Retrograde nephrostomy access for percutaneous nephrolithotomy: a simple and safe technique.

This study aimed at illustrating our experience with the retrograde nephrostomy access technique for percutaneous nephrolithotomy (PCNL).This retrospective study was conducted between June 1997 and September 2018 for 648 patients who underwent PCNL with retrograde nephrostomy access. Included in the study were the patient demographic, operative time, site of the access, fluoroscopic exposure time, stone clearance rate, additional procedures and complications. A total of 648 patients aged between 25 and 70 years had renal stones and were included in this study. Retrograde nephrostomy access was achieved through the upper calyx in 252 patients (38.9%), middle calyx in 348 patients (53.7%) and lower calyx in 48 patients (7.4%). Among those patients, 108 (16.7%) required supracostal access. The average time for the retrograde access and PCNL was 14.4 min and 40 min, respectively. The average fluoroscopic exposure time for the retrograde access was 3.2 min. There were 12 failures (1.9%) as a result of severe hydronephrosis. Complete stone clearance was achieved in 91.8%. Small stone fragments (4 mm or less) were detected in 7.4%. Median hospital stay was 3.5 days (range 3-7). Complications occurred in 39 patients (6%). Eight patients (1.2%) developed significant postoperative hemorrhage that was controlled by transfusion and angioembolization. There were no recorded cases of colonic injuries, pneumothorax or hemothorax, demonstrating that the retrograde access technique is safe and reliable. It provides control over both ends of the wire eliminating the risk of accidental wire displacement. Radiation exposure is minimal. There are low failure and complication rates.

[Using of a dismountable 3D-model of the collecting system with color segmentation to improve the learning curve of residents].

AIM: to determine the efficiency of using a non-biological dismountable 3D-model of the collecting system with color segmentation for better understanding of its anatomy by residents and to determine the optimal tactics of percutaneous nephrolithotomy (PNL). MATERIALS AND METHODS: 3D-models of the collecting system were developed based on CT data of 5 patients with staghorn stones, for whom PNL was planned. CT images were obtained in the Dicom format. RadiAnt DICOM Viewer was used for delineation and segmentation of the collecting system with 3D visualization. Using slicer 4.8.1 software, virtual models were processed to convert DICOM files to STL format. Then, virtual color extraction of each group of calyxes was performed for convenient disassembling and intraluminal study of the anatomy of the collecting system. The final stage included the printing of each area by the method of layer-by-layer deposition using a 3D printer Picaso designer X. To assess the efficiency of the dismountable 3D-model that simulates a certain collecting system, a questionnaire was used. It allowed to evaluate the understanding of the anatomy of the collecting system by residents, as well as the ability to determine the optimal calyx for PNL by comparing the answers with the result of a survey of practicing urologists who had performed more than 50 cases. RESULTS: After studying 3D-models by residents, determination of the number of calyxes in each group was not statistically significantly different from those for practicing urologists who used CT images. The choice of the calyx for primary puncture was not different between groups. However, residents chose the calyx for additional access worse (p=0.009). CONCLUSION: The dismountable 3D-model of the collecting system is promising for training of residents and planning PNL. Studying the anatomy of a single group of calyxes as well as the entire collecting system allows to choose the optimal calyx for percutaneous puncture during PNL.

Pilot Assessment of Immersive Virtual Reality Renal Models as an Educational and Preoperative Planning Tool for Percutaneous Nephrolithotomy.

BACKGROUND: Percutaneous nephrolithotomy (PCNL) requires the urologist to have detailed knowledge of the stone and its relationship with the renal anatomy. Immersive virtual reality (iVR) provides patient-specific three-dimensional models that might be beneficial in this regard. Our objective is to present the initial experience with iVR in surgeon planning and patient preoperative education for PCNL. MATERIALS AND METHODS: From 2017 to 2018 four surgeons, each of whom had varying expertise in PCNL, used iVR models to acquaint themselves with the renal anatomy before PCNL among 25 patients. iVR renderings were also viewed by patients using the same head-mounted Oculus rift display. Surgeons rated their understanding of the anatomy with CT alone and then after CT+iVR; patients also recorded their experience with iVR. To assess the impact on outcomes, the 25 iVR study patients were compared with 25 retrospective matched-paired non-iVR patients. Student's t-test was used to analyze collected data. RESULTS: iVR improved surgeons' understanding of the optimal calix of entry and the stone's location, size, and orientation (p < 0.01). iVR altered the surgical approach in 10 (40%) cases. Patients strongly agreed that iVR improved their understanding of their stone disease and reduced their preoperative anxiety. In the retrospective matched-paired analysis, the iVR group had a statistically significant decrease in fluoroscopy time and blood loss as well as a trend toward fewer nephrostomy tracts and a higher stone-free rate. CONCLUSIONS: iVR improved urologists' understanding of the renal anatomy and altered the operative approach in 40% of cases. In addition, iVR improved patient comprehension of their surgery. Clinically, iVR had benefits with regard to decreased fluoroscopy time and less blood loss along with a trend toward fewer access tracts and higher stone-free rates.

[Non-biological 3D printed simulator for training in percutaneous nephro- lithotripsy].

AIM: To develop a non-biological 3D printed simulator for training and preoperative planning in percutaneous nephrolithotripsy (PCNL), which allows doctors to master and perform all stages of the operation under ultrasound and fluoroscopy guidance. MATERIALS AND METHODS: The 3D model was constructed using multislice spiral computed tomography (MSCT) images of a patient with staghorn urolithiasis. The MSCT data were processed and used to print the model. The simulator consisted of two parts: a non-biological 3D printed soft model of a kidney with reproduced intra-renal vascular and collecting systems and a printed 3D model of a human body. Using this 3D printed simulator, PCNL was performed in the interventional radiology operating room under ultrasound and fluoroscopy guidance. RESULTS: The designed 3D printed model of the kidney completely reproduces the individual features of the intra-renal structures of the particular patient. During the training, all the main stages of PCNL were performed successfully: the puncture, dilation of the nephrostomy tract, endoscopic examination, intra-renal lithotripsy. CONCLUSION: Our proprietary 3D-printed simulator is a promising development in the field of endourologic training and preoperative planning in the treatment of complicated forms of urolithiasis.

Validation of a Novel Cost Effective Easy to Produce and Durable In Vitro Model for Kidney-Puncture and Percutaneous Nephrolitholapaxy-Simulation.

INTRODUCTION: Nephrolithiasis is one of the most common diseases in urology. According to the EAU Guidelines, a percutaneous nephrolitholapaxy (PNL) is recommended when treating a kidney stone >2 cm. Nowadays, PNL is performed even for smaller stones (<1 cm) using miniaturized instruments. The most challenging part of any PNL is the puncture of the planned site. PNL-novice surgeons need to practice this step in a safe environment with an ideal training model. We developed and evaluated a new, easy to produce, in vitro model for the training of the freehand puncture of the kidney. MATERIALS AND METHODS: Porcine kidneys with ureters were embedded in ballistic gel. Food coloring and preservative agent were added. We used the standard imaging modalities of X-ray and ultrasound to validate the training model. An additional new technique, the iPAD-guided puncture, was evaluated. Five novices and three experts conducted 12 punctures for each imaging technique. Puncture time, radiation dose, and number of attempts to a successful puncture were measured. Mann-Whitney-U, Kruskal-Wallis, and U-Tests were used for statistical analyses. RESULTS: The sonography-guided puncture is slightly but not significantly faster than the fluoroscopy-guided puncture and the iPAD-assisted puncture. Similarly, the most experienced surgeon's time for a successful puncture was slightly less than that of the residents, and the experienced surgeons needed the least attempts to perform a successful puncture. In terms of radiation exposure, the residents had a significant reduction of radiation exposure compared to the experienced surgeons. CONCLUSION: The newly developed ballistic gel kidney-puncture model is a good training tool for a variety of kidney-puncture techniques, with good content, construct, and face validity.

A Simple, Non - Biological Model for Percutaneous Renal Access Training.

PURPOSE: Percutaneous renal puncture (PRP) is one of the most important and critical step of urology, especially while performing percutaneous nephrostomy and percutaneous nephrolithotomy (PCNL). In the learning period of this procedures, there is a need for validated, effective, economical models for such training. This study describes a simple non - biological model for learning PRP. The aim was to determine the effectivity of this model as a training and assessment tool, and to assess its cost relative to other models. MATERIALS AND METHODS: We designed a training box, made of foam and rubber with two open sides and performed radiopaque pelvicalyceal system maquettes to insert inside it. Experts in PCNL (i.e., > 100 cases) andnovices (i.e., pediatric surgeons and urologists without PCNL experience) performed percutaneous renal puncture. Novices performed a pre -test and a post - test (i.e., after 2 hour training). Data recorded were total procedure time, X - ray exposure time, and number of puncture attempts. Experts who performed PRP successfully were asked torate the model using a questionnaire. RESULTS: Five experts and 21 novices completed the study. Four experts rated the model as an "excellent" (score 5) training and assessment tool; one expert rated these as "very good" (score 4). Comparisons of novices' pre - and post - test median results revealed significant skill acquisition with shorter procedure time, less X - ray exposure, and fewer attempts for successful puncture (all P < .001). CONCLUSION: This new non - biological training model is an effective training tool that helps learners improve skills in PRP. The model is simple to construct, economical, and highly re-useable compared to others. It provides good visibility and imaging, is portable, and could be used widely in training centres.

[Percutaneous nephrostolithotomy. Technic and learning curve]. / Perkutane Nephrostolithotomie. Technik und Lernkurve.

The closed controlled manipulation of the urinary tract (endourology) has provided rapid advances in urologic therapy. Various methods are available for percutaneous stone removal. After 300 p.c. nephrostolithotomies we present the 'learning curve' leading to our technique of endourologic stone manipulation.