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Sa1624 The Evaluation of Safety Regarding Endoscopic Resection Using Monopolar Versus Bipolar snare in Porcine Rectum
Abstracts
this group of patients. Aims: (1) To characterize synchronous TAs found in patients with HRSPs. (2) To assess the association between HRSPs and SAN. Methods: A retrospective review of a population of US veterans undergoing average-risk screening colonoscopy from January 2011 to September 2014 was performed. Demographic information (age, gender and race), endoscopic (size, morphology and location) and histological features of the polyps were collected. A high risk serrated polyp includes any one of the following features are present: any sessile serrated adenoma/polyp with or without cytological dysplasia, hyperplastic polyp R 10 mm, proximal hyperplastic polyps and traditional serrated adenomas). The colon was divided into proximal (proximal to and including splenic flexure) and distal. For Aim 1 of the study, tubular adenomas found in stand-alone tubular adenoma group were compared to synchronous TAs (TAs found in patients with at least 1 HRSP). Aim 2 of the study assessed the risk of having a SAN (defined as TAs R 10 mm, adenomas with villous features or with high-grade dysplasia or cancer) in patients with HRSP and those with TAs ! 10 mm as controls. Means were compared using two-sided ttest and proportions compared with Pearson chi-square test. Results: 941 patients who have undergone average screening colonoscopy were identified. Of 2412 biospies of colon polyps (204 were excluded due to being artifacts, normal colon mucosa or lymphoid aggregates) 2,208 polyps were found included. 134/941 (14.2%) patients were found to have 198 HRSPs; these patients also had 269 concomitant TAs and 1,209 polyps were found in patients with only TAs. There was no statistically significant difference between the characteristics of the TAs of each group (Table 1). 36/134 (26.9%) of patients with HRSP had SAN compared to 114/525 (21.7%) with TAs ! 10 mm who had SAN (Table 2) and the difference was not statistically significant (p Z 0.204). Conclusions: Synchronous TAs found in patients with HRSP do not differ from the TAs in patients who do not have HRSP. The rates of SAN in patients with HRSP are high, however, not significantly higher when compared to patients with adenomas ! 10 mm. Table 1. Polyp characteristics of TAs in patients with HRSP Tubular adenoma features Size, mean (SD) Morphology type, n (%) Polypoid Non-polypoid Not described Location, n (%) Proximal Distal
In patients with HRS n[269
In patients with TA only n[1209
5.6 (3.7)
5.2 (3.8)
193 (71.8) 6 (2.2) 70 (26.0)
820 (67.8) 24 (2.0) 365 (30.2)
170 (63.2) 99 (36.8)
739 (61.1) 470 (38.9)
p value 0.175 0.395
SAN
No SAN
36 (26.87) 114 (21.71)
98 (73.13) 411 (78.29)
Sa1624 The Evaluation of Safety Regarding Endoscopic Resection Using Monopolar Versus Bipolar snare in Porcine Rectum Kensuke Shinmura*, Hiroaki Ikematsu, Motohiro Kojima, Hiroshi Nakamura, Tomoji Kato, Shozo Osera, Yusuke Yoda, Yasuhiro Oono, Tomonori Yano, Atsushi Ochiai, Kazuhiro Kaneko Department of Gastroenterology, Endoscopy Division, National Cancer Center Hospital East, Kashiwa, Japan Backgroud: Endoscopic resections including cold or hot biopsy, polypectomy, endoscopic mucosal resection(EMR) and endoscopic submucosal dissection(ESD) for colorectal lesions are widely performed. We occasionally experience electrosurgeryrelated complications such as bleeding and perforation even when small lesions are resected. Electrosurgery can be performed using either a monopolar or a bipolar instrument, and the monopolar insturument was generally used in most resections worldwide. In the monopolar instrument, the current passes from the active electrode to the target lesions, through the patient’s body, and finally to exit the patient through a return electrode. In contrast to the bipolar instrument, the current passes through only tissue between the two electrodes of the instrument. Therefore, we predict that there is low risk of the incidence of perforation in bipolar snare. However, there have been few reports compared monopolar snare with bipolar snare in terms of endoscopic resection of the colorectum. Aim: To compare the safety of monopolar and bipolar snare for colorectal polypectomy and EMR in animal models. Methods: We made target lesions of 5mm, 10mm and 15mm on the porcine rectum. Two lesions for individual size were recected by monopolar polypectomy (M-P), monopolar EMR (M-E), bipolar polypectomy (B-P) and bipolar EMR (B-E). An electrosurgery generator unit was used for all resections. Before EMR, a sufficient
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Table 1 Monopolar polypectomy
Monopolar EMR
Bipolar polypectomy
Bipolar EMR
Size of target lesion
Disｔ (mm)
Area (mm2)
Disｔ (mm)
Area (mm2)
Disｔ (mm)
Area (mm2)
Disｔ (mm)
Area (mm2)
5mm 5mm 10mm 10mm 15mm 15mm
0 0.60 0 0 0 0
0.09 0 1.06 1.36 2.56
0.10 0.20 0.30 0 0 0
0 0 0.88 0.77 0.66
1.18 1.05 0.40 1.30 1.35 0.93
0 0 0 0 0 0
0.36 0.18 0.08 0 0 0
0 0 0 0.24 0.06 0.07
Dist: distance from the muscularis propria to the thermal denaturation of submucosal layer Area: area of tissue damage to the muscularis propria
0.528
Table 2. SAN in patients with HRSPs and TAs ! 10 mm HRSP, n (%) TA ! 10 mm, n (%)
volume of saline was injected into the submucosal layer located in the target lesion. We evaluated histopathologically the conditions of perforation and effects of burning in the tissues around the portions of endoscopic resection. The examination items of burning effects were as follows: 1) distance from the muscularis propria to the thermal denaturation of submucosal layer (Dist), 2) area of tissue damage to the muscularis propria (Area). Results: The results are shown in Table 1. In a total of 24 target lesions, EMR and polypectomy were performed. The perforation was pathologically found in one case of M-P and one case of M-E, after removing M-P and M-E for target lesions of 15mm in diameter. In contrast, there was no perforation in endoscopic resection using the bipolar snare. While the thermal denaturation in B-P did not reach the layer of muscularis propria regardless of the size of target lesion, the tissue damage without perforation was found in the layer of muscularis propria in most cases of M-P. The tissue damage to muscularis propria was detected in lesions more than 10mm in diameter in both M-E and B-E. Conclusion: Compared to monopolar snare, bipolar snare was less effective in burning effect to the tissues, especially muscularis propria in the target lesions more than 10mm in diameter. We suggest that bipolar snare is safer than monopolar in respect of colorectal polypectomy and EMR.
Sa1625 Underwater Endoscopic Mucosal Resection (UEMR) vs. Saline Assisted Endoscopic Mucosal Resection (EMR): Does One Confer an Advantage Over the Other? Vishal Gohil*, Yingxing Wu, Sadat Rashid, Vikas Chitnavis, Paul Yeaton, Alan Brijbassie Gastroenterology, Virginia Tech Carilion School of Medicine, Roanoke, VA Background: Underwater Endoscopic Mucosal Resection (UEMR) without submucosal injection has been recently demonstrated as a safe and effective technique in the complete removal of large polyps. We sought to compare UEMR and traditional saline lift assisted EMR. Methods: Using an IRB approved database, cases of advanced polypectomy referred between June 2012 and November 2014 for traditional saline lift EMR as well as UEMR were retrospectively analyzed. The withdrawal time was used as a surrogate marker for the time taken for polypectomy as all polyps were removed during scope withdrawal; complications as well as the recurrence of adenomatous tissue on follow up interval colonoscopy were analyzed. Results: A total of 49 polyps were removed; 33 (67.3%) via traditional saline lift EMR and 16 (32.7%) via UEMR. The mean age for polypectomy was similar for both categories (64.21 +/- 11.0 yrs. [saline lift assisted EMR] and 64.7 +/- 10.1 yrs. [UEMR]) with the mean polyp size being slightly greater for the UEMR group (26.6 +/- 14.5 mm [UEMR] vs. 21.5 +/- 9.6 mm [saline lift EMR]).The withdrawal time was used as a surrogate marker for polypectomy time and was noted to be lower in the UEMR as compared to the saline lift assisted EMR group (43.5 +/- 37.1 minutes vs. 54.3 +/38.1 minutes) (pZ0.37) (Figure 1). The complication rate (delayed bleeding/ perforation) however was observed to be higher in the UEMR group (1 perforation, 2 delayed bleeding) (18.8%) as compared to the saline assisted EMR group (1 delayed bleeding) (3%) (pZ0.10). The recurrence of adenomatous tissue on interval follow-up colonoscopy was also observed to be higher in the UEMR group (2/6 [33.3%] vs. 5/17 [29.4%]) (pZ0.99). Conclusion: Underwater EMR (UEMR) is an effective method employed for large polyp removal as demonstrated by shorter overall procedure times. The technique however appears to be associated with higher complication rates as well as a higher rate of adenomatous tissue regrowth. Additional prospective data is required to confirm this observation.
Volume 81, No. 5S : 2015 GASTROINTESTINAL ENDOSCOPY AB287
this group of patients. Aims: (1) To characterize synchronous TAs found in patients with HRSPs. (2) To assess the association between HRSPs and SAN. Methods: A retrospective review of a population of US veterans undergoing average-risk screening colonoscopy from January 2011 to September 2014 was performed. Demographic information (age, gender and race), endoscopic (size, morphology and location) and histological features of the polyps were collected. A high risk serrated polyp includes any one of the following features are present: any sessile serrated adenoma/polyp with or without cytological dysplasia, hyperplastic polyp R 10 mm, proximal hyperplastic polyps and traditional serrated adenomas). The colon was divided into proximal (proximal to and including splenic flexure) and distal. For Aim 1 of the study, tubular adenomas found in stand-alone tubular adenoma group were compared to synchronous TAs (TAs found in patients with at least 1 HRSP). Aim 2 of the study assessed the risk of having a SAN (defined as TAs R 10 mm, adenomas with villous features or with high-grade dysplasia or cancer) in patients with HRSP and those with TAs ! 10 mm as controls. Means were compared using two-sided ttest and proportions compared with Pearson chi-square test. Results: 941 patients who have undergone average screening colonoscopy were identified. Of 2412 biospies of colon polyps (204 were excluded due to being artifacts, normal colon mucosa or lymphoid aggregates) 2,208 polyps were found included. 134/941 (14.2%) patients were found to have 198 HRSPs; these patients also had 269 concomitant TAs and 1,209 polyps were found in patients with only TAs. There was no statistically significant difference between the characteristics of the TAs of each group (Table 1). 36/134 (26.9%) of patients with HRSP had SAN compared to 114/525 (21.7%) with TAs ! 10 mm who had SAN (Table 2) and the difference was not statistically significant (p Z 0.204). Conclusions: Synchronous TAs found in patients with HRSP do not differ from the TAs in patients who do not have HRSP. The rates of SAN in patients with HRSP are high, however, not significantly higher when compared to patients with adenomas ! 10 mm. Table 1. Polyp characteristics of TAs in patients with HRSP Tubular adenoma features Size, mean (SD) Morphology type, n (%) Polypoid Non-polypoid Not described Location, n (%) Proximal Distal
In patients with HRS n[269
In patients with TA only n[1209
5.6 (3.7)
5.2 (3.8)
193 (71.8) 6 (2.2) 70 (26.0)
820 (67.8) 24 (2.0) 365 (30.2)
170 (63.2) 99 (36.8)
739 (61.1) 470 (38.9)
p value 0.175 0.395
SAN
No SAN
36 (26.87) 114 (21.71)
98 (73.13) 411 (78.29)
Sa1624 The Evaluation of Safety Regarding Endoscopic Resection Using Monopolar Versus Bipolar snare in Porcine Rectum Kensuke Shinmura*, Hiroaki Ikematsu, Motohiro Kojima, Hiroshi Nakamura, Tomoji Kato, Shozo Osera, Yusuke Yoda, Yasuhiro Oono, Tomonori Yano, Atsushi Ochiai, Kazuhiro Kaneko Department of Gastroenterology, Endoscopy Division, National Cancer Center Hospital East, Kashiwa, Japan Backgroud: Endoscopic resections including cold or hot biopsy, polypectomy, endoscopic mucosal resection(EMR) and endoscopic submucosal dissection(ESD) for colorectal lesions are widely performed. We occasionally experience electrosurgeryrelated complications such as bleeding and perforation even when small lesions are resected. Electrosurgery can be performed using either a monopolar or a bipolar instrument, and the monopolar insturument was generally used in most resections worldwide. In the monopolar instrument, the current passes from the active electrode to the target lesions, through the patient’s body, and finally to exit the patient through a return electrode. In contrast to the bipolar instrument, the current passes through only tissue between the two electrodes of the instrument. Therefore, we predict that there is low risk of the incidence of perforation in bipolar snare. However, there have been few reports compared monopolar snare with bipolar snare in terms of endoscopic resection of the colorectum. Aim: To compare the safety of monopolar and bipolar snare for colorectal polypectomy and EMR in animal models. Methods: We made target lesions of 5mm, 10mm and 15mm on the porcine rectum. Two lesions for individual size were recected by monopolar polypectomy (M-P), monopolar EMR (M-E), bipolar polypectomy (B-P) and bipolar EMR (B-E). An electrosurgery generator unit was used for all resections. Before EMR, a sufficient
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Table 1 Monopolar polypectomy
Monopolar EMR
Bipolar polypectomy
Bipolar EMR
Size of target lesion
Disｔ (mm)
Area (mm2)
Disｔ (mm)
Area (mm2)
Disｔ (mm)
Area (mm2)
Disｔ (mm)
Area (mm2)
5mm 5mm 10mm 10mm 15mm 15mm
0 0.60 0 0 0 0
0.09 0 1.06 1.36 2.56
0.10 0.20 0.30 0 0 0
0 0 0.88 0.77 0.66
1.18 1.05 0.40 1.30 1.35 0.93
0 0 0 0 0 0
0.36 0.18 0.08 0 0 0
0 0 0 0.24 0.06 0.07
Dist: distance from the muscularis propria to the thermal denaturation of submucosal layer Area: area of tissue damage to the muscularis propria
0.528
Table 2. SAN in patients with HRSPs and TAs ! 10 mm HRSP, n (%) TA ! 10 mm, n (%)
volume of saline was injected into the submucosal layer located in the target lesion. We evaluated histopathologically the conditions of perforation and effects of burning in the tissues around the portions of endoscopic resection. The examination items of burning effects were as follows: 1) distance from the muscularis propria to the thermal denaturation of submucosal layer (Dist), 2) area of tissue damage to the muscularis propria (Area). Results: The results are shown in Table 1. In a total of 24 target lesions, EMR and polypectomy were performed. The perforation was pathologically found in one case of M-P and one case of M-E, after removing M-P and M-E for target lesions of 15mm in diameter. In contrast, there was no perforation in endoscopic resection using the bipolar snare. While the thermal denaturation in B-P did not reach the layer of muscularis propria regardless of the size of target lesion, the tissue damage without perforation was found in the layer of muscularis propria in most cases of M-P. The tissue damage to muscularis propria was detected in lesions more than 10mm in diameter in both M-E and B-E. Conclusion: Compared to monopolar snare, bipolar snare was less effective in burning effect to the tissues, especially muscularis propria in the target lesions more than 10mm in diameter. We suggest that bipolar snare is safer than monopolar in respect of colorectal polypectomy and EMR.
Sa1625 Underwater Endoscopic Mucosal Resection (UEMR) vs. Saline Assisted Endoscopic Mucosal Resection (EMR): Does One Confer an Advantage Over the Other? Vishal Gohil*, Yingxing Wu, Sadat Rashid, Vikas Chitnavis, Paul Yeaton, Alan Brijbassie Gastroenterology, Virginia Tech Carilion School of Medicine, Roanoke, VA Background: Underwater Endoscopic Mucosal Resection (UEMR) without submucosal injection has been recently demonstrated as a safe and effective technique in the complete removal of large polyps. We sought to compare UEMR and traditional saline lift assisted EMR. Methods: Using an IRB approved database, cases of advanced polypectomy referred between June 2012 and November 2014 for traditional saline lift EMR as well as UEMR were retrospectively analyzed. The withdrawal time was used as a surrogate marker for the time taken for polypectomy as all polyps were removed during scope withdrawal; complications as well as the recurrence of adenomatous tissue on follow up interval colonoscopy were analyzed. Results: A total of 49 polyps were removed; 33 (67.3%) via traditional saline lift EMR and 16 (32.7%) via UEMR. The mean age for polypectomy was similar for both categories (64.21 +/- 11.0 yrs. [saline lift assisted EMR] and 64.7 +/- 10.1 yrs. [UEMR]) with the mean polyp size being slightly greater for the UEMR group (26.6 +/- 14.5 mm [UEMR] vs. 21.5 +/- 9.6 mm [saline lift EMR]).The withdrawal time was used as a surrogate marker for polypectomy time and was noted to be lower in the UEMR as compared to the saline lift assisted EMR group (43.5 +/- 37.1 minutes vs. 54.3 +/38.1 minutes) (pZ0.37) (Figure 1). The complication rate (delayed bleeding/ perforation) however was observed to be higher in the UEMR group (1 perforation, 2 delayed bleeding) (18.8%) as compared to the saline assisted EMR group (1 delayed bleeding) (3%) (pZ0.10). The recurrence of adenomatous tissue on interval follow-up colonoscopy was also observed to be higher in the UEMR group (2/6 [33.3%] vs. 5/17 [29.4%]) (pZ0.99). Conclusion: Underwater EMR (UEMR) is an effective method employed for large polyp removal as demonstrated by shorter overall procedure times. The technique however appears to be associated with higher complication rates as well as a higher rate of adenomatous tissue regrowth. Additional prospective data is required to confirm this observation.
Volume 81, No. 5S : 2015 GASTROINTESTINAL ENDOSCOPY AB287