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How to Perform High-Quality Endoscopic Mucosal Resection During Colonoscopy

2017; Elsevier BV; Volume: 152; Issue: 3 Linguagem: Inglês

10.1053/j.gastro.2016.12.029

1528-0012

Amir Klein, Michael J. Bourke,

Gastrointestinal Tumor Research and Treatment

Colonoscopy with polypectomy reduces mortality from colorectal cancer.1Winawer S.J. Zauber A.G. Ho M.N. et al.Prevention of colorectal cancer by colonoscopic polypectomy. The National Polyp Study Workgroup.N Engl J Med. 1993; 329: 1977-1981Crossref PubMed Scopus (4037) Google Scholar, 2Kahi C.J. Imperiale T.F. Juliar B.E. et al.Effect of screening colonoscopy on colorectal cancer incidence and mortality.Clin Gastroenterol Hepatol. 2009; 7: 770-775Abstract Full Text Full Text PDF PubMed Scopus (330) Google Scholar A small fraction of polyps are >2 cm and termed lateral spreading lesions (LSLs) of the colon.3Rotondano G. Bianco M.A. Buffoli F. et al.The Cooperative Italian FLIN Study Group: prevalence and clinico-pathological features of colorectal laterally spreading tumors.Endoscopy. 2011; 43: 856-861Crossref PubMed Scopus (65) Google Scholar These polyps require advanced resection techniques such as endoscopic mucosal resection (EMR) for safe and effective removal. However, colonic EMR is not routinely part of the general endoscopic curriculum available to gastroenterologists upon completion of their training. It requires dedicated training in advanced endoscopic resection techniques, the acquisition of clinical and interpretive skills, and the knowledge and ability to manage complications.4Klein A. Bourke M.J. Advanced polypectomy and resection techniques.Gastrointest Endosc Clin N Am. 2015; 25: 303-333Abstract Full Text Full Text PDF PubMed Scopus (56) Google Scholar Performing high-quality, safe, and effective colonic EMR requires a team effort both inside and outside the endoscopy suite. To achieve this, colonic EMR for advanced lesions should be performed preferably in tertiary referral centers. This provides a large case volume for training fellows and the opportunity for a multidisciplinary team structure including surgical, radiologic, and anesthetic support. This multifaceted and comprehensive approach provides the necessary context for advanced endoscopic tissue resection procedures. Over the last decade, a steady accumulation of scientific evidence has elucidated the technical aspects of colonic EMR,5Holt B. Bourke M.J. Wide field endoscopic resection for advanced colonic mucosal neoplasia: current status and future directions.Clin Gastroenterol Hepatol. 2012; 10: 969-979Abstract Full Text Full Text PDF PubMed Scopus (90) Google Scholar including safety and efficacy,6Moss A. Bourke M.J. Williams S.J. et al.Endoscopic mucosal resection outcomes and prediction of submucosal cancer from advanced colonic mucosal neoplasia.Gastroenterology. 2011; 140: 1908-1918Abstract Full Text Full Text PDF Scopus (474) Google Scholar long-term outcomes,7Moss 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: 57-65Crossref PubMed Scopus (373) Google Scholar and the clinical and economic benefits compared with surgery.8Ahlenstiel G. Hourigan L.F. Brown G. et al.Actual endoscopic versus predicted surgical mortality for treatment of advanced mucosal neoplasia of the colon.Gastrointest Endosc. 2014; 80: 668-676Abstract Full Text Full Text PDF PubMed Scopus (146) Google Scholar, 9Jayanna M. Burgess N.G. Singh R. et al.A cost analysis of endoscopic mucosal resection (EMR) compared to surgery for large sessile and flat colonic polyps.Clin Gastroenterol Hepatol. 2016; 14: 271-278Abstract Full Text Full Text PDF PubMed Scopus (157) Google Scholar An intimate knowledge of the evidence base is critical to achieve technical competence. Herein we review the step-by-step evidence-based methodology for performing best practice colonic EMR. Community gastroenterologists who discover large LSLs during routine colonoscopy usually refer patients for colonic EMR. It is important to emphasize to the patient the differences between standard polypectomy and EMR, and to ensure the patient is fully consented to the procedure and its alternatives. The patient's medical history including medication list need to be reviewed thoroughly and the patient's comorbidities constantly factored into the therapeutic process. Be prepared and organized. Preferably, a dedicated list should be scheduled for such procedures. All the required equipment should be readily available in the endoscopy suite and both physician and nurse need to be familiar with their use (Table 1).Table 1Recommended Endoscopic Equipment for Colonic EMREquipmentRecommendations/EvidenceMicroprocessor-controlled electrosurgical generatorsMinimizes potential for deep tissue injury during resectionSnare excision - Endocut Q effect 3 (ERBE VIO, Tübingen Germany)Coagulation of bleeding – Soft coagulation 80-W effect 4 (ERBE VIO)10Fahrtash-Bahin F. Holt B. Jayasekeran V. et al.Snare tip soft coagulation achieves effective and safe endoscopic hemostasis during wide-field endoscopic resection of large colonic lesions (with videos).Gastrointest Endosc. 2013; 78: 158-163Abstract Full Text Full Text PDF PubMed Scopus (74) Google ScholarInsufflationCO2 significantly reduces post procedural admissions for pain during colonic EMR11Bassan M.S. Holt B. Moss A. et al.Carbon dioxide insufflation reduces number of postprocedure admissions after endoscopic resection of large colonic lesions: a prospective cohort study.Gastrointest Endosc. 2013; 77: 90-95Abstract Full Text Full Text PDF PubMed Scopus (76) Google ScholarColloid solution for submucosal injectionSuccinylated gelatin (Gelofusine; Braun, Melsungen, Germany) was superior to normal saline in a randomized trial requiring significantly fewer injections, fewer resections, and an overall reduced EMR time12Moss A. Bourke M.J. Metz A.J. A randomized, double-blind trial of succinylated gelatin submucosal injection for endoscopic resection of large sessile polyps of the colon.Am J Gastroenterol. 2010; 105: 2375-2382Crossref PubMed Scopus (126) Google ScholarAlternatives: Normal saline, hydroxyethyl starchInert dye80 mg indigo carmine or 20 mg methylene blue in 500 mL solutionAdrenaline1:100,000May be effective in decreasing delayed bleeding13Bahin F.F. Rasouli K.N. Byth K. et al.Prediction of clinically significant bleeding following wide-field endoscopic resection of large sessile and laterally spreading colorectal lesions: a clinical risk score.Am J Gastroenterol. 2016; 111: 1115-1122Crossref PubMed Scopus (63) Google ScholarSnaresStiff 20- or 15-mm snares with a braided wire are preferred for en bloc and piecemeal EMR, respectively.Small thin wire (0.3-mm monofilament) snares may enable better tissue capture in poorly lifting lesions (ie, previously attempted lesions, recurrence after EMR, periappendiceal lesions)5Holt B. Bourke M.J. Wide field endoscopic resection for advanced colonic mucosal neoplasia: current status and future directions.Clin Gastroenterol Hepatol. 2012; 10: 969-979Abstract Full Text Full Text PDF PubMed Scopus (90) Google ScholarCoagulation of IPBManagement of IPB can be achieved quickly, safely and effectively with STSC10Fahrtash-Bahin F. Holt B. Jayasekeran V. et al.Snare tip soft coagulation achieves effective and safe endoscopic hemostasis during wide-field endoscopic resection of large colonic lesions (with videos).Gastrointest Endosc. 2013; 78: 158-163Abstract Full Text Full Text PDF PubMed Scopus (74) Google ScholarCoagulating forceps are used for more severe bleeding or if STSC fails after 2-3 attemptsClips are used less often as they tend to get in the way, and may not adequately compress small bleeding vessels4Klein A. Bourke M.J. Advanced polypectomy and resection techniques.Gastrointest Endosc Clin N Am. 2015; 25: 303-333Abstract Full Text Full Text PDF PubMed Scopus (56) Google ScholarEMR, endoscopic mucosal resection; IPB, intraprocedural bleeding; STSC, snare tip soft coagulation. Open table in a new tab EMR, endoscopic mucosal resection; IPB, intraprocedural bleeding; STSC, snare tip soft coagulation. Before commencing resection, take time to meticulously inspect the lesion with high-definition white light and chromoendoscopy or "virtual chromoendoscopy" (we use narrow band imaging). A thorough assessment can identify lesions with possible submucosal invasion. This is of great importance, because it may result in a different endoscopic approach or referral for surgical treatment. The Paris classification of superficial neoplasia should be used for morphologic classification14Lambert R. Lightdale C.J. The Paris endoscopic classification of superficial neoplastic lesions: Esophagus, stomach, and colon - Paris, France November 30 to December 1, 2002.Gastrointest Endosc. 2003; 58 Suppl 6: S3-S43Google Scholar, 15Axon A. Diebold M.D. Fujino M. et al.Update on the Paris classification of superficial neoplastic lesions in the digestive tract.Endoscopy. 2005; 37: 570-578Crossref PubMed Scopus (695) Google Scholar in combination with surface topography (granular or nongranular). The Paris classification and surface topography are helpful in stratifying the risk of submucosal invasion.6Moss A. Bourke M.J. Williams S.J. et al.Endoscopic mucosal resection outcomes and prediction of submucosal cancer from advanced colonic mucosal neoplasia.Gastroenterology. 2011; 140: 1908-1918Abstract Full Text Full Text PDF Scopus (474) Google Scholar, 16Hurlstone D.P. Sanders D.S. Cross S.S. et al.Colonoscopic resection of lateral spreading tumours: a prospective analysis of endoscopic mucosal resection.Gut. 2004; 53: 1334-1339Crossref PubMed Scopus (247) Google Scholar, 17Burgess N.G. Hourigan L.F. Zanati S.A. et al.Gross morphology and lesion location stratify the risk of invasive disease in advanced mucosal neoplasia of the colon: results from a large multicenter cohort.Gastrointest Endosc. 2014; 79: AB556Abstract Full Text Full Text PDF Google Scholar Focal interrogation uses narrow band imaging to assess the surface pit pattern according to the Kudo classification18Kudo S. Hirota S. Nakajima T. et al.Colorectal tumours and pit pattern.J Clin Pathol. 1994; 47: 880-885Crossref PubMed Scopus (645) Google Scholar and the vascular patterns according to the Sano classification or more recently the Narrow-Band Imaging International Colorectal Endoscopic (NICE) criteria.19Sano Y. Ikematsu H. Fu K.I. et al.Meshed capillary vessels by use of narrow-band imaging for differential diagnosis of small colorectal polyps.Gastrointest Endosc. 2009; 69: 278-283Abstract Full Text Full Text PDF PubMed Scopus (225) Google Scholar, 20Hayashi N. Tanaka S. Hewett D.G. et al.Endoscopic prediction of deep submucosal invasive carcinoma: validation of the Narrow-Band Imaging International Colorectal Endoscopic (NICE) classification.Gastrointest Endosc. 2013; 78: 625-632Abstract Full Text Full Text PDF PubMed Scopus (330) Google Scholar In expert hands, focal interrogation is accurate in identifying histologic subtypes and predicting submucosal invasive cancer.20Hayashi N. Tanaka S. Hewett D.G. et al.Endoscopic prediction of deep submucosal invasive carcinoma: validation of the Narrow-Band Imaging International Colorectal Endoscopic (NICE) classification.Gastrointest Endosc. 2013; 78: 625-632Abstract Full Text Full Text PDF PubMed Scopus (330) Google Scholar, 21Matsuda T. Saito Y. Nakajima T. et al.Macroscopic estimation of submucosal invasion in the colon.Tech Gastrointest Endosc. 2011; 13: 24-32Abstract Full Text Full Text PDF Scopus (15) Google Scholar, 22Matsuda T. Fujii T. Saito Y. et al.Efficacy of the invasive/non-invasive pattern by magnifying chromoendoscopy to estimate the depth of invasion of early colorectal neoplasms.Am J Gastroenterol. 2008; 103: 2700-2706Crossref PubMed Scopus (278) Google Scholar, 23Wada Y. Kashida H. Kudo S.E. et al.Diagnostic accuracy of pit pattern and vascular pattern analyses in colorectal lesions.Dig Endosc. 2010; 22: 192-199Crossref PubMed Scopus (80) Google Scholar Tubular adenomas typically have large or elongated pits (Kudo type III) and an organized brown capillary network surrounding the pits (Sano type 2/NICE type 2). Villous adenomas have more complex branching gyrus like pits (Kudo type IV). Submucosal invasive cancer is suspected when irregularly mixed types or nonstructural or absent pits are present (Kudo type V), or when irregular complex branching capillaries or avascular areas are seen (Sano type 3/NICE type 3). Often, a clear demarcation line can be discerned between the background regular pattern of the noninvasive adenoma and the irregular area of the suspected invasive component. EMR is a multistep process (Figure 1).•Optimize your access and secure a good endoscopic position with a shortened, straight, and relaxed endoscope. Position the lesion at 6 o'clock in the endoscopic field. Position the patient in a way that any fluid or resected specimens accumulate away from the lesion. This ensures a clean, unobscured working field and enables optimal views and swift therapy in the event of a complication.•Formulate a resection strategy; ideally, commence in the least accessible area.•An uncomplicated inject and resect piecemeal EMR is then typically composed of 3 steps which are performed repetitively: injection, 1–3 snare excisions, and then inspection of the mucosal defect (Figure 2).•A good injection should be dynamic and elevate the tissue into the lumen and toward the colonoscope.•For piecemeal EMR, start at 1 edge of the lesion and try to include a 2- to 3-mm margin of normal mucosa. Use the edge of the advancing mucosal defect as a convenient step for the next snare placement to reduce the risk of adenoma islands.•En bloc snare excision is appropriate for lesions up to 20–25 mm and is associated with lower rates of recurrence compared with piecemeal resection.24Belderbos T.D.G. Leenders M. Moons L. et al.Local recurrence after endoscopic mucosal resection of nonpedunculated colorectal lesions: Systematic review and meta-analysis.Endoscopy. 2014; 46: 388-400Crossref PubMed Scopus (263) Google Scholar Larger LSLs require piecemeal EMR for complete removal.5Holt B. Bourke M.J. Wide field endoscopic resection for advanced colonic mucosal neoplasia: current status and future directions.Clin Gastroenterol Hepatol. 2012; 10: 969-979Abstract Full Text Full Text PDF PubMed Scopus (90) Google Scholar, 25Bourke M. Endoscopic mucosal resection in the colon: a practical guide..Tech Gastrointest Endosc. 2011; 13: 35-49Abstract Full Text Full Text PDF Scopus (54) Google Scholar•Thermal ablative techniques (argon plasma coagulation) to treat visible residual adenoma should be avoided as this is associated with high rates of recurrence.26Zlatanic J. Waye J.D. Kim P.S. et al.Large sessile colonic adenomas: use of argon plasma coagulator to supplement piecemeal snare polypectomy.Gastrointest Endosc. 1999; 49: 731-735Abstract Full Text Full Text PDF PubMed Scopus (189) Google Scholar, 27Veerappan S.G. Ormonde D. Yusoff I.F. Hot avulsion: a modification of an existing technique for management of nonlifting areas of a polyp (with video).Gastrointest Endosc. 2014; 80: 884-888Abstract Full Text Full Text PDF PubMed Scopus (43) Google Scholar Complete snare excision should be the goal.•After each resection, the mucosal defect should be cleaned with the colonoscope fluid jet (these authors use saline because it is isotonic) to ensure no adenoma islands remain and to exclude deep mural injury; it also provides some tissue elevation.•Some LSLs are found in unique locations. In such cases, small adjustments to the standard technique may be necessary (Table 2).Table 2EMR in Unique Situations: Site-Specific Characteristics and Adjustments to the Standard EMR TechniqueSiteAdjustments to Standard TechniqueAnorectal junctionRegion with unique sensory and lymphovascular anatomy. Use a local anesthetic (ropivacaine 0.5%) in the submucosal injectate and consider prophylactic antibiotics.28Holt B. Bassan M.S. Sexton A. et al.Advanced mucosal neoplasia of the anorectal junction: endoscopic resection technique and outcomes (with videos).Gastrointest Endosc. 2014; 79: 119-126Abstract Full Text Full Text PDF PubMed Scopus (38) Google ScholarAppendiceal orificeOften very fibrotic with poor lifting. Use small thin wire snares. If the lesion encompasses >50% of the orifice or if the proximal margin within the appendix, EMR success may not feasible.29Tate D.J. Desomer L. Hourigan L.F. Endoscopic mucosal resection of laterally spreading lesions around or involving the appendiceal orifice (PA LSLs): technique, risk factors for failure and outcomes of a tertiary referral cohort.Gastrointest Endosc. 2016; 83 (AB144)Abstract Full Text Full Text PDF Google ScholarICV involvementHigher rates of recurrence after EMR (OR, 3.38).6Moss A. Bourke M.J. Williams S.J. et al.Endoscopic mucosal resection outcomes and prediction of submucosal cancer from advanced colonic mucosal neoplasia.Gastroenterology. 2011; 140: 1908-1918Abstract Full Text Full Text PDF Scopus (474) Google Scholar, 30Nanda K.S. Tutticci N. Burgess N.G. et al.Endoscopic mucosal resection of laterally spreading lesions involving the ileocecal valve : technique, risk factors for failure, and outcomes.Endoscopy. 2015; 47: 710-718Crossref PubMed Scopus (42) Google Scholar Difficult access often requires both anterograde and retrograde approaches and use of a cap.Sessile serrated polypsComprise up to 15% of LSLs referred for EMR.6Moss A. Bourke M.J. Williams S.J. et al.Endoscopic mucosal resection outcomes and prediction of submucosal cancer from advanced colonic mucosal neoplasia.Gastroenterology. 2011; 140: 1908-1918Abstract Full Text Full Text PDF Scopus (474) Google Scholar Detection may be difficult and the presence of adherent mucus or debris may alert the endoscopist to their presence. Recognition of the true margins is critical to ensuring success and often these may only be fully discerned after submucosal injection. They can be removed by EMR with comparable or superior efficacy to adenomatous LSLs.31Pellise M. Burgess N.G. Tutticci N. et al.Endoscopic mucosal resection for large serrated lesions in comparison with adenomas: a prospective multicentre study of 2000 lesions.Gut. 2016 Jan 19; ([Epub ahead of print])Google ScholarICV, ileocecal valve; EMR, endoscopic mucosal resection; LSL, lateral spreading lesion; OR, odds ratio. Open table in a new tab Figure 1Sequential steps in colonic endoscopic mucosal resection of a large lateral spreading lesion.View Large Image Figure ViewerDownload Hi-res image Download (PPT) ICV, ileocecal valve; EMR, endoscopic mucosal resection; LSL, lateral spreading lesion; OR, odds ratio. Complications during or after EMR are inevitable with any significant procedural volume and to some extent predictable; however, they are managed readily and safely if recognized early. Delayed recognition may lead to serious sequelae. As such, endoscopists performing colonic EMR need to be familiar with their presentations and management. Bleeding is the most common complication and can be categorized as intraprocedural bleeding (IPB) or delayed bleeding.•IPB occurs in up to 11% during EMR, is rarely serious and readily amenable to endoscopic hemostasis.32Burgess N.G. Metz A.J. Williams S.J. et al.Risk factors for intraprocedural and clinically significant delayed bleeding after wide-field endoscopic mucosal resection of large colonic lesions.Clin Gastroenterol Hepatol. 2014; 12: 651-653Abstract Full Text Full Text PDF PubMed Scopus (207) Google Scholar Risk factors for IPB include larger lesions, Paris 0-IIa + Is morphology, villous or tubulovillous histology, and procedures performed at lower volume centers. IPB can be treated safely and effectively with snare tip soft coagulation.10Fahrtash-Bahin F. Holt B. Jayasekeran V. et al.Snare tip soft coagulation achieves effective and safe endoscopic hemostasis during wide-field endoscopic resection of large colonic lesions (with videos).Gastrointest Endosc. 2013; 78: 158-163Abstract Full Text Full Text PDF PubMed Scopus (74) Google Scholar In this technique, active bleeding points are treated using a light touch with 1–2 mm of exposed snare tip in a specific electrosurgical unit mode (Soft Coagulation 80W, Effect 4, ERBE VIO, Tübingen Germany). Coagulation forceps can be used in more severe cases, for example, pulsatile bleeding or when snare tip soft coagulation fails.•Delayed bleeding occurring after the procedure and requiring presentation to the emergency department, hospitalization, or medical intervention is termed clinically significant postendoscopic resection bleeding.32Burgess N.G. Metz A.J. Williams S.J. et al.Risk factors for intraprocedural and clinically significant delayed bleeding after wide-field endoscopic mucosal resection of large colonic lesions.Clin Gastroenterol Hepatol. 2014; 12: 651-653Abstract Full Text Full Text PDF PubMed Scopus (207) Google Scholar Clinically significant postendoscopic resection bleeding occurs in up to 7% of patients after colonic EMR. Proximal colon location is the most consistent risk factor across all studies (odds ratio [OR], 2.3–4.86), with aspirin use (OR, 3.16–6.3), lesion size (OR, 1.91–2.5), age (OR, 2.36), and comorbidities (OR, 1.9) being significant in most.13Bahin F.F. Rasouli K.N. Byth K. et al.Prediction of clinically significant bleeding following wide-field endoscopic resection of large sessile and laterally spreading colorectal lesions: a clinical risk score.Am J Gastroenterol. 2016; 111: 1115-1122Crossref PubMed Scopus (63) Google Scholar, 32Burgess N.G. Metz A.J. Williams S.J. et al.Risk factors for intraprocedural and clinically significant delayed bleeding after wide-field endoscopic mucosal resection of large colonic lesions.Clin Gastroenterol Hepatol. 2014; 12: 651-653Abstract Full Text Full Text PDF PubMed Scopus (207) Google Scholar, 33Albéniz E. Fraile M. Ibanez I.B. et al.A scoring system to determine risk of delayed bleeding after endoscopic mucosal resection of large colorectal lesions.Clin Gastroenterol Hepatol. 2016; 14: 1140-1147Abstract Full Text Full Text PDF PubMed Scopus (69) Google Scholar, 34Metz A.J. Bourke M.J. Moss A. et al.Factors that predict bleeding following endoscopic mucosal resection of large colonic lesions.Endoscopy. 2011; 43: 506-511Crossref PubMed Scopus (152) Google Scholar Recently, 2 predictive clinical risk scores were introduced.13Bahin F.F. Rasouli K.N. Byth K. et al.Prediction of clinically significant bleeding following wide-field endoscopic resection of large sessile and laterally spreading colorectal lesions: a clinical risk score.Am J Gastroenterol. 2016; 111: 1115-1122Crossref PubMed Scopus (63) Google Scholar, 33Albéniz E. Fraile M. Ibanez I.B. et al.A scoring system to determine risk of delayed bleeding after endoscopic mucosal resection of large colorectal lesions.Clin Gastroenterol Hepatol. 2016; 14: 1140-1147Abstract Full Text Full Text PDF PubMed Scopus (69) Google Scholar These stratify patients into low (0.6%-1.7%), medium (5.5%-7.1%), and high (17.5%-40%) risk of delayed bleeding based on weights assigned to independent predictors found in multivariate logistic regression. Most bleeding episodes occur within the first 48 hours after resection and 60% settle with supportive care only. Endoscopic intervention is required for ongoing or recurrent bleeding or those with unresponsive shock, and is usually effective. Rarely, angiography or surgery are needed. Measures to reduce the risk of clinically significant postendoscopic resection bleeding, such as prophylactic coagulation of nonbleeding vessels in the post-EMR mucosal defect or prophylactic clip closure of the defect, have been neither consistently successful nor cost effective thus far.35Bahin F.F. Naidoo M. Williams S.J. et al.Prophylactic endoscopic coagulation to prevent bleeding after wide-field endoscopic mucosal resection of large sessile colon polyps.Clin Gastroenterol Hepatol. 2015; 13: 722-724Abstract Full Text Full Text PDF Scopus (69) Google Scholar, 36Liaquat H. Rohn E. Rex D.K. Prophylactic clip closure reduced the risk of delayed postpolypectomy hemorrhage: experience in 277 clipped large sessile or flat colorectal lesions and 247 control lesions.Gastrointest Endosc. 2013; 77: 401-407Abstract Full Text Full Text PDF PubMed Scopus (215) Google Scholar, 37Bahin F.F. Rasouli K.N. Williams S.J. et al.Prophylactic clipping for the prevention of bleeding following wide-field endoscopic mucosal resection of laterally spreading colorectal lesions: an economic modeling study.Endoscopy. 2016; 48: 754-761Crossref PubMed Scopus (26) Google Scholar•Perforation occurs in 1%–2% of colonic EMR and is readily managed by endoscopic clip closure when recognized intraprocedurally.6Moss A. Bourke M.J. Williams S.J. et al.Endoscopic mucosal resection outcomes and prediction of submucosal cancer from advanced colonic mucosal neoplasia.Gastroenterology. 2011; 140: 1908-1918Abstract Full Text Full Text PDF Scopus (474) Google Scholar It is important to be able to differentiate in real time true muscularis propria (MP) injury from an uncomplicated post-EMR mucosal defect, which can include visible uninjured MP, submucosal fibrosis, submucosal fat, and vessels. True MP injury is manifested by nonstaining, often surface disrupted areas within the relatively homogeneous "blue mat" of the post-EMR defect or by the appearance of a "target sign."38Swan M.P. Bourke M.J. Moss A. et al.The target sign: an endoscopic marker for the resection of the muscularis propria and potential perforation during colonic endoscopic mucosal resection.Gastrointest Endosc. 2011; 73: 79-85Abstract Full Text Full Text PDF PubMed Scopus (122) Google Scholar Recently, a classification system for deep mural injury during colonic EMR was introduced. Risk factors for deep mural injury were transverse colon location (OR, 3.55), en bloc excision (OR, 3.84), and the presence of high-grade dysplasia or invasive cancer (OR, 2.97).39Burgess N.G. Bassan M.S. McLeod D. et al.Deep mural injury and perforation after colonic endoscopic mucosal resection: a new classification and analysis of risk factors.Gut. 2016 Jul 27; ([Epub ahead of print])Google Scholar Topical submucosal chromoendoscopy can be used to improve detection of MP injury.40Holt B a Jayasekeran V. Sonson R. et al.Topical submucosal chromoendoscopy defines the level of resection in colonic EMR and may improve procedural safety (with video).Gastrointest Endosc. 2013; 77: 949-953Abstract Full Text Full Text PDF PubMed Scopus (49) Google Scholar With this technique, dye is flushed on the mucosal defect surface. Poorly staining areas suspicious for deep injury are recognized and treated by clip closure. Full-thickness perforation always warrants immediate treatment, which can usually be readily achieved with clip closure.38Swan M.P. Bourke M.J. Moss A. et al.The target sign: an endoscopic marker for the resection of the muscularis propria and potential perforation during colonic endoscopic mucosal resection.Gastrointest Endosc. 2011; 73: 79-85Abstract Full Text Full Text PDF PubMed Scopus (122) Google Scholar, 40Holt B a Jayasekeran V. Sonson R. et al.Topical submucosal chromoendoscopy defines the level of resection in colonic EMR and may improve procedural safety (with video).Gastrointest Endosc. 2013; 77: 949-953Abstract Full Text Full Text PDF PubMed Scopus (49) Google Scholar, 41Raju G.S. Saito Y. Matsuda T. et al.Endoscopic management of colonoscopic perforations (with videos).Gastrointest Endosc. 2011; 74: 1380-1388Abstract Full Text Full Text PDF PubMed Scopus (83) Google Scholar This technique has revolutionized the safety of advanced colonic endoscopic tissue resection and greatly expanded the horizons of the possible.42Tutticci N. Sonson R. Endoscopic resection of subtotal and complete circumferential colonic advanced mucosal neoplasia.Gastrointest Endosc. 2014; 80: 340Abstract Full Text Full Text PDF PubMed Scopus (9) Google Scholar•Recurrence after colonic EMR ranges from 10% to 30% and is considered the greatest drawback of EMR, particularly piecemeal EMR.7Moss 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: 57-65Crossref PubMed Scopus (373) Google Scholar, 24Belderbos T.D.G. Leenders M. Moons L. et al.Local recurrence after endoscopic mucosal resection of nonpedunculated colorectal lesions: Systematic review and meta-analysis.Endoscopy. 2014; 46: 388-400Crossref PubMed Scopus (263) Google Scholar, 43Knabe 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. 2013; 109: 183-189Crossref PubMed Scopus (119) Google Scholar, 44Buchner 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: 255-263Abstract Full Text Full Text PDF PubMed Scopus (200) Google Scholar Long-term data from the ACE (Australian Colonic Endoscopic Resection) study demonstrates that recurrences are usually small, unifocal, and easily treated during surveillance endoscopy. If the initial EMR was successful, then >95% of patients are free of adenoma during long-term follow-up. However, to ensure such results, a meticulous technique at the initial EMR and a structured surveillance regimen, with colonoscopy and scar examination at intervals of 6 and then 12 months is necessary. Risk factors for recurrence include lesion size >40 mm, piecemeal resection, and the presence of high-grade dysplasia.7Moss 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: 57-65Crossref PubMed Scopus (373) Google Scholar, 24Belderbos T.D.G. Leenders M. Moons L. et al.Local recurrence after endoscopic mucosal resection of nonpedunculated colorectal lesions: Systematic review and meta-analysis.Endoscopy. 2014; 46: 388-400Crossref PubMed Scopus (263) Google Scholar, 45Kim H.H. Kim J.H. Park S.J. et al.Risk factors for incomplete resection and complications in endoscopic mucosal resection for lateral spreading tumors.Dig Endosc. 2012; 24: 259-266Crossref PubMed Scopus (27) Google Scholar, 46Seo J.Y. Chun J. Lee C. et al.Novel risk stratification for recurrence after endoscopic resection of advanced colorectal adenoma.Gastrointest Endosc. 2014; 81: 655-664Abstract Full Text Full Text PDF PubMed Scopus (35) Google Scholar Patients undergoing colonic EMR require close monitoring after the procedure. Patient discomfort and the development of clinical signs of complications should be recognized early and treated expeditiously. Our protocol for uncomplicated cases include 2–3 hours of monitoring in the endoscopy unit and then discharge on a clear fluid diet for an additional 12 hours overnight. First surveillance colonoscopy is performed 5–6 months after the index procedure to assess the scar area for any residual/recurrent tissue. The scar is interrogated carefully using both high-definition white light and narrow band imaging, and biopsies are obtained from any suspicious areas within the scar. We now know that, in expert hands, endoscopic diagnosis of recurrence is feasible and accurate, and routine biopsies from a normal appearing scar are probably not necessary or at least can be better targeted.47Desomer L. Tutticci N. Tate D.J. et al.A standardized imaging protocol is accurate in detecting recurrence after EMR.Gastrointest Endosc. 2016 Jun 22; ([Epub ahead of print])Google Scholar One should be able to differentiate a normal appearing scar from a scar with granulation tissue, or clip artifact48Sreepati G. Vemulapalli K.C. Rex D.K. Clip artifact after closure of large colorectal EMR sites: incidence and recognition.Gastrointest Endosc. 2015; 82: 344-349Abstract Full Text Full Text PDF PubMed Scopus (23) Google Scholar or a true adenomatous recurrence within the scar. Residual/recurrent tissue can be treated with hot snare resection or cold avulsion followed by thermal ablation, however there is no comparative data on the optimal method. Second surveillance is performed after an additional 12 months. Then, the patient can be followed according to the current postpolypectomy recommendations for colorectal cancer screening and prevention.49Hassan C. Quintero E. Dumonceau J.-M. et al.Post-polypectomy colonoscopy surveillance: European Society of Gastrointestinal Endoscopy (ESGE) Guideline.Endoscopy. 2013; 45: 842-851Crossref PubMed Scopus (451) Google Scholar Performing high-quality EMR in the colon has the following prerequisites.•Training, experience, and support are required. A well-trained endoscopy team including trained nursing staff and at least 1 additional experienced endoscopist, is extremely valuable. High-volume centers should train fellows. The teaching and mentoring process is essential to the professional development of the fellow, but also contributes to that of the mentor.•Owing to their complexity, these procedures are best performed in a tertiary level environment with multidisciplinary support.•Quality measures are important and should be implemented. Continuous evaluation of performance and outcomes, including detailed photo documentation and video recording, is recommended. This type of ongoing reflection is crucial.•Do not forget the follow-up. It is the endoscopist's responsibility to ensure that patients return for surveillance. We recommend that at least the first surveillance colonoscopy be conducted with the physician who performed the index EMR, thus ensuring adequate assessment of the scar.