Development and preliminary evaluation of a novel low-cost endoscopic retrograde cholangiopancreatography simulator with electrocautery training capability: a proof-of-concept study from India

Abstract

Background/Aims

Endoscopic retrograde cholangiopancreatography (ERCP) requires extensive training, with around 350–400 supervised cases being required for proficiency. Existing simulators face costs, limited availability, and limited realism. Therefore, we developed and preliminarily evaluated a minimal ERCP training model that incorporated electrocautery capabilities.

Methods

A five-phase development process was employed, including needs assessment, iterative prototyping with material optimization, technical performance testing across 50 training sessions, comparative analysis against existing simulators, and preliminary expert evaluation by eight experienced endoscopists (mean ERCP experience: 12.3±4.2 years). The primary outcomes included verification of functional capability, cost analysis, durability assessment, and expert ratings on 5-point Likert scales for realism and educational value.

Results

The simulator successfully achieved biliary cannulation in 48/50 sessions (96.0%), supported needle knife precut training with functional electrocautery, and demonstrated compatibility with C-arm fluoroscopy, providing adequate contrast visualization. The total material cost per unit was 47.32 United States dollars (USD), compared to 180,000–250,000 USD for commercial virtual reality simulators. The model withstood 50 sessions without structural failure (onion bulb replacement was required every 8.2±1.4 precut attempts). Expert ratings indicated high scores for anatomical realism (4.1±0.6), tactile feedback (3.9±0.7), and educational value (4.4±0.5).

Conclusions

This novel, low-cost ERCP simulator demonstrated technical feasibility and face validity. This proof-of-concept requires formal prospective validation studies to establish construct validity, concurrent validity, and educational effectiveness through trainee learning outcomes before conclusions regarding the impact on clinical training can be drawn. The innovation addresses significant accessibility barriers but represents preliminary evidence that requires formal educational validation.

Graphical abstract

INTRODUCTION

Endoscopic retrograde cholangiopancreatography (ERCP) is one of the most technically demanding procedures in gastroenterology, with complication rates of 5%–10% in experienced surgeons and significantly higher rates during the learning curve.1 Studies demonstrate that 350–400 supervised cases are necessary to achieve 80% biliary cannulation success rates; however, most fellowship programs cannot provide such volumes within standard training periods.2 This training deficit poses substantial patient safety risks as inexperienced operators demonstrate higher rates of post-ERCP pancreatitis, perforation, and failed cannulation.3

The imperative for simulation-based ERCP training is well-established, with the Accreditation Council for Graduate Medical Education now expecting the integration of simulation into gastroenterology training programs.4 However, existing training modalities have significant limitations. Live animal models provide excellent realism; however, these require specialized facilities, veterinary support, ethical approval, and costs exceeding 2,000 United States dollars (USD) per session.5 Conversely, virtual reality (VR) simulators offer varied scenarios but lack realistic haptic feedback and cost 180,000–250,000 USD, limiting accessibility to well-resourced academic centers.6 Similarly, ex vivo tissue models provide authentic tactile feedback but are single-use, require preparation, and lack standardization.7 Previous mechanical simulators have addressed some of these limitations; however, they cannot generally incorporate advanced procedures such as needle-knife precut sphincterotomy, which is an essential technique for managing complex cannulation cases in a cost-efficient manner.8 Table 1 presents a comparative overview of existing simulators, and Figure 1 presents a cost comparison for each of these.

Table 1.

Comparison of various ERCP simulators

Modality	Anatomical realism	Haptic feedback	Portability & accessibility	Estimated cost (USD)	Electrocautery capability	Evidence source
Live animal (porcine)	High (5/5)	High (real tissue)	Low (requires specialized facility, veterinary support)	High (1,000–2,000 per session)	True	Published validation studies5; literature synthesis11
Ex vivo animal tissue	High (tissue); low (anatomy)	High (tissue texture); moderate (lack of vital reaction)	Moderate (requires tissue prep and storage)	Low–moderate (50–200 per session)	True	Published studies6,8; literature synthesis by authors
VR Simulators	Moderate–high (graphics dependent)	Low–moderate (artificial resistance)	Moderate (heavy equipment, dedicated space needed)	Very high (180,000–250,000 initial+maintenance)	False	Manufacturer specifications (GI Mentor, EndoVR); published studies7,10
Commercial mechanical models	Moderate (fixed anatomy)	Moderate (synthetic materials)	High (easily transportable)	Moderate–high (2,000–10,000)	True	Manufacturer specifications; literature synthesis5,8
Novel minimalistic model (current study)	Moderate (4.1/5)a)	Moderate–high (4.3/5)a),b)	Very high (lightweight, bedside setup)	Very low (<25 total materials)	True	Phase 5 expert evaluation (current study); bill of materials

Evidence source key: Ratings and descriptors in this table are derived from: (1) Published comparative validation studies where available (cited by reference number); (2) Manufacturer technical specifications for commercial simulators; (3) Direct expert ratings from the phase 5 evaluation in the current study (4) Structured literature synthesis for attributes not directly measured, based on cited references. Rating sources indicated in 'Evidence Source' column.

ERCP, endoscopic retrograde cholangiopancreatography; USD, United States dollar; VR, virtual reality.

^a)Numerical ratings for the Novel Minimalistic Model represent mean scores derived from the phase 5 expert evaluation (n=8 experts) using a 5-point Likert scale (1=Very Poor to 5=Excellent), as detailed in the RESULTS section.

^b)Haptic feedback rating for the novel model specifically refers to the resistance felt during guidewire manipulation and needle-knife incision on the biological tissue module.

Fig. 1.

Bar diagram showing a cost comparison of various endoscopic retrograde cholangiopancreatography simulators. USD, United States dollar; avg, average; VR, virtual reality; 3D, three-dimensional.

We developed a minimal ERCP teaching model designed to overcome these barriers through (1) construction from readily available, low-cost materials, (2) replication of essential gastrointestinal anatomy relevant to ERCP, (3) compatibility with standard duodenoscopes and fluoroscopic imaging, (4) incorporation of electrocautery capability for advanced technique training, and (5) modular design enabling scenario customization.9 This report describes a systematic development process, technical performance verification, preliminary expert evaluation, and comparative positioning within the ERCP simulation landscape. Table 1 provides a comparison of various ERCP simulators, and Figure 1 shows a cost comparison of the simulators.5-8,10,11

Study objectives

To develop a functional, anatomically representative ERCP simulator capable of supporting both basic cannulation and advanced electrosurgical techniques, as well as to conduct preliminary technical and expert validation establishing a proof-of-concept prior to formal educational effectiveness studies.

METHODS

Study design and objectives

This technical innovation development study was conducted between August 2024 and January 2025 at a tertiary referral center with a high-volume ERCP program (>400 cases annually). The development process followed a structured five-phase protocol approved as a quality improvement initiative (Fig. 2). Because the study did not involve human participants and was limited to expert evaluation of the device, approval from the institutional review board (IRB)was not required.

Fig. 2.

Study flow diagram. Development and preliminary evaluation of a novel low-cost endoscopic retrograde cholangiopancreatography (ERCP) simulator with electrocautery training capability. VR, virtual reality; 3D, three-dimensional; CI, confidence interval.

Phase 1: needs assessment

A structured needs assessment was conducted through (1) a literature review of existing ERCP simulators identifying gaps in accessibility, cost, and advanced technique training; (2) a survey of 15 gastroenterology fellows regarding training barriers (response rate: 93%); and (3) consultation with five expert endoscopists (>500 lifetime ERCPs) regarding essential training features and technical requirements.

Phase 2: iterative development

1) Design conceptualization

Based on the findings from the needs assessment, the design specifications prioritized the following: anatomical representation of the esophagus-duodenum-papilla pathway, compatibility with standard side-viewing duodenoscopes, integration capability for fluoroscopy, tactile realism for cannulation, support for electrocautery-based advanced techniques, modularity for varying difficulty scenarios, and a material cost of under 50 USD per unit.

2) Material selection and rationale

Materials were selected through iterative testing across four prototype versions (Tables 2–4). (1) Foam base: High-density polyurethane foam (40 kg/m³) provided structural stability, compressibility mimicking tissue resistance, radiolucency for fluoroscopy, and cost-effectiveness (12.50 USD per 40×30×10 cm block). (2) Esophageal tube: Flexible cardboard tubing (25-cm length, 2.5-cm internal diameter) allowed duodenoscope passage, appropriate friction simulation, and minimal equipment wear (3.20 USD per unit). (3) Duodenal tube: Similar cardboard construction (2.5-cm length, 2.0-cm internal diameter) positioned perpendicular to the esophageal tube (1.80 USD per unit). (4) Bile duct tube: Curved PVC tubing (10-cm length, 7-mm internal diameter) with a tapered distal opening simulating the papillary orifice, providing appropriate resistance to cannulation (4.50 USD per unit). (5) Papilla orifice: PVC ring (3–4-mm aperture) creating realistic cannulation resistance (2.80 USD per unit). (6) Advanced module components: Natural onion bulb for incisable tissue simulation (0.35 USD per bulb), standard electrosurgical grounding pad (8.50 USD), saline-soaked gauze for electrical conductivity (0.50 USD), toothpick for stent simulation (0.12 USD).

Table 2.

Itemized material costs for construction of the minimalistic endoscopic retrograde cholangiopancreatography simulator

Component	Specification	Unit cost (USD)	Replacement frequency
Foam base	40×30×10 cm, high-density polyurethane	12.50	>50 Sessions
Esophageal tube	25 cm length, 2.5 cm internal diameter, cardboard	3.20	>50 Sessions
Duodenal tube	2.5 cm length, 2.0 cm internal diameter, cardboard	1.80	>50 Sessions
Bile duct tube	10 cm length, 7 mm internal diameter, curved PVC	4.50	>50 Sessions
Papilla orifice	PVC ring, 3–4 mm aperture	2.80	>50 Sessions
Electrosurgical grounding pad	Standard patient grounding plate	8.50	>50 Sessions
Assembly supplies	Adhesive, fasteners, tape	3.85	>50 Sessions
Onion bulb	Natural onion bulb	0.35	Every 8.2±1.4 precut attempts
Saline-soaked gauze	Sterile gauze pad	0.50	Every 3–4 precut attempts
Toothpick (stent substitute)	Wooden stick	0.12	As needed
Miscellaneous	Additional supplies	9.20	Variable
Total initial cost		47.32

Table 3.

Per-session cost analysis based on training type

Training type	Cost calculation	Cost per session (USD)
Basic cannulation only	47.32 USD÷50 sessions	0.95
Precut practice (consumable)	0.35 USD÷8.2 attempts	0.04 per attempt
Comprehensive session (cannulation+precut)	Base+consumables	1.00–1.50

USD, United States dollar.

Table 4.

Comparative cost analysis of the minimalistic model versus existing endoscopic retrograde cholangiopancreatography simulators

Simulator type	Cost (USD)	Sessions/uses	Cost per session (USD)
Minimalistic model (current)	47.32	>50 sessions	~1.00
Live porcine model	2,000–3,500	Single use	2,000–3,500
Ex vivo tissue model	150–400	1–3 uses	50–400
Virtual reality simulator	180,000–250,000	Unlimited	Amortized
Prior mechanical simulators	5,000–35,000	Multiple	Variable
3D-printed silicone model	800–1,500	Multiple	Variable

Costs exclude endoscopic equipment (duodenoscope, sphincterotome, guidewires) and fluoroscopy, which are assumed available at training institutions.

USD, United States dollar; 3D, three-dimensional.

3) Construction protocol

A standardized assembly protocol was developed to ensure reproducibility: (1) Foam base preparation with marked anatomical landmarks. (2) Esophageal tube fixation along the midline axis. (3) Duodenal tube placement at a 90° angle, 5 cm distal to the esophageal tube terminus. (4) Bile duct tube embedded at a 45° oblique angle with a tapered end simulating an opening into the duodenal wall. (5) Papilla orifice insertion at the bile duct-duodenum junction. (6) Advanced module attachment: onion bulb secured to the bile duct tube distal end, positioned over an electrosurgical grounding pad with a saline-soaked gauze interface.

4) Electrocautery safety protocol

The electrocautery module design incorporated standard safety measures: (1) dedicated electrosurgical grounding pad (1196 Reusable Split Electrode [3M], 25×15 cm) positioned beneath the onion bulb maintaining continuous contact, (2) saline-soaked gauze (0.9% sodium chloride solution) providing an electrical conductivity pathway, (3) isolation of an electrocautery current path from operator contact areas through insulated instrument handles, (4) standard electrosurgical generator settings (ESG-300 [Olympus Corp.], monopolar mode: 30 W cutting current, 15 W coagulation current), and (5) verbal confirmation of proper grounding before each precut attempt. Current pathway: generator → needle-knife→onion bulb tissue→saline-soaked gauze→grounding pad→generator return.

A comprehensive do-it-yourself (DIY) guide is provided in Supplementary Material 1, accompanied by Supplementary Video 1 for construction and training. Photographic documentation of the assembled simulator, individual components, and functional procedures is presented in Figure 3. Additionally, a patent application for the model was filed in India under application number 202531003689, which was published on January 24, 2025.9 and formal grant of Indian Patent No. 585921 by the Patent Office, Government of India, granted on 30 March 2026.9

Fig. 3.

Minimalistic endoscopic retrograde cholangiopancreatography simulator assembly and function. (A) Fully assembled model with duodenoscope in situ. (B) Close-up of simulated papilla orifice. (C) Endoscopic view during cannulation. (D) Needle-knife precut using onion tissue module. (E) Fluoroscopic image demonstrating guidewire cannulation of bile duct.

Phase 3: technical performance testing

1) Functional capability verification

The finalized model underwent systematic testing across 50 standardized training sessions using an Olympus TJF-Q190V therapeutic duodenoscope, Olympus CleverCut 3V sphincterotome, and standard 0.035-inch guidewires. Testing included (1) Basic cannulation: 50 attempts by the primary investigator (>100 ERCPs); recording success rate, time to cannulation, and equipment compatibility. (2) Advanced techniques: 25 needle-knife precut attempts using an KD-V411M-0525 (Olympus Corp.) needle knife with an electrosurgical current (30 W cutting, 15 W coagulation), performed while documenting incision quality and tissue durability. Advanced Technique Performance Criteria: Needle knife precut attempts were assessed using the following objective criteria. Technical success: visible tissue layer separation >3 mm upon gross inspection. Electrocautery function: audible generator activation with visible tissue effects (whitening/coagulation). Structural integrity: absence of unintended tissue fragmentation or base material damage. Educational utility: rated by performing endoscopist as ‘suitable for training’ (yes/no). (3) Fluoroscopy integration: 15 sessions of Allengers Plus LDHD C-arm (Allengers Medical Systems Ltd.) fluoroscopy with contrast injection (Omnipaque 300; GE HealthCare), guidewire visibility assessment, cholangiogram simulation, and model stability under imaging. Verification of fluoroscopy compatibility: The foam base (polyurethane), cardboard tubing (cellulose), and PVC components possess low atomic number elements (carbon, hydrogen, and oxygen) and low density, resulting in minimal X-ray attenuation. This radiolucency permits fluoroscopic visualization of metallic components (guidewires, sphincterotomes, contrast agents containing iodine, atomic number 53) comparable to visualization through human soft tissue (effective atomic number of ~7.4). Preliminary fluoroscopy compatibility testing confirmed the following: (i) adequate radiolucency of all model materials, (ii) stable positioning under the C-arm without movement artifacts, and (iii) absence of scattered radiation interference from the model materials. (4) Durability assessment: continuous use across all 50 sessions, recording of component failures, replacement requirements, and structural integrity.

2) Quantitative metrics

Time to cannulation (s), guidewire advancement length (cm), number of cannulation attempts, precut incision depth (mm), onion bulb durability (number of precut attempts before replacement), and contrast column visibility under fluoroscopy (subjective 5-point scale, Fig. 4).

Fig. 4.

Technical performance metrics across 50 training sessions. (A) Cannulation success rate. (B) Time to successful cannulation. (C) Attempts per successful cannulation. (D) Onion bulb durability (precut training). CI, confidence interval; SD, standard deviation.

3) Statistical analysis

Descriptive statistics (mean±standard deviation [SD]) were used to characterize the performance metrics. Equipment compatibility was assessed as a binary success/failure.

Phase 4: comparative analysis methodology

A structured comparative analysis was used to evaluate the minimalistic model against existing ERCP training modalities across various domains. Comparative ratings represent a synthesis of published literature, manufacturer specifications, and expert consensus opinions. Direct head-to-head comparative studies are not available; therefore, cross-simulator comparisons should be interpreted as indicative rather than definitive.

Phase 5: preliminary expert evaluation

Eight experienced endoscopists were selected to ensure diverse levels of expertise. The inclusion criteria were as follows: (1) >200 lifetime ERCP procedures, (2) >5 years of post-fellowship experience, (3) current active ERCP practice (>50 cases annually), and (4) prior exposure to at least one alternative simulator type. The exclusion criteria were as follows: (1) potential conflict of interest with study outcomes, (2) consideration for co-authorship, and (3) <3 years of independent practice. Experts were recruited through professional networks, with 8 of the 11 invited participants completing the evaluation (73% participation rate). Two declined due to scheduling, and one declined due to a lack of VR simulator experience for comparative assessment.

1) Evaluation protocol

Each expert provided a step-by-step guide for constructing the model in a DIY format, accompanied by a Supplementary Video 1. All participants engaged in the following activities: (1) an unstructured 10-minute familiarization period, (2) five standardized cannulation attempts with recorded time and success rates, (3) three needle-knife precut attempts, (4) completion of an immediate post-session questionnaire, and (5) a semi-structured interview to gather qualitative feedback.

2) Assessment instrument

The 15-item structured questionnaire employed a 5-point Likert scale (1=poor, 2=fair, 3=satisfactory, 4=good, 5=excellent) across four domains: (1) Anatomical Realism (5 items): overall anatomical configuration, papilla positioning and orientation, scope maneuverability through the model, duodenal curve replication, and bile duct axis representation. (2) Tactile Feedback (three items): papillary cannulation resistance, guidewire advancement sensation, and scope friction simulation. (3) Educational Value (4 items): utility for basic cannulation training, value for teaching scope manipulation, effectiveness of precut technique practice, and overall educational impact. (4) Overall Utility (three items): recommendation for fellowship training programs, value relative to cost, and likelihood of adoption, if available.

The complete questionnaire instrument is provided in Supplementary Material 1.

3) Data collection and statistical analysis for expert evaluation

Data were collected using a structured pro forma and entered into an Excel spreadsheet. Inter-rater reliability was evaluated using intraclass correlation coefficients (ICC) with 95% confidence intervals (CIs). Responses on the Likert scale were summarized as mean±SD. Comparative rankings of simulator preferences were analyzed using the Friedman test. Statistical significance was defined as p<0.05. All analyses and graphical representations were performed using R V4.5 (2025; R Foundation for Statistical Computing) and R Studio 2025.09.2 Build 418.

Ethical considerations

As this was a device development study without patient involvement, formal IRB approval was not required per institutional policy. Expert participants provided informed consent for the evaluation activities. This study adhered to the reporting standards of the EQUATOR Network guidelines for technological innovation reports.

RESULTS

Development outcomes

The iterative development process successfully produced a functional ERCP training model that achieved all specified design objectives. The final specifications included overall dimensions of 40×30×10 cm (foam base), an esophageal tube length of 25 cm (internal diameter, 2.5 cm), a duodenal tube length of 2.5 cm (internal diameter, 2.0 cm), a bile duct tube length of 10 cm (internal diameter, 7 mm; curved at 45°), and a papilla orifice aperture of 3–4 mm. The total weight is 1.8 kg, enabling single-person transport and setup within five minutes. The prototype setup and assembly procedure are detailed in Supplementary Material 1, and a demonstration video is provided in Supplementary Video 1. Figure 3 presents the photographic documentation of the assembled simulator showing all the major components, an endoscopic view during cannulation, fluoroscopic imaging, and the needle-knife precut technique.

Technical performance verification

1) Basic cannulation capabilities

Across 50 standardized cannulation attempts, successful selective biliary cannulation was achieved in 48 sessions (success rate, 96.0%). The mean time to successful cannulation was 127±34 seconds (range, 78–215 seconds). The mean number of attempts per successful cannulation was 2.1±0.8 (range, 1–4). Guidewire advancement averaged 8.2±0.6 cm (bile duct tube length 10 cm), with external port exit confirming successful duct access in 100% of cases.

2) Advanced technique performance

Twenty-five needle-knife precut attempts demonstrated functional electrocautery capability with adequate tissue incision. A successful precut was operationally defined as: (1) an incision depth ≥3 mm, (2) visible tissue separation along the intended axis, (3) minimal carbonization, and (4) controlled current application without tissue fragmentation. Technical success achieved in 24/25 attempts (96.0%): the mean incision depth was 4.2±1.1 mm (range, 2.8–6.5 mm), full-thickness onion bulb penetration was achieved in 23/25 (92.0%) of cases, and visible coagulation effects were observed in 25/25 (100.0%) of cases. Educational utility was rated as ‘suitable for training’ by performing endoscopists in 24/25 attempts. One attempt failed due to excessive tissue fragmentation (incision depth, 8.2 mm) resulting from prolonged current application (>6 seconds). Onion bulb durability averaged 8.2±1.4 attempts (median, 8; range, 6–11) before tissue degradation prevented further incision training, defined as the inability to achieve clean tissue separation or excessive fragmentation. The cost per onion bulb was 0.35 USD, yielding a per-precut consumable cost of 0.04 USD.

3) Electrocautery safety verification

No electrical safety incidents occurred during the 25 precut attempts. Grounding pad impedance monitoring remained within normal limits (<200 Ω) throughout all sessions. Thermal injury to the operator or unintended activation of the current pathway was not observed.

4) Fluoroscopy integration verification

All 15 fluoroscopy sessions demonstrated adequate radiolucency of the model materials, permitting clear visualization of the metallic components. Guidewire visibility under fluoroscopy was rated 4.4±0.5 on a 5-point scale. Contrast injection through the cannulation catheter produced a visible cholangiogram-like filling of the bile duct tube in 14/15 sessions (93.3%), with one session experiencing contrast extravasation through the tube junction. This occurred due to dye leakage along the wall of the curved biliary duct. Leaks also occurred due to poor apposition of the sphincterotome to the inner wall of the PVC tube. Nevertheless, model positioning remained stable under the C-arm throughout all sessions without requiring additional securing devices.

5) Equipment compatibility

The model accommodated multiple standard ERCP devices without damage: an Olympus TJF-Q190V duodenoscope (tested across all 50 sessions), a ED34-i10T duodenoscope (Pentax Medical, 10 sessions), an CleverCut 3V sphincterotome (Olympus Corp., primary device), a Fusion sphincterotome (Boston Scientific Corp., 5 sessions), 0.035-inch guidewires from multiple manufacturers (Olympus, Boston Scientific, Cook Medical), and an Olympus KD-V411M needle. No equipment damage or excessive wear was observed in any of the endoscopic instruments.

6) Durability assessment

Structural integrity remained intact across all 50 sessions, without foam base deterioration or tube displacement. Component replacement requirements included: onion bulb replacement after every 8.2±1.4 precut attempts (planned consumable), saline-soaked gauze replacement every 3–4 precut attempts (minimal cost impact), and no replacement required for the foam base, esophageal tube, duodenal tube, bile duct tube, papilla orifice, or electrosurgical grounding pad.

7) Cost analysis

(1) Itemized material costs (per unit in USD)

Foam base: 12.50 USD; esophageal tube: 3.20 USD; duodenal tube: 1.80 USD; bile duct tube: 4.50 USD; papilla orifice: 2.80 USD; electrosurgical grounding pad: 8.50 USD; assembly supplies (adhesive, fasteners): 3.85 USD; onion bulb (initial): 0.35 USD; saline gauze (initial): 0.50 USD; toothpick (stent substitute): 0.12 USD; miscellaneous: 9.20 USD; total per-unit cost: 47.32 USD.

(2) Comparative cost analysis (Tables 2–4)

Minimalistic model: 47.32 USD per unit (reusable for >50 sessions); live porcine model: 2,000–3,500 USD per session (single use); ex vivo tissue model: 150–400 USD per session (1–3 uses); VR simulator: 180,000–250,000 USD (institutional purchase); prior mechanical simulators: 5,000–35,000 USD (if commercially available); three-dimensional (3D)-printed silicone model: 800–1,500 USD per unit (reusable).

8) Cost-per-training-session analysis

Assuming 50 training sessions before major component replacement, the minimalistic model costs 0.95 USD per session (excluding the onion bulb), with onion bulb replacement adding an additional 0.04 USD per precut attempt. The total cost per comprehensive training session (including basic cannulation and precut) is approximately 1.00–1.50 USD.

9) Comparative analysis summary

A structured comparison with existing modalities (Table 1) revealed that the minimalistic model occupied a unique niche, combining moderate anatomical realism comparable to prior mechanical simulators, broader training capabilities than most mechanical models (through electrocautery integration), dramatically lower cost than VR or animal models, superior durability to ex vivo models, authentic fluoroscopy integration exceeding VR simulation, and portability unmatched by institutional VR systems. Accordingly, the key differentiators of this model include its status as the only low-cost simulator supporting needle-knife precut training with functional electrocautery, a system available for under 50 USD with true fluoroscopy compatibility, and the lowest per-session cost among all modalities, excluding equipment amortization.

10) Preliminary expert evaluation results

(1) Participant characteristics

Eight experts participated (mean age 44.3±6.1 years, mean post-fellowship experience 12.3±4.2 years, mean lifetime ERCP volume 687±203 cases). Five participants had prior exposure to VR simulators (three GI Mentors and two EndoVR), four to mechanical simulators, and six to ex vivo porcine models. Five participants regularly performed needle-knife precuts (mean 15±8 precuts annually).

(2) Quantitative ratings (5-point Likert scales, mean±SD) (Fig. 5)

Fig. 5.

Expert evaluation ratings across assessment domains. SD, standard deviation.

Anatomical realism domain

Overall anatomical configuration: 4.1±0.6; papilla positioning and orientation: 4.3±0.5; scope maneuverability through the model: 3.9±0.7; duodenal curve replication: 3.8±0.8; bile duct axis representation: 4.0±0.6; domain average: 4.0±0.5.

Tactile feedback domain

Papilla cannulation resistance: 3.9±0.7; guidewire advancement sensation: 3.8±0.6; scope friction simulation: 4.0±0.5; domain average: 3.9±0.6.

Educational value domain

Utility for basic cannulation training: 4.5±0.5; value for teaching scope manipulation: 4.2±0.7; effectiveness for precut technique practice: 4.4±0.6 (n=5 experts performing precut); overall educational impact: 4.4±0.5; domain average: 4.4±0.5.

Overall utility assessment

Recommendation for fellowship training programs: 4.6±0.5; value relative to cost: 4.9±0.3; likelihood of adoption if available: 4.3±0.7; domain average: 4.6±0.4.

11) Statistical reliability

Inter-rater reliability across all questionnaire items demonstrated substantial agreement (ICC, 0.78; 95% CI, 0.65–0.87; p<0.001), indicating consistent expert perceptions.

12) Comparative rankings

Among experts with prior simulator experience (n=8), the minimalistic model was ranked as superior to mechanical simulators for advanced technique training (5/4 experts with prior mechanical experience), inferior to live animal models for tissue realism but superior for accessibility (6/6 experts with porcine experience, p<0.01, Friedman test), and complementary to VR simulators, with a preference for a minimalistic model for tactile learning (5/5 experts with VR experience).

13) Qualitative feedback themes

Content analysis of open-ended responses identified recurring themes: enthusiasm for electrocautery training capability (7/8 experts), appreciation for fluoroscopy integration (6/8), concerns about the lack of pancreatic duct simulation (5/8), suggestions for variable papilla difficulty modules (4/8), and strong endorsement of cost accessibility, enabling widespread adoption (8/8).

DISCUSSION

Principal findings

This study established only technical feasibility and face validity; it did not assess construct validity (performance discrimination across expertise levels), concurrent validity (correlation with clinical performance), or educational effectiveness (trainee learning outcomes). These questions require formal validation. However, the model demonstrated a 96% successful cannulation rate, confirming functional capability for basic ERCP training, incorporated electrocautery-based needle-knife precut training absent from most existing low-cost simulators, achieved compatibility with standard fluoroscopic imaging, enabling authentic endoscopic-radiographic coordination training, and demonstrated exceptional cost-effectiveness at 47.32 USD per unit compared to 180,000–250,000 USD for commercial VR systems. The device exhibited substantial durability across 50 training sessions and received favorable preliminary expert ratings (mean scores 4.0–4.6 on 5-point scales) with substantial inter-rater reliability (ICC, 0.78; 95% CI, 0.65–0.87).

At present, this innovation represents only preliminary evidence, corresponding to the lowest level in the validation hierarchy for simulation training devices. Consequently, the absence of trainee learning data, competency assessment metrics, or correlations with clinical outcomes represents a fundamental limitation and underscores the need for structured follow-up studies before implementation in formal training programs. Such studies should build upon and extend prior mechanical simulator innovations. For example, Leung et al.11’s pioneering 2007 mechanical simulator demonstrated effectiveness for basic cannulation training; however, it lacked advanced technique capability and authentic fluoroscopy integration. Similarly, the 2020 Korean 3D-printed silicone model developed by Kwon et al.10 achieved superior anatomical detail but required specialized fabrication equipment and incurred costs of 800–1,500 USD per unit, thereby limiting accessibility. In contrast, our approach achieves a middle-ground level of realism using commonly available materials while incorporating electrocautery training capability absent from both predecessors. When positioned against animal models, complementary roles also emerge. Although live porcine models remain superior for tissue realism and comprehensive therapeutic technique training, the minimalistic model directly addresses the accessibility barrier that restricts animal model use to well-resourced centers.5 Notably, the substantial cost differential (47.32 USD versus >2,000 USD per session) enables training programs to provide high-volume deliberate practice, a recognized driver of skill acquisition, without prohibitive expenditure. With respect to VR simulators, our model sacrifices scenario variety and automated performance metrics; however, it provides superior tactile feedback and a more authentic tool-handling experience. Accordingly, expert comparative rankings suggesting complementary roles are well aligned with educational theory, which advocates VR for cognitive skill development and pattern recognition, mechanical models for psychomotor skill refinement, and platforms offering realistic haptic feedback for procedural mastery.12

The integration of electrocautery represents a significant innovation of the present model. Needle-knife precut sphincterotomy has historically been learned through apprenticeship during difficult clinical cases, a process that inherently entails patient risk. Although Katanuma et al.13 developed a dry sphincterotomy model, functional electrocautery training was not reported. By contrast, our onion-bulb approach provides layered incisable tissue texture, effective electrosurgical current conductivity, and exceptional cost-effectiveness at 0.04 USD per precut attempt, thereby enabling unlimited practice. Moreover, this development followed a systematic five-phase process involving iterative prototyping, quantitative technical performance verification across 50 sessions, structured preliminary expert evaluation using standardized assessment instruments with documented inter-rater reliability, transparent cost documentation to support reproducibility, and explicit positioning within the existing simulation landscape through comparative analysis. Collectively, the device’s advantages include an exceptionally low cost (47.32 USD), facilitating democratization of ERCP simulation training; a modular design supporting scenario customization; authentic fluoroscopy integration, which is rare among mechanical simulators; electrocautery capability for advanced technique training; compatibility with standard endoscopic equipment that minimizes institutional barriers; portability enabling diverse training settings; and substantial durability verified through extended testing.

Reproducibility considerations

Reproducibility is an important consideration for a manually assembled device compared to a prefabricated product. We acknowledge that hand constructions introduce potential inter-unit variability. Several mitigation strategies have been proposed to address this problem.

1) Standardized construction protocol

Detailed assembly instructions with specific measurements, material specifications, and quality control checkpoints (Supplementary Video 1).

2) Video documentation

Comprehensive step-by-step construction video demonstrating each assembly stage, material preparation, and component integration technique (Supplementary Video 1).

An important strength of this minimalistic design is its inherent upgradability, low cost, and accessibility. The current DIY-type model serves as a foundational prototype emphasizing core competencies, specifically the basic biliary cannulation technique, bile duct axis orientation, proper scope-papilla positioning, and correct accessory alignment, while simultaneously addressing the training gap for approximately 10%–15% of ERCPs requiring advanced access techniques. The electrocautery-capable precut module utilizes an onion bulb to provide realistic layered tissue simulation, offering trainees critical tactile feedback and visual insight into the progressive incision technique required for needle-knife fistulotomy and precut sphincterotomy; this hands-on experience is difficult to replicate in virtual simulators and cost-prohibitive in animal models. Although we acknowledge that the manual construction of these prototypes cannot achieve manufacturing-grade consistency, programs adopting this model can mitigate variability by verifying functional performance using the provided checklist. Furthermore, future commercialization could employ injection molding or 3D printing to achieve greater reproducibility while maintaining the low-cost profile of the model.

Several technical limitations of the presented model should be acknowledged. First, its anatomical simplification excludes the pancreatic duct, precluding training in inadvertent pancreatic cannulation. In addition, the static tissue design lacks sphincter contraction or bleeding simulation, and the model does not reproduce duodenal motility or patient respiratory movement. The simulator is also unsuitable for contrast cholangiography and does not allow practice of suction or insufflation maneuvers due to inherent design constraints. While the papillary orifice provides resistance, it cannot replicate the full spectrum of tissue compliance observed in vivo. Moreover, this study represents only the lowest level of evidence (face validity) within the validation hierarchy. The absence of trainee performance data, competency assessments, or correlations with clinical outcomes therefore constitutes a fundamental limitation that necessitates structured follow-up studies. Additional limitations include the model’s focus on cannulation and precut techniques, excluding other therapeutic interventions such as stone extraction, stricture dilation, and stent exchange. Although the modular design permits future adaptations, the current configuration addresses only a subset of ERCP training needs.14

3) Safety considerations

The electrocautery module requires proper operator training on electrosurgical safety principles. Training programs implementing this simulator must ensure the (1) verification of proper grounding before each use, (2) inspection of all electrical connections, (3) adherence to the manufacturer's recommended generator settings, and (4) supervision by personnel experienced in electrosurgical equipment. Although the model isolates the electrical current from the intended tissue target, operator training in electrosurgery safety principles remains essential.

If validated through formal studies, the widespread adoption of accessible ERCP simulators could substantially influence procedural training. Specifically, current evidence suggests that simulation-based training shortens learning curves and may reduce early complications. In support of this, a 2023 systematic review by Georgiou et al. reported that simulation training is associated with improved ERCP performance; however, heterogeneity across studies limited definitive conclusions.6 Importantly, the cost-accessibility factor is particularly relevant for resource-limited settings and smaller training programs, as democratized access to simulation may reduce training disparities between well-funded academic centers and community-based programs.15 Beyond this, international implications include the potential for global dissemination, particularly in low- and middle-income countries where ERCP training infrastructure remains limited. From a patient safety perspective, needle-knife precut training capability addresses a critical concern, as precut techniques are associated with higher complication risks, particularly during the learning curve.16 Accordingly, providing safe environments for deliberate practice may improve technical proficiency prior to clinical application and reduce rates of perforation and pancreatitis in difficult cannulation scenarios. Finally, integration into competency-based curricula represents a practical application pathway, allowing programs to establish simulation milestones—such as achieving 50 successful cannulations on the simulator—before progressing to supervised patient cases, analogous to requirements in surgical simulation training. Moreover, the low cost of the model enables individual trainee ownership and facilitates distributed practice rather than reliance on scheduled simulation laboratory sessions.

Future directions and validation plans

Formal validation requires structured multicenter studies addressing: construct validity—demonstrating performance differentiation among novice, intermediate, and expert endoscopists using standardized metrics (time, success rates, procedural errors); content validity—systematic expert consensus determining whether the model adequately represents essential ERCP skills; concurrent validity—correlating simulator performance with clinical ERCP competency assessments; predictive validity—longitudinal studies assessing whether simulator training predicts clinical success rates and complication avoidance; and Educational effectiveness—randomized trials comparing simulation-enhanced curricula versus traditional training on patient outcomes.17

Planned studies include the following: a phase 1 validation study (n=30 endoscopists across experience levels) assessing construct validity through standardized performance testing; a phase 2 educational trial (n=40 fellows) randomizing simulation-enhanced versus standard training, measuring cannulation success rates during the first 50 clinical ERCPs; and a phase 3 multicenter implementation study evaluating adoption barriers and refinement needs across diverse training environments.

Model refinements under development include: interchangeable papilla modules simulating varied difficulty (stenotic, flat, diverticular papillae), the addition of a pancreatic duct simulator enabling recognition of inadvertent pancreatic cannulation, a “stone” simulation using radio-opaque markers for extraction practice, and stent insertion in a transparent tube variant for direct visualization training before progressing to fluoroscopy-dependent practice.

In conclusion, this study represents a proof-of-concept that establishes the technical feasibility and acceptable face validity of the model. The model has not been validated in terms of construct validity (performance discrimination across expertise levels), concurrent validity (correlation with clinical ERCP performance), predictive validity (association with patient outcomes), or educational effectiveness (trainee learning outcomes). Accordingly, claims regarding training impact or improvements in clinical performance cannot be made based on the present evidence.

By democratizing access to ERCP simulation through dramatic cost reduction while maintaining functional realism for essential skills, this innovation may contribute to narrowing training disparities and ultimately improve patient safety during the ERCP learning curve (Fig. 6).

Fig. 6.

Endoscopic retrograde cholangiopancreatography (ERCP) training competency assessment using a minimalistic teaching model.

Supplementary Material

Supplementary Material 1. Expert evaluation questionnaire.

Supplementary Video 1.

Comprehensive do-it-yourself construction guide with a step-by-step assembly demonstration and electrocautery safety setup (duration: 12 minutes, available at https://youtu.be/-S-VdvdybMM).

Supplementary materials related to this article can be found online at https://doi.org/ce.2025.438.