Introduction: Endoscopic retrograde cholangiopancreatography (ERCP) and endoscopic sphincterotomy (EST) are essential skills for performing endoscopic cholangiopancreatic procedures. However, these procedures have a high incidence of adverse events, and current training predominantly relies on patient-based approaches. Herein, we aimed to develop an ERCP/EST simulator model to address the need for safer training alternatives, especially for learners with limited ERCP experience. Methods: The model was designed to facilitate the use of actual endoscopic devices, supporting learning objectives that align with the components of the validated Bethesda ERCP Skill Assessment Tool (BESAT). BESAT focuses on skills, such as papillary alignment, maintenance of duodenoscope position, gentle and efficient cannulation, controlled sphincterotomy in the correct trajectory, and guidewire manipulation. Thirty gastroenterology trainees used the simulator between May 2022 and March 2023, and their satisfaction was assessed using a visual analog scale (VAS) and pre- and post-training questionnaires. Results: The novel simulator model comprised a disposable duodenal papillary section, suitable for incision with an electrosurgical knife, alongside washable upper gastrointestinal tract and bile duct sections for repeated use. The duodenal papillary section enabled reproduction of a realistic endoscope position and the adverse bleeding events due to improper incisions. The bile duct section allowed for the reproduction of fluoroscopic-like images, enabling learners to practice guidewire guidance and insertion of other devices. Following training, the median VAS score reflecting the expectation for model learning significantly increased from 69.5 (interquartile range [IQR]: 55.5–76.5) to 85.5 (IQR: 78.0–92.0) (p < 0.01). All participants expressed a desire for repeated simulator training sessions. Conclusions: This innovative simulator could serve as a practical educational tool, particularly beneficial for novices in ERCP. It could facilitate hands-on practice with actual devices, enhancing procedural fluency and understanding of precise incisions to minimize the risk of bleeding complications during EST.

Endoscopic retrograde cholangiopancreatography (ERCP) and endoscopic sphincterotomy (EST) are the primary skills necessary for performing endoscopic cholangiopancreatic procedures to treat various pancreaticobiliary disorders. One of these disorders is acute cholangitis, which is a severe condition with reported mortality rate of 2.7–24% since the 2000s, requiring emergency treatment [1‒9]. EST involves the use of an endoscopic knife to incise the papillary bile duct with a high-frequency current, offering advantages, such as effective placement of large-diameter bile duct drainage stents [10] and removal of bile duct stones in a single procedure. Endoscopic treatments have become more prevalent; thus, reducing procedure-related adverse events has become increasingly important. Among ERCP-related procedures, EST has the highest incidence of adverse events in Japan [11]. Therefore, high-quality learning methods are required to understand ERCP procedures, including an adequate response to adverse events.

Currently, on-the-job training with real patients remains the primary method for learning ERCP/EST procedures for beginner trainees, as effective alternative learning methods are limited. For instance, the American Society for Gastrointestinal Endoscopy recommends that a beginner trainee should have assisted in approximately 200 ERCP procedures, including 40 EST and 10 stenting procedures, before performing ERCP alone [12]. Similarly, the Japanese EST guidelines recommend that ERCP trainees undergo training supervised by an experienced ERCP expert [13]. However, because on-the-job training requires trainees to learn under high-pressure situations, learning through simulator models may be effective in acquiring fundamental knowledge and understanding ERCP/EST techniques and procedures. Several simulator models have been reported for practicing ERCP and EST, including wet laboratory models using explanted porcine [14‒18] or chicken [17‒19] organs that mimic the human duodenum and papilla and dry laboratory models represented by computerized virtual reality [20] or artificially made plastic [21] or silicone [22] models. However, these models have certain limitations. For instance, wet laboratory models require animal sacrifice and hygiene processes, whereas dry laboratory models often lack a sense of reality.

The safe completion of ERCP and EST requires multiple skills, including precise duodenoscope manipulation, the use of therapeutic devices, and the prevention of adverse events. In particular, the manipulation of the side-viewing duodenoscope in ERCP differs significantly from the techniques used in upper or lower gastrointestinal endoscopy, underscoring the need for specific training. Based on our experience in establishing a bleeding ulcer model using artificial vessels for endoscopic hemostasis [23], we developed a novel simulator model for learning comprehensive ERCP/EST procedures, mainly targeting learners with limited ERCP experience. This educational simulator model provides an immersive learning experience, systematically teaching endoscopic manipulation and fundamental procedural flow when using various devices. Furthermore, it emphasizes the importance of recognizing the risk of adverse events, particularly focusing on scenarios, such as bleeding due to improper incisions during EST.

Development and Key Concepts of the Novel ERCP/EST Simulator Model

In developing the novel simulator model for ERCP/EST, we adhered to two key concepts: the ability to use various actual endoscopic devices employed in clinical practice and the provision of sufficient opportunities to achieve learning objectives based on the Bethesda ERCP Skill Assessment Tool (BESAT), a validated assessment tool for ERCP/EST procedures [24]. After receiving approval to improve the “Billy MAX” fixtures produced by Olympus for publicizing ERCP-related products to enable training similar to actual clinical practice, we developed the novel ERCP training model through discussions with the manufacturer. We established new learning objectives using the simulator based on BESAT components. First, the endoscopist’s appropriate body orientation and scope position are reproduced when the endoscope projects a duodenal papilla forward. Second, the duodenal papilla and its ducts are imitated with human-like elasticity, allowing cannulation in the appropriate direction. Third, the incidence of adverse bleeding events in the papillae is reduced if the EST incisions are too large or in an unrecommended direction. Finally, the bile duct section provides a field of view similar to ERCP fluoroscopic images.

For simulator development and educational studies, we used a video duodenoscope (JF-260V; Olympus, Tokyo, Japan), a guidewire (VisiGlide 2; Olympus, Tokyo, Japan), a cannula (StarTip V; Olympus, Tokyo, Japan), an electrosurgical knife (CleverCut 3V; Olympus, Tokyo, Japan), and a basket catheter (Flower Basket V; Olympus, Tokyo, Japan). We also used an electrosurgical unit (VIO 3; ERBE, Tübingen, Germany) in the ENDO cut mode on effect 2. Additionally, we used an iPod touch (Apple Inc., CA, USA) as a mobile device to provide fluoroscopic-like images.

Evaluation Methodology and Statistical Analysis

To evaluate the general impression of the simulator model, 30 gastroenterology trainees from Tohoku University Hospital participated in simulator training as a part of an educational study between May 2022 and March 2023. After providing a detailed explanation of the study and obtaining oral informed consent, questionnaires were administered to assess the trainees’ subjective satisfaction with the simulator training. Based on a visual analog scale (VAS), these questionnaires were administered before, immediately after, and 3 months after the training sessions. The 3-month period was chosen to allow trainees sufficient time to independently reflect on and reassess their experience with the simulator, without being influenced by their immediate post-training responses. Statistical comparisons were performed using the Wilcoxon signed-rank test with adjustments for multiple comparisons made using the Bonferroni method. A p value <0.05 denoted a significant difference. EZR (Easy R) version 1.53 (Tokyo, Japan) was used for the statistical analysis. Post-training, the study also investigated the similarity of the simulator training to ERCP/EST procedures in actual clinical situations and the preferred interval for simulator training. This observational study was conducted in accordance with the principles outlined in the Declaration of Helsinki and Good Practice Guidelines and was approved by the Ethics Committee of Tohoku University Graduate School of Medicine (Registry No. 2020-4-195) and prospectively registered with the UMIN Clinical Trials Registry (UMIN000044823).

Overview of the Simulator Model

This novel simulator model consists of a luminal section of the upper gastrointestinal tract made of soft materials, such as silicone and polyvinyl chloride. Additionally, it includes a duodenal papillary section made of hydrogel and a bile duct made of silicone (shown in Fig. 1). The luminal portion of the upper gastrointestinal tract was designed to replicate the prone patient position, and the luminal portions of the esophagus and stomach were appropriately angled to create a realistic scope position when facing the duodenal papillae. This enabled the trainees to practice pushing, pulling, and twisting the duodenoscope, similar to actual clinical practice (shown in online suppl. Video 1; for all online suppl. material, see https://doi.org/10.1159/000536217). The esophagus, stomach, and duodenum were removed and washed with water to ensure cleanliness.

Fig. 1.

Overview of the ERCP/EST model. ERCP, endoscopic retrograde cholangiopancreatography; EST, endoscopic sphincterotomy.

Fig. 1.

Overview of the ERCP/EST model. ERCP, endoscopic retrograde cholangiopancreatography; EST, endoscopic sphincterotomy.

Close modal

The duodenal papillary component of the simulator was formulated from a hydrogel mixture, comprising 69 wt% glucose, 7 wt% locust bean gum, 9 wt% carrageenan, 2 wt% dipotassium phosphate, and 13 wt% polyvinyl alcohol pigment. These ingredients were proportionally mixed according to their weight percentages and dissolved in water. This composition was durable enough to sustain gentle cannulation, closely replicating the characteristics of human tissue. A bile duct that imitated the normal anatomic course was created inside the papilla, and electrodes were attached to an electrosurgical knife for a safe EST procedure. Artificial blood vessels were placed within the duodenal papilla to simulate adverse bleeding events when an excessive or incorrect incision was made, deviating from the 11:00–12:00 o’clock direction, as recommended by the Japanese EST guidelines (shown in Fig. 2a–c). Pulsatile bleeding was reproduced manually by connecting a syringe to an artificial blood vessel (shown in Fig. 2d). The duodenal papillary portion was disposable and easily replaceable after each training session.

Fig. 2.

a Artificial blood vessels are placed within the duodenal papilla to simulate adverse bleeding events when an excessive or incorrect incision, deviating from the recommended 11:00–12:00 o’clock direction, was made. b Endoscopic image during EST. c Endoscopic image of bleeding due to excessive incision. d Manual reproduction of pulsatile bleeding with a syringe connected to the artificial vessel. EST, endoscopic sphincterotomy.

Fig. 2.

a Artificial blood vessels are placed within the duodenal papilla to simulate adverse bleeding events when an excessive or incorrect incision, deviating from the recommended 11:00–12:00 o’clock direction, was made. b Endoscopic image during EST. c Endoscopic image of bleeding due to excessive incision. d Manual reproduction of pulsatile bleeding with a syringe connected to the artificial vessel. EST, endoscopic sphincterotomy.

Close modal

The bile duct portion of the simulator allowed the reproduction of fluoroscopic-like images by continuously imaging the bile duct area and displaying it on a monitor via a mobile device simultaneously with endoscopic images (shown in Fig. 3). This allowed the trainees to practice guidewire guidance and retention and the insertion of other devices. In addition, stone placement in the bile duct before the simulation enabled trainees to perform stone removal procedures, including using a basket catheter (shown in Fig. 4).

Fig. 3.

Endoscopic and fluoroscopic-like images obtained using this simulator model.

Fig. 3.

Endoscopic and fluoroscopic-like images obtained using this simulator model.

Close modal
Fig. 4.

Endoscopic (left) and fluoroscopic-like (right) images obtained during a series of stone removal procedures.

Fig. 4.

Endoscopic (left) and fluoroscopic-like (right) images obtained during a series of stone removal procedures.

Close modal

Trainee Evaluation for ERCP/EST Simulation

We recruited 30 consecutive gastroenterology trainees (24 men and 6 women) from Tohoku University Hospital. Their median age was 32 years, and the median number of years since graduation was 7 (range 5–10) years. Only 30% of the trainees performed the EST more than 50 times. We evaluated the performance of the simulator model among the trainees by asking the question, “Do you think this simulator will improve your ERCP skills?” The median VAS score prior to simulator training was 69.5 (interquartile range [IQR]: 55.5–76.5). This score significantly increased to 85.5 (IQR: 78.0–92.0) immediately after training and remained elevated at 82.5 (IQR: 74.3–91.8) 3 months after. Therefore, simulator training not only led to a statistically significant improvement in VAS scores immediately post-training but also sustained these high scores at the 3-month follow-up (p < 0.01; shown in online suppl. Fig. 1). Furthermore, immediately following training, 100% of the trainees indicated that the duodenal papillary incision closely resembled that in actual clinical scenarios, and 86.7% found cannulation into the bile duct realistic. All participants expressed a desire for repeated simulator training sessions.

ERCP, particularly EST, is a challenging procedure involving numerous complex components. Furthermore, duodenoscopic manipulation differs significantly from the upper and lower endoscopic methods, necessitating specialized training. BESAT, a clinically validated technique for ERCP evaluation, encompasses competencies, such as alignment and positioning maintenance, cannulation, sphincterotomy, wire manipulation and positioning, and procedural judgment. These competencies are then integrated into a global assessment tool [24]. BESAT has strong evidence of validity and the potential to promote learner growth and support decision-making when incorporated into training [25]. However, providing comprehensive feedback on each aspect of BESAT to trainees during on-the-job training with real patients can be difficult, especially in urgent situations, making simulator-based learning crucial. A retrospective analysis including over 28,000 participants, who underwent ERCP in the USA, revealed that ERCP performed by a trainee under the guidance of a supervisor increased operating time but reduced the incidence of severe endoscopic adverse events [26]. In another study, moderate or severe adverse events were reported more frequently in the control group than in the trainee group [27]. In other words, the current on-the-job training method may allow instructors to carefully select cases and perform the ERCP procedure with the trainee.

EST training is required for making an incision in a direction that minimizes adverse bleeding events. Mirjalili et al. [28] identified 98 arteries near the duodenal papilla in 19 autopsy cases and reported the distribution of vessels in an endoscopic view. According to this report, the distribution of vessels around the 11 o’clock direction was 10–11% less, and the risk of bleeding was low when incisions were made in this direction. Although literature reports on the development of wet laboratory models using porcine and chicken organs to reproduce adverse bleeding events are available [17], there are no reports on dry models with the same capability. A unique feature of this simulator model is its ability to replicate adverse bleeding events in a dry laboratory setting. Consequently, this is the first dry laboratory simulator model to replicate both the position of the duodenoscope when it reaches the duodenal papilla and adverse bleeding events due to improper incisions. This enables users to learn the comprehensive procedural flow required for BESAT assessment using an actual endoscope. In addition to the educational benefits, our simulator model addresses the ethical concerns associated with animal sacrifice and hygiene processes required in wet laboratory models. This artificial model reduces the need for animal use, alleviates ethical concerns, and provides a sustainable and cost-effective training tool. Nonetheless, the costs and ethical benefits of transitioning from wet laboratory models to our simulator model should be quantified in further research.

The questionnaire results indicated that the simulator model was well received by the trainees, with high ratings for realism and a desire for continuous training. These results also suggested that the simulator model might improve endoscopic skills, although further research is required to confirm this hypothesis.

Nevertheless, the simulation model had a few important limitations. First, assessing the model’s effectiveness in improving endoscopy skills in clinical practice proved challenging. To achieve this, we need to objectively evaluate and compare real-world clinical EST with and without the educational intervention of simulator training. As we work to validate the simulator’s efficacy, we bear in mind the ASGE’s “Preservation and Incorporation of Valuable Endoscopic Innovations statement” from 2012. This policy suggests that for a simulator to be justified in training, it should lead to a 25% reduction in clinical cases necessary for trainees to achieve minimum procedural competency. Additionally, it should correlate with real-world competencies with a kappa value of ≥0.70 [29]. Second, we did not confirm the efficacy of hemostasis in this model, although this was theoretically achievable. Moreover, we had limited access to certain types of clips for duodenoscopy, which prevented us from using balloon compression or local drug injections to achieve hemostasis in the model. Therefore, there is a need to develop methods for achieving hemostasis after bleeding in next-generation models. Finally, although a short hole was created at the entrance of the pancreatic duct, a pancreatic duct was not created using this model. This decision was made to allow trainees to cannulate the bile duct. However, we may consider creating a pancreatic duct in the future for procedures, such as stenting. In conclusion, this novel simulator model provides learners with a comprehensive procedural experience of practicing ERCP and EST with actual endoscopes and treatment devices while minimizing the incidence of adverse bleeding events from an incorrect EST incision.

This observational study was conducted in accordance with the principles outlined in the Declaration of Helsinki and Good Practice Guidelines. All participants were provided with a thorough explanation of the study’s purpose, procedures, potential risks, and benefits. An oral informed consent protocol, not a written consent form, was used for the collection of participant data for research purposes. This consent procedure was reviewed and approved by the Ethics Committee of Tohoku University Graduate School of Medicine, approval number 2020-4-195, date of decision March 15th, 2021. This study was prospectively registered with the UMIN Clinical Trials Registry (UMIN000044823).

Dr. Hatayama, Dr. Takikawa, Dr. Matsumoto, Mr. Arata, Dr. Suzuki, Dr. Ogata, Dr. Saito, Dr. Jin, Dr. Miura, Dr. Hamada, Dr. Uno, Dr. Kume, Dr. Kikuta, Dr. Asano, Prof. Imatani, and Prof. Masamune have no conflicts of interest to disclose. Dr. Hatta is one of the Associate Editors of Digestion. Dr. Kanno received a joint research fund from the Denka Co. for the development of medical simulators. However, the company had no control over the interpretation, writing, or publication of this article.

This study was supported by a Grant-in-Aid for Scientific Research (JP22K10460) and the Japanese Foundation for Research and Promotion of Endoscopy. The funder had no role in the design, data collection, data analysis, and reporting of this study.

Conception and design: Y.H., T. Kanno, T.T., and Y.A.; analysis and interpretation of the data and drafting of the article: Y.H. and T. Kanno; critical revision of the article for important intellectual content: R.M., S.S., Y.O., M.S., X.J., S.M., W.H., S.H., K.U., K. Kikuta, K. Kume, N.A., A.I., and T. Koike; and final approval of the article: A.M.

The data that support the findings of this study are available on request from the corresponding author (T. Kanno). The data are not publicly available due to their containing information that could compromise the privacy of research participants.

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