for incomplete resection. Four hundred sixty-two eligible polyps (248 UR vs 214 CR) from 255 patients were removed. Incomplete resection rates for UR and CR were low and did not differ (2% vs 1.9%, P= .91). UR was performed significantly faster for lesions≥10mm in size (10-19mm, 2.9 minutes vs 5.6 minutes, P< .0001); ≥20 mm, 7.3 minutes vs 9.5 minutes, P = .015). Low incomplete resection rates are achievable with UR and CR. UR is effective and safe with the advantage of faster resection and potential cost savings for removal of larger (≥10mm) lesions by avoiding submucosal injection. As an added approach, UR has potential to improve the cost-effectiveness of colonoscopy by increasing efficiency and reducing cost while maintaining quality. (Clinical trial registration number: NCT02889679.).

Underwater endoscopic mucosal resection of serrated adenomas

OBJECTIVES:Serrated polyps, which are considered to be precursors of colorectal carcinoma, include hyperplastic polyps, sessile serrated adenomas and traditional serrated adenomas. With the exception of hyperplastic polyps, all of these lesions must be removed. This study sought to examine whether underwater endoscopic mucosal resection is a safe and effective technique for treating serrated polyps.METHODS:Cases in which patients were submitted for underwater endoscopic mucosal resection and histologically diagnosed with sessile serrated adenoma were prospectively registered.RESULTS:The median patient age was 54.5 years (range, 48 to 72 years), and the patients included 4 men (28.5%) and 10 women (71.5%). One lesion (6.2%), 10 lesions (62.5%), 1 lesion (6.2%), 3 lesions (18.8%) and 1 lesion (6.2%) were found in the cecum, the ascending colon, the hepatic flexure, the transverse colon and the descending colon, respectively. The median lesion size was 20 mm (range, 10 to 35 mm). Eight lesions (50%) were removed en bloc, and the remaining eight lesions (50%) were removed using a piecemeal technique. None of the cases were complicated by perforation or delayed bleeding.CONCLUSION:Underwater resection could be a feasible, safe and effective alternative for the resection of sessile serrated adenomas.

Underwater endoscopic colorectal polyp resection: Feasibility in everyday clinical practice.

Endoscopic mucosal resection is well-established for resecting flat or sessile benign colon polyps. The novel underwater endoscopic mucosal resection eschews submucosal injection prior to endoscopic mucosal resection. Reports about underwater endoscopic mucosal resection were limited to small series of single and/or tertiary-care referral centers, with single or supervised operators. The purpose of this study was to determine feasibility and efficacy of underwater resection of polyps of any morphology (underwater polypectomy, here includes underwater endoscopic mucosal resection) in routine clinical practice. This study involved a comparison of colonoscopy records of two community hospitals (January 2015-December 2016) for underwater polypectomy (n = 195) and gas insufflation polypectomy (n = 186). Comparable demographics, procedural data, overall distribution, morphology and size of resected lesions, number of en bloc and R0 resections (any polyp morphology and size); exception: overall, underwater polypectomy pedunculated polyps were significantly larger than those in the gas insufflation polypectomy group, p = 0.030. Underwater polypectomy (median, min) resection time was significantly shorter than gas insufflation polypectomy: sessile and flat polyps 6-9 mm, 0.8 vs 2.7 (p = 0.040); 10-19 mm, 2.0 vs 3.3 (p = 0.025), respectively; pedunculated polyps 6-19 mm, 0.8 vs 3.3 (p < 0.001). Underwater polypectomy resection of pedunculated polyps 6-19 mm showed significantly less immediate bleeding: 11.1% vs 1.5%, respectively (p = 0.031). Underwater polypectomy can be efficaciously used in routine clinical practice for the complete resection of colon polyps, with several advantages over gas insufflation polypectomy.

Underwater endoscopic resection: an alternative for difficult colorectal polyps.

Background and AimsUnderwater endoscopic resection can be an alternative to standard resection techniques to remove difficult colorectal polyps. This video shows 4 cases of underwater resection of large colorectal polyps.MethodsUnderwater resection consists of complete filling of the lumen through the accessory channel, using an infusion pump followed by snare resection of the polyp. We present 4 cases: a 3-cm pseudodepressed laterally spreading tumor (LST) in the sigmoid colon, a 6-cm pedunculated polyp with a thick stalk in the sigmoid, a 7-cm sessile lesion in the midrectum, and a 4-cm LST in the distal rectum close to the dentate line, resected with a monofilament snare or a multifilament snare.ResultsAll tumors were successfully resected without any adverse events or residual lesions during follow-up.ConclusionsThe underwater technique is a good alternative to standard resection techniques to remove difficult colorectal lesions.

Su1723 Underwater Resection of Benign Colorectal Neoplasia in Routine Clinical Practice: A VA Experience

Su1723 Underwater Resection of Benign Colorectal Neoplasia in Routine Clinical Practice: A VA Experience

Underwater Resection of Colorectal Neoplasia: Taking the Plunge Into a New Technique

FigureIntroduction: The optimal method for safe and effective endoscopic resection of benign colorectal neoplasia is dictated by lesion size, location and configuration, with the ideal goal of en bloc resection to reduce the risk of local neoplastic recurrence. Resection of colorectal lesions is traditionally performed with the colon fully distended with gas. Submucosal injection of fluid is also often utilized for larger lesions to assist with safe resection. Methods: An emerging approach to polypectomy involves gas exclusion in a partially distended, water filled lumen, without the use of submucosal injection.Observed and theoretical advantages to this technique can be broadly divided into 4 categories: 1) Enhanced visualization and detection: - Water creates a natural magnification affect, enhancing detection of lesions and allowing detailed examination of vasculature, pit patterns and mucosal irregularities. - The buoyancy of mucosal lesions in a fluid filled lumen suspends polyps, even flat ones, above the surrounding tissue. 2) Separation of mucosa and muscularis propria (MP) - The MP retains its circular shape even when the lumen is collapsed, creating natural separation between the mucosa and deeper muscle layer. - The need for submucosal injection prior to mucosal resection is eliminated as the chance for muscle injury is decreased with the natural separation of layers. - Wall tension is reduced in a collapsed lumen, allowing the MP to retain its full thickness, further decreasing the chance of perforation. 3) Alterations in polyp size, morphology and configuration - The mucosal surface area in a distended or collapsed colon remains constant, so the mucosa must involute and invaginate in a non-distened lumen, altering the normal mucosal topography and reducing the footprint of mucosally based lesions, increasing the success of en bloc resection. 4) Reduced resource utilization - Fewer endoscopic accessories used with elimination of submucosal injection. - Less frequent endoscopic follow up exams with higher en bloc resection rates. - Decreased need to refer difficult or large polyps to other providers. Results: We present 4 examples of underwater resection of colorectal lesions. Conclusion: Underwater resection of colorectal lesions is a novel approach. It has potential advantages that may assist with safer, more efficient, effective and less resource intensive therapy. It is easily learned by endoscopists familiar with conventional techniques and is another tool in the armamentarium for polypectomy.

“Underwater” EMR without submucosal injection for large sessile colorectal polyps (with video)

Submucosal injection is widely performed before EMR of large sessile colorectal polyps to facilitate resection and decrease perforation risk. We developed a novel method of water immersion ("underwater") EMR (UEMR) that eliminates submucosal injection. To evaluate the feasibility and outcomes of UEMR without submucosal injection for large sessile colorectal polyps. Prospective, observational study. Single, tertiary-care referral center. The standardized EMR technique involves full water immersion for the entire procedure and piecemeal resection with a 15-mm "duck bill" snare. Complete resection, bleeding, perforation, postpolypectomy syndrome, residual or recurrence adenoma. Sixty patients with 62 large sessile colorectal polyps underwent UEMR. The mean/median polyp size was 34/30 mm, and the mean/median resection time was 21/18 minutes. Histology revealed the following: tubular adenoma (n = 22), tubulovillous adenoma (n = 19), villous adenoma (n = 4), serrated adenoma (n = 11), and high-grade dysplasia/carcinoma in situ (n = 6). The mean/median interval until a follow-up colonoscopy in 54 patients (90%) was 20.4/15.2 weeks. One of 54 patients (2%) had an adenoma smaller than 5 mm outside of the postresection scar, consistent with a residual lesion missed on index UEMR. There was no perforation or postpolypectomy syndrome. Delayed bleeding occurred in 3 patients and was managed conservatively. Limited follow-up; single-center, single-endoscopist, uncontrolled study. The underwater resection technique enables complete removal of large sessile colorectal polyps without submucosal injection. The technique was safe in a large patient cohort, and the early recurrence rate appears low. Use of a water interface for UEMR has potential advantages that deserve further study.