論文

Objectives: Fever and increased inflammatory responses sometimes occur following endoscopic resection (ER). However, the differences in causes according to the organ are scarcely understood, and several modified ER techniques have been proposed. Therefore, we conducted a comprehensive prospective study to investigate the cause of fever and increased inflammatory response across multiple organs after ER. Methods: We included patients who underwent gastrointestinal endoscopic submucosal dissection (ESD) and duodenal endoscopic mucosal resection at our hospital between January 2020 and April 2022. Primary endpoints were fever and increased C-reactive protein (CRP) levels following ER. The secondary endpoints were risk factors for aspiration pneumonia. Blood tests and radiography were performed on the day after ER, and computed tomography was performed if the cause was unknown. Results: Among the 822 patients included, aspiration pneumonia was the most common cause of fever and increased CRP levels after ER of the upper gastrointestinal tract (esophagus, 53%; stomach, 48%; and duodenum, 71%). Post-ER coagulation syndrome was most common after colorectal ESD (38%). On multivariate logistic regression analysis, lesions located in the esophagus (odds ratio [OR] 3.57; P < 0.001) and an amount of irrigation liquid of ≥1 L (OR 3.71; P = 0.003) were independent risk factors for aspiration pneumonia. Conclusions: Aspiration pneumonia was the most common cause of fever after upper gastrointestinal ER and post-ER coagulation syndrome following colorectal ESD. Lesions in the esophagus and an amount of irrigation liquid of ≥1 L were independent risk factors for aspiration pneumonia.

Background and Aims: Although lesions occupying a large circumference are associated with the risk of post–endoscopic submucosal dissection (ESD) strictures, the corresponding data for duodenal lesions are unknown. We aimed to analyze the incidence of post-ESD strictures after wide-field duodenal ESD. Methods: In this retrospective study of duodenal lesions treated with ESD between July 2010 and August 2021, we included lesions that resulted in mucosal defects occupying more than half of the circumference and excluded lesions located in bulbs and involving Vater's papilla. We analyzed the incidence rates of stricture and luminal narrowing, in addition to bleeding and perforation as the outcomes in this study. Stricture was defined as the inability of the endoscope to pass through the lumen. A single endoscopist reviewed all endoscopic images and judged the degree of luminal narrowing. Results: Eighty lesions were included, of which 2 involved mucosal defects occupying more than 90% of the circumference. The wound was closed, at least partially, in 90% in all lesions and in 86% of lesions with a mucosal defect occupying more than 75% of the circumference. None of the lesions caused delayed perforation and stricture, whereas 2 lesions caused delayed bleeding. Only 6 lesions caused luminal narrowing. When examined by the degree of closure, the rate of luminal narrowing increased with complete closure, incomplete closure, and nonclosure (4.9%, 9.1%, and 25.0%, respectively). Conclusions: Suturing may prevent post-ESD bleeding and perforation as well as stricture formation in cases of duodenal tumors, with mucosal defects occupying a large circumference.

OBJECTIVES: Ulcerative colitis-associated neoplasia (UCAN) often presents as flat-type dysplasia that is difficult to characterize endoscopically. We developed a FOCUS (Flat-type dysplasia Optical assessment by Chromoendoscopy in Ulcerative colitiS) classification and evaluated its diagnostic performance and reproducibility. METHODS: This single-center retrospective study included 33 UCAN lesions from 26 patients. Prospectively recorded FOCUS classifications at 230 biopsy sites were compared with histopathology. Chromoendoscopic patterns were categorized as Type I ("suggestive of non-dysplasia,"), Type II ("suggestive of dysplasia with low confidence"), or Type III ("suggestive of dysplasia with high confidence"). Diagnostic performance was assessed using two prespecified thresholds: Types II/III versus Type I and Type III versus Types I/II. Eight endoscopists independently classified all images; interobserver and intraobserver agreement were assessed using Fleiss' and Cohen's κ, respectively. RESULTS: The dysplasia-bearing rate increased stepwise from Type I to Type III (Type I 15.5%, Type II 58.3%, Type III 81.8%). Using the primary threshold, sensitivity was 82.0%, and specificity 75.4% (positive likelihood ratio 3.33; negative likelihood ratio 0.24). Interobserver agreement for the three-category classification was moderate to substantial (Fleiss' κ 0.629; 95% CI 0.545-0.712), and median intraobserver agreement was substantial (Cohen's κ 0.738). CONCLUSIONS: The FOCUS classification provides clinically meaningful risk stratification for flat-type dysplasia in a high-risk UCAN cohort, with acceptable interobserver and intraobserver reproducibility.

Background: Differential diagnosis of superficial duodenal epithelial tumors (SDETs) and non-neoplastic lesions (NNLs) in duodenum by endoscopy is difficult. Here, we attempted to distinguish them by magnified endoscopic examination with image-enhanced endoscopy (IEE-ME). Methods: Various IEE-ME findings of 95 SDETs who underwent endoscopic resection and 58 NNLs who underwent biopsy were retrospectively reviewed. Results: When we compared the IEE-ME findings of SDETs and NNLs, the presence of demarcation line (DL) (97.9% vs. 79.3%, P = 0.0002), white opaque substance (WOS) (84.2% vs. 1.7%, P < 0.0001) and light blue crest (LBC) (93.7% vs. 32.8%, P < 0.0001) and the absence of enlarged marginal epithelium (EME) (98.9% vs. 62.1%, P < 0.0001) were significantly more frequent in SDETs than NNLs. When divided into each superficial structure, it was the most effective to evaluate the combination of WOS and LBC as SDET with open-loop structure (OLS), and the combination of DL and EME as SDET with closed-loop structure (CLS). However, LBC was excluded because of low inter- and intra-observer agreements. Finally, the sensitivity, specificity and accuracy for the diagnosis of SDETs were 88.4%, 98.3% and 92.2%, respectively, and we developed an algorithm for the differential diagnosis of duodenal lesions. Conclusion: We could distinguish SDET from NNL, diagnosed SDET as presence of WOS indicated OLS of superficial structure, and presence of DL and absence of EME indicated CLS of superficial structure.

The incidence of duodenal tumors (DTs) is increasing. However, the mechanisms underlying its development remain unclear. Environmental factors, including the microbiome and bile acids (BAs), are believed to influence tumor development. Therefore, we conducted a single-center, prospective, observational study to investigate the potential differences between patients with DTs and healthy controls (HCs) based on these factors. In addition, the BAs in the duodenal fluid were measured using liquid chromatography-tandem mass spectrometry. We recruited 41 patients and performed 16S rRNA-seq. There was no difference in the observed ASVs or PCoA plot of Bray–Curtis dissimilarity between the DTs and HCs. The lithocholic acid concentration was significantly lower in the DT group than in the control group. The ratio of CDCA to LCA was significantly higher in patients with DTs. No significant differences in microbiota were observed between DTs and HCs. In patients with DTs, the lithocholic acid concentration in duodenal was significantly lower than in HCs.

Background and aim: Underwater endoscopic mucosal resection (UEMR) has been reported as effective endoscopic treatment for superficial duodenal epithelial tumors (SDETs). However, it has been reported that a notable problem of UEMR for SDETs is that en bloc resection rate is relatively low. Therefore, we proposed a novel technique to improve en bloc resection rate: UEMR combining partial submucosal injection (PI-UEMR). The aim of this study is to evaluate efficacy and safety of PI-UEMR for SDETs by comparing to UEMR. Methods: This is a retrospective observational study in a single center. The patients who underwent UEMR or PI-UEMR from June 2010 to August 2020 were included in this study. Eligible patients were selected from included patients in a 1:1 ratio using propensity score matching. The clinical outcomes of endoscopic resection (procedure time, en bloc resection rate, complication rate [immediate perforation, delayed bleeding, delayed perforation]), and histopathological diagnosis (adenoma/cancer) were compared between each group. Results: Two hundred and twenty-eight patients were included in this study. Of included patients, 47 patients were selected in each group by propensity score matching. There were no statistical differences in procedure time (11 ± 1.2 min vs. 9 ± 1.2 min, P = 0.30), complication rate (immediate perforation [0% vs. 2%, P = 0.12], delayed bleeding [0% vs. 2%, P = 0.12], and no delayed perforation) and histopathological diagnosis (adenoma; 100% vs. 96%, P = 0.14) in each group. However, en bloc resection rate of PI-UEMR was significantly higher than UEMR (96% vs. 83%, P < 0.05). Conclusion: Partial submucosal injection UEMR might be superior procedure for en bloc resection in SDETs compare to UEMR.

Objectives: Endoscopic hand suturing (EHS) is expected to decrease the risk of post-endoscopic submucosal dissection (ESD) bleeding by closing mucosal defects. We investigated the efficacy of EHS after gastric ESD in patients with antithrombotic agents. Methods: In this prospective single-arm trial, patients taking antithrombotic agents for cardiovascular disease, arrhythmia, cerebrovascular disease and/or peripheral arterial disease and having <3-cm gastric neoplasms were recruited. The mucosal defects after ESD were closed by EHS in which the needle was delivered through an overtube, and the mucosal rim of the defect was continuously sutured in a linear fashion by manipulating the needle grasped with the needle holder, followed by cutting the remnant suture and retrieval of the needle. The primary endpoint was the incidence of postoperative bleeding within 4 weeks after ESD. Results: Twenty-two lesions in 20 patients (continuing antiplatelet agents in 11, anticoagulant agents in eight, both in one) underwent ESD followed by EHS. All defects (median size, 30 mm; range, 12–51 mm) were completely closed by EHS and remained closed on postoperative day 3. The median number of stitches was six (range, 4–8) and median suturing time was 36 (range, 24–60) min. There were no adverse events during/after EHS or postoperative bleeding. Conclusions: Postoperative bleeding was not observed in patients taking antithrombotic agents without perioperative cessation. EHS appears to be useful for prevention of post-gastric ESD bleeding in high-risk patients. (Clinical registration number: UMIN000024184).

Background: A standard treatment method for pedunculated duodenal lesions has not yet been established. This study aimed to evaluate the feasibility of endoscopic resection (ER) for pedunculated duodenal lesions, especially for large lesions. Methods: This study retrospectively reviewed cases of pedunculated duodenal lesions treated with ER at our institute between July 2010 and January 2021. We collected data on the clinical characteristics and treatment outcomes. In addition, the cases were divided based on the treatment provided for the lesion, i.e., the ESD and snare resection groups, and we compared the data between the two groups. Results: Thirty-eight cases were included in this study. The overall en bloc resection rate was 95%. No perforation occurred in any of the cases. There were 10 cases treated with ESD, which were considered difficult to achieve en bloc resection using snare forceps, and 28 cases treated with snare resection. Although the median lesion size was significantly larger in the ESD group than in the snare resection group (27 [range 23–66] vs. 19 [range 6–55] mm, P = 0.0052), treatment outcomes were not significantly different between the two groups. Among the 10 cases treated using ESD, en bloc resection was achieved in all cases, along with specimen retrieval without any perforations, despite the large size of the lesions. Conclusion: ER could be performed to achieve a high en bloc resection rate without any perforations in pedunculated duodenal lesions, even in extremely large (e.g., ≧ 60 mm) lesions, suggesting that ER is feasible and may be an alternative to surgical resection for large pedunculated duodenal lesions.

Objectives: Endoscopic papillectomy (EP) is a low-invasive treatment for duodenal tumors including papilla. The limit of lesion size and local recurrence have been issues in EP. We developed endoscopic submucosal dissection (ESD) for the duodenal tumors including papilla (ESDIP: ESD including papilla) to overcome the problems. The aim of this study was to evaluate the feasibility of ESDIP. Methods: We included the patients who underwent ESDIP from August 2010 to January 2024 in this study. We evaluated the retrospective characteristics of patients and lesions, clinical results of ESDIP and of endoscopic retrograde cholangiopancreatography (ERCP) as prevention for delayed adverse events, and pathological findings. We also calculated the cumulative recurrence rate and overall survival rate at 12 months after ESDIP. Results: Fifty-four patients were included in this study. The mean lesion size was 39 mm. The third-quarter cases revealed a less than half-circumferential lesion, and the one case with a full-circumferential lesion. Resection was accomplished in 96% (n = 52), and also the en-bloc resection rate was 96%. Of the cases in accomplished resection, 98% of patients were intubated with a pancreaticobiliary drainage tube by ERCP. Intraprocedural perforation occurred in eight cases. Delayed bleeding occurred in 10 cases. Delayed perforation was seen only in one case. The incidence of post-ERCP pancreatitis was 25%. Cumulative local recurrence rate and the overall survival rate were 15% and 96%, respectively. Conclusion: ESDIP may be feasible for duodenal tumors including papilla, and is a potential alternative option to avoid pancreaticoduodenectomy.

Background A modified double-layered suturing procedure (origami method; OGM) can achieve robust closure, even for large mucosal defects, by folding the muscle layer using through-the-scope clips. This study aimed to evaluate the feasibility of OGM in duodenal endoscopic submucosal dissection (ESD). Methods This retrospective, observational study was conducted at a tertiary care hospital. We reviewed cases of OGM attempted after duodenal ESD between June 2022 and April 2023.We excluded lesions located in the duodenal bulb or involving the major papilla. We measured the clinical characteristics and outcomes. Results OGM was attempted in 28 cases after duodenal ESD. The median mucosal defect size was 38mm (range 26 ?110). Complete closure was achieved in 27 cases (96%), including the largest lesion. The median closure time was 16 minutes. There were no perforations caused by clips. Delayed perforation and bleeding were not observed. Among 28 cases, 21 underwent follow-up endoscopy 3 5 days after ESD, and the muscle layer remained folded in all cases. Conclusion OGM achieved a high rate of complete closure even after duodenal ESD. Closure with OGM was robust enough to maintain the folded muscle layer for at least 3 days postoperatively.

Background and Aims: Endoscopic mucosal resection (EMR) and Underwater EMR have been reported as effective endoscopic treatment for superficial duodenal tumor (SDET). However, a notable problem of EMR for SDET is technical difficulty for the lesion with non-lifting sign, and it of UEMR is that en bloc resection rate is relatively low. Therefore, we performed partial submucosal injection combining UEMR (PI-UEMR). The aim of this study is to evaluate feasibility and safety of this technique for duodenal tumor. Methods: This is a prospective observational study from tertiary care hospital. We performed PI-UEMR in patients with SDET that is 13–20 mm in diameter, or less than 13 mm with technical difficulty for EMR and UEMR from January 2019 to March 2020. Primary outcome was en bloc resection rate. Secondary outcomes were R0 resection rate, mean total procedure time, intra- and post-procedure complication. Results: Thirty patients were included in this study. Mean age was 62 ± 12 years old. Three fourths lesions were located at anal side from major papilla. Median lesion size was 12 mm [IQR 10–16 mm]. Twenty-four cases were taken endoscopic biopsy in prior hospital and observed biopsy scar. En bloc resection rate was 97%. Ro resection rate was 83%. Mean total procedure time was 17 ± 12 min. And there was an only one case of complication, intra-procedure bleeding that was controllable endoscopically. Conclusions: PI-UEMR might be very useful and safe technique of endoscopic resection for SDET including relatively large lesions.

A 79-year-old man was found to have a tumor located at the descending part of the duodenum. Duodenoscopy showed a 20-mm smooth-elevation covered mucosa with partially whitish color and rough texture (Picture 1A). We considered the tumor component to be unexposed at the surface, as magnifying-image-enhanced endoscopy showed no irregularity of the surface structures nor vessels with a demarcation line (Picture 1B). We decided to perform endoscopic submucosal dissection to achieve a therapeutic diagnosis. The resected specimen showed a tumor localized within the lamina propria (Picture 2A, B) covered with duodenal epithelium (Picture 2C). The tumor was well-differentiated tubular adenocarcinoma against a lymphoid structure with a germinal center (Picture 2D). Therefore, we diagnosed the lesion as gut-associated lymphoid tissue (GALT) carcinoma. GALT carcinoma has been reported as a very rare colorectal tumor with a relatively good prognosis and pathognomonic lymphoid structure of unknown origin (1, 2). This is the first case report of duodenal GALT carcinoma. The further accumulation of similar cases will be necessary for detailed assessments.

Background and Aims Endoscopic closure may prevent stricture after duodenal endoscopic submucosal dissection (ESD) beyond the superior duodenal angle. However, the incidence and risk factors for stricture after ESD in the duodenal bulb, which is difficult to close completely, remain unclear. This study aims to evaluate the incidence and risk factors for stricture after ESD in the duodenal bulb. Methods This retrospective observational study included lesions in the duodenal bulb treated by ESD at our institute between July 2010 and December 2023. We excluded cases in which confirmation of healing of the defect could not be completed endoscopically for any reason. We assessed the incidence and risk factors for stricture. Results A total of 786 duodenal lesions were treated by ESD, of which 124 were located in the bulb. Finally, 101 cases were analyzed, with 82% left unclosed. Stricture occurred in 5 cases (5%). The median maximum diameter of mucosal defects was significantly greater in the stricture group (71 mm [range, 52-94] vs 37 mm [range, 10-120]; P = .0058). In addition, the circumferential extent of the defect was correlated with stricture risk ( P < .0001), with stricture occurring in 63% of cases with circumferential involvement of seven-eighths or greater. Higher rates of resections over the pyloric ring and triamcinolone injections were noted in the stricture group (5 [100%] vs 40 [42%], P = .015; 5 [100%] vs 7 [8%], P < .0001). Conclusions Stricture developed in 5% of cases after ESD in the duodenal bulb and was associated with larger defects, pyloric resections, and triamcinolone injection.

Background and Aim: Multiple duodenal polyposis associated with familial adenomatous polyposis (FAP) is a high risk of duodenal cancer development. We evaluated the feasibility of intensive endoscopic resection that is a comprehensive treatment strategy combining multiple kinds of endoscopic treatments. Methods: This is a retrospective observational study. From January 2012 to July 2022, a total of 28 consecutive patients in FAP who underwent endoscopic resection for multiple duodenal polyposis more than twice were included. Various endoscopic treatments, such as cold polypectomy (CP), endoscopic mucosal resection (EMR), underwater EMR (UEMR), endoscopic submucosal dissection (ESD), and endoscopic papillectomy (EP), were applied depending on lesions size and location. We evaluated individual information from patients' medical records, including patient characteristics, lesion characteristics, details of endoscopic treatment, pathologic findings, and Spigelman index (SI). We compared the differences in the number of treatments and observation periods with and without SI decrease. Results: A total of 1040 lesions were removed by 138 sessions of endoscopic resections. The median follow-up period was 3.2 years. At the beginning of the endoscopic intervention, median SI was 9 (6–11) and the proportion of Spigelman stage (SS) IV was 61%. Repeated endoscopic treatments finally reduced SI in 26 patients (93%), and the proportion of SS IV significantly decreased to 13% with every endoscopic treatment. The mean SI change was −4.2 points per year (95% confidence interval: −0.6 to −5.9). There were no patients required surgical duodenectomy during the follow-up period. Conclusion: Intensive resection has a potential of downstaging duodenal lesions associated with FAP.

Colonoscopists occasionally encounter mixed lesions with overlapping histological features. The frequency and combinations of such mixed colorectal polyps remain poorly understood. We comprehensively analyzed the frequencies and combinations of histologically mixed premalignant colorectal polyps. This study had a retrospective, single-center, cross-sectional design. Patients who underwent colonoscopy at the Toyoshima Endoscopy Clinic between March 2022 and July 2023 were eligible. We excised lesions diagnosed as conventional adenomas or clinically significant serrated polyps. Among these polyps, we focused on mixed lesions and analyzed their frequency and combinations. Among 9,682 resected colorectal lesions, 61 (0.63%) were classified as mixed lesions. The most common combination was microvesicular hyperplastic polyp (MVHP) + goblet cell-rich hyperplastic polyp (GCHP) (41.0%), followed by sessile serrated lesion (SSL) + traditional serrated adenoma (TSA) (21.3%), MVHP + conventional adenoma (9.8%), and TSA + conventional adenoma (9.8%). The mixed rates for MVHPs, GCHPs, SSLs, TSAs, and conventional adenomas were 2.3%, 3.7%, 2.9%, 53.5%, and 0.28%, respectively. Mixed MVHP + GCHP lesions were significantly larger than pure GCHPs (5.3 mm vs 4.0 mm, p<0.01). The frequencies and combinations of mixed premalignant colorectal lesions found in this study may reflect the histogenesis of neoplasia and genetic mutations.

Background and Aims: Through-the-scope clips (TTSCs) are among the most common devices used to close colorectal post–endoscopic submucosal dissection (ESD) defects. Although TTSCs are easy to deliver, even to the proximal colon, simple clipping of large defects results in mucosa–mucosa closure, which could be unreliable. We developed a novel endoscopic closure technique using a modified double-layered suturing called the origami method (OGM). This method closes not only the mucosal layer but also the muscle layer with only TTSCs, which can obtain robust closure even for large defects. This study aimed to evaluate the feasibility of this new closure method for colorectal post-ESD defects. Methods: This retrospective observational study was conducted at a tertiary care hospital. We reviewed the cases of the OGM attempted after colorectal ESD at our institute between October 2021 and October 2022 and measured the clinical characteristics and outcomes of enrolled cases. Results: The OGM was attempted in 47 cases after colorectal ESD. Thirty-one cases (66%) were in the proximal colon, 5 (11%) in the distal colon, 6 (13%) in the upper rectum, and 5 (10%) in the lower rectum. The median defect size was 38 mm, with the largest being 85 mm. Complete closure was achieved in 44 cases (94%), including all lower rectum cases. No perforations were caused by clips during closure, and delayed perforation and bleeding were not observed. Conclusions: This new closure method is feasible and recommended. The OGM could achieve reliable closure of large defects in any location, including the proximal colon and thick-walled lower rectum, using only TTSCs.

Background: Superficial non-ampullary duodenal epithelial tumors (SNADETs) are being increasingly detected during routine endoscopy. However, biological malignancy and optimal risk stratification remain poorly defined. We aimed to clarify the association between mucin phenotypes and histological malignancies in SNADETs using a prospective study design. Methods: In this prospective observational study, patients with suspected SNADETs underwent a standardized magnified endoscopic examination with image-enhanced endoscopy (IEE-ME), followed by endoscopic resection. All specimens were centrally reviewed by expert gastrointestinal pathologists. Mucin phenotypes were classified as G type (gastric, predominantly gastric, or mixed) or I type (intestinal or predominantly intestinal). Histological malignancy was assessed using the Vienna classification (VCL). Clinicopathological and endoscopic factors associated with mucin phenotype and malignancy were systematically analyzed. Results: Among the 401 SNADETs, adenomas were predominant (72.1%), whereas submucosal invasive cancers were rare (2.5%). G-type SNADETs comprised 15.5% of lesions but demonstrated a markedly higher frequency beyond VCL category 4.1 compared to I-type SNADETs (P < 0.0001). The risk of histological malignancy increased stepwise with the proportion of gastric phenotypic components. Most invasive submucosal cancers exhibit a gastric phenotype. Multivariate analysis of the endoscopic findings identified a closed-loop structure, the absence of a white opaque substance on IEE-ME, and protruding morphology as independent predictors of G-type SNADETs. Conclusion: The gastric phenotype is strongly associated with increased histological malignancy in SNADETs. Specific endoscopic features can predict G-type SNADETs, suggesting that mucin phenotype-oriented endoscopic diagnosis may provide useful information for pretreatment risk stratification and treatment planning.

Water pressure method (WPM) is useful for colorectal endoscopic submucosal dissection (ESD), characterized not only by underwater conditions but also by active water pressure via the waterjet function. However, the extension of the colorectum by injecting excess water and contaminating the operative field by stool and bleeding have been issues. This study aimed to evaluate the feasibility of a novel perfusion system using a continuous liquid-suction catheter attachment (CLCA) in colorectal ESD with WPM. We retrospectively reviewed cases in which the perfusion system was used in colorectal ESD with WPM between August 2022 and September 2023. We evaluated clinical characteristics, treatment outcomes, volume of injection by the waterjet function, volume of suction by the endoscope and CLCA, and concentration of floating matter in the operative field over time. Thirty-one cases were enrolled. The median lesion size was 30 (range, 15–100) mm. In all cases, en bloc resection was achieved without perforation. The median injection volume was 2312 (range, 1234–13,866) g. The median suction volumes by the endoscope and CLCA were 918 (range, 141–3162) and 1147 (range, 254–11,222) g, respectively. The median concentration of floating matter in the operative field (measured in 15 cases) was 15.3 (range, 7.3–112) mg/mL when the endoscope arrived at the lesion and 8.0 (range, 3.2–16) mg/mL after endoscopically washing at the beginning of the ESD. It ranged from 7.6 to 13.4 mg/dL every 20 min during ESD. This perfusion system could prevent the extension of the lumen and maintain a good field of view in colorectal ESD with WPM.

Objectives: Although endoscopic submucosal dissection (ESD) training is important, quantitative assessments have not been established. This study aimed to explore a novel quantitative assessment system by analyzing an electrical surgical unit (ESU). Methods: This was an ex vivo study. Step one: to identify the novel efficiency indicators, 20 endoscopists performed one ESD each, and we analyzed correlations between their resection speed and electrical status. Step two: to identify the novel precision indicators, three experts and three novices performed one ESD each, and we compared the stability of the electrical status. Step three: three novices in step two performed 19 additional ESDs, and we analyzed the learning curve using novel indicators. Results: Step one: the percentage of total activation time (AT) of ESU in the procedure time (β coefficient, 0.80; P < 0.01) and AT required for submucosal dissection (β coefficient, −0.57; P < 0.01) were significantly correlated with the resection speed. Step two: coefficient of variation of the AT per one pulse (0.16 [range, 0.13–0.17] vs. 0.26 [range, 0.20–0.41], P = 0.049) and coefficient of variation of the peak electric power per pulse during mucosal incision (0.14 [range, 0.080–0.15] vs. 0.25 [range, 0.24–0.28], P = 0.049) were significantly lower in the experts than in the novices. Regarding the learning curve, the percentage of total AT of ESU in the procedure time and AT required for submucosal dissection had a trend of improvement. Conclusion: Novel indicators identified by analyzing ESU enable quantitative assessment for endoscopist's skill.

Background and Aims Underwater endoscopic mucosal resection (UEMR) has been widely adopted for the treatment of superficial nonampullary duodenal epithelial tumors (SNADETs). The aim of this study was to identify predictors of local recurrence and piecemeal resection in UEMR for SNADETs. Methods This is a retrospective single-center study. Patients who underwent UEMR for SNADETs between November 2017 and October 2024 were included. We documented clinicopathologic characteristics of patients and lesions, noted procedure-related outcomes, and evaluated local recurrence. Kaplan-Meier analysis was used to assess recurrence-free survival, and logistic regression analysis was performed to identify the predictors of piecemeal resection. Results Among the 367 patients, the rate of piecemeal resection was 11.2%, and the rate of en bloc resection with histologically tumor-free horizontal and vertical margins (R0) was 65.1%. No intraoperative perforations occurred; intraoperative bleeding was observed in 1.9%. Kaplan-Meier analysis of recurrence-free survival showed significantly poorer outcomes in the piecemeal resection group than the en bloc resection group (log-rank test, P < .001; Wilcoxon test, P < .001). According to multivariate logistic regression analysis, each 1-mm increase in lesion size (odds ratio [OR], 1.20; 95% confidence interval [CI], 1.11-1.31; P < .001) and a flat macroscopic type (OR, 12.49; 95% CI, 1.45-107.98; P = .02) were significant independent predictors of piecemeal resection. Conclusions Piecemeal resection was a risk factor for local recurrence in UEMR for SNADETs. In addition, each 1-mm increase in lesion size and a flat macroscopic type were significant independent predictors of piecemeal resection.