Virtual reality flexible cystoscopy: a validation study

To validate a flexible cystoscopy simulator by determining if it could differentiate between expert and novice cystoscopists.

Seventeen subjects (10 novices with no previous endoscopic experience and seven urologists who had all carried out > 1000 flexible cystoscopies each) were asked to undertake a flexible cystoscopy task on the URO Mentor (Simbionix, Israel) virtual reality (VR) machine. In the task used the bladder mucosa has 10 flags (numbered 1-10) at key positions in the bladder; by visualizing each of the 10 flags and photographing them the subject will have indirectly visualized the entire mucosa. Subjects were asked to carry out the task 10 times, to allow their rate of acquisition of skill to be assessed. The total time taken for the task and the number of flags visualized were used as measures of performance.

The experienced urologists were significantly better at flexible cystoscopy than the medical students on the first trial for the mean number of flags seen (9.57 vs 8.0, P = 0.01) and the mean time to complete the task (2.33 vs 4.89 min, P = 0.03). At the 10th trial there was still a significant difference for the time taken, between the medical students and the urologists (2.33 vs 0.81 min, P = 0.01) but not for the number of flags seen (9.2 vs 9.6, P = 0.46). The medical students improved between the first and the 10th attempt, being significantly quicker for trial 10 than trial 1 (P = 0.005). However, although the medical students appeared to see more flags (8.0 vs 9.2) this was not significant (P = 0.05). The urologists did not differ in the number of flags visualized between the first and 10th trial, although they were significantly quicker in completing the task (P = 0.02). The urologists were significantly faster in trial 2 than trial 1, but no faster thereafter (P = 0.04).

Using the URO Mentor simulator, it was possible to assess the level of experience of flexible cystoscopy, and therefore the system has construct validity. As in the real situation there is a period of learning during which the subject becomes familiar with the computer/machine/human interface, the task and the handling of the instruments. These results support the view that there is a role for VR simulators in urological training.