1 2 1 3 Figure 1. The GI Mentor II virtual reality simulator, the setup for training in lower endoscopy.  4 6 Objective The main objectives of this study were: (1) to establish the degree of representation of real-life colonoscopy on the Simbionix GI Mentor II VR colonoscopy simulation, as judged by experts (expert validity), (2) to determine whether the GI Mentor II simulator can distinguish between various degrees of expertise in endoscopy, judged by novice, intermediate experienced, experienced and expert endoscopists performing VR colonoscopy (construct validity), and (3) to assess the didactic value of the simulator, as judged by experts. Material and Methods Simulator 1 Participants experienced 4 6 8 9 2 Figure 2. The study design.  Questionnaire All participants were asked to fill out a questionnaire on demographics and their general medical and endoscopy experience. It also included the number of endoscopies performed annually and number of years registered as a skilled professional endoscopist. 10 Simulation modules All participants first performed the hand–eye coordination task (EndoBubble level 1) of popping all 20 balloons in the test as quickly as possible, without touching the walls. Next, the participants performed VR case numbers 1 and 3, both from colonoscopy module 1. These cases were carefully selected for their discriminative value; both cases are straightforward colonoscopies, without any abnormalities such as polyps, tumours, or inflammation. Case number 1 is a relatively easy colonoscopy to perform, whereas case number 3 is more difficult, requiring the endoscopist to apply techniques such as straightening the endoscope during loop formation and applying torque to the endoscope shaft. The assignment given for the VR colonoscopies was to reach the cecum as quickly as possible with as little patient discomfort as possible. Patient discomfort was defined as the estimated percentage of time the virtual patient was in excessive pain and the number of times excessive local pressure was caused. Other relevant test parameters were the percentage of time spent with clear view and the number of times view of the lumen was lost. The task was considered accomplished when the cecum was reached. Data analysis U p Results Participants Thirty-five novices, 15 intermediates, 20 experienced, and 35 expert endoscopists participated in the study. The average number of colonoscopies performed annually by experts was 445, and their mean number of years registered as a gastroenterologist was 7.7 (range 0–35 years). Construct validity 1 2 1 p 3 N N N N Table 1. EndoBubble hand–eye coordination task Experience  Time to finish (min:sec) Number of times wall touched N Mean 6:56 1.9 Median 5:58 1.0 Range 1:24–20:25 0–20 N Mean 1:56 1.1 Median 1:41 0.0 Range 0:54–4:02 0–5 N Mean 1:37 0.9 Median 1:21 0.0 Range 0:43–5:33 0–9 N Mean 1:24 0.3 Median 1:13 0.0 Range 0:49–3:25 0–2 Kruskal-Wallis Chi- square 63.151 9.374 Asymp. sign .000 0.025 Table 2. Colonoscopy module 1, cases 1 and 3  Experience  Time to reach cecum (hour:min:sec) % of time spent with clear view Lost view of lumen Excessive local pressure % of time patient was in pain Excessive loop formed Case 1 N Mean 6:47 96 0.4 0.5 13.3 0.83 Median 6:16 97 0 0 11 0 Range  1:53–15:08  82–99  0–3 0–3 0–44  0–6 N Mean 1:36 97 0 0 8 0.6 Median 1:40 98 0 0 5 0 Range 0:55–2:52 91–100 0 0 0–30 0–3 N Mean 1:23 98 0 0.2 9.2 0.7 Median 1:21 98 0 0 8 1 Range 0:48–2:43 89–100 0 0–1 0–27 0–3 N Mean 1:23 98 0 0 14.5 1.49 Median 1:17 98 0 0 12 1 Range 0:42–3:16 94–100 0–1 0 0–57 0–10 Case 3 N Mean 29:57 86 3.2 3.89 2.2 4.77 Median 23:42 85 3 3 0 1 Range 4:48–1:28:19 72–96 0–12 1–14 0–24 0–34 N Mean 5:45 89 1.1 2.1 0.9 1.13 Median 4:21 92 1 2 0 0 Range 2:28–13:41 78–97 0–4 0–6 0–4 0–8 N Mean 4:19 91 0.6 1.9 1.0 1.6 Median 3:50 91 0 1 0 1 Range 2:27–7:02 73–99 0–3 0–8 0–4 0–9 N Mean 4:56 89 0.9 1.6 2 2.51 Median 4:03 90 1 1  1 Range 1:38–15:39 68–99 0–4 0–6 0–10 0–12 Table 3. Statistics colonoscopy module 1, cases 1 and 3   Time to reach cecum % of time spent with clear view Lost view of lumen Excessive local pressure % of time patient was in pain Excessive loop formed Case 1 Chi square 69.043 13.889 18.415 19.783 7.101 10.691 Asymp. sig. 0.000 0.003 0.000 0.000 0.069 0.014 Case 3 Chi Square 65.559 6.978 41.936 28.794 4.284 4.856 Asymp. sig. 0.000 0.073 0.000 0.000 0.232 0.183 Kruskal-Wallis test U 4 Table 4. Differences between groups module 1, cases 1 and 3   Time to reach cecum % of time spent with clear view Eost view of lumen Excessive local pressure % of time patient was in pain Excessive loop formed Case 1 Novice vs. intermediate 0.000 0.177 0.039 0.013 0.070 0.743 Intermediate vs. experienced 0.166 0.617 1.000 0.244 0.385 0.547 Experienced vs. expert 0.962 0.621 1.000 0.043 0.077 0.020 Intermediate vs. expert 0.141 0.259 1.000 1.000 0.018 0.009 Case 3 Novice vs. intermediate 0.000 0.104 0.000 0.004 0.584 0.040 Intermediate vs. experienced 0.257 0.394 0.285 0.503 0.771 0.184 Experienced vs. expert 0.969 0.297 0.153 0.942 0.154 0.726 Intermediate vs. expert 0.326 0.757 0.870 0.416 0.111 0.090 Mann–Whitney two-tailed test, exact significance Expert validity The group of expert endoscopists rated the colonoscopy simulation 2.95 on a four-point Likert scale for overall realism. Anatomical representation was rated 2.58, and the simulator setup 3.14. Endoscope control scored 3.21. Haptic feedback was rated 2.57. Didactic value Expert opinion was that the GI Mentor II simulator should be included in the training of novice endoscopists (3.51 on a four-point Likert scale) and that expertise gained on the simulator was considered applicable in a clinical curriculum (rated 3.29 out of 4). The simulator was not considered suitable for certification of trained endoscopists (rated 2.29 out of 4). Discussion 4 4 6 11 12 5 11 4 4 6 7 11 12 The colonoscopy tasks were considered as accomplished once the participants reached the cecum. Asking the participants to inspect the mucosa on the way back through the colon does not, in our opinion, provide a proper representation of the endoscopist’s skills in manoeuvring through the colon, as other aspects besides the basic navigation skills of the endoscopist could influence the performance parameters provided by the simulator considerably in this case. This might lead to very different end times depending, for example, on the carefulness of the endoscopist. This study demonstrates that the GI Mentor II simulator offers a convincing, realistic representation of colonoscopy according to experts. The overall assessment was good. Expert opinion was that the simulator can be used as a teaching tool for novice endoscopists. The simulator’s haptic feedback is doubtful. Inexperienced residents can be trained in the skills necessary in flexible endoscopy such as steering control, straightening the endoscope during loop formation and applying torque up to a certain level. Conclusion The current study demonstrates that the GI Mentor II simulator offers a convincing, realistic representation of colonoscopy according to experts (expert validity) and that the simulator can discriminate up to the level of intermediate experienced endoscopists (construct validity) in colonoscopy. In the cases used the simulator could not discriminate between intermediate, experienced and expert endoscopists. The next step will be a study to determine whether novice endoscopists can develop a learning curve that will actually improve their endoscopic skills applied to real patients.