Underwater EMR for colorectal lesions: a systematic review with meta-analysis (with video)

Published:October 25, 2018DOI:

      Background and Aims

      Underwater EMR is an alternative way to have nonpedunculated colorectal lesions lifted before being resected. The endoscopist takes advantage of the behavior of mucosal lesions floating away from the muscular layer, once immersed in liquid. We performed a systematic review with meta-analysis to evaluate the efficacy and safety of this technique.


      Electronic databases (Medline, Scopus, EMBASE) were searched up to May 2018. Full articles including patients with colorectal lesions resected by the underwater EMR technique were eligible. The complete resection (primary outcome), en bloc resection, recurrence, and adverse event rates were pooled by means of a random or fixed-effect model.


      Ten studies were eligible, providing data on 508 lesions removed from 433 patients (male/female = 239/194; mean age range 62.2-75.0 years). Six studies were performed in the United States and the other in Europe; 7 studies were prospective. The specific indications for performing underwater EMR varied widely across studies. The complete resection rate was 96.36% (95% confidence interval [CI], 91.77-98.44), with a rate of en bloc resection of 57.07% (95% CI, 43.20%-69.91%). The recurrence rate was 8.82% (95% CI, 5.78-13.25) in a mean endoscopy surveillance period of 7.7 months (range 4-15 months). The postprocedural bleeding rate was 2.85% (95% CI, 1.64-4.90). Bleeding during the procedure was always mild and was considered as part of the procedure in all series. The overall adverse event rate was 3.31% (95% CI, 1.97%-5.52%). No cases of perforation were reported.


      According to the results of this systematic review, underwater EMR appears to be an effective and extremely safe technique for resecting nonpolypoid colorectal lesions.

      Graphical abstract

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        • Burgess N.G.
        • Bahin F.F.
        • Bourke M.J.
        Colonic polypectomy (with videos).
        Gastrointest Endosc. 2015; 81: 813-835
        • Ahmad N.A.
        • Kochman M.L.
        • Long W.B.
        • et al.
        Efficacy, safety, and clinical outcomes of endoscopic mucosal resection: a study of 101 cases.
        Gastrointest Endosc. 2002; 55: 390-396
        • Rosenberg N.
        Submucosal saline wheal as safety factor in fulguration or rectal and sigmoidal polypi.
        AMA Arch Surg. 1955; 70: 120-122
        • Norton I.D.
        • Wang L.
        • Levine S.A.
        • et al.
        Efficacy of colonic submucosal saline solution injection for the reduction of iatrogenic thermal injury.
        Gastrointest Endosc. 2002; 56: 95-99
        • Nelson D.B.
        Techniques for difficult polypectomy.
        MedGenMed. 2004; 6: 12
        • Khashab M.
        • Eid E.
        • Rusche M.
        • et al.
        Incidence and predictors of "late" recurrences after endoscopic piecemeal resection of large sessile adenomas.
        Gastrointest Endosc. 2009; 70: 344-349
        • Belderbos T.D.
        • Leenders M.
        • Moons L.M.
        • et al.
        Local recurrence after endoscopic mucosal resection of nonpedunculated colorectal lesions: systematic review and meta-analysis.
        Endoscopy. 2014; 46: 388-402
        • Moss A.
        • Williams S.J.
        • Hourigan L.F.
        • et al.
        Long-term adenoma recurrence following wide-field endoscopic mucosal resection (WF-EMR) for advanced colonic mucosal neoplasia is infrequent: results and risk factors in 1000 cases from the Australian Colonic EMR (ACE) study.
        Gut. 2015; 64: 57-65
        • Buchner A.M.
        • Guarner-Argente C.
        • Ginsberg G.G.
        Outcomes of EMR of defiant colorectal lesions directed to an endoscopy referral center.
        Gastrointest Endosc. 2012; 76: 255-263
        • Binmoeller K.F.
        • Weilert F.
        • Shah J.
        • et al.
        “Underwater” EMR without submucosal injection for large sessile colorectal polyps (with video).
        Gastrointest Endosc. 2012; 75: 1086-1091
        • Shamseer L.
        • Moher D.
        • Clarke M.
        • et al.
        Preferred reporting items for systematic review and meta-analysis protocols (PRISMA-P) 2015: elaboration and explanation.
        BMJ. 2015; g7647: 350
        • DerSimonian R.
        • Laird N.
        Meta-analysis in clinical trials revisited.
        Contemp Clin Trials. 2015; 45: 139-145
        • Begg C.B.
        • Mazumdar M.
        Operating characteristics of a rank correlation test for publication bias.
        Biometrics. 1994; 50: 1088-1101
        • Binmoeller K.F.
        • Hamerski C.M.
        • Shah J.N.
        • et al.
        Attempted underwater en bloc resection for large (2-4 cm) colorectal laterally spreading tumors (with video).
        Gastrointest Endosc. 2015; 81: 713-718
        • Binmoeller K.F.
        • Hamerski C.M.
        • Shah J.N.
        • et al.
        Underwater EMR of adenomas of the appendiceal orifice (with video).
        Gastrointest Endosc. 2016; 83: 638-642
        • Wang A.Y.
        • Flynn M.M.
        • Patrie J.T.
        • et al.
        Underwater endoscopic mucosal resection of colorectal neoplasia is easily learned, efficacious, and safe.
        Surg Endosc. 2014; 28: 1348-1354
        • Kim H.G.
        • Thosani N.
        • Banerjee S.
        • et al.
        Underwater endoscopic mucosal resection for recurrences after previous piecemeal resection of colorectal polyps (with video).
        Gastrointest Endosc. 2014; 80: 1094-1102
        • Amato A.
        • Radaelli F.
        • Spinzi G.
        Underwater endoscopic mucosal resection: the third way for en bloc resection of colonic lesions?.
        United European Gastroenterol J. 2016; 4: 595-598
        • Schenck R.J.
        • Jahann D.A.
        • Patrie J.T.
        • et al.
        Underwater endoscopic mucosal resection is associated with fewer recurrences and earlier curative resections compared to conventional endoscopic mucosal resection for large colorectal polyps.
        Surg Endosc. 2017; 31: 4174-4183
        • Siau K.
        • Ishaq S.
        • Cadoni S.
        • et al.
        Feasibility and outcomes of underwater endoscopic mucosal resection for ≥ 10 mm colorectal polyps.
        Surg Endosc. 2018; 32: 2656-2663
        • Curcio G.
        • Granata A.
        • Ligresti D.
        • et al.
        Underwater colorectal EMR: remodeling endoscopic mucosal resection.
        Gastrointest Endosc. 2015; 81: 1238-1242
        • Uedo N.
        • Nemeth A.
        • Johansson G.W.
        • et al.
        Underwater endoscopic mucosal resection of large colorectal lesions.
        Endoscopy. 2015; 47: 172-174
        • Cadoni S.
        • Liggi M.
        • Gallittu P.
        • et al.
        Underwater endoscopic colorectal polyp resection: feasibility in everyday clinical practice.
        United European Gastroenterol J. 2018; 6: 454-462
        • Wells G.
        • Shea B.
        • O’Connell D.
        • et al.
        Newcastle-Ottawa Scale (NOS) for assessing the quality of nonrandomized studies in meta-analyses.
        (2013. Available at:)
        • Hassan C.
        • Repici A.
        • Sharma P.
        • et al.
        Efficacy and safety of endoscopic resection of large colorectal polyps: a systematic review and meta-analysis.
        Gut. 2016; 65: 806-820
        • Knabe M.
        • Pohl J.
        • Gerges C.
        • et al.
        Standardized long-term follow-up after endoscopic resection of large, nonpedunculated colorectal lesions: a prospective two-center study.
        Am J Gastroenterol. 2014; 109: 183-189
        • Ferlitsch M.
        • Moss A.
        • Hassan C.
        • et al.
        Colorectal polypectomy and endoscopic mucosal resection (EMR): European Society of Gastrointestinal Endoscopy (ESGE) Clinical Guideline.
        Endoscopy. 2017; 49: 270-297

      Linked Article

      • Underwater EMR for colorectal lesions
        Gastrointestinal EndoscopyVol. 90Issue 3
        • Preview
          We read with interest the article by Spadaccini et al1 evaluating underwater EMR (UEMR) for colorectal lesions. The authors found UEMR to be an effective and safe technique for resecting colorectal lesions. Because their findings are important to current practice, several questions deserve attention.
        • Full-Text
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      • Underwater EMR without submucosal injection: Is less more?
        Gastrointestinal EndoscopyVol. 89Issue 6
        • Preview
          Conventional injection-assisted EMR is well established as the preferred method for the removal of sessile colonic polyps. Submucosal injection is based on the rationale that a fluid “cushion” separates the superficial mucosa-based lesion from the underlying muscular layer, thus protecting against perforation and transmural thermal injury when snare resection is performed. The 2015 ASGE Technology Status Evaluation Report on EMR states, “The cushion lifts the lesion, facilitating capture and removal by using a snare while minimizing mechanical or electrocautery damage to the deeper layers of the GI wall.”1 This practice has disseminated to become the standard of care despite an absence of studies proving its clinical benefit.
        • Full-Text
        • PDF