endoscopic submucosal dissection ( esd ) has been developed to enable the endoluminal en bloc resection of superficial gastrointestinal neoplasms , thus producing an adequate specimen for a reliable histologic assessment . several devices and tools have been proposed to make it possible to perform esd safely and in an effective manner 1 
 2 
 3 . despite these advances , esd still is a challenging and time - consuming procedure . in order to promote the widespread availability of esd , measures to facilitate and standardize the procedure one of the main problems associated with esd is hemorrhage control 4 
 5 , and a correct vascular approach is key to preventing bleeding and improving the submucosal dissection 6 
 7 . whenever bleeding occurs , the examiner s field of vision is critically impaired , and esd becomes less efficient and more hazardous . we propose a simple and widely available measure to improve the visibility of the submucosal space when bleeding occurs during esd : polyethylene glycol ( peg ) irrigation . a 70-year - old man was referred to kobe university hospital , kobe , japan , for endoscopic treatment of a laterally spreading tumor ( lst ) in the left side of the colon . after discussion with the patient , he agreed to undergo esd and signed a consent form covering all the components of esd : preparation , the surgical procedure with related endoscopic maneuvers , and postoperative care . 1 shows a large , flat    elevated , homogeneous , granular - type lst . after mucosal incision and submucosal dissection with a 1.5-mm ball - tipped flushknife ( fujifilm , tokyo , japan ) , we observed massive bleeding from large vessels , which was stopped with a coagulation grasper . 2 shows the condition of the field after control of the bleeding and irrigation with water . submucosal hematoma and covered blood clot still interfere with clear vision and disturb the orientation of the submucosal layer . submucosal hematoma and covered clot were cleared by flushing with peg ( niflec ; ajinomoto pharmaceuticals , tokyo , japan ) in a 30-ml syringe up to three times through the working channel , and the submucosal transparency was restored ( fig . a clearer view of the surface of the muscular layer through the transparent submucosa enabled further submucosal dissection safely . peg irrigation also proved to be useful by making it possible to identify the oozing vessel precisely , facilitating direct hemostasis . a complete en bloc resection ( fig . 4 ) was obtained successfully in 80 minutes , and the specimen was fixed for histologic assessment ( fig . the patient experienced an uneventful recovery and was discharged home after 4 days of in - hospital observation . no adverse event related to the use of peg as an irrigation method was noted . histology showed a tubulovillous adenoma with high grade dysplasia , no lymph node or vascular invasion , and free horizontal and vertical margins . large , flat - elevated , homogeneous , granular - type laterally spreading tumor in the ascending colon of a patient referred for endoscopic submucosal dissection . after control of bleeding and flushing with water , submucosal hematoma and covered blood clot still impair visibility . note the restored transparency , allowing a better view of the submucosal layer and surface of the muscular layer . peg is a polymer of ethylene oxide with a wide range of applications in medicine 8 . it has been used in gastroenterology mainly as a laxative for bowel preparation before colonoscopy or the management of chronic constipation . peg also is safely used as a pharmaceutical ingredient in ointments , suppository formulations , creams , lotions , lubricants , coating materials of tablets , and solubilizers for injection 8 . this polymer has a low level of toxicity , and when absorbed , it is eliminated through hepatic or renal pathways 8 . previously , the only application of peg related to endoscopic resection has been reported in experimental settings , as a submucosal injectant 9 . peg irrigation is a simple and effective means to improve visibility in submucosal dissection , particularly when bleeding occurs ; it facilitates esd by allowing a better recognition of the submucosal fibers . as demonstrated in this case report , peg irrigation improved the field of view substantially and made it possible to continue esd in a safer fashion . when bleeding takes place during esd , hemostatic control with coagulation forceps or the knife blade is immediately attempted , together with water irrigation as needed . however , when the control of bleeding takes a long time and the field is occupied by blood or clots , irrigation with water is not very efficient , and visibility is compromised . in such situations , proceeding with blind hemostatic maneuvers without a clear vision of the submucosal space is hazardous and may lead not only to a failure of bleeding control but also , most importantly , to accidental damage and perforation of the muscularis propria layer . it is in this situation that we recommend cleaning the submucosal space by means of irrigation with peg . we assume that the effectiveness of peg irrigation to clear blood clots is due to its property as a dispersing agent ; however , the mechanism of this effect remains to be clarified . in addition , we have noted that peg irrigation is also useful when persistent bowel residual covers a colonic flat lesion . peg irrigation makes it possible to clean the lesion surface very effectively , optimizing conditions for chromoendoscopy and magnifying the examination . in conclusion , we propose a novel use for peg during endoscopic procedures , aimed at cleaning the submucosal space of blood clots and improving visibility for submucosal dissection whenever bleeding occurs and can not be controlled promptly . further studies are required to reproduce our experience in a large number of patients and to confirm the reliability of this approach .
in order to expand the availability of endoscopic submucosal dissection ( esd ) , 
 measures to facilitate the procedure are necessary . when bleeding occurs , the 
 examiner s field of vision is critically impaired , and esd becomes less 
 efficient and more hazardous because of the presence of submucosal hematoma and 
 covered blood clot . 
 we propose the use of polyethylene glycol ( peg ) irrigation 
 as a simple and effective measure to improve visibility during submucosal 
 dissection , particularly when bleeding occurs . 
 peg irrigation facilitates 
 further dissection by allowing a better recognition of the submucosal fibers and 
 muscularis propria layer .