[Non-biological simulator for training intrarenal navigation during retrograde intrarenal surgery].

Introduction: The most complex stage of retrograde intrarenal surgery (RIRS) is intrarenal navigation in the collecting system. The existing simulators for training have drawbacks or are unavailable, so a non-biological simulator was developed to teach the technique of this procedure.

Aim: To provide the characteristics of the developed non-biological simulator for teaching the RIRS technique and the results of its testing.

Materials and methods: We have developed a non-biological simulator for teaching the RIRS technique, the main part of which is a quadrangular box of 60 30 cm, having special internal recesses for models of the bladder, ureters and 3D-collecting system, as well as transparent and dark covers. The simulator has three or more pairs of 3D-models of the collecting system. After the insertion of the ureteral access sheath and instructions from an expert urologist at the RIRS, a training session with 15 urologists (10 without experience and 5 with experience in endourology, except for the RIRS) was carried out. Intrarenal navigation with inspection of all groups of calyces was initially performed with the simulator closed with a transparent top, while the trainee looked at the 3D model of the kidney itself. Then the training continued with an opaque top and the physician looked only at the video monitor. Ten navigations were performed on each side. The navigation time from the moment of insertion of the flexible ureteroscope into the renal pelvis was determined.

Results: A total of 268 intrarenal navigations were performed (134 on each side). Thirty-two (10.7%) tests were not completed, since 6 and 4 urologists stopped the training on the 8th and 9th tests, showing the minimum navigation time. For all trials, the average navigation time was 155.8+/-92.4 s, and it significantly decreased from 252.6+/-107.0 in the first to 94.5+/-34.0 s in the last attempt (p<0.001). In experienced physicians, the navigation time decreased from 185.0+/-52.4 to 85.6+/-26.8 s (p=0.045), while in inexperienced urologists from 290.5+/-109.6 to 96.7+/-35.4 s (p<0.0001). The experienced urologists demonstrated better results in the initial test compared to the inexperienced group (185.0+/-52.4 s vs. 290.5+/-109.6 s, p=0.037), but after training, the navigation time in the final test did not differ (85.6+/-26.8 s vs. 96.7+/-35.4 s, p=0.984).

Conclusions: Our non-biological simulator allows to improve surgical skills in RIRS. The obtained results show that both experienced and inexperienced urologists significantly improve their skills in the navigation in the collecting system.