Endoscopic submucosal dissection (ESD) for ileocecal valve (ICV) lesions poses unique technical challenges because of its anatomic complexity. This study aimed to evaluate the effectiveness and safety of ESD for ICV lesions.

From December 2016 to June 2023, the clinic characteristics and outcomes of ESD on 51 ICV lesions and 84 cecal lesions were reviewed. Factors related to longer procedure time were analyzed for ESD of ICV lesions.

Baseline characteristics and clinical features of the lesions were not significantly different between the groups. The median procedure time of the ICV group was significantly longer than that of the cecal group (35 min vs. 24 min, respectively; P =.04). There were no significant differences in en bloc resection rates between the ICV and cecal groups (92.2% vs. 97.6%, respectively; P =.14). During the median follow-up of 32 months (IQR, 6-89), there was no case of recurrence in the ICV group. A specimen diameter of ≥25 mm and a circumferential spread of ≥1/2 were factors related to a longer procedure time (specimen diameter: OR=4.2 95%CI, 2.1-15.4, P =.02; circumferential spread: OR=3.7, 95%CI, 1.2-12.7, P =.03).

ESD for ICV lesions requires a longer procedure duration than ESD for cecal lesions, but it is safe and effective, making it a challenging and promising therapeutic approach.

Large non-pedunculated colorectal polyps ≥20 mm (LNPCPs) constitute approximately 1% of all colorectal polyps and present a spectrum of risks, including overt and covert submucosal invasive cancer (T1 colorectal cancer (CRC)). Importantly, a curative resection may be achieved for LNPCPs with superficial T1 CRC (T1a or T1b <1000 µm into submucosa), if an enbloc R0 excision (clear margins) with favourable histology is achieved (ie, absence of high-grade tumour budding, lympho-vascular invasion, and poor differentiation). Thus, while consensus recommendations advocate for endoscopic resection as the primary treatment option for LNPCPs, thorough optical assessment is imperative for selecting the most suitable ER strategy. In this review, we highlight the critical components of optical evaluation that assist in predicting the risk of T1 CRC, including morphology (Paris and LST classifications), surface pit/vascular pattern (JNET and Kudo classifications), and lesion location. Different resection modalities, including endoscopic submucosal dissection and endoscopic mucosal resection are discussed, along with important considerations that may influence the resection strategy of choice, such as access to the LNPCP and submucosal fibrosis.

The ileocecal valve (ICV) is considered to be one of the most difficult locations for endoscopic submucosal dissection (ESD). The objective of this study was to evaluate the efficacy and safety of traction-assisted ESD in this situation.

All patients who underwent traction-assisted ESD for an ICV lesion at three centers were identified from a prospective ESD database. En bloc and R0 rates were evaluated. Factors associated with non-R0 resection were explored.

106 patients with an ICV lesion were included. The median lesion size was 50 mm (interquartile range 38-60) and 58.5% (62/106) invaded the terminal ileum. The en bloc and R0 resection rates were 94.3% and 76.4%, respectively. Factors associated with non-R0 resection were lesions covering ≥75% of the ICV (odds ratio [OR] 0.21. 95%CI 0.06-0.76; P=0.02), and involving the anal lip (OR 0.36, 95%CI 0.13-0.99; P=0.04) or more than two sites on the ICV (OR 0.27, 95%CI 0.07-0.99; P=0.03).

Traction-assisted ESD for treatment of ICV lesions was a safe and feasible option. Large lesions and anal lip involvement appeared to be factors predictive of difficulty.

Endoscopic resection (ER) for jejunoileal lesions (JILs) has been technically challenging. We aimed to characterize the clinicopathologic characteristics, feasibility, and safety of ER for JILs.

We retrospectively investigated 52 patients with JILs who underwent ER from January 2012 to February 2022. We collected and analyzed clinicopathological characteristics, procedure-related parameters, outcomes, and follow-up data.

The mean age was 49.4 years. Of the 52 JILs, 33 ileal tumors within 20 cm from the ileocecal valve were resected with colonoscopy, while 19 tumors in the jejunum or the ileum over 20 cm from the ileocecal valve received enteroscopy resection. The mean procedure duration was 49.0 min. The en bloc resection and en bloc with R0 resection rates were 86.5% and 84.6%, respectively. Adverse events (AEs) included one (1.9%) major AE (delayed bleeding) and five (9.6%) minor AEs. During a median follow-up of 36.5 months, two patients had local recurrence (3.8%), while none had metastases. The 5-year recurrence-free survival (RFS) and disease-specific survival (DSS) were 92.9% and 94.1%, respectively. Compared with the enteroscopy group, overall AEs were significantly lower in the colonoscopy group (P < 0.05), but no statistical differences were observed in RFS (P = 0.412) and DSS (P = 0.579). There were no significant differences in AEs, RFS, and DSS between the endoscopic submucosal dissection (ESD) and the endoscopic mucosal resection (EMR) group.

ER of JILs has favorable short-term and long-term outcomes. Both ESD and EMR can safely and effectively resect JILs in appropriately selected cases.

Colonoscopy has been shown to be an effective modality to prevent colorectal cancer (CRC) development. CRC reduction is achieved by detecting and removing adenomas, which are precursors of CRC. Most colorectal polyps are small and do not pose a significant challenge for trained and skilled endoscopists. However, up to 15% of polyps are considered "difficult", potentially causing life-threatening complications. A difficult polyp is defined as any polyp that is challenging for the endoscopist to remove owing to its size, shape, or location. Advanced polypectomy techniques and skills are required to resect difficult colorectal polyps. There were various polypectomy techniques for difficult polyps such as endoscopic mucosal resection (EMR), underwater EMR, Tip-in EMR, endoscopic submucosal dissection (ESD), or endoscopic full-thickness resection. The selection of the appropriate modality depends on the morphology and endoscopic diagnosis. Several technologies have been developed to aid endoscopists in performing safe and effective polypectomies, especially complex procedures such as ESD. These advances include video endoscopy system, equipment assisting in advanced polypectomy, and closure devices/techniques for complication management. Endoscopists should know how to use these devices and their availability in practice to enhance polypectomy performance. This review describes several useful strategies and tips for managing difficult colorectal polyps. We also propose the stepwise approach for difficult colorectal polyps.

Mucosal lesions located at the ileocecal valve may be challenging for endoscopic intervention because of angulated anatomy and a thinner wall with narrower lumen when compared to other locations of the bowel. This study aimed to evaluate the management and outcomes of ileocecal valve lesions treated endoscopically.

Patients with mucosal neoplasms involving the ileocecal valve managed with advanced endoscopy at a quaternary care hospital between 2011 and 2021 were included from a prospectively collected database. Patient demographics, lesion characteristics, complications, and outcomes are reported.

From 1005 lesions, 80 patients (8%) underwent resection for neoplasms involving ileocecal valve by ESD (n = 38), hybrid ESD (n = 38), EMR (n = 2), and CELS (n = 2). The median age of the study group was 63(37-84) years, and 50% of patients were female. The median lesion size was 34 mm (5-75). The mean procedure time was 66 ± 44 min(range:18-200). The dissection was completed as piecemeal in 41(51%) patients and 35(44%) had en-bloc dissection. Seven(8%) endoscopic interventions required conversion to laparoscopic surgery due to inability to lift the mucosa(n = 4) and perforation(n = 3). No immediate bleeding occurred in the study group. Five patients had late rectal bleeding and two were admitted with post-polypectomy pain within 30 days of intervention. Pathology revealed 4(5%) adenocarcinomas, 33(41.2%) tubular adenomas, 30(37.8%) tubulovillous adenomas, and 5(6.2%) sessile serrated adenomas. Sixty-seven (84.5%) patients completed at least one follow-up colonoscopy and were followed for a median of 11(0-64) months. Six (8.9%) patients had recurrence and were managed with subsequent endoscopic removal.

Advanced endoscopy can be safely and effectively performed for the management of ileocecal valve polyps with low complication and acceptable recurrence rates. Advanced endoscopy promises an alternative approach to oncologic ileocecal resection while attaining organ preservation. Our study demonstrates the impact of advanced endoscopy for the treatment of mucosal neoplasms involving ileocecal valve.

The efficacy and safety of endoscopic submucosal dissection (ESD) for tumors extending into the terminal ileum remain obscure. We aimed to evaluate the outcomes of ESD for tumors involving the ileocecal valve (ICV) with extension into the terminal ileum.

Sixty-eight patients (40 men; mean age, 67 years) with 68 tumors involving the ICV that were resected by ESD between December 2013 and December 2018 were included and classified into Group A (21 tumors with extension into the terminal ileum) and Group B (47 tumors without extension). ESD outcomes were compared between groups.

The clinical features of the patients and tumors were not significantly different between the groups. There were no significant differences in en bloc resection rate (95% and 94%, respectively; p = 0.79), R0 resection rate (90% and 89%, respectively; p = 0.89), procedure time (95 ± 54 min and 94 ± 69 min, respectively; p = 0.64), postoperative bleeding rate (5% and 3%, respectively; p = 0.79), intraoperative perforation rate (0% and 4%, respectively; p = 0.34), delayed perforation rate (0% and 0%, respectively), or postoperative symptomatic stenosis rate (0% and 0%, respectively) between Groups A and B. No specific factors related to the outcomes of ESD were found by subgroup analysis according to the dominance and degree of circumference of the ICV. Local recurrence was observed in 1 patient in Group A who was retreated using ESD.

ESD for tumors involving the ICV with extension into the terminal ileum is safe and effective.

Although endoscopic submucosal dissection (ESD) enables en bloc removal of colorectal neoplasms, its effectiveness for larger lesions (≥ 10 cm in diameter) is undetermined. We aimed to investigate the feasibility and safety of ESD for colorectal lesions ≥ 10 cm wide.

This retrospective study included 3591 consecutive colorectal lesions managed with ESD from June 2012 through December 2020. Clinicopathological characteristics and treatment outcomes were compared between lesions ≥ 10 cm wide and lesions 5-10 cm wide.

There were 50 patients in the ≥ 10 cm group and 270 patients in the 5-10 cm group. Among patients in the ≥ 10 cm group, lesions were most often in the rectum (50.0%), and the laterally spreading tumor-granular nodular mixed type (LST-G-M) was most prevalent (41/50, 82%). Although patients in the ≥ 10 cm group a longer mean ESD procedure time (186.0 vs. 94.4 min, p < 0.001), the dissection speed was significantly higher in this group (0.50 vs. 0.41 cm2/min, p = 0.003). The en bloc and curative resection rates were comparable between the ≥ 10 cm and 5-10 cm groups (100% vs. 99.6% and 86.0% vs. 88.5%, respectively). Although the stenosis rate was higher in the ≥ 10 cm group (4% vs. 0%), the delayed bleeding and perforation rates were similar between the two groups.

ESD for colorectal lesions ≥ 10 cm wide is feasible and curative, even though it is associated with higher technical difficulty and longer procedure times compared with ESD for smaller lesions (Number: UMIN 000044313).

Endoscopic submucosal dissection (ESD) for diverticulum-associated colorectal lesions is generally contraindicated because of the high risk of perforation. Several studies on patients with such lesions treated with ESD have been reported recently. However, the feasibility and safety of ESD for lesions in proximity to a colonic diverticulum (D-ESD) have not been fully clarified. The aim of this study was to evaluate the feasibility and safety of D-ESD.

D-ESD was defined as ESD for lesions within approximately 3 mm of a diverticulum. Twenty-six consecutive patients who underwent D-ESD were included. Two strategic approaches were used depending on whether submucosal dissection of the diverticulum-related part was required (strategy B) or not (strategy A). Treatment outcomes and adverse events associated with each strategy were analyzed.

The en bloc resection rate was 96.2%. The rates of R0 and curative resection in strategies A and B were 80.8%, 73.1%, 84.6%, and 70.6%, respectively. Two cases of intraoperative perforation and one case of delayed perforation occurred. The delayed perforation case required emergency surgery, but the other cases were managed conservatively.

D-ESD may be a feasible treatment option. However, it should be performed in a high-volume center by expert hands because it requires highly skilled endoscopic techniques.

In patients with Crohn's disease (CD) and small bowel stenosis, endoscopic balloon dilation (EBD) is considered to be useful in improving stenotic symptoms and avoiding surgery. However, it carries risks such as bleeding and perforation. The aim of this study was to identify the indications for endoscopic intervention in patients with CD and small bowel stenosis.

From November 2007 to March 2020, 143 CD patients with small bowel stenosis were enrolled in this study. We identified the factors associated with not requiring endoscopic intervention during long-term follow-up of these patients.

Forty of the 143 patients had abdominal symptoms of stenosis and had undergone EBD, whereas the remaining 103 were asymptomatic and had not undergone endoscopic intervention. During long-term follow-up, 95 of those 103 patients never required endoscopic or surgical intervention. Multivariate logistic regression analysis revealed that not consuming an elemental diet (OR 3.18, 95% CI 1.48-6.82; p < .01) and ileocecal valve (ICV) stenosis (OR 0.30, 95% CI 0.11-0.83; p = .02) were independently associated with not requiring EBD. The cumulative emergency hospitalisation-free rate also tended to be higher in patients not consuming an elemental diet or with ICV stenosis.

Two factors, namely not consuming an elemental diet and ICV stenosis, predict a long-term intervention-free prognosis in CD patients with small bowel stenosis.Key messagesWhen an endoscopically impassable small bowel stenosis is found in a CD patient, long-term follow-up without endoscopic intervention may be possible if the patient is asymptomatic, is not using an elemental diet, and the stenosis is ICV.

Endoscopic submucosal dissection (ESD) is the treatment of choice for colorectal superficial neoplasia, but certain anatomical locations are challenging even for skilled endoscopists. Ileocecal valve (ICV) is considered a technically challenging site for ESD.

Aim of this study was to analyze efficacy and safety of Endoscopic Submucosal Dissection in the treatment of colorectal neoplasia involving the ileocecal valve (ICV) DESIGN: Retrospective study.

We retrospectively evaluated 1507 consecutive patients undergoing ESD at two tertiary referral centres for ESD (Italy and Japan) from January 2008 to March 2020.

Demographic, clinical, procedural, and follow-up data was collected, analysed, and compared between patients with ileocecal valve lesions (ICVL) and patients with non-ICVL.

Overall, 1507 patients were enrolled (872 M, 57.8%), of these 53 patients had lesions involving the ICV. Mean age was 70.2 years (range, 53-83 years). En-bloc resection was achieved in 52 (98%) patients. The median specimen size of ICVL was 36.4 mm (range, 8-80 mm), significantly smaller than non-ICVL (p = 0.005). Procedure time was significantly longer in the ICVL group, (71.3 vs. 58.9 min; p = 0.03). Non Granular Type Laterally Spreading Tumors (LST-NG) were significantly more frequent in the ICVL group compared to rectum (52.8% vs. 25.7; p = 0.0001). En-bloc resection rate in the ileocecal region did not differ significantly between groups (p = 0.20). Complications such as perforation and postoperative occurred respectively in 3/53 (5.7%) and 1/53 (2%) patient, and were treated conservatively. At first surveillance colonoscopy performed at 6 months, recurrent adenoma was detected in 2/53 patients (3.9%).

ESD is safe and effective for the treatment of colorectal neoplasia involving the ileocecal valve if performed by expert endoscopist in referral centres.

Endoscopic submucosal dissection (ESD) was developed in 2000s to overcome the limitations of endoscopic mucosal resection (EMR), especially to accomplish en-bloc resection, and it has been accepted worldwide in the past decades. Many ESD devices and diagnosis modalities are currently available, which include pit pattern and narrow band imaging (NBI) diagnoses to evaluate the depth of the tumor preoperatively with sensitivities of 70 to 90%. Depending on the Japanese colorectal guideline, the intramucosal cancer and shallow invasion of the submucosal layer are the main good indications of ESD; however, the ESD practices between Japan and Western countries still vary, including pathologic definition of cancer, tumor/node/metastasis classification, and handling of ESD specimen. In the United States, despite the large demand for treatment of colorectal neoplasm, pit pattern and magnified NBI diagnoses are not widely accepted yet, and piecemeal EMR is still the major method in most of the institutions. Moreover, the specific guideline of ESD is also not available yet. More new technologies are being developed other than conventional ESD methods in Eastern and Western countries, and ESD is now expected to change in the next generation. It is recommended that not only gastroenterologists but also colorectal surgeons have appropriate knowledge of colorectal lesions and their management to ensure current treatments is applied to patients.

Ileocecal valve (ICV) lesions are difficult to resect endoscopically and patients are often referred for laparoscopic colectomy. ICV involvement has been shown to be related to technical failure and tumor recurrence after endoscopic mucosal resection (EMR) and represents a challenge for endoscopic submucosal dissection (ESD). Few publications have focused specifically on endoscopic management of ICV lesions.

We developed a novel ESD technique, the "doughnut resection," for circumferential ICV adenomas with terminal ileum involvement. Two circumferential mucosal incisions are performed, one in the ileum and the other in the cecum, followed by submucosal dissection of the disk of tissue between the two incisions around a guiding stent placed across the valve that helps guide the dissection as it crosses the valve orifice. The lesion is removed en bloc in the shape of a "doughnut" with two concentric assessable lateral margins. The underwater ESD technique and a gastroscope were used to facilitate the resection.

Seven patients received the doughnut resection. The median patient age was 67 years. All patients had prior biopsy and three had prior endoscopic resection (1-6 times). The median specimen diameter was 4.5 cm (range 3-8). All resections were en bloc and R0. There was no perforation, delayed bleeding, or other clinically significant adverse events. After a median follow-up of 21 months (range 12-32), there was no tumor recurrence.

The "doughnut resection" is a feasible, safe, and effective method to remove circumferential ICV lesions endoscopically even for patients with multiple prior tumor manipulations.

Colorectal endoscopic submucosal dissection (ESD) is considered one of the most challenging endoscopic procedures for novice endoscopists. When compared with the stomach, the colon and rectum have a narrower tubular lumen, greater angulation at the flexures, and a thinner muscle layer. These factors make endoscopic control and maneuverability difficult. ESD of the colorectum was considered more difficult than gastric and esophageal ESD. However, with learning from the experts, practicing, and selecting an appropriate technique, most of colorectal ESD could be performed successfully. Nevertheless, some colorectal locations are extremely specialized either from unique anatomy or given unstable scope position. Accordingly, the objective of this review was to provide endoscopists with an overview of the techniques and outcomes associated with ESD at these special colorectal locations. ESD at the discussed special locations of the ileo-colo-rectum was found to be feasible, and outcomes were comparable to those of ESD performed in non-special locations of the ileo-colo-rectum. Practice for skill improvement and awareness of the unique characteristics of each special location is the key to performing successful ESD.

Background and study aims  Previously, we reported that esophageal muscle layer thickness was associated with technical complexity of peroral endoscopic myotomy (POEM). However, there are no data regarding the mid-term effects of POEM procedures on esophageal muscle layer thickness. Therefore, we conducted this study to elucidate mid-term effects of POEM procedures, and to examine whether postoperative changes in esophageal muscle layer thickness were related to particular clinico-pathological features in patients with esophageal motility disorders. Patients and methods  Seventy-four consecutive patients with esophageal motility disorders who underwent POEM at Kobe University Hospital from April 2015 to December 2016 were prospectively recruited into this study. First, we investigated the esophageal muscle layer thickness values obtained at 1 year after POEM. Second, we evaluated the effects of a reduction in muscle layer thickness on various clinico-pathological features. Results  At 1 year after POEM, mean thickness of the inner circular muscle at 0 cm, 5 cm, and 10 cm from the esophagogastric junction was 1.06 ± 0.45 mm, 0.99 ± 0.36 mm, and 0.97 ± 0.44 mm, respectively. Among all sites, muscle layer thickness had significantly decreased after POEM. However, univariate logistic regression analysis demonstrated that no clinical factors were associated with esophageal muscle layer thickness after POEM procedure. Conclusions  We demonstrated for the first time that thickness of the esophageal muscle layer was significantly decreased after POEM. This result reveals that changes in esophageal muscle layer thickness caused by esophageal motility disorders are reversible.

 Severe fibrosis poses a challenge in colorectal endoscopic submucosal dissection (ESD). Recently, the pocket-creation method (PCM) has been developed for overcoming various difficulties of ESD. A specific tapered hood is used for adequate traction in the PCM, and endoscopic operability becomes stable in the pocket. In this study, we investigated the efficacy of the PCM in ESD for cases with severe fibrosis.

We retrospectively reviewed 1000 consecutive colorectal ESD cases (April 2006 to January 2017). Since 2016, the PCM was performed in 58 cases. The indications for ESD included (1) tumors ≥ 20 mm in size diagnosed as intramucosal cancer or high-grade dysplasia and part of T1a cancer using magnifying endoscopic examinations and (2) tumors that appeared impossible to resect with endoscopic mucosal resection because of suspected fibrosis. We identified 120 cases with severe fibrosis and compared them to cases without severe fibrosis. Additionally, the 120 severe fibrosis cases were divided into the PCM and non-PCM groups. En bloc resection, procedure time, discontinuation, and complications were analyzed between these 2 groups.

 Among all 1000 ESDs, severe fibrosis and discontinuation rates were 12.0 % (120 cases) and 1.8 % (18 cases), respectively. Regarding the comparison between cases with severe fibrosis and with no severe fibrosis, there were significant differences about en bloc resection rate (78.3 % vs. 95.7 %, P  < 0.001), discontinuance rate (12.5 % vs. 0.3 %, P  < 0.001), and perforation rate (8.3 % vs. 2.6 %, P  = 0.001). Among the 120 cases with severe fibrosis, 21 and 99 cases were in the PCM and non-PCM groups, respectively. The PCM group had a higher en bloc resection rate (95.2 vs. 74.7, P  =  0.03), a shorter mean procedure time (min) (79.6 ± 26.5 vs. 118.8 ± 71.0, P  = 0.001), and no cases of discontinuation. An analysis of the interobserver agreement for the diagnosis of severe fibrosis among the 3 endoscopists showed kappa values of > 0.6.

 In cases with severe fibrosis, the PCM with ESD improved en bloc resection rates and shortened the procedure time compared to the conventional non-PCM method. Additionally, the PCM reduced the discontinuation rate.

Few studies have investigated the use of endoscopic submucosal dissection (ESD) for cecal tumors extending into the appendiceal orifice. Herein, we assessed the feasibility and safety of ESD for cecal tumors extending into the appendiceal orifice.

We retrospectively examined the outcomes of ESD for 78 patients with 78 cecal tumors (male/female ratio, 40/38; mean [standard deviation, SD] age, 67 [9] years; mean [SD] tumor size, 32 [15] mm), who underwent ESD at the Hiroshima University Hospital between October 2008 and March 2016. The indication for ESD in cecal tumors extending into the appendiceal orifice was recognition of the distal edge of the lesion in the appendix. They were classified into two groups: patients with cecal tumors extending (Group A: 29 patients, 29 tumors) and not extending (Group B: 49 patients, 49 tumors) into the appendiceal orifice. We compared the outcomes of ESD between both groups.

No significant differences in clinicopathological characteristics were observed between both groups. The rate of severe submucosal fibrosis in Group A (48%) was significantly higher than that in Group B (24%) (p < 0.05). The mean (SD) procedure speed in Group A (14 [10] mm²/min) was significantly slower than that in Group B (23 [16] mm²/min) (p < 0.01). The en bloc resection rates in Groups A and B were 90% and 96%, respectively. There were no significant differences in adverse events reported between both groups.

ESD for cecal tumors with extension into the appendiceal orifice is effective and safe.

The treatment results of endoscopic submucosal dissection (ESD) for colorectal lesions have improved markedly, but some lesions remain difficult to treat. Hence the cecum is considered a technically challenging site for ESD. We examined the feasibility of ESD for cecal lesions.

Among a total of 708 colorectal ESD performed in our hospital between March 2006 and December 2016, 549 procedures performed after April 2012 were studied, at a time when the techniques of ESD had stabilized and the procedure was covered by health insurance in Japan. Among 549 cases, 61 were cecal lesions and 488 were noncecal lesions. The treatment outcomes were analyzed.

For cecal lesions, the en bloc resection rate was 95.1%, R0 resection rate was 91.8%, perforation rate was 0%, delayed bleeding rate was 6.6%, median diameter of resected specimen was 32 mm (16-65 mm), median time of the procedure was 44 minutes (8-140 min). The corresponding results for noncecal lesions were 97.3%, 95.5%, 0.4%, 2.7%, 30 mm (10-109 mm), and 37 min (7-225 min). No significant differences were observed and the good treatment results were seen. When the outcomes were analyzed for cecal sites considered to be particularly challenging; proximity to appendiceal orifice, the ileocecal valve, and the bottom of cecum, the treatment results were not inferior to other sites.

ESD is safe and effective even for cecal lesions considered challenging to treat. ESD is feasible for cecal lesions.

With respect to the knife's design in colorectal endoscopic submucosal dissection (ESD), diameter, water jet function, and electric power are important because these relate to efficient dissection. In this study, we analyzed a novel, narrow ball tip-typed ESD knife with water jet function (Flush knife BT-S, diameter: 2.2 mm, length: 2000 mm, Fujifilm Co., Tokyo, Japan) compared to a regular diameter knife (Flush knife BT, diameter: 2.6 mm, length: 1800 mm).

In laboratory and clinical research, electric power, knife insertion time, vacuum/suction amount with knife in the endoscopic channel, and water jet function were analyzed. We used a knife 2.0 mm long for BT-S and BT knives.

The BT-S showed faster mean knife insertion time (sec) and better vacuum amount (ml/min) compared to the BT (insertion time: 16.7 versus 21.6, p < 0.001, vacuum amount: 38.0 versus 14.0, p < 0.01). Additionally, the water jet function of the BT-S was not inferior. In 39 colorectal ESD cases in two institutions, there were mean 4.7 times (range: 1-28) of knife insertion. Suction under knife happened 59% (23/39) and suction of fluid could be done in 100%.

Our study showed that the narrow knife allows significantly faster knife insertion, better vacuum function, and effective clinical results.

Colorectal endoscopic submucosal dissection (ESD) is recommended to be carried out only by endoscopists with sufficient experience in gastric ESD. However, early gastric carcinoma is less common in Western countries than in Japan, and endoscopic maneuverability differs between the stomach and colorectum. We assessed the feasibility of colorectal ESD carried out by endoscopists with no or little experience in gastric ESD.

We analyzed en bloc resection, R0 resection and perforation rates in 180 consecutive colorectal ESD carried out by three endoscopists who had no or <5 cases of experience in gastric ESD. We also identified factors associated with R0 resection failure.

Overall en bloc and R0 resection rates were 93.3% (168/180) and 82.2% (148/180), respectively. All 11 cases with perforation were treated endoscopically. Dividing 180 cases into three learning phases (early, middle, or late phases), the en bloc and R0 resection rates increased from 88.3% and 75.0% in the early phase to 98.3% and 88.3% in the late phase, respectively. Perforation rate also improved from 10.0% to 3.3%. Factors associated with R0 resection failure were location at junctions (odds ratio: 6.8, 95% CI: 1.9-27.5), preoperative factors reflecting fibrosis (5.8, 1.9-19.0), and late phase (0.2, 0.1-0.7).

Endoscopists without experience in gastric ESD carried out colorectal ESD safely. In the early and middle phases (≤40 cases), they should treat mainly rectal lesions but may also resect lesions in the colon avoiding flexures. Lesions located at junctions and those with preoperative factors reflecting fibrosis should be resected after completing 40 procedures.

In Japan, endoscopic submucosal dissection (ESD) becomes one of standard therapies for large colorectal tumors. Recently, the efficacy of ESD has been reported all over the world. However, it is still difficult even for Japanese experts in some situations. Right-sided location, large tumor size, high degree of fibrosis, difficult manipulation is related with the difficulty. However, improvements on ESD devices, suitable strategies, and increase of operators' experiences enable us to solve these problems. In this chapter, we introduce recent topics about various difficult factors of colorectal ESD and the tips such as strategy, devices, injection, and traction method [Pocket-creation method (PCM) etc.].