Advanced assessment of a novel 3D-printed LLETZ simulation model

doi:10.21203/rs.3.rs-6632887/v1

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Research Article

Advanced assessment of a novel 3D-printed LLETZ simulation model

https://doi.org/10.21203/rs.3.rs-6632887/v1

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Background

Traditional surgical training methods, such as "learning-by-doing," raise ethical and methodological concerns, particularly for procedures such as LLETZ which are frequently performed by gynecology residents. To improve training and reduce patient risk, a novel 3D-printed simulator was developed. While initial studies showed advantages over a conventional model, they were limited to medical students and lacked comparison with a commercially available simulator. This study aimed to address these gaps by comparing the in-house developed simulator to a commercial model using objective metrics, expert video assessments, and participant feedback.

Methods

A single-center study was conducted at the University Hospital Wuerzburg between June 2022 and October 2023. 60 medical students without prior LLETZ experience and 10 Gynecology residents with prior exposure were randomly assigned to train on either a commercial or the novel in-house simulator. Each participant performed five electrosurgical excisions. Performance was evaluated using LEEP scores, resection status (R0 resections), and blinded video assessments by two senior clinicians. Additionally, participants completed questionnaires, to capture subjective training impressions.

Results

The in-house simulator demonstrated advantages over the commercial model. Higher R0 resection rates were achieved in the third and fourth attempts (100% vs. 83.3%, p < 0.05; 96.7% vs. 73.3%, p < 0.05). LEEP scores indicated significantly better surgical precision and learning progression from the fourth attempt onward (0.867 vs. 0.433, p < 0.05 and 1.200 vs. 0.167, p < 0.001). Blinded video evaluations by two senior experts confirmed these findings, showing higher checklist, GRS, and overall mean scores for the in-house simulator from the second or third attempt onward (all p-values < 0.05). Participant feedback further supported these results, highlighting improved confidence, skills, and educational value.

Conclusion

This study demonstrated that the novel in-house 3D-printed simulator significantly outperformed the commercial model in objective surgical performance, learning progression and user satisfaction. By promoting higher resection quality, improved surgical precision, and greater participant confidence, the simulator presents a valuable advancement in LLETZ training. Its integration into gynecological education could enhance surgical competency while addressing ethical concerns associated with traditional training methods.

3D printing

LLETZ simulation

surgical training

LEEP score

video evaluation

simulation training

gynecologic surgery

In 2020, approximately 4640 women in Germany were diagnosed with cervical cancer (1). Worldwide cervical cancer was the fourth leading cause of cancer-related illness and death, with an estimated 662,044 new cases in 2022 (2). As most cervical carcinomas develop from cervical dysplasia (3), a well-established national screening program aims to detect precancerous lesions at an early stage to prevent progression to invasive cancer. In cases of high-grade dysplasia, therapeutic excisional procedures, such as large loop excision of the transformation zone (LLETZ), are often indicated (3–6). It is estimated that more than 100,000 such procedures are performed annually in Germany (7). Although LLETZ is considered a routine gynecologic procedure, it carries the risk of several complications, which are directly related to the extent of the excision. While excessive tissue removal increases the risk of obstetric complications (8–14), an incomplete excision may elevate oncologic risk and necessitate resurgery (10, 12, 15, 16). Further potential risks include acute vaginal injuries leading to hemorrhage, stenosis, fibrosis or even rectal injury (17–25). Thus, surgical training plays a crucial role in minimizing potential complications (15, 26, 27).

Traditional surgical education often relies on a "learning-by-doing" approach, which is increasingly criticized due to both ethical and methodological concerns (28, 29). As LLETZ procedures are frequently performed by gynecology residents, simulation models should be prioritized to mitigate the risks associated with inadequate experience. To address this need, Kiesel et al. developed a novel 3D-printed simulator designed to facilitate both the diagnosis of cervical dysplasia and the performance of LLETZ (30). In a follow-up study, this model was compared to a conventional simulator which was designed based on the findings of Takacs et al. (31, 32). While the in-house simulator demonstrated several advantages in training for the diagnosis and management of precancerous cervical lesions compared to the conventional simulator, the study had notable limitations. The simulator was assessed exclusively by medical students with no prior experience in performing electrosurgical excisions, thus limiting their capacity to accurately evaluate the realism of the simulator (30). Moreover, the novel simulator was not compared to a commercially available model, which may have offered enhanced fidelity. To address these limitations, the presented study expands upon the previous evaluation by comparing the validated 3D-printed simulator with a commercially available model. Furthermore, the quality of the excision was not only assessed based on the LEEP score (loop electrosurgical excision procedure score) of the excised specimen (32) but also through a video-based analysis of surgical performance by two independent senior experts in gynecology and colposcopy. Lastly, feedback from obstetrics and gynecology residents was incorporated, offering a more robust and clinically relevant evaluation of both simulators.

Study design and study population

This single center study was conducted at the Department of Gynecology and Obstetrics of the University Hospital Wuerzburg between June 2022 and October 2023. A certificate of non-objection was obtained from the Ethics Committee of the University Hospital Wuerzburg (application number 2020080401). The study population consisted of two cohorts. The first cohort included 60 medical students from Julius-Maximilians-University Wuerzburg, all of whom were in at least in the final third of their medical studies. None had prior experience performing LLETZ procedures. The second cohort consisted of 10 obstetrics and gynecology residents from the University Hospital Wuerzburg. In contrary to the medical students, these residents had prior hands-on experience in performing LLETZ. Participants (students and residents) were randomly assigned to either Group A or Group B by drawing a ticket from a box. Group A trained using the commercially available LLETZlearn® Training Simulator from DTR Medical (DTR Medical Ltd, Swansea, UK), referred to as the conventional simulator. In accordance with the manufacturer’s guidelines and prior research, a sausage was utilized as a cervical substitute. Group B utilized the novel simulator, which had been introduced and validated in prior studies by Kiesel et al. (30, 31), referred to as the in-house simulator. As described by Kiesel et al., modified algae powder, 3D-printing and casting techniques were utilized to create this simulator.

Organization and implementation of the seminar

Each training session lasted approximately 1.5 hours and included a theoretical introduction delivered via Microsoft PowerPoint (Microsoft Corporation, Redmond, USA). The lecture provided an overview of essential topics, including female anatomy and physiology, the pathophysiology of cervical dysplasia, its diagnosis and treatment, and the principles, operation, and safety considerations of electrosurgery. For residents, who were already familiar with these concepts through their clinical experience, the theoretical introduction was omitted. Electrosurgical excisions were performed using the VIO 300D® electrosurgical generator, with neutral electrodes provided by the NESSY® Omega Plate (both from Erbe Elektromedizin GmbH, Tuebingen, Germany). Participants selected the appropriate electrosurgical loop following an inspection of both the simulator and the cervix, choosing from three available sizes (10×10 mm, 15×12 mm, and 20×15 mm; all loops were 130 mm long, Wolfram Schlingenelektrode, Erbe Elektromedizin GmbH, Tuebingen, Germany). Before their first attempt, participants were informed that the ideal depth of the excised cone should be between eight to ten millimeters. During the procedure, the instructor assisted in preparing the simulators, but did not provide surgical guidance. Following each excision, the depth of the cone was measured using a caliper and participants received immediate feedback, enabling them to determine, whether a further excision was necessary. The number of attempts and the corresponding cone depths were documented. Additionally, each excision process was recorded anonymously with the video camera of the colposcope only showing the loop and the cervix. After each procedure, the artificial cervix was replaced, and participants repeated the process until they had completed five electrosurgical excisions. The residents' simulations were neither evaluated using the LEEP score nor recorded on video. The primary objective for the residents was to gather their feedback, to assess the clinical acceptance of the simulator.

Methods for objective evaluation

To evaluate the excised tissue, both the resection status and the LEEP score were assessed. The LEEP score is an objective evaluation method established by Takacs et al. (32, 33), which has been validated and applied by the aforementioned research group as well as in our previous studies (30, 31). Each excision was scored based on the depth of the excised cone and the number of resections required, in order to achieve the desired depth. Each mm deviation of the optimal cone depth of 8 to 10 mm added one point. Each additionally performed resection also added one point. The optimal outcome was a score of zero points. In such a case, a cone depth of 8 to 10 mm was achieved with one single resection. Hence, higher scores indicated a greater deviation of the excised cone from the study’s ideal target and/or more excisions. The resection status (R-status) was also assessed, based on the first excision attempt. Each cervix-model showed a similarly marked area depicting the precancerous lesion by using white color. If visible white residual tissue remained after the initial cut, the attempt was classified as R1. This classification remained unchanged even if subsequent corrective excisions completely removed the white tissue. Conversely, if the white tissue was entirely excised in the first attempt, the procedure was classified as R0. To assess surgical proficiency and learning process, video evaluations were conducted by two independent senior experts in gynecology and colposcopy. The assessment was based on three scoring systems previously evaluated and applied by Wilson et al. (34). The first scoring system, the checklist score, evaluated three key aspects: (1) whether the procedure was completed in a single step, (2) whether an adequate tissue sample was obtained, and (3) whether damage to the surrounding tissue was avoided. Each category was scored on a scale of 0 to 3 points, with a maximum possible total of 9 points. The second scoring system, the Global Rating Scale (GRS) score, assessed four criteria: (1) tissue handling, (2) time and motion efficiency, (3) instrument handling, and (4) procedural fluidity. Each category was rated on a scale from 1 to 5 points, with higher scores indicating superior performance. To calculate the overall score, the checklist score and the GRS score assigned by each expert were summed. For further analysis, the mean values of the checklist score (checklist mean), the GRS score (GRS mean) and the overall score (overall score mean) were determined across both evaluators.

Methods for subjective evaluation

The second part of data collection aimed to assess the participants' subjective impressions. Both medical students and residents completed questionnaires at the end of the seminar. Responses were recorded using a 10-point Likert scale (1: "strongly agree/very good" to 10: "strongly disagree/very bad"). The questionnaire was adopted from the previous study by Kiesel et al., which was based on a validated questionnaire developed by Takacs et al. (31–33). Depending on the participant group (students vs. residents, conventional simulator vs. novel simulator), certain questions varied between versions of the questionnaire.

Statistical analysis

All variables were documented in an Excel file (Microsoft Office Excel 2013, Washington, USA). The data was analyzed using the statistical software SPSS (Version 29) from IBM (SPSS Inc., Chicago, IL. USA) and the following statistical test procedures:

Descriptive Data Analysis
Chi squared test
Mann-Whitney U test
Friedman-test

p-values of < 0.05 were considered statistically significant.

Use of Large Language Models

ChatGPT Version 4.0 (OpenAI Inc., San Francisco, USA) was used for language quality check.

The in-house simulator showed advantages over the conventional simulator.

Resection status and LEEP score

Regarding R0 resections, there was no statistically significant difference between the two simulators concerning the LEEP score of the first a second resection. In the third attempt, all students (100%) achieved R0 resection with the in-house simulator, whereas while only 25 out of 30 students (83.3%) did so with the conventional simulator (p = 0.020). In the fourth attempt, 29 students (96.7%) achieved R0 resection with the in-house simulator, compared to only 22 out of 30 students (73.3%) with the conventional simulator (p = 0.011). A graphical representation of the R0 resections for both simulators is displayed in Fig. 1.

Regarding the LEEP scores, the average of all recorded scores for LLETZ attempts one to five was calculated for both simulators. A LEEP Score of zero points was regarded as best possible result. In such a case, a cone depth of 8 to 10 mm was achieved with one single resection. Hence, higher scores indicated a greater deviation of the excised cone from the study’s ideal target and/or more excisions. The mean scores facilitated a more accurate comparison between the two phantoms. The mean scores for the conventional simulator exhibited a downward trend at the beginning, starting from an initial value of 1.667 in the first attempt, dropping to 1.167 in the second attempt and further decreasing to 0.633 in the third attempt. The LEEP scores then began to rise again: in the fourth attempt, the average LEEP score was 0.867, and in the fifth attempt, it increased to 1.200. The mean LEEP scores for the in-house simulator consistently decreased. The average score in the first attempt was 1.233, which dropped to 0.767 in the second attempt, 0.567 in the third, and 0.433 in the fourth attempt. Finally, in the fifth and last attempt, an average LEEP score of 0.167 was reached. Comparing the LEEP score results for the individual attempts between the two simulators, a statistically significant difference between both simulators was found from attempt four onwards (p = 0.036 and p < 0.001) (Fig. 2).

The variation in LEEP scores with the use of each simulator across the five attempts was assessed using the Friedman test. Pairwise comparisons of attempts one to five for each simulator revealed statistically significant differences from attempt three onwards for both simulators (p = 0.006). For the conventional simulator a statistically significant difference was also observed between attempt one and attempt four (p = 0.037), but not for attempt five (p = 0.079). For the in-house simulator significant differences in the LEEP score between attempt one and attempt four (p = 0.003) and between attempt one and attempt five (p < 0.001) were noted. However, the improvement between attempts three and four and five was no longer statistically significant for either simulator (Table 1).

Table 1

Pairwise comparison of LEEP scores across five attempts for both simulators
Comparison of two samples	Conventional simulator (p-value)	In-house simulator (p-value)
LLETZ1 – LLETZ3	0.006*	0.006*
LLETZ1 – LLETZ4	0.037*	0.003*
LLETZ1 – LLETZ5	0.079 (n.s.)	< 0.001*

Legend: * indicate statistically significant differences between the LEEP scores. Differences between the LEEP scores of other attempts were not statistically significant.

Video evaluation by two senior experts

Initially, following the methodology of Wilson et al. (33), the inter-rater reliability between the two blinded senior experts was assessed. This measure reflects the degree of consistency in the ratings provided by both assessors. Values above 0.75 are considered to represent very strong agreement. In our study, the inter-rater reliability was 0.70 for the checklist mean score, 0.80 for the GRS mean score, and 0.79 for the overall mean score. These results demonstrate strong consistency, confirming the validity of the data for further analysis. Subsequently, the mean scores for the checklist mean, GRS mean, and overall mean were compared between the two simulators across the five attempts. The checklist score assessed three key aspects, each rated on a scale from 0 to 3, with a maximum possible total of 9 points. The Global Rating Scale (GRS) evaluated four criteria, with each category scored between 0 and 5, allowing for a highest possible total of 20 points. To calculate the overall score, the checklist score and the GRS score were summed. resulting in a maximum achievable score of 29. For the checklist mean, both simulators demonstrated an increase in mean scores. The mean score of the conventional simulator rose from 6.45 points in the first attempt to 7.5 points in the fifth attempt. Similarly, the in-house simulator showed an increase, starting at 5.75 in the first attempt and rising to 8.5 in the fifth attempt. The GRS mean values also showed a steady increase for both simulators over the five attempts. The conventional simulator's mean score increased from 15.17 in the first attempt to 16.95 in the fifth attempt. For the in-house simulator, the mean score started at 15.52 in the first attempt and increased to 19.20 in the fifth attempt. The overall mean values also steadily increased for both simulators. The mean score for the conventional simulator increased from 21.62 in the first attempt to 24.45 in the fifth attempt, while the in-house simulator’s mean score rose from 21.27 to 27.85.

As with the LEEP score, the checklist mean, GRS mean, and overall mean for each attempt were compared between the two simulators. The in-house simulator demonstrated a statistically significant advantage over the conventional simulator starting from the third attempt for the checklist mean (p = 0.009, p = 0.006, p > 0.001), from the second attempt for the GRS mean (p = 0.011, p < 0.001, p < 0.001, p < 0.001), and from the third attempt onward for the overall mean (all p < 0.001) (Table 2–4).

Table 2

Mean "checklist mean" scores across five electrosurgical excisions for both simulators
	LLETZ1	LLETZ2	LLETZ3*	LLETZ4*	LLETZ5*
checklist mean (conventional)	6,450	7,150	7,100	7,150	7,500
checklist mean (in-house)	5,750	7,050	8,100	8,050	8,500
p-value (checklist mean)	0,083	0,944	0,009	0,006	< 0,001
Legend: The checklist score evaluates three key aspects: (1) whether the procedure was completed in a single step, (2) whether an adequate tissue sample was obtained and (3) whether damage to the surrounding tissue was avoided. Each category is scored on a scale of 0 to 3 points, with a maximum possible total of 9 points. * indicate statistically significant differences between the conventional simulator and the in-house simulator

Table 3

Mean "GRS mean" scores across five electrosurgical excisions for both simulators
	LLETZ1	LLETZ2*	LLETZ3*	LLETZ4*	LLETZ5*
GRS mean (conventional)	15,167	15,900	16,150	16,550	16,950
GRS mean (in-house)	15,517	16,967	18,083	18,500	19,200
p-value (GRS mean)	0,431	0,011	< 0,001	< 0,001	< 0,001
Legend: The Global Rating Scale (GRS) score assesses four criteria: (1) tissue handling, (2) time and motion efficiency, (3) instrument handling, and (4) procedural fluidity. Each category was rated on a scale from 1 to 5 points, with higher scores indicating superior performance. * indicate statistically significant differences between the conventional simulator and the in-house simulator

Table 4

Mean "Overall mean" scores across five electrosurgical excisions for both simulators
	LLETZ1	LLETZ2	LLETZ3*	LLETZ4*	LLETZ5*
Overall mean (conventional)	21,617	23,050	23,250	23,700	24,450
Overall mean (in-house)	21,267	24,017	26,241	26,517	27,850
p-value (overall mean)	0,700	0,083	< 0,001	< 0,001	< 0,001
Legend: To calculate the overall score, the checklist score and the GRS score assigned by each expert is summed. * indicate statistically significant differences between the conventional simulator and the in-house simulator

Students’ assessment of both simulators

A total of 60 participating students answered 21 identical questions for both simulators. Additionally, Group A answered one extra question, while Group B responded to two additional simulator-specific questions. Responses were recorded using a 10-point Likert scale (1: "strongly agree/very good" to 10: "strongly disagree/very bad").

The statement "The surgical simulation training was enjoyable" received an average rating of 1.1 in both groups. Both cohorts indicated that the simulation training had a positive impact on their education. The statement "The simulation training improved my medical skills" was rated 1.4 in Group A and 1.3 in Group B. Similarly, "The simulation training enhanced my knowledge and medical skills in gynecological examinations" was rated 1.6 in Group A and 1.2 in Group B. Both groups stated that "Surgical simulation helps me in real-life surgeries", with scores of 1.5 (Group A) and 1.4 (Group B). Additionally, "I would like to participate in further simulation training in gynecology and obstetrics" was rated 1.3 in Group A and 1.2 in Group B. The broader statement "I would like to participate in simulation training in other medical specialties" received an average score of 1.3 from both groups. Regarding professional interest, participants were asked whether "The training sparked or strengthened my interest in gynecology", with Group A rating it at 2.2 and Group B at 2.0. The statement "How well did the model simulate a LLETZ procedure?" was rated 2.4 by Group A and 2.1 by Group B. The question "Is the representation of an artificial cervical canal useful for surgical simulation?" received ratings of 1.3 (Group A) and 1.2 (Group B). Further, participants evaluated the variation between the cervix of a nulliparous vs. multiparous patient in surgical simulation. Those using the conventional simulator rated it 3.5, while the in-house simulator group rated it 2.6. Students were also asked whether "Performing the LLETZ procedure enhanced their gynecological knowledge", with Group A rating it at 1.7 and Group B at 1.4. The question "Would you be able to perform a real LLETZ procedure under supervision?" was rated 3.3 in Group B and 3.1 in Group A. Participants were further surveyed on their confidence and knowledge regarding electrosurgery. When asked if they had "acquired sufficient technical knowledge about electrosurgery", Group A rated it 2.2 and Group B 2.4. Confidence in handling electrosurgery was rated at 2.3 in Group A and 2.2 in Group B. Regarding the improvement of operative skills through electrosurgery, Group A rated it 2.1, while Group B gave it 1.8 points. Participants using the conventional simulator were specifically asked, "I did not like working with raw meat", with 23% answering "yes" and 77% "no." For those using the in-house simulator, the variation in the length and depth of the artificial vagina for surgical simulation was rated 2.2, while the ability to actively perform a Lugol iodine test scored an average rating of 1.6. The only statistically significant difference was found in the question: "Training in electrosurgery improved my medical education". (p < 0.05), with Group A rating it 1.2 and Group B 1.6.

Residents' assessment of both simulators

Overall, the simulator training received positive feedback. The statement "The operative simulation training was enjoyable" was rated 2.0 by Group A and 1.0 by Group B. The question "The simulation of surgical procedures helps me in real operations" received mean scores of 1.4 (Group A) and 1.2 (Group B). Furthermore, participants expressed a willingness to undergo additional simulation training in gynecology and obstetrics (Group A: 1.2; Group B: 1.0). The statement "The simulation training improved my medical skills" was rated 3.2 by Group A and 1.6 by Group B. The assertion "The simulation training improved my knowledge and skills regarding gynecological examination" received scores of 3.6 in Group A and 2.2 in Group B. Regarding the simulation of the LLETZ procedure, participants indicated an improvement in gynecological knowledge (Group A: 3.6; Group B: 1.2). The suitability of the simulators for replicating diagnostic procedures was also assessed. The simulation of a real PAP smear was rated 4.6 by Group A and 2.0 by Group B. The ability to simulate a cervical biopsy was rated 4.8 (Group A) and 3.0 (Group B). The replication of an endocervical curettage received scores of 5.4 (Group A) and 3.6 (Group B). The statement "Thanks to the simulator, I feel more confident in independently diagnosing cervical dysplasia" was rated 4.6 in Group A and 1.6 in Group B. Additionally, the potential of the simulator for LLETZ simulation was evaluated. The question "How well did the given simulator replicate a real LLETZ procedure?" was rated 4.0 by Group A and 2.0 by Group B. The artificial cervical canal representation received 1.2 points in Group A and 1.0 points in Group B. The inclusion of a variation between nulliparous and multiparous cervices was rated 2.8 by Group A and 3.6 by Group B. Regarding confidence in performing an actual LLETZ, Group A gave a mean of 4.4 and Group B a mean of 1.6 points. Residents were also surveyed regarding their knowledge of electrosurgery. The statement "I have acquired sufficient technical knowledge in electrosurgery" received ratings of 3.0 (Group A) and 2.8 (Group B). The assertion "Using electrosurgery has improved my surgical skills" was rated 3.0 by Group A and 1.6 by Group B. In the final overall assessment of electrosurgery training, Group B rated with 1.2 points and Group A with 3.6 points. Furthermore, doctors who trained with Simulator A were asked if they found working with raw meat unpleasant. Three participants responded "no," while two answered "yes." The opportunity to actively perform a Lugol’s iodine test was rated 1.4. The only statistically significant difference was found in the question: "I feel more confident handling electrosurgery" with Group A rating it 4.2 and Group B 1.6 (p = 0.032). Concerning the question "How well did the given model simulate a real LLETZ procedure?" Group A gave a mean of 4.0 and Group B a mean of 2.0 points (p = 0.056).

The in-house developed simulator demonstrated notable advantages over the conventional simulator across multiple performance indicators, suggesting its potential as a superior training tool for the LLETZ procedure. First, significantly higher rates of R0 resections were achieved with the in-house simulator in the third and fourth training attempts (100% vs. 83.3%, p = 0.020; and 96.7% vs. 73.3%, p = 0.011, respectively). Second, to objectively assess surgical precision and learning progression, the LEEP score was employed. This score facilitated a standardized comparison between the simulators’ generated learning curve and revealed statistically superior results for the in-house simulator starting from the fourth attempt (p = 0.036 and p < 0.001). Third, these findings were confirmed by blinded video evaluations conducted by two senior clinicians using the evaluated, structured assessment tools “checklist mean” and “Global Rating Scale (GRS) mean,” which were combined into an overall mean score. The participants training with the in-house simulator received significantly higher ratings beginning from the third attempt in checklist and overall scores, and from the second attempt in GRS scores. These performance-based outcomes were further validated by participant feedback. Both students and residents reported a high degree of satisfaction with the training experience, emphasizing the simulator’s educational value and its impact on building confidence and skills in electrosurgery and LLETZ.

Possible explanations for the superiority of the in-house simulator

Several factors may account for the superior performance observed with the in-house simulator. First, its wider vaginal opening allows for greater speculum expansion, enhancing visualization of the cervix and aceto-white lesions—an essential aspect for precise resections. While such visibility is often achievable in clinical practice, anatomical variability and patient discomfort can limit this. Given that the study focused on novices without prior experience, optimized and comfortable training conditions were a priority. Second, the consistency of the cervical model likely influenced performance. The in-house simulator uses agar-agar, whereas the commercial version employs processed meat. Prior research has highlighted the technical challenges posed by meat-based models, particularly regarding optimal loop excision speed (35). Deviations in speed may lead to thermal damage or suboptimal excisions, potentially contributing to the variability observed in LEEP scores with the commercial simulator. Third, differences in material composition also affect smoke production during electrosurgery (36, 37). Excessive smoke, more prominent in meat-based models, may impair visibility—especially for beginners—thus limiting the training’s effectiveness. Although lower smoke output in the in-house simulator may reduce perceived realism, it creates a more accessible learning environment. Taken together, the narrower vaginal canal, higher material-related demands, and increased smoke production likely rendered the commercial simulator more challenging. While such complexity could better simulate clinical reality, the primary objective of this study was to assess the suitability of simulators for training LLETZ novices—an aim more effectively met by the in-house simulator.

Strengths and limitations

A notable strength of this study is the inclusion of both medical students and residents, thereby facilitating a comprehensive evaluation of simulator performance across varying levels of clinical experience. The cohort of medical students, all of whom lacked prior exposure to the LLETZ procedure, provided a homogeneous group with a uniform baseline of skills. This design minimized potential biases associated with differing levels of previous training or experience, which are often present among residents. The use of medical students in simulator evaluation is well-supported by existing literature, which attests to their suitability for such studies (35, 38, 39). Moreover, the inclusion of residents allowed for the validation of the students' perspectives, thus providing additional insights into the simulators realism and practical applicability. Additionally, the study's multi-dimensional evaluation approach, combined with the use of several validated metrics, strengthens the credibility of the results. The LEEP score, originally developed by Takacs et al. and previously employed by Kiesel et al. (30–34), along with the widely used OSATS framework (objective structured assessment of technical skills) (38, 40–44) offered reliable and comprehensive measures of performance.

One limitation of this study is the small sample size of residents, which was primarily due to the challenges associated with recruiting participants from this group, given their professional commitments and busy schedules. A larger sample size would likely have enhanced the statistical power and provided more robust conclusions. Additionally, the inclusion of an "expert" group, consisting of experienced physicians with substantial practical knowledge and expertise in performing the LLETZ procedure, could have further enriched the study. Another limitation is the lack of long-term follow-up. The study focused on short-term learning success over five attempts, but it did not address the retention of surgical skills or the transferability of these skills to real-life clinical procedures. Without long-term data, conclusions regarding the simulator’s impact on clinical competence remain limited.

Transferability to real-life surgery and future aspects

Wilson et al. emphasized the need for additional research to better understand the correlation between simulator performance and real-world surgical competence (34). A 2019 study demonstrated that simulation-based education led to improvements in specific aspects of procedural performance among trainees (44). Several other studies have similarly supported the transferability of simulation skills to clinical practice (46–48). However, this assumption has been questioned in other surgical fields. For instance, in colonoscopy, while simulator-trained physicians initially showed better performance, this advantage diminished after approximately 30 procedures, with no significant differences observed thereafter (49). Despite this, early improvements in skill acquisition may optimize the use of instructor resources and enhance patient safety by elevating the baseline skill level of trainees. Given the relationship between the surgeon's experience and the risk of obstetric complications, an early and sustainable success of simulator training for LLETZ is desirable (8–14). If the skills gained through simulation were entirely transferable, the in-house simulator—given its superior learning outcomes—would likely provide a more effective training experience. However, this remains a hypothetical assumption. Future research could explore whether participation in simulator-based training programs during residency results in improved outcomes in real-world surgical settings. Furthermore, integrating Virtual Reality (VR) technologies into simulator training represents another promising direction for future research. In other surgical disciplines, VR-based training has been shown to shorten learning curves (50) and it holds considerable potential for enhancing the effectiveness of LLETZ training as well.

This study demonstrated that the novel in-house 3D-printed simulator provides significant advantages over a commercially available model for LLETZ training. It enabled higher rates of complete (R0) resections, superior LEEP scores, and better structured performance evaluations, as confirmed by blinded expert ratings. Participants also perceived the in-house simulator as more realistic, educationally valuable, and effective for improving surgical skills and confidence. Several factors, including better visualization and reduced smoke production, likely contributed to its superior performance, creating a more conducive learning environment for novices. While the findings are robust due to the comprehensive evaluation approach and inclusion of learners with varying experience levels, limitations such as a small resident sample size and the lack of long-term follow-up must be acknowledged. Overall, the results suggest that the in-house simulator is a highly effective training tool for early LLETZ skill acquisition. Future studies should explore the long-term transferability of these skills to clinical practice and assess the potential of integrating advanced technologies, such as Virtual Reality, to further enhance training outcomes.

LLETZ

Large Loop Excision of the Transformation Zone

LEEP

Loop Electrosurgical Excision Procedure

GRS

Global Rating Scale

Virtual reality

OSATS

Objective Structured Assessment of Technical Skill

Explanation why the manuscript should be published in 3D Printing in Medicine:

This manuscript is well-suited for publication in 3D Printing in Medicine as it introduces an innovation in 3D printing that advances surgical training. It presents a novel, 3D-printed simulator that outperforms commercial models in teaching the LLETZ procedure, achieving higher success rates, improved surgical precision, and greater user satisfaction. The use of validated metrics such as the LEEP score and the OSATS framework provides a robust, objective evaluation of the simulator’s effectiveness.

Declaration of potential competing interests:

All authors declare that they have no competing interests.

Approval of manuscript:

All authors confirm that they have approved the manuscript for submission.

Conformation concerning prior publication:

All authors confirm that the manuscript has not been published or submitted for publication elsewhere.

Ethics approval and consent to participate:

This study was registered with the Institutional Review Board (Ref. No. 2020080401).

Consent for publication:

Not applicable

Funding:

DTR Medical (Swansea Enterprise Park, 17 Clarion Cl, Llansamlet, Swansea SA6 8RF, United Kingdom) provided the study group with two identical models of their commercial simulator LLETZlearn®

Author Contribution

AQ: Project development, acquisition, interpretation of data, manuscript writingKR and STS: Analysis of dataJD and AA: video evaluationJB, BBS and BDB: Manuscript editingAW: Project supervisionMK: Project development and supervision, conceptualization, design of the work, acquisition and analysis of data, manuscript writing

Acknowledgement

none

Availability of data and materials:

The datasets used and analysed during the current study are available from the corresponding author on reasonable request.

Competing interests: The authors declare that they have no competing interests

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No competing interests reported.

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Advanced assessment of a novel 3D-printed LLETZ simulation model

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