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Objectives: In this study we aimed to develop an artificial intelligence-based model for predicting postendoscopic retrograde cholangiopancreatography (ERCP) pancreatitis (PEP)., Methods: We retrospectively reviewed ERCP patients at Nagoya University Hospital (NUH) and Toyota Memorial Hospital (TMH). We constructed two prediction models, a random forest (RF), one of the machine-learning algorithms, and a logistic regression (LR) model. First, we selected features of each model from 40 possible features. Then the models were trained and validated using three fold cross-validation in the NUH cohort and tested in the TMH cohort. The area under the receiver operating characteristic curve (AUROC) was used to assess model performance. Finally, using the output parameters of the RF model, we classified the patients into low-, medium-, and high-risk groups., Results: A total of 615 patients at NUH and 544 patients at TMH were enrolled. Ten features were selected for the RF model, including albumin, creatinine, biliary tract cancer, pancreatic cancer, bile duct stone, total procedure time, pancreatic duct injection, pancreatic guidewire-assisted technique without a pancreatic stent, intraductal ultrasonography, and bile duct biopsy. In the three fold cross-validation, the RF model showed better predictive ability than the LR model (AUROC 0.821 vs. 0.660). In the test, the RF model also showed better performance (AUROC 0.770 vs. 0.663, P = 0.002). Based on the RF model, we classified the patients according to the incidence of PEP (2.9%, 10.0%, and 23.9%)., Conclusion: We developed an RF model. Machine-learning algorithms could be powerful tools to develop accurate prediction models., (© 2023 Japan Gastroenterological Endoscopy Society.)

Objectives: Comprehensive assessments of the long-term outcomes of endoscopic submucosal dissection (ESD) for early gastric cancer (EGC) in the elderly are unavailable. We aimed to create a scoring system to predict the long-term prognosis after ESD for EGC among patients aged ≥75 years., Methods: We conducted retrospective studies of two cohorts: a single-center cohort (2006-2011) for developing the scoring system, and a multicenter cohort for validating the developed system (2012-2016). In the development cohort, factors related to death after ESD were identified using multivariable Cox regression analysis, and a predictive scoring system was developed. In the validation cohort, the scoring system was validated in 295 patients., Results: In the development cohort, Charlson comorbidity index (CCI) ≥3 (hazard ratio [HR] 3.017), high psoas muscle index (PMI) (HR 2.206), and age ≥80 years (HR 1.978) were significantly related to overall survival after ESD. Therefore, high CCI, low PMI, and age ≥80 years were assigned 1 point each. The patients were categorized into low (≤1 point) and high (≥2 points) score groups based on their total scores. In the validation cohort, 184 and 111 patients were assigned to the low- and high-score groups, respectively. In comparisons based on Kaplan-Meier curves, the 5-year survival rate was 91.5% in the low-score group and 57.8% in the high-score group (log-rank test; P < 0.001)., Conclusion: Our scoring system including high CCI, low PMI, and age ≥80 years could stratify the long-term prognosis of elderly patients aged ≥75 years after ESD for EGC., (© 2022 Japan Gastroenterological Endoscopy Society.)

Endoscopic management for perihilar cholangiocarcinoma (PHCC) is evolving toward more accurate diagnosis and safer drainage. In imaging, it is important to diagnose the entire lesion using multidetector-row computed tomography to determine resectability and optimal surgical planning, followed by local diagnosis using endoscopic retrograde cholangiopancreatography. Video peroral cholangioscopy and probe-based confocal laser endomicroscopy have been newly introduced as diagnostic imaging methods and are being applied clinically. In transpapillary forceps biopsy for PHCC diagnosis, the location in the bile duct (for mapping biopsy) and the number of biopsy samples should be determined depending on resectability, the morphological type, and future surgical planning. Preoperative drainage has shifted from percutaneous transhepatic biliary drainage to endoscopic nasobiliary drainage given the possibility of seeding metastasis. In addition, considering potential patient discomfort from a nasal tube, the usefulness of the placement of a plastic stent above the papilla (inside stent) as a bridging therapy for surgery has been reported. For drainage of unresectable PHCC, the improved prognosis due to advances in chemotherapy has necessitated a strategy that accounts for reintervention. Thus, in addition to uncovered self-expandable metallic stents (SEMS), exchangeable slim fully covered SEMS and inside stents have started to be used. In addition to the conventional transpapillary approach, an endoscopic ultrasonography-guided approach has been introduced, and a combination of both methods has also been proposed. To improve the quality of life and prognosis of PHCC patients, endoscopists need to understand and be able to use the various methods of endoscopic management for PHCC., (© 2022 Japan Gastroenterological Endoscopy Society.)

Objectives: Although black stools are one of the signs of upper gastrointestinal bleeding, not all patients without hematemesis need endoscopic intervention. There is no apparent indicator to select who needs treatment thus far. The aim of this study was to establish a novel score that predicts the need for endoscopic intervention in patients with black stools without hematemesis., Methods: We retrospectively enrolled 721 consecutive patients with black stools without hematemesis who underwent emergency endoscopy from two facilities. In the development stage (from January 2016 to December 2018), risk factors that predict the need for endoscopic intervention were determined from the data of 422 patients by multivariate logistic regression analysis, and a novel scoring system, named the modified Nagoya University score (modified N score), was developed. In the validation stage (from January 2019 to September 2020), we evaluated the diagnostic value of the modified N score for 299 patients., Results: Multivariate logistic regression analysis revealed four predictive factors for endoscopic intervention: syncope, the blood urea nitrogen (BUN) level, and the BUN/creatinine ratio as positive indicators and anticoagulant drug use as a negative indicator. In the validation stage, the area under the curve of the modified N score was 0.731, and the modified N score showed a sensitivity of 82.0% and a specificity of 58.8%., Conclusions: Our modified N score, which consists of only four factors, can identify patients who need endoscopic intervention among those with black stools without hematemesis., (© 2022 Japan Gastroenterological Endoscopy Society.)

Objectives: Endoscopic submucosal dissection (ESD) in the duodenum is challenging. The water pressure method (WP-ESD) has been developed with a decreased rate of perforation. However, details of perioperative adverse events of WP-ESD are unknown. The purpose of this study was to clarify the frequency and related factors of fecal incontinence and oral regurgitation during WP-ESD., Methods: A chart-based retrospective analysis was performed on 43 patients who underwent duodenal WP-ESD. The saline volume given into the body was calculated in all cases. All adverse events during WP-ESD until 6 weeks were extracted, and factors related to intraoperative fecal incontinence or oral regurgitation were analyzed. The frequency of fecal incontinence and oral regurgitation was also compared to those of 83 conventional ESD cases., Results: In WP-ESD, intraoperative fecal incontinence occurred in 12 (28%), oral regurgitation in six (14%), and aspiration pneumonia in one patient. For fecal incontinence, the infusion speed (saline volume divided by resection time) around 17 mL/min was a significant factor in multivariable analysis. For oral regurgitation, only tumor size was a significant factor in univariate analysis (P = 0.027). Significant difference was observed in the frequency of fecal incontinence between WP-ESD and conventional ESD (28% vs. 0%, P < 0.001), but no difference was observed in oral regurgitation or aspiration pneumonia., Conclusions: Intraoperative fecal incontinence is a unique adverse event of WP-ESD related to the infusion speed. WP-ESD did not pose a risk for oral regurgitation, but we should be aware of the risk in large tumor cases., (© 2021 Japan Gastroenterological Endoscopy Society.)

Objectives: There are few reports on the long-term prognosis of papillary tumors after endoscopic papillectomy. Here, we report a retrospective study of the therapeutic effects, long-term prognosis, and affecting factors., Methods: The inclusion criteria were papillary adenoma with/without an adenocarcinoma component on biopsy results and ≤10 mm intraductal extension, and the exclusion criteria were moderate to poorly differentiated adenocarcinoma on biopsy results. If no residual lesion was confirmed ≥6 months after the last endoscopic treatment, remission was defined. Subsequently, follow-up endoscopy was scheduled once a year. Surgery was required in the case of adenocarcinoma recurrence or intraductal lesions >10 mm. The rates of adverse events, remission, recurrence, and need for surgery were examined. The affecting factors were calculated., Results: There were a total of 253 subjects, including 65 with adenocarcinoma. Pancreatitis (7.5%), bleeding (9.1%) and perforation (2.8%) were observed as adverse events. Among 221 subjects with ≥6 months of follow-up, 212 (95.9%) were in remission. The cumulative recurrence rate using the Kaplan-Meier analysis at 5 years was 16.9% (22 cases), with the need for surgery in 5.9% (5 cases). Intraductal extension on preoperative diagnosis was the only significant risk factor for both recurrence (P < 0.001) and the need for surgery (P = 0.005). The presence of adenocarcinoma had no significant effect., Conclusion: Although remission was achieved in more than 95% of our patients, we observed a high rate of recurrence at the long-term follow-up, which was significantly associated with intraductal extension but not with the presence of adenocarcinoma., (© 2020 Japan Gastroenterological Endoscopy Society.)

Background and Aims: Endoscopic ultrasound (EUS) elastography (EUS-EG) is a minimally invasive diagnostic method for evaluating tissue elasticity. The aim of this study was to evaluate the feasibility of newly developed EUS shear-wave measurement (EUS-SWM) and to compare diagnostic performance between EUS-SWM and the conventional strain elastography (SE) for the measurement of elasticity of solid pancreatic lesions (SPLs)., Methods: From December 2017 until August 2019, we retrospectively reviewed 64 consecutive cases with SPLs who underwent both EUS-SWM and SE. EUS-SWM was used to measure the shear-wave velocity, Vs (m/s), and the unique measurement reliability index, VsN (%), in the target lesion. SE images were assessed by strain histogram (SH) analysis, and the mean strain value of the elasticity index was measured. We evaluated the diagnostic performance of EUS-SWM and SE with SH to characterize the SPLs., Results: The Vs (m/s) values of SPLs were 2.19 for pancreatic cancer (PC), 1.31 for pancreatic neuroendocrine neoplasm (PanNEN), 2.56 for mass-forming pancreatitis (MFP) and 1.58 for metastatic tumors. Vs showed no significant difference based on the disease. The mean strain values were 45.5 for PC, 47.3 for PanNEN, and 74.5 for MFP. In the comparison of tissue elasticity between PC and MFP, Vs showed no significant difference (P = 0.5687); however, the mean strain value was significantly lower in PC cases (45.4 vs 74.5: P = 0.0007)., Conclusion: Endoscopic ultrasound SWM tended to be unstable for the measurement of elasticity of SPLs, and conventional SE with SH was superior for their characterization., (© 2020 Japan Gastroenterological Endoscopy Society.)

Objectives: Accurate diagnosis of invasion depth is important for reliable treatment of esophageal squamous cell carcinoma (ESCC), but it is limited to the muscularis mucosae to slight submucosal invasion (MM/SM1). The diagnostic accuracy of invasion depth is unsatisfactory and remains to be improved. We aimed to investigate the association between the color of the superficial ESCC and invasion depth using linked color imaging (LCI) under light-emitting diode (LED) light sources., Methods: Lesions diagnosed as superficial ESCC were observed using white light imaging and then by LCI. The color values were calculated using Commission Internationale de l'Eclariage - L*a*b* color space, and the color difference was calculated according to invasion depth. The vascular diameters and vascular angles of the intrapapillary capillary loops were pathologically analyzed. Their correlation with mucosal color was also investigated by LCI., Results: In all, 52 lesions from 48 patients were analyzed. On the basis of invasion depth, the color difference between the normal mucosa and the lesion was larger in the MM/SM1 or deeper group than in the epithelium and the lamina propria mucosa (EP/LPM) group using LCI (P = 0.025). The vascular diameter was positively correlated with the b* color value (correlation coefficient = 0.302, P = 0.033)., Conclusion: Observation using LCI under LED light sources may improve the endoscopic diagnosis of the invasion depth of superficial ESCC. Further research is needed to validate its usefulness. (UMIN000024615)., (© 2019 Japan Gastroenterological Endoscopy Society.)

Objectives: The time to recurrent biliary obstruction (TRBO) of unresectable distal malignant biliary obstruction is generally thought to be longer when a self-expandable metal stent (SEMS) with a thicker inner diameter is used for drainage, but the dependence on the inner diameter using a fully covered SEMS (FCSEMS) is uncertain. The objective of this multicenter prospective study was to compare TRBO and adverse events, such as cholecystitis and pancreatitis, in treatment of patients with unresectable malignant biliary obstruction using 8- and 10-mm diameter FCSEMS., Methods: Eighteen tertiary-care centers participated in the study. Patients were allocated to the 8- and 10-mm diameter groups. TRBO, non-inferiority of the 8-mm FCSEMS, overall survival time, frequency and type of adverse events, and non-recurrent biliary obstruction (RBO) rate at the time of death were compared between the two groups., Results: Median TRBO did not differ significantly between the 8-mm (n = 102) and 10-mm (n = 100) groups (275 vs 293 days, P = 0.971). The hazard ratio of the 8- to 10-mm groups was 0.90 (80% confidence interval, 0.77-1.04; upper limit lower than the acceptable hazard ratio [1.33] of the null hypothesis). Based on these findings, the 8-mm diameter stent was determined to be non-inferior to the 10-mm diameter stent. Survival time, incidence of adverse events and non-RBO rate at the time of death did not differ significantly between the two groups., Conclusions: Time to RBO with an 8-mm diameter FCSEMS was non-inferior to that with a 10-mm diameter FCSEMS. This finding is important for development of future SEMS., (© 2019 Japan Gastroenterological Endoscopy Society.)

Endoscopic ultrasonography (EUS) has high spatial and contrast resolution, and is thought to be one of the most reliable and efficient diagnostic modalities for pancreatobiliary diseases. Recent progress in EUS, especially in the development of the electronic scanning method, has enabled the application of several utilities and software of a high-end transabdominal ultrasound apparatus as an image-enhanced EUS. Tissue harmonic imaging (THI) is a novel US acquisition method that provides better US images by using second harmonic signals. The potential advantages of THI are improved lateral resolution, reduced side lobe artifact and an increased signal-to-noise ratio. EUS-elastography is another novel technique that provides information about the distributed pattern of tissue hardness. Clinical benefits of EUS-elastography for the differential diagnosis of pancreatic tumors and the evaluation of pancreatic fibrosis have been reported. It is necessary to develop a unified and objective method of imaging and analysis to increase the use of EUS-elastography in the future., (© 2015 The Authors. Digestive Endoscopy © 2015 Japan Gastroenterological Endoscopy Society.)

Background and Aim: In therapeutic endoscopic retrograde cholangiography (ERC) using a balloon-assisted enteroscope, each instrument insertion requires a long time, which prolongs the duration of the procedure. We conducted a retrospective single-center study to compare instrument insertability of a double-balloon enteroscope (DBE) with a 2.8-mm instrument channel diameter and a prototype short single-balloon enteroscope (SBE) with a 3.2-mm instrument channel diameter., Methods: We used a stop-watch to measure instrument insertion time from the instrument channel port to the tip of the enteroscope when balloon-assisted ERC was done. The instruments were divided into two groups (outer diameter larger or smaller than 2 mm). Lengths from the instrument channel port to the tip of the DBE (EI-530B; FUJIFILM, Tokyo, Japan) and the prototype SBE (SIF-Y0004-V01; Olympus Medical Systems, Tokyo, Japan) were identical (1680 mm). ERC using DBE was carried out in four cases, as was ERC using SBE., Results: There was a significant time difference (P= 0.001) when using instruments whose outer diameters were >2 mm (53.5 ± 19.0 s in DBE vs 28.4 ± 8.4 s in SBE)., Conclusion: The prototype SBE with a 3.2-mm channel demonstrated not only that many types of instrument can be used, but also that the time required to insert instruments may be shorter than that with DBE with a 2.8-mm channel., (© 2014 The Authors. Digestive Endoscopy © 2014 Japan Gastroenterological Endoscopy Society.)

Clinical guidelines of the European Society of Gastrointestinal Endoscopy recommend the insertion of self-expandable metallic stents (SEMS) as opposed to plastic stents (PS) in patients with unresectable malignant perihilar stricture (MHS). However, PS are cheaper and easier to insert into the biliary duct compared to SEMS. Furthermore, PS are removable and easy to move into subsequent drainage procedures. We conducted the present retrospective single-center study to elucidate the predictive factors associated with stent patency period duration in patients with unresectable MHS who would benefit from a long patency period after PS placement. This study included 56 consecutive patients with unresectable MHS who were drained using PS. PS failure occurred in 26 (46.4%) patients. The median patency period was 72 days (95% confidence interval: 29.8-114). The only significant predictive factor associated with the length of the stent patency period was history of previous endoscopic sphincterotomy (EST). Median patency periods with and without previous EST were 28 and 109 days, respectively (P = 0.016). In conclusion, we suggest that conventional biliary drainage with PS is still a suitable option for the treatment of unresectable MHS in patients without previous EST., (© 2013 The Authors. Digestive Endoscopy © 2013 Japan Gastroenterological Endoscopy Society.)

Background: The sensitivity of transpapillary biliary forceps biopsy for malignancy has been reported as varying from 43-81%. Therefore, there are false negatives in more than 20% of patients, which makes it difficult to diagnose benign biliary stricture as benignancy in a clinical setting., Methods: To clarify the number of tissue samples that should be obtained during transpapillary forceps biopsy to distinguish benign biliary stricture from malignancy, patients undergoing transpapillary biliary forceps biopsy at our institute were examined retrospectively in this study., Results: Seventy-two biliary forceps biopsy procedures were performed on 61 patients. The final diagnoses were malignant biliary stricture in 34 patients and benign stricture in 27 patients. The overall sensitivity and specificity for malignancy in this study were 76.5% and 100%, respectively. There were zero out of 10 (0%) false-negative patients when three or more tissue samples were obtained. In contrast, when four or more tissue samples were obtained, eight out of eight (100%) patients had negative diagnoses for malignancy and were finally diagnosed with benignancy., Conclusion: We suggest that three or more tissue samples are recommended for the diagnosis of biliary malignant stricture., (© 2012 The Authors. Digestive Endoscopy © 2012 Japan Gastroenterological Endoscopy Society.)

Two randomized controlled trials comparing endoscopic nasobiliary drainage (ENBD) and internal endoscopic biliary drainage (internal EBD) for acute suppurative cholangitis (ASC) showed no significant difference in efficacy and both preferred internal EBD to ENBD. In this study, the necessity of ENBD was re-examined. Over five years, 59 patients underwent an emergency endoscopic procedure for ASC in our institute. If drainage was needed, we selected internal EBD as a first choice and ENBD was used in patients predicted to have early obstruction of the tube or retrograde infection of the bile duct. The rate of ENBD, for which reason ENBD was selected, and the efficacy of drainage were examined retrospectively. In the 59 patients, 40 patients had the stones completely removed without drainage, five internal EBD and two ENBD were performed without removal of stones and five internal EBD and seven ENBD were performed after removal of stones. In terms of white blood cell count and direct bilirubin level, no significant difference was observed between ENBD and internal EBD patients. ENBD was mainly selected for the patients with multiple biliary strictures, hemorrhage tendency and excessive purulent bile. Even though internal drainage is suitable in many ASC patients, ENBD is necessary in selected patients.