Flexible ureteroscopy training for surgeons using isolated porcine kidneys in vitro

Compared with laparoscopic training, reports on flexible ureteroscopy training are relatively rare. Urologists have been trained by using validated simulators or computer-based models [8, 9] without true anatomical experience and simulation environment [10]. Animal surgery has also been performed by using pigs under general endotracheal anesthesia [11]. By using pigs as models, the following factors should be considered before training. A double J tube must be placed on the pigs 2 weeks to 4 weeks before surgery to insert the ureteroscope access sheath that will be used as a working channel during surgery. This process is complex and time consuming with disregard to anesthesia or operating procedures. The key point of flexible ureteroscopy training is to observe the different renal calyces, particularly the lower ones, and thus, a live/intact pig or an enclosed abdomen is unnecessary. By contrast, carbon dioxide pneumoperitoneum is needed in laparoscopic training to perform the operation in a closed space. We conducted trainings by using pigs in the early stages, and found that inserting an ureteroscope access sheath and performing the subsequent operations are difficult because experimental pigs are relatively young. Unlike adult pigs, the urethra and ureter of young pigs are considerably thinner, and thus, the trainees cannot finish the training program easily.

Based on these situations, we used isolated porcine kidneys as training objects. Compared with a live/intact pig, the main advantages and characteristics of isolated porcine kidneys are summarized as follows. (1) Omission of the preoperative preparation, thereby increasing training and learning time. (2) As training objects, isolated kidneys are cheaper and easier to obtain than experimental pigs, thereby reducing training cost. (3) Changes in the visual field caused by different handling manipulations can be shown intuitively and clearly. The specific advantage of a modular flexible ureteroscope is its lens, which can only bend in one direction. However, the ureteroscope body and handle can be moved forward and backward and rotated 360°. In addition, the visual field of flexible ureteroscopy is different from that of rigid ureteroscopy, which has a linear scan imaging characteristic because unconscious shaking and handle grip strength change the direction of the lens and the visual range. All these differences emphasize the difficulty of flexible ureteroscopy training. To enable the urologists to master a sense of position as soon as possible, we enhanced the brightness of light to allow it to penetrate the surface of the kidney. Under such condition, verifying whether target renal calyces are reached accurately is convenient, and positioning differences between rigid and flexible ureteroscopy can then be compared visually. However, these experiences could not be accumulated in an experimental pig during endoscopic operation. (4) Side injury and complications of flexible ureteroscopy can be summarized intuitively. At the start of the preliminary training, the urologists inserted a flexible ureteroscope directly without placing an access sheath because of the relatively low temperature and stiff ureter. As a result, renal subcapsular edema and swelling occurred during water irrigation several minutes later. Afterward, the sheath could be inserted smoothly when the isolated kidneys and ureters have been soaked in warm water for a certain period of time. This process cautions the young urologists to learn from the training and avoid side injury during actual clinical work because we could not find any kidney and perirenal tissue damage in vivo. (5) Various training programs are easy to increase. At the end of the training, we placed small stones or mung beans in the renal pelvis through the access sheath to simulate a realistic experience. The foreign bodies were washed with water randomly into one of the renal calyx, and then the trainees were instructed to find the foreign bodies accurately by using a flexible ureteroscope. After several trainings, the urologists gradually accumulated operating experience.

After the training, the ability of the urologists was significantly improved. The global rating scale and the pass/fail rating verified their advancement. In addition, with the improvement in proficiency, the time to finish the task was decreased gradually and a relatively stable level was achieved after several operations. Thus, for urologists with endourological experiences, mastering this technique is possible, primarily through animal training, as long as they mastered the differences and features of the two types of ureteroscopes, particularly eye–hand–ureteroscope coordination. In the subsequent study, we decided to train the 20 urologists during actual operations with patients to verify their performance. Moreover, the differences in side injuries, such as trauma and perforation, between the pre-test and the post-test were insignificantly different. We thought that these complications could be easily experienced by junior residents. Our subjects had endourological experience on rigid ureteroscopy and cystoscopy. Thus, with regard to flexible ureteroscopy training, the main differences are the visual field and the manipulation habit rather than the basic skills required in rigid ureteroscopy. Surgical errors/injuries are unrelated to technical skills, but to other skills, such as communication, teamwork, supervision, and decision making [12]. Different medical environments may also affect the occurrence of injuries.