Cadaver-based therapeutic endoscopic training for peroral endoscopic myotomy: A realistic model for skill acquisition

Cadaver-based therapeutic endoscopic training for peroral endoscopic myotomy: A realistic model for skill acquisition | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Method Article Cadaver-based therapeutic endoscopic training for peroral endoscopic myotomy: A realistic model for skill acquisition Maiko Tabuchi, Keiichi Hashiguchi, Hitomi Minami, Aya Wakamatsu, and 12 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7965920/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 29 Dec, 2025 Read the published version in Anatomical Science International → Version 1 posted You are reading this latest preprint version Abstract The rarity of achalasia has led to limited opportunities for practical training in educational environments. Cadaver surgical training was developed to enhance surgical skills by providing physicians with experience comparable to that of on-the-job training using structures identical to living organs, thereby proving highly beneficial. Recently, cadavers have been preserved using the Thiel method, which maintains both mobility and organizational flexibility. However, there are few reports on therapeutic endoscopy, including peroral endoscopic myotomy, in the context of cadaver surgical training. We investigated the feasibility of using cadaver surgical training for therapeutic endoscopy training, termed Cadaver-based Therapeutic Endoscopy Training, for peroral endoscopic myotomy. This study was conducted in 2024 at the Cadaver Surgical Center of Nagasaki University using four cadavers preserved using the Thiel method. We performed peroral endoscopic myotomies on three cadavers and evaluated the observability of the esophageal mucosa, penetration of the local injection fluid, feasibility of creating a submucosal tunnel, visibility of indocyanine green injection, and inner circular muscle incision. The layered structure of the digestive tract was well preserved in the Thiel-fixed cadavers, and peroral endoscopic myotomy was performed without major issues. Cadaver-based Therapeutic Endoscopy Training may serve as a realistic training model comparable to living organs and may be beneficial for peroral endoscopic myotomy training. Achalasia cadaver surgical training Cadaver-based Therapeutic Endoscopy Training peroral endoscopic myotomy training model Figures Figure 1 Figure 2 Figure 3 Introduction Peroral endoscopic myotomy (POEM) is an endoscopic procedure used to treat achalasia [1](Inoue et al. 2009 ). The rarity of achalasia poses significant challenges for medical trainees to gain adequate experience managing this condition [2](Gonzalez et al. 2023 ). According to the POEM training guidelines of the European Society of Gastrointestinal Endoscopy [3](Tate et al. 2025 ), at least 20 cases of ex vivo or animal training and at least 10 cases under expert supervision for initial human POEM, as on-the-job training (OJT), are needed [3](Tate et al. 2025 ). Human training involves learning through direct patient care. This step provides real-world experience and cultivates essential skills, such as managing bleeding or perforation, which are difficult to replicate through the simulator, although it can be stressful for trainees and involves potential risks. In addition, due to the low prevalence of achalasia, trainees often have limited opportunities to encounter and manage patients with achalasia during their training periods. Consequently, trainees may struggle to develop the skills and confidence necessary to effectively manage patients with achalasia. To compensate for the scarcity and concern for safety in POEM training, ex vivo training and animal models have been the predominant approaches for initial training in endoscopic procedures, including POEMs [2,3](Gonzalez et al. 2023 ; Tate et al. 2025 ). However, the use of animal models poses several challenges, such as the need for ethical considerations regarding animal welfare and limited reproducibility due to anatomical differences. Cadaver surgical training (CST) is a valuable training method used before OJT [4](Tominaga et al. 2022 ). This allows for repeated practice, error correction, and experimentation, fostering a deeper understanding of surgical procedures. The embalming method reported by Thiel utilizes a lower concentration of formalin (3–6%) than the conventional method (8–10%) and incorporates food-grade additives, such as propylene glycol and sodium bisulfite [5](Thiel 1992 ). This technique preserves the texture and mobility of the skin, muscles, blood vessels, nerves, and ligaments. Therefore, the motility and flexibility of the organs are sufficiently maintained to perform surgery. Cadaver training on cadavers preserved via the Thiel method has been conducted since 2017 at Nagasaki University, with a focus on surgical training [4](Tominaga et al. 2022 ). Although the utility of CST as an educational instrument is recognized within the surgical discipline, there are only a few studies addressing its application in endoscopic procedures [6–8](Rohr et al. 2023 ; Finocchiaro et al. 2021 ; Balekuduru and Appaji 2021 ). Furthermore, the human anatomy of cadavers ensures a consistent training experience and facilitates procedural skills applicable to actual clinical practice. To the best of our knowledge, there are no reports of advanced endoscopy methods, such as POEMs, in Thiel-fixed cadavers. In this study, we assessed whether cadaver-based therapeutic endoscopic training (CTET) could serve as an effective form of POEM training. Methods In 2024, we conducted POEMs on four cadavers preserved using the Thiel method. The training was conducted using human cadavers donated for medical education, with full respect for donor dignity and the “Guidelines for Cadaver Dissection in Education and Research of Clinical Medicine” in Japan. The study protocol was reviewed and approved by the Ethics Committee of the Nagasaki University Graduate School of Biomedical Sciences (approval number: 21052801-2). Consent for CST was obtained from the donors and their families before death. The equipment used in this study comprised a scope (GIF-H290T; Olympus, Tokyo, Japan) and a VIO 300D (AMCO, Tokyo, Japan) electrosurgical generator. The procedure used a Flush knife BT-S (FUJIFILM, Tokyo, Japan), Triangle Tip Knife J (Olympus, Tokyo, Japan), and normal saline stained with indigo carmine as the injection solution. The treatment devices used in this study were reused with a prior cleaning process. The evaluation of the POEM procedure comprised observability of the mucosa, penetration of local injection fluid into the submucosal layer, feasibility of creating a submucosal tunnel, and visibility of indocyanine green (ICG) injection [9](Minami et al. 2015 ) (attempted in cases 2 and 3), and the ability to incise the circular muscles of the esophagus while leaving the longitudinal muscle intact. During POEM, it is customary to close the entry point into the submucosal tunnel using clips at the conclusion of the surgery. However, this step was not performed in this study due to the inability to secure consent from the bereaved families for the presence of foreign bodies. CTET for POEM Four cadavers underwent computed tomography (CT) scans before fixation. In three cases, the esophagus and stomach were confirmed to be empty (cases 1–3: each case shown in Figs. 1 – 3 , respectively), allowing POEM performance. However, in one case, POEM was not performed because the stomach was full due to intestinal obstruction. In all three cases (cases 1–3), the esophageal mucosa was intact, permitting normal observation (Figs. 1 a, 2 a, and 3 a). Although the pharyngeal section was stiff, we were able to insert the fiberscope into the esophagus. In Case 1, residual material was present during the initial observation; however, it was removed after applying water. The submucosal injection was successfully performed in all three cadavers (Figs. 1 b, 2 b, and 3 b). The integrity of the submucosal layer was preserved by using the Thiel method. Each layer, including the epithelium, submucosal layer, and muscular layer, was distinctly visualized and separated in a manner analogous to that observed in living tissues (Figs. 1 c, 2 c, and 3 b). Subsequently, a submucosal tunnel was successfully established in all three cadavers. The green coloration of the ICG was clearly detectable as a benchmark by administering a local injection into the gastric cardia (Figs. 2 d, 3 c, and 3 d) in the cadaveric cases (all ICG attempted cases, cases 2 and 3). The demarcation line between the submucosal layer and the inner circular muscle was clearly observable in all cases (Figs. 1 c, 2 c, and 3 d). Subsequently, a myotomy of the circular muscle was performed. Separation of the circular and longitudinal muscle layers was successfully achieved in all three cases. We confirmed that the longitudinal muscle was well-preserved after the procedure (Figs. 1 d, 1 e, 2 e, 2 f, 3 e, and 3 f). A representative case (case 3) is shown in the POEM video (Video 1). Video 1 Discussion This feasibility study suggests that CTET is suitable as a training model for POEM. This is because our procedural cases confirmed that all mucosal layer structures were preserved using the Thiel method. In particular, the ability to incise only the circular muscle while preserving the longitudinal muscle, along with confirming gastric access using ICG, demonstrates the high utility of this model for POEM training. In this validation study, POEM was performed at the 2 o'clock position in all cases. However, it was possible to perform three POEM procedures per cadaver at the 2, 5, and 7 o'clock positions, allowing trainees to gain additional opportunities for experience. The rarity of achalasia results in limited opportunities for trainees to practice POEMs. Thiel-fixed cadavers provide realistic anatomical representations, enabling trainees to familiarize themselves with human structures and variations. This is the first report to propose that cadaver therapeutic endoscopy training using POEM may significantly enhance the availability of ex vivo endoscopic treatment techniques. Cadaver training has certain limitations, particularly in replicating hemostatic procedures and managing intraoperative complications. Moreover, the selection of suitable cadavers for endoscopic training requires careful evaluation of the cause of death and pre-assessment using CT imaging. Another limitation is the restrictions on facilities. In Japan, CST is legally permitted only in medical universities and must be supervised by the Department of Anatomy [10](Japan Surgical Society and Japanese Association of Anatomists 2018). Furthermore, after cadaver training, OJT offers an invaluable experience in terms of patient interaction, real-time decision-making, and adaptation to unforeseen circumstances, which are essential components of therapeutic endoscopy practices that cannot be entirely replicated in cadaver training with experts. Conclusions CTET may serve as a realistic training model comparable to living organs and may be beneficial for POEM training. Declarations Conflict of Interest The authors declare that they have no conflicts of interest. Funding This research received no external funding. Author Contribution M.T. and K.H. prepared the initial draft and visual materials. K.H., A.W., K.S., D.E., Y.N., and K.O-T. organized the image data and verified image quality. H.M., H.I., J.S., T.A., M.T., K.M. and N.Y. supervised the interpretation of anatomical findings. K.O-T, H.M. and Y.A. provided overall academic supervision, coordinated the study, and finalized the manuscript. All authors have read and approved the final manuscript. Acknowledgement The authors sincerely thank those who donated their bodies to the field of anatomical research. The results of such research can potentially increase humankind’s overall knowledge and improve patient care. Therefore, the donors and their families deserve our highest gratitude. The authors also appreciate Olympus Medical Systems Corporation, Japan, for supplying the endoscopic equipment. References Balekuduru AB, Appaji AC (2021) Therapeutic endoscopic procedures on a human cadaver—A pilot feasibility study. J Dig Endosc 12:036–042 Finocchiaro M, Cortegoso Valdivia P, Hernansanz A, et al. (2021) Training simulators for gastrointestinal endoscopy: Current and future perspectives. Cancers (Basel) 13:1427 Gonzalez JM, Meunier E, Debourdeau A, et al. (2023) Training in esophageal peroral endoscopic myotomy (POEM) on an ex vivo porcine model: learning curve study and training strategy. Surg Endosc 37:2062–2069 Inoue H, Minami H, Satodate H, Kudo SE (2009) First clinical experience of submucosal endoscopic esophageal myotomy for esophageal achalasia with no skin incision. Gastrointest Endosc 69:AB122 Japan Surgical Society and Japanese Association of Anatomists. Guidelines for cadaver dissection in education and research of clinical medicine. 2018; Internet: https://jp.jssoc..jp/uploads/files/aboutus/guidelines/info20180406-01.pdf; Accessed: 07/01/2025 Minami H, Inoue H, Haji A, et al. (2015) Per-oral endoscopic myotomy: emerging indications and evolving techniques. Dig Endosc 27:175–181 Rohr A, Perrenot C, Pitta A, et al. (2023) Reperfused human cadaver as a new simulation model for colonoscopy: a pilot study. Surg Endosc 37:3224–3232 Tate DJ, Rodriguez de Santiago E, Montori M, et al. (2025) Curriculum for training in peroral endoscopic myotomy (POEM) in Europe (Part II) - Best Practice Techniques: European Society of Gastrointestinal Endoscopy (ESGE) Position Statement. Endoscopy 57:912–941 Thiel W (1992) The preservation of the whole corpse with natural color. Ann Anat 174:185–195 Tominaga T, Nonaka T, Fukuda A, et al. (2022) Usefulness of structured-cadaveric training for trans-anal pelvic exenteration. Asian J Endosc Surg 15:299–305 Additional Declarations No competing interests reported. Cite Share Download PDF Status: Published Journal Publication published 29 Dec, 2025 Read the published version in Anatomical Science International → Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. 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1","display":"","copyAsset":false,"role":"figure","size":955374,"visible":true,"origin":"","legend":"\u003cp\u003eEndoscopic findings in cadaver case 1. a) Esophageal mucosa. b) Local injection of normal saline and subsequent mucosal incision. c) The image illustrates the formation of a submucosal tunnel. The white arrow represents the inner circular muscle. d) Endoscopic image of the circular and longitudinal muscles (white arrows). e) The incision of the circular muscle was completed.\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-7965920/v1/b12f799c72994a3c57b1391e.png"},{"id":96049334,"identity":"0544ce46-0451-4d43-8416-25b5d3c6ca00","added_by":"auto","created_at":"2025-11-17 06:31:48","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":1091591,"visible":true,"origin":"","legend":"\u003cp\u003eEndoscopic findings in cadaver case 2. a) Esophageal mucosa. b) Local injection of normal saline and subsequent mucosal incision. c) The image illustrates the formation of a submucosal tunnel. The white arrow represents the inner circular muscle. d) Image showing the green color of indocyanine green in the submucosal tunnel. e) Endoscopic image revealing the incision of the circular muscle, thereby exposing the longitudinal muscle (white arrow). f) The myotomy was successfully completed.\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-7965920/v1/1ed3cb377f24986e4849dc8a.png"},{"id":96049335,"identity":"4be65c4f-db76-42e2-8af4-113965cf5677","added_by":"auto","created_at":"2025-11-17 06:31:48","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":1029443,"visible":true,"origin":"","legend":"\u003cp\u003eEndoscopic findings in cadaver case 3. a) The mucosa of the esophagus was observed to be in a condition closely resembling that of a living organism, with no residual matter detected. b) Following endoscopic injection of normal saline and subsequent mucosal incision, the submucosal layer becomes readily observable. c) The image illustrates the indocyanine green injection at the gastric cardia to indicate the endpoint (white arrow). d) Image showing the green color of the indocyanine green observed from the submucosal tunnel. e) Endoscopic image revealing the incision of the circular muscle, thereby exposing the longitudinal muscle (white arrow). f) The incision of the circular muscle was successfully completed.\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-7965920/v1/ee418c0edaaaaa6b589342b5.png"},{"id":99545268,"identity":"a02d6814-61fc-491c-95b5-a2d7821f73d7","added_by":"auto","created_at":"2026-01-05 16:04:56","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":4647086,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7965920/v1/18137e94-d58b-431e-bc21-5e19e33c3e85.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Cadaver-based therapeutic endoscopic training for peroral endoscopic myotomy: A realistic model for skill acquisition","fulltext":[{"header":"Introduction","content":"\u003cp\u003ePeroral endoscopic myotomy (POEM) is an endoscopic procedure used to treat achalasia [1](Inoue et al. \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e2009\u003c/span\u003e). The rarity of achalasia poses significant challenges for medical trainees to gain adequate experience managing this condition [2](Gonzalez et al. \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e2023\u003c/span\u003e). According to the POEM training guidelines of the European Society of Gastrointestinal Endoscopy [3](Tate et al. \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e2025\u003c/span\u003e), at least 20 cases of ex vivo or animal training and at least 10 cases under expert supervision for initial human POEM, as on-the-job training (OJT), are needed [3](Tate et al. \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e2025\u003c/span\u003e). Human training involves learning through direct patient care. This step provides real-world experience and cultivates essential skills, such as managing bleeding or perforation, which are difficult to replicate through the simulator, although it can be stressful for trainees and involves potential risks. In addition, due to the low prevalence of achalasia, trainees often have limited opportunities to encounter and manage patients with achalasia during their training periods. Consequently, trainees may struggle to develop the skills and confidence necessary to effectively manage patients with achalasia.\u003c/p\u003e\u003cp\u003eTo compensate for the scarcity and concern for safety in POEM training, ex vivo training and animal models have been the predominant approaches for initial training in endoscopic procedures, including POEMs [2,3](Gonzalez et al. \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e2023\u003c/span\u003e; Tate et al. \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e2025\u003c/span\u003e). However, the use of animal models poses several challenges, such as the need for ethical considerations regarding animal welfare and limited reproducibility due to anatomical differences.\u003c/p\u003e\u003cp\u003eCadaver surgical training (CST) is a valuable training method used before OJT [4](Tominaga et al. \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e2022\u003c/span\u003e). This allows for repeated practice, error correction, and experimentation, fostering a deeper understanding of surgical procedures. The embalming method reported by Thiel utilizes a lower concentration of formalin (3\u0026ndash;6%) than the conventional method (8\u0026ndash;10%) and incorporates food-grade additives, such as propylene glycol and sodium bisulfite [5](Thiel \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e1992\u003c/span\u003e). This technique preserves the texture and mobility of the skin, muscles, blood vessels, nerves, and ligaments. Therefore, the motility and flexibility of the organs are sufficiently maintained to perform surgery. Cadaver training on cadavers preserved via the Thiel method has been conducted since 2017 at Nagasaki University, with a focus on surgical training [4](Tominaga et al. \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e2022\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eAlthough the utility of CST as an educational instrument is recognized within the surgical discipline, there are only a few studies addressing its application in endoscopic procedures [6\u0026ndash;8](Rohr et al. \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e2023\u003c/span\u003e; Finocchiaro et al. \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2021\u003c/span\u003e; Balekuduru and Appaji \u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e2021\u003c/span\u003e). Furthermore, the human anatomy of cadavers ensures a consistent training experience and facilitates procedural skills applicable to actual clinical practice. To the best of our knowledge, there are no reports of advanced endoscopy methods, such as POEMs, in Thiel-fixed cadavers.\u003c/p\u003e\u003cp\u003eIn this study, we assessed whether cadaver-based therapeutic endoscopic training (CTET) could serve as an effective form of POEM training.\u003c/p\u003e"},{"header":"Methods","content":"\u003cp\u003eIn 2024, we conducted POEMs on four cadavers preserved using the Thiel method. The training was conducted using human cadavers donated for medical education, with full respect for donor dignity and the \u0026ldquo;Guidelines for Cadaver Dissection in Education and Research of Clinical Medicine\u0026rdquo; in Japan. The study protocol was reviewed and approved by the Ethics Committee of the Nagasaki University Graduate School of Biomedical Sciences (approval number: 21052801-2). Consent for CST was obtained from the donors and their families before death.\u003c/p\u003e\u003cp\u003eThe equipment used in this study comprised a scope (GIF-H290T; Olympus, Tokyo, Japan) and a VIO 300D (AMCO, Tokyo, Japan) electrosurgical generator. The procedure used a Flush knife BT-S (FUJIFILM, Tokyo, Japan), Triangle Tip Knife J (Olympus, Tokyo, Japan), and normal saline stained with indigo carmine as the injection solution. The treatment devices used in this study were reused with a prior cleaning process.\u003c/p\u003e\u003cp\u003eThe evaluation of the POEM procedure comprised observability of the mucosa, penetration of local injection fluid into the submucosal layer, feasibility of creating a submucosal tunnel, and visibility of indocyanine green (ICG) injection [9](Minami et al. \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e2015\u003c/span\u003e) (attempted in cases 2 and 3), and the ability to incise the circular muscles of the esophagus while leaving the longitudinal muscle intact. During POEM, it is customary to close the entry point into the submucosal tunnel using clips at the conclusion of the surgery. However, this step was not performed in this study due to the inability to secure consent from the bereaved families for the presence of foreign bodies.\u003c/p\u003e\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e\u003ch2\u003eCTET for POEM\u003c/h2\u003e\u003cp\u003eFour cadavers underwent computed tomography (CT) scans before fixation. In three cases, the esophagus and stomach were confirmed to be empty (cases 1\u0026ndash;3: each case shown in Figs.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e\u0026ndash;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e, respectively), allowing POEM performance. However, in one case, POEM was not performed because the stomach was full due to intestinal obstruction.\u003c/p\u003e\u003cp\u003eIn all three cases (cases 1\u0026ndash;3), the esophageal mucosa was intact, permitting normal observation (Figs.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ea, \u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ea, and \u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ea). Although the pharyngeal section was stiff, we were able to insert the fiberscope into the esophagus. In Case 1, residual material was present during the initial observation; however, it was removed after applying water.\u003c/p\u003e\u003cp\u003eThe submucosal injection was successfully performed in all three cadavers (Figs.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eb, \u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eb, and \u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eb). The integrity of the submucosal layer was preserved by using the Thiel method. Each layer, including the epithelium, submucosal layer, and muscular layer, was distinctly visualized and separated in a manner analogous to that observed in living tissues (Figs.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ec, \u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ec, and \u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eb). Subsequently, a submucosal tunnel was successfully established in all three cadavers. The green coloration of the ICG was clearly detectable as a benchmark by administering a local injection into the gastric cardia (Figs.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ed, \u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ec, and \u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ed) in the cadaveric cases (all ICG attempted cases, cases 2 and 3). The demarcation line between the submucosal layer and the inner circular muscle was clearly observable in all cases (Figs.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ec, \u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ec, and \u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ed). Subsequently, a myotomy of the circular muscle was performed. Separation of the circular and longitudinal muscle layers was successfully achieved in all three cases. We confirmed that the longitudinal muscle was well-preserved after the procedure (Figs.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ed, \u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ee, \u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ee, \u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ef, \u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ee, and \u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ef). A representative case (case 3) is shown in the POEM video (Video 1).\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eVideo 1\u003c/p\u003e\u003c/div\u003e"},{"header":"Discussion","content":"\u003cp\u003eThis feasibility study suggests that CTET is suitable as a training model for POEM. This is because our procedural cases confirmed that all mucosal layer structures were preserved using the Thiel method. In particular, the ability to incise only the circular muscle while preserving the longitudinal muscle, along with confirming gastric access using ICG, demonstrates the high utility of this model for POEM training. In this validation study, POEM was performed at the 2 o'clock position in all cases. However, it was possible to perform three POEM procedures per cadaver at the 2, 5, and 7 o'clock positions, allowing trainees to gain additional opportunities for experience.\u003c/p\u003e\u003cp\u003eThe rarity of achalasia results in limited opportunities for trainees to practice POEMs. Thiel-fixed cadavers provide realistic anatomical representations, enabling trainees to familiarize themselves with human structures and variations. This is the first report to propose that cadaver therapeutic endoscopy training using POEM may significantly enhance the availability of ex vivo endoscopic treatment techniques.\u003c/p\u003e\u003cp\u003eCadaver training has certain limitations, particularly in replicating hemostatic procedures and managing intraoperative complications. Moreover, the selection of suitable cadavers for endoscopic training requires careful evaluation of the cause of death and pre-assessment using CT imaging. Another limitation is the restrictions on facilities. In Japan, CST is legally permitted only in medical universities and must be supervised by the Department of Anatomy [10](Japan Surgical Society and Japanese Association of Anatomists 2018). Furthermore, after cadaver training, OJT offers an invaluable experience in terms of patient interaction, real-time decision-making, and adaptation to unforeseen circumstances, which are essential components of therapeutic endoscopy practices that cannot be entirely replicated in cadaver training with experts.\u003c/p\u003e"},{"header":"Conclusions","content":"\u003cp\u003eCTET may serve as a realistic training model comparable to living organs and may be beneficial for POEM training.\u003c/p\u003e"},{"header":"Declarations","content":"\u003ch2\u003eConflict of Interest\u003c/h2\u003e\u003cp\u003eThe authors declare that they have no conflicts of interest.\u003c/p\u003e\u003ch2\u003eFunding\u003c/h2\u003e\u003cp\u003eThis research received no external funding.\u003c/p\u003e\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eM.T. and K.H. prepared the initial draft and visual materials. K.H., A.W., K.S., D.E., Y.N., and K.O-T. organized the image data and verified image quality. H.M., H.I., J.S., T.A., M.T., K.M. and N.Y. supervised the interpretation of anatomical findings. K.O-T, H.M. and Y.A. provided overall academic supervision, coordinated the study, and finalized the manuscript. All authors have read and approved the final manuscript.\u003c/p\u003e\u003ch2\u003eAcknowledgement\u003c/h2\u003e\u003cp\u003eThe authors sincerely thank those who donated their bodies to the field of anatomical research. The results of such research can potentially increase humankind\u0026rsquo;s overall knowledge and improve patient care. Therefore, the donors and their families deserve our highest gratitude. The authors also appreciate Olympus Medical Systems Corporation, Japan, for supplying the endoscopic equipment.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n \u003cli\u003eBalekuduru AB, Appaji AC (2021) Therapeutic endoscopic procedures on a human cadaver\u0026mdash;A pilot feasibility study. J Dig Endosc 12:036\u0026ndash;042\u003c/li\u003e\n \u003cli\u003eFinocchiaro M, Cortegoso Valdivia P, Hernansanz A, et al. (2021) Training simulators for gastrointestinal endoscopy: Current and future perspectives. Cancers (Basel) 13:1427\u003c/li\u003e\n \u003cli\u003eGonzalez JM, Meunier E, Debourdeau A, et al. (2023) Training in esophageal peroral endoscopic myotomy (POEM) on an ex vivo porcine model: learning curve study and training strategy. Surg Endosc 37:2062\u0026ndash;2069\u0026nbsp; \u0026nbsp;\u0026nbsp;\u003c/li\u003e\n \u003cli\u003eInoue H, Minami H, Satodate H, Kudo SE (2009) First clinical experience of submucosal endoscopic esophageal myotomy for esophageal achalasia with no skin incision. Gastrointest Endosc 69:AB122\u003c/li\u003e\n \u003cli\u003eJapan Surgical Society and Japanese Association of Anatomists. Guidelines for cadaver dissection in education and research of clinical medicine. 2018; Internet: https://jp.jssoc..jp/uploads/files/aboutus/guidelines/info20180406-01.pdf; Accessed: 07/01/2025\u003c/li\u003e\n \u003cli\u003eMinami H, Inoue H, Haji A, et al. (2015) Per-oral endoscopic myotomy: emerging indications and evolving techniques. Dig Endosc 27:175\u0026ndash;181\u003c/li\u003e\n \u003cli\u003eRohr A, Perrenot C, Pitta A, et al. (2023) Reperfused human cadaver as a new simulation model for colonoscopy: a pilot study. Surg Endosc 37:3224\u0026ndash;3232\u003c/li\u003e\n \u003cli\u003eTate DJ, Rodriguez de Santiago E, Montori M, et al. (2025) Curriculum for training in peroral endoscopic myotomy (POEM) in Europe (Part II) - Best Practice Techniques: European Society of Gastrointestinal Endoscopy (ESGE) Position Statement. Endoscopy 57:912\u0026ndash;941\u003c/li\u003e\n \u003cli\u003eThiel W (1992) The preservation of the whole corpse with natural color. Ann Anat 174:185\u0026ndash;195\u003c/li\u003e\n \u003cli\u003eTominaga T, Nonaka T, Fukuda A, et al. (2022) Usefulness of structured-cadaveric training for trans-anal pelvic exenteration. Asian J Endosc Surg 15:299\u0026ndash;305\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Achalasia, cadaver surgical training, Cadaver-based Therapeutic Endoscopy Training, peroral endoscopic myotomy, training model","lastPublishedDoi":"10.21203/rs.3.rs-7965920/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7965920/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eThe rarity of achalasia has led to limited opportunities for practical training in educational environments. Cadaver surgical training was developed to enhance surgical skills by providing physicians with experience comparable to that of on-the-job training using structures identical to living organs, thereby proving highly beneficial. Recently, cadavers have been preserved using the Thiel method, which maintains both mobility and organizational flexibility. However, there are few reports on therapeutic endoscopy, including peroral endoscopic myotomy, in the context of cadaver surgical training. We investigated the feasibility of using cadaver surgical training for therapeutic endoscopy training, termed Cadaver-based Therapeutic Endoscopy Training, for peroral endoscopic myotomy. This study was conducted in 2024 at the Cadaver Surgical Center of Nagasaki University using four cadavers preserved using the Thiel method. We performed peroral endoscopic myotomies on three cadavers and evaluated the observability of the esophageal mucosa, penetration of the local injection fluid, feasibility of creating a submucosal tunnel, visibility of indocyanine green injection, and inner circular muscle incision. The layered structure of the digestive tract was well preserved in the Thiel-fixed cadavers, and peroral endoscopic myotomy was performed without major issues. Cadaver-based Therapeutic Endoscopy Training may serve as a realistic training model comparable to living organs and may be beneficial for peroral endoscopic myotomy training.\u003c/p\u003e","manuscriptTitle":"Cadaver-based therapeutic endoscopic training for peroral endoscopic myotomy: A realistic model for skill acquisition","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-11-17 06:31:43","doi":"10.21203/rs.3.rs-7965920/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"3f6c87fd-8dd5-4c40-a8b2-9d36318ae6be","owner":[],"postedDate":"November 17th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2026-01-05T15:59:59+00:00","versionOfRecord":{"articleIdentity":"rs-7965920","link":"https://doi.org/10.1007/s12565-025-00914-6","journal":{"identity":"anatomical-science-international","isVorOnly":false,"title":"Anatomical Science International"},"publishedOn":"2025-12-29 15:57:34","publishedOnDateReadable":"December 29th, 2025"},"versionCreatedAt":"2025-11-17 06:31:43","video":"","vorDoi":"10.1007/s12565-025-00914-6","vorDoiUrl":"https://doi.org/10.1007/s12565-025-00914-6","workflowStages":[]},"version":"v1","identity":"rs-7965920","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7965920","identity":"rs-7965920","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}