A successful single-step endoscopic resection of a 40 millimeter flat-elevated tumor in the rectum: endoscopic mucosal resection using sodium hyaluronate

Exploring different techniques for endoscopic submucosal dissection of gastrointestinal lesions: a review of the literature

INTRODUCTION

Endoscopic submucosal dissection (ESD) has revolutionized the management of early gastrointestinal (GI) neoplasms by enabling en bloc resection with high R0 rates. Several modifications of conventional ESD (C-ESD) have been introduced, including pocket-creation (PCM-ESD), tunnel (T-ESD), traction-assisted (TA-ESD), and saline immersion therapeutic endoscopy (SITE-ESD) methods.

AREAS COVERED

A comprehensive literature search was conducted across main databases through February 2025 using keywords related to ESD, with studies selected based on their relevance. While no single technique has demonstrated superior efficacy and safety across different GI regions, a tailored and integrative approach to different techniques could enhance effectiveness. PCM-ESD and T-ESD are particularly advantageous circumferential lesions in the esophagus and rectum, whereas TA-ESD significantly reduces procedure time, particularly in colonic lesions. Moreover, PCM-ESD has demonstrated higher effectiveness for colorectal lesions compared to C-ESD. SITE-ESD has shown benefits in colorectal resections by improving trimming, submucosal space visualization and coagulation control.Advanced traction systems and resection tools has optimized ESD performance. However, selecting the most appropriate approach requires careful consideration of lesion characteristics (particularly fibrosis and location).

EXPERT OPINION

While conventional ESD remains the foundation, TA and SITE are expected to become the preferred approach in select GI regions during the following years.

Polysaccharides as submucosal injection materials (SIMs) in endoscopic resection: A comprehensive review

Submucosal injection materials (SIMs) play a vital role in the endoscopic treatment of benign and early malignant gastrointestinal lesions by effectively elevating lesions while significantly reducing the risks of thermal injury and bleeding. However, the traditional use of normal saline (NS) presents challenges due to its rapid absorption, which necessitates frequent reapplications and complicates procedural efficiency. Therefore, there is a pressing need for ideal SIMs that are cost-effective, readily available, and suitable for personalized therapy, while also demonstrating excellent biocompatibility and physicochemical stability. Recent advancements have highlighted the potential of polysaccharide-based natural polymers, such as sodium hyaluronate, cellulose, starch derivatives, chitosan, and sodium alginate, due to their superior biocompatibility and biodegradability. These polysaccharides have exhibited enhanced operational characteristics and therapeutic efficacy in animal and clinical studies. Nevertheless, ongoing research must address several challenges, including optimizing cost-effectiveness, improving mechanical strength and bioactivity, and mitigating intraoperative and postoperative complications. This review systematically examines the progress of polysaccharide-based natural polymers in SIMs, evaluates their current status and challenges in both research and clinical applications, and proposes future directions to enhance their utilization in gastrointestinal endoscopic therapy.

Temperature-sensitive injectable chitosan-based hydrogel for endoscopic submucosal dissection

Endoscopic submucosal dissection (ESD) is an effective treatment for polyps and early gastrointestinal cancers, but requires a high level of operator skill. Injecting submucosal materials (SIM) helps create a fluid cushion between the mucosal and muscular layers, making the procedure easier and reducing associated risks. However, SIMs commonly used in current clinical practice tend to spread quickly and fail to provide long-lasting submucosal fluid cushions (SFC). Thus, there is a critical need for a material that is easy to inject while also maintaining a durable barrier. We prepared succinylated hydroxybutyl chitosan (HBC-SA) by adding succinic anhydride (SA) to hydroxybutyl chitosan (HBC). The hydrogel had excellent temperature-sensitive properties and was able to be injected via an endoscopic injection needle even after gel formation. In vitro and in vivo studies showed that it has satisfactory biocompatibility. Functional experiments showed that the submucosal lifting properties of this hydrogel were significantly better than that of normal saline (NS) and sodium hyaluronate (SH), two commonly used clinical materials. In addition, the hydrogel possessed excellent hemostatic properties. Based on these results, HBC-SA is a promising candidate for submucosal injection during ESD.

Emerging Technologies in Endoscopy for Gastrointestinal Neoplasms: A Comprehensive Overview

Gastrointestinal neoplasms are a growing global health concern, requiring prompt identification and treatment. Endoscopic procedures have revolutionized the detection and treatment of gastrointestinal tumors by providing accurate, minimally invasive methods. Early-stage malignancies can be treated with endoscopic excision, leading to improved outcomes and increased survival rates. Precancerous lesions, like adenomatous polyps, can be prevented by removing them, reducing cancer occurrence and death rates. Advanced techniques like chromoendoscopy, narrow-band imaging, and confocal laser endomicroscopy improve the ability to see the mucosa surface and diagnose conditions. Artificial Intelligence (AI) applications in endoscopy can enhance diagnostic accuracy and predict histology outcomes. However, challenges remain in accurately defining lesions and ensuring precise diagnosis and treatment selection. Molecular imaging approaches and therapeutic modalities like photodynamic therapy and endoscopic ultrasonography-guided therapies hold potential but require further study and clinical confirmation. This study examines the future prospects and obstacles in endoscopic procedures for the timely identification and treatment of gastrointestinal cancers. The focus is on developing technology, limits, and prospective effects on clinical practice.

Early Rectal Cancer and Local Excision: A Narrative Review

A rise in the incidence of early rectal cancer consequent to bowel-screening programs around the world and an increase in the incidence in young adults has led to a growing interest in organ-sparing treatment options. The rectum, being the most distal portion of the large intestine, is a fertile ground for local excision techniques performed with endoscopic or surgical techniques. Moreover, the advancement in endoscopic optical evaluation and the better definition of imaging techniques allow for a more precise local staging of early rectal cancer. Although the local treatment of early rectal cancer seems promising, in clinical practice, a significant number of patients who could benefit from local excision techniques undergo total mesorectal excision (TME) as the first approach. All relevant prospective clinical trials were identified through a computer-assisted search of the PubMed, EMBASE, and Medline databases until January 2024. This review is dedicated to endoscopic and surgical local excision in the treatment of early rectal cancer and highlights its possible role in current and future clinical practice, taking into account surgical completion techniques and chemoradiotherapy.

Advances in endoscopic resection: a review of endoscopic submucosal dissection (ESD), endoscopic full thickness resection (EFTR) and submucosal tunneling endoscopic resection (STER)

Subepithelial lesions are often detected incidentally in patients undergoing an endoscopy. They are common tumors of the gastrointestinal (GI) tract which can originate from different layers of the GI tract wall. These lesions can be further classified based on GI layer of origin and unique histochemical staining. While most are benign and asymptomatic, some of these lesions have malignant potential with distant metastases. However, current diagnostic modalities including endoscopy with biopsy or endoscopic ultrasound with fine needle aspiration are not always reliable. In addition, management of these lesions has historically involved surgical resection via open or laparoscopic approaches. In recent years, with advancement in endoscopic techniques and improvement in endoscopists' skills, less invasive procedures such as endoscopic submucosal dissection (ESD), endoscopic full thickness resection (EFTR) and submucosal tunneling endoscopic resection (STER) have been developed and now are being used by endoscopists worldwide. Upon reviewing the literature, multiple studies have shown the advantages of these endoscopic techniques when compared with surgical treatment. As a result, there has been a dramatic shift towards minimally invasive endoscopic procedures for the management of these subepithelial lesions. In this review article, we will discuss these endoscopic resection techniques in detail, their safety and efficacy, as well as comparison studies to other therapeutic modalities.

EndoClot®SIS Polysaccharide Injection as a Submucosal Fluid Cushion for Endoscopic Mucosal Therapies: Results of Ex Vivo and In Vivo Studies

BACKGROUND

There are many studies on submucosal injection materials, but their clinical use is restricted for various reasons. The objective of this study was to compare the feasibility and safety of injected EndoClot^®SIS polysaccharide as a submucosal injection material (SFC) in ESD in the pig stomach to that of injected sigMAVisc™ or Eleview™.

METHODS

Four pig stomachs were used for the ex vivo study. Eighteen pigs were used for the in vivo study. In the ex vivo study, four injections were made in the gastric submucosa to induce submucosal uplift and extend its duration. Tissue change was observed. The in vivo study was performed in 2 steps. First, 3 injections were made in the esophageal mucosa to induce submucosal uplift and extend its duration. Histological change was observed. Second, ESD was performed in the stomach by injecting EndoClot^®SIS polysaccharide, sigMAVisc™, or Eleview™ (each, n = 6) as an SFC. The effects of these agents on wound healing were examined. We evaluated the efficacy and safety of endoscopic surgery after EndoClot^®SIS polysaccharide injection.

RESULTS

EndoClot^®SIS polysaccharide produced a longer-lasting elevation with clearer margins than was achieved by sigMAVisc™, Eleview™, or 0.9% NaCl and thereby enabled precise ESD without complications, such as bleeding and perforation. No obvious histopathological damage was observed at the injection site on endoscopy and histology.

CONCLUSION

Submucosally injected EndoClot^®SIS polysaccharide increased the effective separation of the mucosa and submucosa and reduced surgical complications. Hence, EndoClot^®SIS polysaccharide injection is a safe and effective submucosal injection material.

Endoscopic submucosal dissection: a cognitive task analysis framework toward training design

BACKGROUND

One of the major impediments to the proliferation of endoscopic submucosal dissection (ESD) training in Western countries is the lack of sufficient experts as instructors. One way to address this gap is to develop didactic systems, such as surgical simulators, to support the role of trainers. Cognitive task analysis (CTA) has been used in healthcare for the design and improvement of surgical training programs, and therefore can potentially be used for design of similar systems for ESD.

OBJECTIVE

The aim of the study was to apply a CTA-based approach to identify the cognitive aspects of performing ESD, and to generate qualitative insights for training.

MATERIALS AND METHODS

Semi-structured interviews were designed based on the CTA framework to elicit knowledge of ESD practitioners relating to the various tasks involved in the procedure. Three observations were conducted of expert ESD trainers either while they performed actual ESD procedures or at a training workshop. Interviews were either conducted over the phone or in person. Interview participants included four experts and four novices. The observation notes and interviews were analyzed for emergent qualitative themes and relationships.

RESULTS

The qualitative analysis yielded thematic insights related to four main cognition-related categories: learning goals/principles, challenges/concerns, strategies, and decision-making. The specific insights under each of these categories were systematically mapped to the various tasks inherent to the ESD procedure.

CONCLUSIONS

The CTA approach was applied to identify cognitive themes related to ESD procedural tasks. Insights developed based on the qualitative analysis of interviews and observations of ESD practitioners can be used to inform the design of ESD training systems, such as virtual reality-based simulators.

Identification of the critical viscoelastic factor in the performance of submucosal injection materials

High-performance submucosal injection materials (SIMs) contribute to the success of endoscopic therapy for early-stage gastrointestinal neoplasms. This study aimed to identify the most important factor (viscoelastic parameter) that determines SIM performance and the ease of injection. To determine the ideal viscoelastic parameters of SIMs, submucosal elevation heights (SEHs) and the ease of submucosal injection [characterized by injection pressures (IPs)] were evaluated using a newly developed ex vivo model, in which a constant tension was applied to the studied specimen. The strongest positive correlation was observed between the loss modulus determined at an oscillation frequency of 0.1 rad/s and SEH (correlation coefficient > 0.9) and between the loss modulus at 10 rad/s and IP (correlation coefficient > 0.9). SIMs with high loss moduli (0.1 rad/s) also contributed to maintenance of the submucosal elevation. Moreover, the SEHs of pseudoplastic fluid SIMs (whose loss moduli increased slightly with increasing angular frequency) were greater than those of Newtonian fluid SIMs (whose loss modulus increased drastically with increasing angular frequency). In this study, the ideal viscoelastic SIM parameters were clarified. The loss modulus (0.1 rad/s) was the most important viscoelastic factor affecting SIM performance. Additionally, the development of pseudoplastic fluid SIMs may lead to the creation of next-generation SIMs, with a performance superior to that of sodium hyaluronate, which is currently used widely in endoscopic treatments.

A New Ex Vivo Model for the Evaluation of Endoscopic Submucosal Injection Material Performance

Increasing the performance of submucosal injection materials (SIMs) is important for endoscopic therapy of early gastrointestinal cancer. It is essential to establish an ex vivo model that can evaluate SIM performance accurately, for developing high-performance SIMs. In our previous study, we developed a new ex vivo model that can be used to evaluate the performance of various SIMs in detail by applying constant tension to the specimen's ends. We also confirmed that the proposed new ex vivo model allows accurate submucosal elevation height (SEH) measurement under uniform conditions and detailed comparisons of the performances of various types of SIMs. Here, we describe the new ex vivo model and explain the detailed setup methodology of this model. Since all parts of the new model were easy to obtain, the setup of the new model could be completed quickly. SEH of various SIMs could be measured more accurately by using the new model. The critical factor that determines SIM performance can be identified using the new model. SIM development speed will drastically increase after the factor has been identified.

Transanal endoscopic microsurgical submucosa dissection in the treatment of rectal adenomas and T1 rectal cancer

Background

The treatment of flat rectal adenomas is challenging. The technical difficulty and the potential of malignancy in suspected benign lesions are the factors in question. Surgical and interventional endoscopic techniques are implemented in Europe without a clear strategy. To minimize recurrent adenoma and unclear histopathological work up en bloc excision is desirable.

Methods and results

We demonstrate in this article the transanal endoscopic microsurgical submucosa dissection (TEM-ESD) procedure as a feasible method for en bloc excision of rectal adenomas and early rectal cancer. The surgical technique is demonstrated in detail with the help of a video of the operation that is available online. The results of a consecutive series of 78 patients are presented.

Conclusion

TEM-ESD is a safe procedure for resection of rectal adenomas and low risk carcinomas. It offers the possibility of organ preservation and minimizes functional disturbances. In case of a necessary salvage operation, the preserved integrity of the rectal muscle tube grants maximal oncological safety.

Electronic supplementary material

The online version of this article (10.1007/s00053-018-0291-3) includes a video on the surgical technique: TEM ESD. The article and supplemental material are available at http://www.springermedizin.de/der-chirurg. The supplemental material can be found at the end of the article under “Supplementary material”.

Development of Mucoadhesive Chitosan Derivatives for Use as Submucosal Injections

Endoscopic mucosal resection (EMR) and endoscopic submucosal dissection (ESD) have been used for surgical treatment of early gastric cancer. These endoscopic techniques require proper submucosal injections beneath the tumor to provide a sufficiently high submucosal fluid cushion (SFC) to facilitate clean dissection and resection of the tumor. Until now, the submucosal injection materials developed for endoscopic techniques such as EMR and ESD of tumors have been composed of macromolecules, proteins, or polysaccharides. We have been investigating the use of chitosan, a product that is obtained by the alkaline deacetylation of chitin, the second-most abundant natural polysaccharide. Specifically, we have been studying a photocrosslinked chitosan hydrogel (PCH) and solubilized chitosan derivatives for use as novel submucosal injections for endoscopic techniques. Notably, chitosan derivatives with lactose moieties linked to the amino groups of its glucosamine units can specifically interact with acidic mucopolysaccharides and mucins in submucosa without the need for the incorporation of harmful photoreactive groups nor potentially mutagenic ultraviolet irradiation.

Development of a new ex vivo model for evaluation of endoscopic submucosal injection materials performance

BACKGROUND AND AIMS

Development of high-performance submucosal injection materials (SIMs) contribute to the advancement of endoscopic therapy for early-stage gastrointestinal neoplasms. This study aimed to develop a new ex vivo model that mimics the human gastrointestinal tract to evaluate the performance (the height and duration of the submucosal elevation) of various SIMs in detail.

METHODS

A new ex vivo model that applies a constant tension to the tested specimen (the porcine gastric specimen) was developed. SIMs were injected into the submucosa at the center or edge of the tested specimen, and submucosal elevation heights (SEHs) were measured over time.

RESULTS

The average value and standard deviation of SEH determined using the conventional model (the tested specimen was fixed with pins) were higher than those obtained using the new model, which showed that the new model could precisely measure the SEH of a given SIM. In addition, the performance (SEH) of SIMs decreased with increasing tension applied to the specimen, suggesting that the performance of SIMs deteriorates with the over-expansion of the gastrointestinal tract. The submucosal elevation formed at the specimen edge disappeared faster than that formed at the specimen's center.

CONCLUSIONS

The proposed new ex vivo model allows accurate SEH measurement under uniform conditions and detailed comparison of the performances of various types of SIMs and can contribute to the development of high-performance materials.

Gastric endoscopic submucosal dissection using sodium carboxymethylcellulose as a new injection substance

AIM

To investigate the feasibility of endoscopic submucosal dissection (ESD) using sodium carboxymethylcellulose (SCMC) for gastric cancer.

METHODS

During October 2011 through April 2013, 98 lesions from 98 patients who underwent ESD using SCMC (ESD-SCMC) for early gastric cancer were enrolled in this study.　Two endoscopists, who had each performed fewer than 30 ESD procedures (less-experienced ESD physicians), performed ESD-SCMC under the supervision of two experts.　The primary outcome was the en bloc resection rate.　Secondary outcomes included the complete resection rate, the procedural time, the bleeding rate after SCMC injection, and complications.　Patient characteristics, time necessary for hemostasis after SCMC injection, rate of treatment completion by less-experienced ESD physicians alone, and the effects of SCMC during ESD and on resected specimens were also evaluated.

RESULTS

The en bloc resection rate was 100%.　Among these resections, 87.8% of the cases were completed by a less-experienced ESD physician alone.　The complete resection rate was 98.0%.　The mean total procedural time was 75.4 min.　The mean incidence of intraoperative bleeding following SCMC local injection was 1.7 times.　No bleeding was observed after SCMC injection in 29.6% of cases (29/98).　Five complications occurred: one case of microperforation (1.0%) and four cases of postoperative bleeding (4.0%).　SCMC remained in the submucosa.　The submucosa was readily manipulated when the deep submucosa was dissected, even after placing the specimen on a slide.

CONCLUSION

ESD-SCMC is feasible for the resection of early gastric cancer.

What is the best therapeutic strategy for colonoscopy of colorectal neoplasia? Future perspectives from the East

Development and improvement of endoscopic techniques and devices have changed the treatment of colorectal tumors over the last decade. For the treatment of diminutive polyps, the cold snare technique of the West is becoming a promising treatment in the East because of its short procedure time and low rate of delayed bleeding by eliminating the delayed effect of electrocautery. Rather than using piecemeal endoscopic mucosal resection or surgical resection for the treatment of large superficial tumors, the technique of the East of endoscopic submucosal dissection (ESD) achieves a high success rate of en bloc R0 resection, enabling detailed pathological evaluation with less invasive treatment. This procedure should also be useful in the West where large colorectal tumors are more frequent than in the East. Regarding outcomes, however, in the literature, the definition of 'curative resection' remains somewhat inconsistent and long-term outcomes of patients with deep submucosal and/or lymphovascular invasion in the en bloc specimen have not yet been determined. Large prospective, as well as retrospective, studies of these patients are warranted. When colorectal ESD is difficult because of size or location, the pocket-creation method and/or double-balloon-assisted technique may be useful. In the East, high-quality magnified chromoendoscopy is widely available, and endoscopists try to identify focal submucosal invasion. In the West, a systematic evaluation of surveillance for the prevention of colorectal cancer has been done and is highly refined. The East and West have much to learn from each other.

Efficacy and safety of endoscopic submucosal dissection for superficial colorectal tumors more than 50 mm in diameter

BACKGROUND AND AIMS

The feasibility of endoscopic submucosal dissection (ESD) for large superficial colorectal tumors is undefined. The aim of this study was to assess the outcomes for patients undergoing ESD of superficial colorectal tumors larger than 50 mm.

METHODS

A total of 472 patients who underwent ESD for superficial colorectal tumors from 2010 to 2014 were enrolled. We retrospectively reviewed their records.

RESULTS

We compared patients with 20-mm to 50-mm lesions and those with lesions >50 mm regarding demographics, the ESD procedure, and histopathology. Among patients with lesions >50 mm, laterally spreading tumors nongranular and protruded types were uncommon. Histopathologically, deeply invasive (≥1000 μm) submucosal carcinomas were more frequent in lesions >50 mm (14% [10/70] vs 5% [20/402], P < .01). Technically, en bloc resection was successfully accomplished in 99% of patients (69/70). Although the total dissection time for lesions >50 mm was significantly longer than for lesions 20 mm to 50 mm (mean ± SD, 157 ± 114 minutes vs 68 ± 50 min; P < .01), dissection speed for lesions >50 mm was significantly faster than for lesions 20 mm to 50 mm (P < .01). There were no significant differences in en bloc R0 resection rate comparing both groups (>50 mm, 83% vs 20 mm to 50 mm, 87%; P = .31). No perforations or postoperative bleeding occurred in patients with lesions >50 mm. Post-ESD colorectal strictures requiring intervention did not develop in any patient.

CONCLUSIONS

ESD for superficial colorectal tumors >50 mm is feasible. ESD of these lesions had a high R0 resection rate and a low adverse event rate. En bloc resection by ESD provides adequate pathological specimens and may limit the need for surgical intervention.

Biological ablation of sentinel lymph node metastasis in submucosally invaded early gastrointestinal cancer

Currently, early gastrointestinal cancers are treated endoscopically, as long as there are no lymph node metastases. However, once a gastrointestinal cancer invades the submucosal layer, the lymph node metastatic rate rises to higher than 10%. Therefore, surgery is still the gold standard to remove regional lymph nodes containing possible metastases. Here, to avoid prophylactic surgery, we propose a less-invasive biological ablation of lymph node metastasis in submucosally invaded gastrointestinal cancer patients. We have established an orthotopic early rectal cancer xenograft model with spontaneous lymph node metastasis by implantation of green fluorescent protein (GFP)-labeled human colon cancer cells into the submucosal layer of the murine rectum. A solution containing telomerase-specific oncolytic adenovirus was injected into the peritumoral submucosal space, followed by excision of the primary rectal tumors mimicking the endoscopic submucosal dissection (ESD) technique. Seven days after treatment, GFP signals had completely disappeared indicating that sentinel lymph node metastasis was selectively eradicated. Moreover, biologically treated mice were confirmed to be relapse-free even 4 weeks after treatment. These results indicate that virus-mediated biological ablation selectively targets lymph node metastasis and provides a potential alternative to surgery for submucosal invasive gastrointestinal cancer patients.

Endoscopic submucosal dissection versus endoscopic mucosal resection for the treatment of early esophageal carcinoma: a meta-analysis

Endoscopic submucosal dissection (ESD) was originally developed for en bloc resection of large, flat gastrointestinal lesions. Compared with endoscopic mucosal resection (EMR), ESD is considered to be more time consuming and have more complications for treatment of early esophageal carcinoma, such as bleeding, stenosis and perforation. The objective of this study was to compare the efficacy and safety of ESD and EMR for such lesions. We searched databases, such as PubMed, EMBASE, Cochrane Library and Science Citation Index updated to 2013 for related trials. In the meta-analysis, the main outcome measurements were the en bloc resection rate, the histologically resection rate and the local recurrence rate. We also compared the operation time and the incidences of procedure-related complications. Five trials were identified, and a total of 710 patients and 795 lesions were included. The en bloc and histologically complete resection rates were higher in the ESD group compared with the EMR group (odds ratio (OR) 27.3; 95% CI, 11.5-64.8; OR 18.4; 95% CI, 8.82-38.59). The local recurrence rate was lower in the ESD group (OR 0.13, 95 % CI 0.04-0.43). The meta-analysis also showed ESD was more time consuming, but did not increase the complication rate (P=0.76). The results implied that compared with EMR, ESD showed better en bloc and histologically resection rates, and lower local recurrence, without increasing the incidence of procedure-related complications in the treatment of early esophageal carcinoma.

Creation of simulated papillae for endoscopic sphincterotomy and papillectomy training by using in vivo and ex vivo pig model (with videos)

BACKGROUND

There are few in vivo and ex vivo models for training in endoscopic sphincterotomy (ES) and endoscopic papillectomy (EP).

OBJECTIVE

We describe in vivo and ex vivo training pig models that use a simulated papilla for hands-on teaching of ES and EP.

DESIGN

Animal experiment.

SETTING

A referral center.

MATERIALS AND INTERVENTIONS

Hyaluronate solution (0.4%) was injected submucosally using a 25-gauge sclerotherapy needle to create a submucosal bleb by using porcine in vivo stomach, ex vivo stomach, and ex vivo rectum. ES and EP were then performed by using a pull-type sphincterotome and snare, respectively.

MAIN OUTCOME MEASUREMENT

The feasibility of creating a simulated papilla for ES and EP procedures was tested by experienced and nonexperienced ERCP endoscopists.

RESULTS

Creation of a hemispheroidal bulge was successful in 13 of 17 (76%) areas within an in vivo stomach, 13 of 16 (81%) areas of an ex vivo stomach, and 16 of 16 (100%) areas in an ex vivo rectum. In the in vivo stomach model, ES was successfully and realistically performed on the anterior wall of the stomach rather than in other walls. In the ex vivo stomach model, endoscopists experienced in ERCP and trainees performed ES without difficulty, whereas it was difficult or impossible for nonexperienced trainees to perform ES. In the ex vivo rectum model, all 3 endoscopists were able to complete not only ES but also EP.

LIMITATIONS

Pilot study.

CONCLUSIONS

Although further studies are necessary to evaluate the reproducibility and cost-effectiveness, this novel pig model appears useful for ES and EP training.

Endoscopic resection of large colon polyps

Endoscopic resection, including polypectomy, endoscopic mucosal resection, and endoscopic submucosal dissection, is the preferred treatment method of large colorectal polyps. Its safety and efficacy have been shown. Endoscopic removal techniques are important because they provide a resection specimen for precise histopathologic staging to further direct diagnosis, prognosis, and management decisions. Used according to its indications, it provides curative resection and obviates the higher morbidity, mortality, and cost associated with alternative surgical treatment.

Endoscopic submucosal dissection--current success and future directions

More than 10 years have passed since endoscopic submucosal dissection (ESD) was first developed in Japan. ESD enables en bloc complete resection of superficial gastrointestinal neoplasms regardless of the size and location of the lesions. With improvements in techniques and devices, excellent therapeutic results have been achieved despite the inherent technical difficulties of this procedure. ESD aiming for curative treatment can be performed for gastrointestinal neoplasms without risk of lymph node metastasis. Accurate histopathologic examination of the resected specimen is required to determine the risk of lymph node metastasis, for which en bloc resection is beneficial. Owing to the high success rate of en bloc complete resection and accurate histopathologic examination, tumour recurrence rates after ESD are reported to be very low in Japan. Excellent results of ESD in a large number of cases have also been reported from other Asian countries such as South Korea, Taiwan and China. Although scepticism exists among Western clinicians regarding the application of ESD, it is developing slowly and reports indicate promising results in some European countries. With further development of technologies, such as endoscopic robotics, ESD could become the worldwide treatment of choice for early gastrointestinal neoplasms.

[Endoscopic submucosal dissection in our practice -- new possibilities in the endoscopic treatment of neoplastic changes in the alimentary canal]

Endoscopic submucosal dissection is a promising new endoscopic technique for en block resection of early, superficial, flat, and laterally spreading gastrointestinal neoplasms. The primary aims of this prospective study were to summarize the first Hungarian experience with endoscopic submucosal dissection, and to compare the experimental in vivo procedures in pigs with the human application of this technique in two academic centers.

METHODS

The ex vivo Erlangen pig model was used until initial competence was achieved. Thereafter 15 endoscopic submucosal dissection procedures were performed in up to 5 sessions in living pigs under general anesthesia. After submucosal injection with saline Fujinone ball tip, a Flush knife was used with a transparent hood for circumferential incision and submucosal dissection. The following variables were analyzed: specimen size, complete and en bloc resection rate, total duration of the procedure, and complications. Furthermore, between 2009 and 2012, 14 endoscopic submucosal dissections were carried out in humans; 1 duodenal, 3 gastric and 10 colorectal interventions were performed due to large laterally spreading intramucosal neoplasms. The specimen size, en bloc resection rate, total duration of the procedure and complications were next analyzed.

RESULTS

87% complete resection rate, 29.4 ± 19.5 cm2 specimen size and 136.2 ± 26.8 min of procedure duration were achieved in the live pig models. Nontransmural damages of the muscular layer occurred in 3/15 (20%) cases which were successfully closed with hemoclips, except in one pig that died due to fatal esophageal perforation. All bleedings were easily managed with hot biopsy forceps coagulation and hemoclips without hemodynamic instability. In humans, endoscopic submucosal dissection was accomplished with an 11/14 (79%) en block resection rate, with average resected specimen size of 11.56 ± 4.9 cm2 and with 157 ± 55 min of operating time. Two cases of bleeding and 2 cases of perforation occurred (14%), all of which were managed endoscopically. After 1.5 year of average follow up, local recurrence occurred in one case only. In addition, due to the 3 incomplete resections and unsuccessful endoscopic submucosal dissection, surgical intervention was required in 4 cases altogether.

CONCLUSIONS

This study demonstrates the first Hungarian experience with endoscopic submucosal dissection. Training in live pig models could help endoscopists to overcome the learning curve and minimize the risk of complications before starting the procedure in humans. Reduction in the resection time and low risk of complications, especially bleeding, could be achieved by the application of a flush knife.

Tumor budding as a risk factor of lymph node metastasis in submucosal invasive T1 colorectal carcinoma: a retrospective study

Background

This study was designed to identify risk factors for lymph node metastasis of early stage colorectal cancer, which was confirmed to a carcinoma that invaded the submucosa after radical resection.

Methods

In total, 55 patients revealing submucosal invasive colorectal carcinoma on pathology who underwent curative radical resection at the Department of Surgery, St. Vincent’s Hospital, The Catholic University of Korea from January 2007 to September 2010 were evaluated retrospectively. Tumor size, depth of submucosal invasion, histologic grade, lymphovascular invasion, tumor budding, and microacinar structure were reviewed by a single pathologist. Student t-test for continuous variables and Chi-square test for categorical variables were used for comparing the clinicopathological features between two groups (whether lymph node involvement existed or not). Continuous variables are expressed as the mean ± standard error while statistical significance is accepted at P < 0.05.

Results

The mean age of 55 patients (34 males and 21 females) was 61.2 ± 9.6 years (range, 43–83). Histologically, eight (14.5%) patients had metastatic lymph node. In the univariate analysis, tumor budding (P = 0.047) was the only factor that was significantly associated with lymph node metastasis. Also, the tumor budding had a sensitivity of 83.3%, a specificity of 60.5%, and a negative predictive value of 0.958 for lymph node metastasis in submucosal invasive T1 colorectal cancer.

Conclusions

The tumor budding seems to have a high sensitivity (83.3%), acceptable specificity (60.5%), and a high negative predictive value (0.958). A close examination of pathologic finding including tumor budding should be performed in order to manage early CRC properly.

Effective training system in colorectal endoscopic submucosal dissection

Although colorectal endoscopic submucosal dissection (ESD) is superior to endoscopic mucosal resection (EMR) in en bloc resection rate, it is technically quite difficult because of the anatomical and histological characteristics of the colorectal wall. This difficulty prevents wide spread of the technique. Establishment of the training system for colorectal ESD is necessary to standardize training and to achieve wider acceptance of this technique. Herein, we describe our training system for colorectal ESD, and assess the validity of the training system for colorectal ESD, based on the clinical outcomes and learning curve of trainees. Our training system for colorectal ESD would help the spread of this procedure.

Endoscopic submucosal dissection for pig esophagus by using photocrosslinkable chitosan hydrogel as submucosal fluid cushion

BACKGROUND

Hypertonic saline solution (HS) as a submucosal fluid cushion (SFC) for endoscopic submucosal dissection (ESD) has several disadvantages, including a short effect duration and increased risk of bleeding and perforation. Photocrosslinkable chitosan hydrogel in DMEM/F12 medium (PCH) can be converted into an insoluble hydrogel by UV irradiation for 30 seconds.

OBJECTIVE

To evaluate the feasibility, usefulness, and safety of PCH as an SFC for ESD of esophagi, compared with HS and sodium hyaluronate (SH).

DESIGN

Survival animal study.

SETTINGS

Research laboratory study of 24 pig models in vivo.

INTERVENTIONS

Twenty-four pigs were used in the 2 steps: First, ESD of the esophagus was performed with PCH, SH, or HS (each n = 6) as an SFC, and the effects of these agents on wound healing were examined endoscopically and histologically. Second, in vivo degradation of PCH (n = 3) and HS (n = 3) was examined in independent pig esophagi.

MAIN OUTCOME MEASUREMENTS

Outcome measurements included feasibility and safety of PCH-assisted ESD of esophagus, gross and histologic evidence of the treated esophagus, biodegradation of injected PCH, and clinical tolerance by the animals.

RESULT

PCH injection led to a longer-lasting elevation with clearer margins compared with SH and HS, thus enabling precise ESD along the margins of the elevated mucosa without complications such as bleeding and perforation. The aspects of wound repair after PCH-assisted ESD were similar to those of SH- and HS-assisted ESDs. Biodegradation of PCH was confirmed to be almost completed within 8 weeks on the basis of endoscopic and histologic observations.

LIMITATIONS

In vivo animal model study.

CONCLUSION

PCH permits more reliable ESD of the esophagus without complications than do SH and HS. Furthermore, the applied PCH appeared to be completely biodegraded within 8 weeks. Thus, PCH is a promising agent as an SFC in ESD of the esophagus.

Sodium alginate as an ideal submucosal injection material for endoscopic submucosal resection: preliminary experimental and clinical study

BACKGROUND

Sodium alginate is used clinically in the treatment of peptic ulcer disease. Because of its viscosity, sodium alginate could possibly become a new submucosal injection material for use in endoscopic resection.

OBJECTIVE

We evaluated the feasibility of endoscopic submucosal dissection (ESD) using sodium alginate.

SETTING AND INTERVENTIONS

The lesion-lifting properties of sodium alginate were examined in porcine stomachs and were compared with those of normal saline solution and sodium hyaluronate solution. After confirming the proper concentration of sodium alginate, ESD using sodium alginate was performed in 11 patients with gastric mucosal cancer or adenoma.

MAIN OUTCOME MEASUREMENT

The lesion-lifting properties of sodium alginate and clinical outcomes were assessed.

RESULTS

The thickness of the submucosal elevation created by 3% sodium alginate in porcine stomach was equivalent to that of sodium hyaluronate. ESD using sodium alginate was completed successfully in all patients without adverse effects except in 1 patient in whom transient shrinkage of the gastric wall disappeared spontaneously after approximately 30 minutes. The mean tumor size was 15.3 mm. En bloc resection and a negative resection margin were obtained in all. Histopathologic examination revealed that all tumors were confined to the mucosal layer except for 1 that was confined to the submucosal layer without lymphovascular invasion, and there were no adverse effects such as tissue damage. No patient required additional treatment, and none showed recurrence during a median follow-up period of 28 months.

LIMITATIONS

Small sample size.

CONCLUSION

This preliminary study suggests that sodium alginate might be a novel, safe submucosal injection material for use in endoscopic resection. Further investigation of the properties of sodium alginate is warranted.

Endoscopic submucosal dissection for colonic lesions: why and how should we do it?

Endoscopic submucosal dissection (ESD) is a safe and effective alternative to surgery for large non-polypoid colonic lesions and early colorectal carcinoma. In this article, we discuss the development, efficacy and safety of ESD. As the incidence of colorectal cancer is rapidly increasing in Asia, we advocate standardization of ESD program, including patient selection, hardware prerequisites, and training of operators.

Learning curve for endoscopic submucosal dissection of large colorectal tumors

BACKGROUND AND AIM

No studies have previously described the learning curve for colonic endoscopic submucosal dissection (ESD). The aim of the present study was to describe the learning curve for ESD of large colorectal tumors based on a single colonoscopist's experience.

METHODS

ESD was carried out for 120 colorectal tumors in 115 patients (68 males, median age 70 years). All procedures were carried out by a single experienced colonoscopist. The cases were grouped chronologically into three periods: (1st): cases 1-40; (2nd): cases 41-80; and (3rd): cases 81-120.

RESULTS

The learning curve was the changes in proficiency over time. Proficiency was expressed as procedure time per unit area of specimen. In the 1st, 2nd and 3rd periods, the proficiencies were 18.9, 12.6 and 12.9 (min/cm(2) ), respectively. The proficiencies in the 2nd and 3rd periods were significantly shorter than in the 1st period (t-test, P < 0.05). The en-bloc resection rates of the 1st, 2nd and 3rd periods were 92.5% (37/40), 90% (36/40) and 97.5% (39/40), respectively. The en-bloc and R0 resection rates of the 1st, 2nd and 3rd periods were 85% (34/40), 77.5% (31/40) and 92.5% (37/40), respectively. The perforation rates of the 1st, 2nd and 3rd periods were 12.5% (5/40), 5% (2/40) and 5% (2/40), respectively.

CONCLUSION

Based on our analysis of the learning curve, approximately 80 procedures must be carried out to acquire skill with ESD for large colorectal tumors. However, approximately 40 procedures were sufficient to acquire skill in avoiding perforations during the ESD procedure.

Comparative performance of novel solutions for submucosal injection in porcine stomachs: An ex vivo study

BACKGROUND

Submucosal injection of normal saline (NS) is commonly used during endoscopic mucosal resection (EMR) and endoscopic submucosal dissection (ESD) but is quickly absorbed. Sodium hyaluronate (SH) produces longer lasting mucosal elevation but is expensive.

AIMS

To evaluate the performance of novel solutions for submucosal injection in comparison with NS and SH.

METHODS

One ml of the following solutions was injected in the submucosa of fresh specimens of porcine stomachs: NaCl 0.9%, SH 0.4%, human albumin 25%, two artificial tears solutions, namely, hydroxypropyl methylcellulose (HPMC) 0.3%/dextran 70.1% and polyvinyl alcohol (PVA) 1.4%, hydroxyethyl starch (HES) 6% and polyethylene glycol (PEG) 50%. The time until the disappearance of the mucosal elevation was recorded in a blind manner.

RESULTS

The median duration of mucosal elevation was significantly longer with HPMC/dextran, PVA, HES, PEG and SH (29, 26, 38, 31.5, and 41.5min, respectively) compared with NS (12min) (p<0.05 for each comparison). There were no significant time differences between SH and HPMC/dextran, HES and PEG (p>0.05).

CONCLUSIONS

Novel viscous or hypertonic solutions for submucosal injection, perform better than normal saline and equally well as sodium hyaluronate in porcine stomachs in vitro.

Evaluation of venous invasion by Elastica van Gieson stain and tumor budding predicts local and distant metastases in patients with T1 stage colorectal cancer

Evaluation of pathologic predictors of metastases in T1 stage colorectal cancer may be difficult with hematoxylin and eosin (HE) staining alone. The aim of this study was to clarify the role of pathologic predictors by using immunohistochemical staining and Elastica van Gieson (EVG) staining. One hundred and twenty-four patients who underwent bowel resection for single T1 stage colorectal cancer from 1990 to 2004 in 1 institution were studied. D2-40, EVG staining, and CAM5.2 were used to detect lymphatic invasion, venous invasion, and tumor budding, respectively. These 3 factors were separately evaluated based on HE staining. Histology was reviewed by 1 pathologist. Lymph node metastases in the surgical specimen were the standard reference, and distant metastases were identified by periodic computed tomography for 2 years or more after surgery. A logistic regression model was applied to analyze risk factors for lymph node metastases and a Cox regression model for distant metastases. In predicting lymph node metastases, univariate analysis demonstrated significance for all predictors except venous invasion by HE staining. Multivariate analysis showed that venous invasion by EVG and tumor budding by HE showed significance as predictors. In predicting distant metastases, univariate analysis showed significance for lymphatic invasion shown by D2-40, tumor budding shown by CAM5.2 and HE, and lymph node metastases. Multivariate analysis showed only venous invasion by EVG stain as being significantly associated with distant metastases (P=0.001). In conclusion, venous invasion evaluated shown by EVG staining is a useful pathologic predictor for metastases in T1 stage colorectal cancer.

Local recurrence after endoscopic resection of colorectal tumors

BACKGROUND AND AIMS

Local recurrence frequently occurs after endoscopic resection of large colorectal tumors. However, appropriate intervals for surveillance colonoscopy to assess local recurrence after endoscopic resection have not been clarified. The aim of the present study was to determine local recurrence rates following en-bloc and piecemeal endoscopic resection and establish appropriate surveillance colonoscopy intervals based on retrospective analysis of local recurrences.

MATERIALS AND METHODS

A total of 461 patients with 572 > or = 10-mm lesions underwent endoscopic resection and follow-up. We retrospectively compared local recurrence rates on lesion size, macroscopic type, and histological type after en-bloc resection (440 lesions) and piecemeal resection (132 lesions). Cumulative local recurrence rates were analyzed using the Kaplan-Meier method.

RESULTS

Local recurrence occurred for 34 lesions (5.9%). Local recurrence rates for the en-bloc and piecemeal groups was 0.7% (3/440) and 23.5% (31/132), respectively (P < 0.001). The difference between the two groups was distinct in terms of lesion size, macroscopic type, and histological type. Of the 34 local recurrences, 32 were treated endoscopically and two cases required additional surgery. The 6-, 12-, and 24-month cumulative local recurrence rate of the en-bloc group was 0.24%, 0.49%, and 0.81%. Then the 6-, 12-, and 24-month cumulative local recurrence rate for the piecemeal group was 18.4%, 23.1%, and 30.7%.

CONCLUSION

Local recurrence occurred more frequently after piecemeal resection than en-bloc resection. However, almost all cases of local recurrences could be cured by additional endoscopic resection, so piecemeal resection can be acceptable treatment.

Colorectal endoscopic submucosal dissection: present status and future perspective, including its differentiation from endoscopic mucosal resection

Endoscopic submucosal dissection (ESD) allows en bloc resection of a lesion, irrespective of the size of the lesion. ESD has been established as a standard method for the endoscopic ablation of malignant tumors in the upper gastrointestinal (GI) tract in Japan. Although the use of ESD for colorectal lesions has been studied via clinical research, ESD is not yet established as a standard therapeutic method for colorectal lesions because colorectal carcinoma has unique pathological, organ specific characteristics that differ radically from those of the esophagus and stomach, and scope handling and control is more difficult in the colorectum than in the upper GI tract. Depending on the efficacy of endoscopic mucosal resection (EMR) and the clinicopathological characteristics of the colorectal tumor, the proposed indications for colorectal ESD are as follows: (1) lesions difficult to remove en bloc with a snare EMR, such as nongranular laterally spreading tumors (particularly the pseudo depressed type), lesions showing a type VI: pit pattern, and large lesions of the protruded type suspected to be carcinoma; (2) lesions with fibrosis due to biopsy or peristasis; (3) sporadic localized lesions in chronic inflammation such as ulcerative colitis; and (4) local residual carcinoma after EMR. Colorectal ESD is currently in the development stage, and a standard protocol will be available in the near future. We hope that colorectal tumors will be efficiently treated by a treatment method appropriately selected from among EMR, ESD, and surgical resection after precise preoperative diagnosis based on techniques such as magnifying colonoscopy.

Usefulness and safety of 0.4% sodium hyaluronate solution as a submucosal fluid "cushion" for endoscopic resection of colorectal mucosal neoplasms: a prospective multi-center open-label trial

BACKGROUND

Sodium hyaluronate (SH) solution has been used for submucosal injection in endoscopic resection to create a long-lasting submucosal fluid "cushion". Recently, we proved the usefulness and safety of 0.4% SH solution in endoscopic resection for gastric mucosal tumors. To evaluate the usefulness of 0.4% SH as a submucosal injection solution for colorectal endoscopic resection, we conducted an open-label clinical trial on six referral hospitals in Japan.

METHODS

A prospective multi-center open-label study was designed. A total of 41 patients with 5-20 mm neoplastic lesions localized in the colorectal mucosa at six referral hospitals in Japan in a single year period from December 2002 to November 2003 were enrolled and underwent endoscopic resection with SH. The usefulness of 0.4% SH was assessed by the en bloc complete resection and the formation and maintenance of mucosal lesion-lifting during endoscopic resection. Safety was evaluated by analyzing adverse events during the study period.

RESULTS

The usefulness rate was high (82.5%; 33/40). The following secondary outcome measures were noted: 1) steepness of mucosal lesion-lifting, 75.0% (30/40); 2) intraoperative complications, 10.0% (4/40); 3) time required for mucosal resection, 6.7 min; 4) volume of submucosal injection, 6.8 mL and 5) ease of mucosal resection, 87.5% (35/40). Two adverse events of bleeding potentially related to 0.4% SH were reported.

CONCLUSION

Using 0.4% SH solution enabled sufficient lifting of a colorectal intramucosal lesion during endoscopic resection, reducing the need for additional injections and the risk of perforation. Therefore, 0.4% SH may contribute to the reduction of complications and serve as a promising submucosal injection solution due to its potentially superior safety in comparison to normal saline solution.

Different solutions used for submucosal injection influenced early healing of gastric endoscopic mucosal resection in a preclinical study in experimental pigs

Background

We hypothesised that different solutions for submucosal injection may influence early healing of endoscopic mucosal resection (EMR). The aim of this study was to evaluate histological and immunological changes after EMR in experimental pigs.

Materials and methods

Two parallel EMRs on the anterior and posterior wall of the gastric body were performed by means of the cap technique in 21 female pigs. A glycerol-based solution (anterior EMR) and hydroxypropyl methylcellulose solution (posterior EMR) were applied for submucosal injection. The animals were sacrificed 7 days later, and tissue sections of all EMRs were stained using combined trichrome. Computer image analysis was used for objective evaluation of elastic and collagen fibres content. Two-colour indirect immunophenotyping of blood and gastric samples were performed using mouse anti-pig monoclonal antibodies.

Results

The values of collagen fibre content 7 days after EMR were significantly higher in lesions after the use of solution A in comparison with solution B (2.10 ± 0.25% versus 1.57 ± 0.25%, p = 0.009). Concordant results were found in elastic fibres (3.23 ± 0.49% versus 2.93 ± 0.61%, p = 0.018). No systemic changes in major leukocyte subpopulations were found. In gastric tissue, lymphocyte subsets exhibited only minor changes. CD4⁺ T-lymphocytes were increased in the healing tissue after EMR using solution A (17.08 ± 9.24% versus 9.76 ± 7.97%, p = 0.011). Significant increase of SWC3⁺ leukocytes was observed after EMR using solution B (47.70 ± 25.41% versus 18.70 ± 12.16%, p = 0.001).

Conclusions

The use of glycerol-based solution for submucosal injection was associated with more pronounced histological signs of early healing of EMRs compared with hydroxypropyl methylcellulose.

Usefulness and safety of 0.4% sodium hyaluronate solution as a submucosal fluid "cushion" in endoscopic resection for gastric neoplasms: a prospective multicenter trial

BACKGROUND

Sodium hyaluronate (SH) solution has been used for submucosal injection in endoscopic resection to create a long-lasting submucosal fluid "cushion."

OBJECTIVES

Our purpose was to assess the usefulness and safety of 0.4% SH solution in endoscopic resection.

DESIGN

A prospective multicenter randomized controlled trial.

SETTING

Six referral hospitals in Japan.

PATIENTS

One hundred forty patients with 5- to 20-mm gastric intramucosal neoplastic lesions.

INTERVENTIONS

Patients were randomized into 0.4% SH and control groups. Endoscopic resection was performed with 0.4% SH or normal saline solution for submucosal injection.

PRIMARY OUTCOME MEASURE

The usefulness of 0.4% SH solution was assessed by en bloc complete resection and the formation and maintenance of mucosal lesion-lifting during endoscopic resection.

SECONDARY OUTCOME MEASURES

(1) steepness of mucosal lesion lifting, (2) complications, (3) time required for mucosal resection, (4) volume of submucosal injection solution, and (5) ease of mucosal resection. Safety was assessed by analyzing adverse events during the study period.

RESULTS

The usefulness rate was significantly higher for the 0.4% SH group (88.4%, 61/69) than for the control group (58.6%, 41/70). As secondary outcome measures, significant intergroup differences (P < .001) were noted for (1) steepness of mucosal lesion lifting, (2) volume of submucosal injection solution, and (3) ease of mucosal resection. No serious adverse events were encountered in either group.

LIMITATIONS

Lack of blinding. Safety was not a powered outcome measure.

CONCLUSIONS

Using 0.4% SH as a submucosal injection solution in endoscopic resection enabled the formation and maintenance of sufficient mucosal lesion lifting for gastric intramucosal lesions, reducing the need for additional injections and simplifying mucosal resection. Use of 0.4% SH thus simplifies the complicated procedures involved in endoscopic resection.

Submucosal cushioning with water jet before endoscopic mucosal resection : Which fluids are effective?

BACKGROUND

Several new techniques have recently been described that allow the endoscopic mucosal resection even of broad-based flat lesions in the gastrointestinal tract. The technique recently described by us of using a water jet dissector (Helix HydroJet) for a selective deposition of liquid in the submucosal lamina has now been combined with different substances, and their effects have been compared.

MATERIAL AND METHODS

Gastroscopies were carried out in 8 pigs under intubation anesthesia, and 2 submucosal cushions each were created in the stomach using one out of 4 test substances (gelatin, glucose 50, hydroxyethyl starch [HES] 10%, dextran 40), as well as one cushion of isotonic saline solution placed in each area via the Helix HydroJet). The height of the submucosal cushions was intermittently measured over a period of 40 or 20 min, respectively, by miniprobe endosonography. In 7 of the animals the stomach was subsequently subjected to mucosal resection. The specimens and the gastric wall were histologically assessed to evaluate the localization of the liquid cushion and the effect on adjacent layers of the gastric wall.

RESULTS

All test substances produced strictly selective liquid cushions in the submucosa. With HES 10% and dextran the maximum height of the cushions initially increased and then decreased during the further course to an average of 90% of the initial height within 40 min. Isotonic saline solution showed the most rapid decrease in height (72% after 20 min). The histological assessment confirmed the selective nature of the liquid deposit in the submucosa.

DISCUSSION

Plasma expanders produced cushions that initially increased in height but then remained constant for a longer period than cushions produced using glucose 50, gelatin, or isotonic saline solution. The combination of transmucosal jet application for elevation of the mucosa with plasma expanders is therefore an interesting approach to optimize endoscopic mucosal resections.

Technology insight: endoscopic submucosal dissection of gastrointestinal neoplasms

Gastrointestinal neoplasms can be cured by local resection as long as the lesions are in the early stage and have not metastasized. Endoscopic resection is a minimally invasive treatment for early-stage gastrointestinal neoplasms, and endoscopic submucosal dissection (ESD) is one type of endoscopic resection that has been developed in the past 10 years. For ESD to be a reliable, curative treatment for gastrointestinal neoplasms, it is necessary for the endoscopist to detect the lesion early, make a precise pretreatment diagnosis, ensure that the patient has the correct indication for endoscopic resection, and have the skill to perform ESD. For early lesion detection, endoscopists should pay attention to subtle changes in the surface structure, the color of the mucosa and the visibility of underlying submucosal vessels. Chromoendoscopy and magnifying endoscopy are useful for determining the margin of the lesions for pretreatment diagnosis, and endoscopic ultrasonography and magnifying endoscopy are useful for determining the depth of invasion. For ESD to be successful, local injection of sodium hyaluronate helps maintain mucosal elevation during dissection. Selecting the appropriate knife, using transparent hoods wisely, employing a good strategy that uses gravity, and having good control of bleeding are all needed to make ESD reliable.