Fluid dynamics within renal cavities during endoscopic stone surgery: does the position of the flexible ureteroscope and ureteral access sheath affect the outflow rate?

PURPOSE: To evaluate the impact of ureteroscope position within renal cavities as well as different locations of the tip of the ureteral access sheath (UAS) on fluid dynamics during retrograde intrarenal surgery (RIRS). MATERIALS AND METHODS: A prospective observational clinical study was performed. Measurements with a flexible ureteroscope placed in the upper, middle and lower calyces were obtained with the tip of the UAS placed either 2 cm below the pyelo-ureteric junction (PUJ), or at the level of the iliac crest. RESULTS: 74 patients were included. The outflow rates from the middle and upper calyxes were statistically significantly higher compared to the lower calyx, both with the UAS close to the pyelo-ureteric junction and at the iliac crest. When the UAS was withdrawn and positioned at the level of the iliac crest, a significant decrease in outflow rates from the upper (40.1 ± 4.3 ml/min vs 35.8 ± 4.1 ml/min) and middle calyces (40.6 ± 4.0 ml/min vs 36.8 ± 4.6 ml/min) and an increase in the outflow from the lower calyx (28.5 ± 3.3 ml/min vs 33.7 ± 5.7 ml/min) were noted. CONCLUSIONS: Our study showed that higher fluid outflow rates are observed from upper and middle calyces compared to lower calyx. This was true when the UAS was positioned 2 cm below the PUJ and at the iliac crest. Significant worsening of fluid dynamics from upper and middle calyces was observed when the UAS was placed distally at the level of the iliac crest. While the difference was statistically significant, the absolute change was not significant. In contrast, for lower calyces, a statistically significant improvement was documented.

Trends in the use of radiation protection and radiation exposure of European endourologists: a prospective trial from the EULIS-YAU Endourology Group.

INTRODUCTION: Due to the radiation exposure for the urology staff during endourology, our aim was to evaluate the trends of radiation protection in the operation room by endourologists from European centers and to estimate their annual radiation. METHODS: We conducted a multicenter study involving experienced endourologists from different European centers to evaluate whether the protection and threshold doses recommended by the International Commission on Radiation Protection (ICRP) were being followed. A 36-question survey was completed on the use of fluoroscopy and radiation protection. Annual prospective data from chest, extremities, and eye dosimeters were collected during a 4-year period (2017-2020). RESULTS: Ten endourologists participated. Most surgeons use lead aprons and thyroid shield (9/10 and 10/10), while leaded gloves and caps are rarely used (2/10 both). Six out of ten surgeons wear leaded glasses. There is widespread use of personal chest dosimeters under the apron (9/10), and only 5/10 use a wrist or ring dosimeter and 4 use an eye dosimeter. Two endourologists use the ALARA protocol. The use of ultrasound and fluoroscopy during PCNL puncture was reported by 8 surgeons. The mean number of PCNL and URS per year was 30.9 (SD 19.9) and 147 (SD 151.9). The mean chest radiation was 1.35 mSv per year and 0.007 mSv per procedure. Mean radiation exposure per year in the eyes and extremities was 1.63 and 11.5 mSv. CONCLUSIONS: Endourologists did not exceed the threshold doses for radiation exposure to the chest, extremities and lens. Furthermore, the ALARA protocol manages to reduce radiation exposure.

Emerging Trends in AI and Radiomics for Bladder, Kidney, and Prostate Cancer: A Critical Review.

This comprehensive review critically examines the transformative impact of artificial intelligence (AI) and radiomics in the diagnosis, prognosis, and management of bladder, kidney, and prostate cancers. These cutting-edge technologies are revolutionizing the landscape of cancer care, enhancing both precision and personalization in medical treatments. Our review provides an in-depth analysis of the latest advancements in AI and radiomics, with a specific focus on their roles in urological oncology. We discuss how AI and radiomics have notably improved the accuracy of diagnosis and staging in bladder cancer, especially through advanced imaging techniques like multiparametric MRI (mpMRI) and CT scans. These tools are pivotal in assessing muscle invasiveness and pathological grades, critical elements in formulating treatment plans. In the realm of kidney cancer, AI and radiomics aid in distinguishing between renal cell carcinoma (RCC) subtypes and grades. The integration of radiogenomics offers a comprehensive view of disease biology, leading to tailored therapeutic approaches. Prostate cancer diagnosis and management have also seen substantial benefits from these technologies. AI-enhanced MRI has significantly improved tumor detection and localization, thereby aiding in more effective treatment planning. The review also addresses the challenges in integrating AI and radiomics into clinical practice, such as the need for standardization, ensuring data quality, and overcoming the "black box" nature of AI. We emphasize the importance of multicentric collaborations and extensive studies to enhance the applicability and generalizability of these technologies in diverse clinical settings. In conclusion, AI and radiomics represent a major paradigm shift in oncology, offering more precise, personalized, and patient-centric approaches to cancer care. While their potential to improve diagnostic accuracy, patient outcomes, and our understanding of cancer biology is profound, challenges in clinical integration and application persist. We advocate for continued research and development in AI and radiomics, underscoring the need to address existing limitations to fully leverage their capabilities in the field of oncology.

Percutaneous antegrade management of large proximal ureteral stones using non-papillary puncture.

Objective: To evaluate the feasibility and the safety of medial non-papillary percutaneous nephrolithotomy (npPCNL) for the management of large proximal ureteral stones. Methods: We evaluated prospectively collected data of 37 patients with large proximal ureteral stones more than 1.5 cm in diameter treated by prone npPCNL. Depending on stone size, in-toto stone removal or lithotripsy using the Lithoclast® Trilogy (EMS Medical, Nyon, Switzerland) was performed. Perioperative parameters including operative time (from start of puncture to the skin suturing), stone extraction time (from the first insertion of the nephroscope to the extraction of all stone fragments), and the stone-free rate were evaluated. Results: Twenty-one males and 16 females underwent npPCNL for the management of large upper ureteral calculi. The median age and stone size of treated patients were 58 (interquartile range [IQR]: 51-69) years and 19.3 (IQR: 18.0-22.0) mm, respectively. The median operative time and stone extraction time were 25 (IQR: 21-29) min and 8 (IQR: 7-10) min, respectively. One case (2.7%) of postoperative bleeding and two cases (5.4%) of prolonged fever were managed conservatively. The stone-free rate at a 1-month follow-up was 94.6%. Conclusion: The npPCNL provides a straight route to the ureteropelvic junction and proximal ureter. Approaching from a dilated portion of the ureter under low irrigation pressure with larger diameter instruments results in effective and safe stone extraction within a few minutes.

How long do we need to reach sufficient expertise with the avatera® robotic system?

PURPOSE: To investigate the learning curve in four basic surgical skills in laparoscopic and robotic surgeries, and evaluate the approximate time needed to reach sufficient expertise in performing these tasks with the avatera® system. METHODS: Twenty urology residents with no previous experience in dry-lab and robotic surgery were asked to complete four basic laparoscopic tasks (peg transfer, circle cutting, needle guidance, and suturing) laparoscopically and robotically. All participants were asked to complete the tasks first after watching the Uroweb educational material and, second, after undertaking a 2-hour training in robotic and laparoscopic dry-lab. Thereafter, all trainees continued to undertake 2-hour training programs until being able to complete the tasks with the avatera® robot at the desired time. Paired t test and one-way ANOVA test were used to analyze time differences between the groups. RESULTS: Time needed to complete all tasks either robotically or laparoscopically was significantly less in the second compared to the first attempt for all Groups in each Task. In the robotic dry-lab, time needed to complete the tasks was significantly less than in the laparoscopic dry-lab. A significant effect of previous laparoscopic experience of the participants on the training time needed to achieve most of the goal times was detected. CONCLUSION: The results of the study highlight the role of previous laparoscopic experience in the training time needed to achieve the performance time goals and demonstrate that the learning curve of basic surgical skills using the avatera® system is steeper than the laparoscopic one.

Radiological Density, Atomic Numbers, and Stone Fragmentation of Bego Stones Used for Research in Endourology: Comparison to Real Urinary Stones.

Objective: The aim of the study was to characterize artificial stones used for research in endourology in terms of radiological properties and hardness, based on stone fragmentation, and to compare them with real stones. Materials and Methods: We built artificial stones using BegoStone Plus™ powder (BEGO, Lincoln, RI), with powder (g)-water (mL) ratios ranging from 15:03 to 15:12. The CT Gemstone Spectral Imaging Software® (GE Medical Systems, LLC, Waukesha, WI) was used to evaluate the radiological density in HU and spectral properties. Stone fragmentation was assessed in an in vitro experimental setting. These properties of artificial stones were compared with real urinary calculi. Results: Regarding radiological density in terms of HUs, 15:03 artificial calculi showed similar results when compared with real stones comprising calcium oxalate and calcium phosphate. The 15:03 and 15:04 artificial stones showed similar spectral property results to calcium pyrophosphate stones. The 15:11 artificial stones showed similar stone fragmentation results to real stones comprising uric acid, and 15:03 artificial calculi showed similar results to apatite and cystine stones. Conclusions: Artificial stones are useful for research in endourology. Stones with a powder (g)-water (mL) ratio of 15:03 proved to mimic real hard stones in terms of HUs, atomic number, and stone fragmentation in our study and could be used as artificial hard stones, and 15:11 stones showed similar stone fragmentation to uric acid stones. Our study might suggest that standard Bego stones are useful to investigate different areas in endourology, but not radiological properties because radiological homogeneity is not ensured unless more sophisticated mixing methods are used.

Worldwide trends of practice and intervention in paediatric endourology: comparison of European versus Non-European responses.

Introduction: The area of paediatric endourology is unique and is recognised to be challenging, and it requires a certain level of focused training and expertise. Our aim was to conduct a worldwide survey in order to gain an overview regarding the current practice patterns for minimally invasive treatments of paediatric upper urinary tract stone patients. Material and methods: The survey was distributed between December 2021 and April 2022 through urology sections and societies in United Kingdom, Latin America and Asia. The survey was made up of 20 questions and it was distributed online using the free online Google Forms (TM). Results: 221 urologists answered the survey with 56 responses each from India, South America and UK and 53 responses from the rest of Europe (15 countries). In total, 163 responders (73.7%) managed paediatric stone patients in their daily practice. Of the responders, 60.2% were adult urologists and 39.8% were paediatric urologists. 12.9% adult urologists and 20.4% paediatric urologists run independent clinics while some run combined adult and paediatric clinics sometimes with the support of the nephrologists. Only 33.9% urologists offered all surgical treatments [extracorporeal shock wave lithotripsy (ESWL), percutaneous nephrolithotomy (PCNL), ureteroscopy (URS) and retrograde intrarenal surgery (RIRS)]. Conclusions: Treatment of paediatric stones can vary according to country and legislations. Based on the results of this survey, minimally invasive methods such as URS and mini PCNL seem to have become more popular. In most institutions a collaboration exists between adult and paediatric urologists, which is the key for a tailored decision making, counselling and treatment success.

Location of ureteral access sheath in the ureter. Does it affect the fluid flow in different calyces?

Introduction: The aim of this study was to evaluate outflow variation in different locations of the pyelocaliceal system with the use of different ureteral access sheath (UAS) sizes and different UAS positioning. Material and methods: The experimental setup included an anaesthetised porcine model, a 7.5-Fr ureteroscope with a 200-µm laser fibre inserted in the working channel, a hand-held pumping irrigating system, and UAS of different sizes, namely: 9.5/11.5 Fr, 12/14 Fr, and 14/16 Fr. Each UAS was placed just below the ureteropelvic junction (UPJ) or in the mid-ureter. The ureteroscope was placed in the renal pelvis, upper and lower calyces, and outflow measurements were obtained with 3-second interval pumping for one minute in every experimental setup. Results: The UAS positioning in the mid-ureter was associated with significantly higher outflow rates in the lower calyx (p = 0.041). While the UAS was below the UPJ, we observed a trend of lower outflow rate in the lower calyx, which was completely inverted when the UAS was in the mid-ureter. Increasing the UAS size from 9.5/11.5 Fr to 12/14 Fr led to a significant increase in outflow in the renal pelvis and upper calyx (p = 0.007), but not in the lower calyx. A further increase to 14/16 Fr did not produce increased flow. Conclusions: Different locations of the pyelocaliceal system have different fluid mechanics during fURS. In the renal pelvis and upper calyx increasing the diameter of the UAS improved the outflow, whereas in the lower calyx the position of the UAS seems to be the most relevant factor. These variables should be considered when performing fURS, especially with high-power laser lithotripsy.

Sphincter preservation techniques during radical prostatectomies: Lessons learned.

Prolonged urinary incontinence represents one of the most severe complications after a radical prostatectomy procedure, significantly affecting patients' quality of life. In an attempt to ameliorate postprostatectomy continence rates, several sphincter preservation techniques have been reported. The purpose of this article is to report several different sphincter preservation techniques and identify the ones which affect postoperative outcomes the most. For our narrative review, PubMed was searched using the keywords "sphincter," "continence," "preservation," "techniques," and "prostatectomy." Other potentially eligible studies were identified using the reference lists of included studies. Sphincter preservation techniques can be summarized into bladder neck preservation, minimizing injury to the external urethral sphincter, and preserving the maximal length of the external sphincter and of the membranous urethra. Three anatomical structures must be recognized and protected in an attempt to maintain the sphincter complex: the bladder neck, the external urethral sphincter and the musculature of the membranous urethra. While there is strong evidence supporting the importance of bladder neck preservation, the role of maximal preservation of the external sphincter and of the intraprostatic part of the membranous urethra in improving continence rates has not yet been reported in a statistically significant manner by high-quality studies.

Feasibility study of a novel robotic system for transperitoneal partial nephrectomy: An in vivo experimental animal study.

PURPOSE: To evaluate the safety and feasibility of partial nephrectomy with the use of the novel robotic system in an in vivo animal model. METHODS: Right partial nephrectomy was performed in female pigs by a surgical team consisting of one surgeon and one bedside assistant. Both were experienced in laparoscopic surgery and trained in the use of the novel robotic system. The partial nephrectomies were performed using four trocars (three trocars for the robotic arms and one as an assistant trocar). The completion of the operations, set-up time, operation time, warm ischemia time (WIT) and complication events were recorded. The decrease in all variables between the first and last operation was calculated. RESULTS: In total, eight partial nephrectomies were performed in eight female pigs. All operations were successfully completed. The median set-up time was 19.5 (range, 15-30) minutes, while the estimated median operative time was 80.5 minutes (range, 59-114). The median WIT was 23.5 minutes (range, 17-32) and intra- or postoperative complications were not observed. All variables decreased in consecutive operations. More precisely, the decrease in the set-up time was calculated to 15 minutes between the first and third attempts. The operative time was reduced by 55 minutes between the first and last operation, while the WIT was decreased by 15 minutes during the consecutive attempts. No complications were noticed in any operation. CONCLUSIONS: Using the newly introduced robotic system, all the advantages of robotic surgery are optimized and incorporated, and partial nephrectomies can be performed in a safe and effective manner.

How Safe Are the Laparoscopic and Robotic Graspers? Evaluation of the Novel Avatera Robotic Surgical System: An Acute In Vivo Study on a Porcine Model.

OBJECTIVE: To evaluate the tissue injury caused by the force applied by the roboticassisted graspers of avatera robotic surgical system on bowel tissue. METHODS: An experimental in vivo porcine model with 1 pig was conducted. After a standard transperitoneal setup of the avatera robotic surgical system, different laparoscopic and robotic graspers were used on the bowel with maximum force applied each time. Robotic atraumatic grasper, laparoscopic right angle grasper, laparoscopic curved grasper, and laparoscopic atraumatic grasper were used. After using all graspers, the pig was sacrificed. The bowel segments were resected and sent for histological analysis. RESULTS: The pathologist reported that all the graspers caused signs of acute inflammation without any irreversible damage or signs compatible with ischemia of the tissue. No significant difference in histology was observed between the graspers. CONCLUSION: No permanent damage was caused by graspers, except for acute, reversible inflammation. Concluding, the avatera grasper could be safe to use on bowel segments, independent of the applied pressure.

Effect of patient positioning on anesthesiologic risk in endourological procedures.

Objective: The objective is to compare supine and prone positions in terms of arterial blood gas during lithotripsy endourology procedures in different stages. Material and Methods: Cases of during lithotripsy endourology procedures in our department from March to September 2020 were included prospectively. The variables registered were body mass index, age, the American Society of Anesthesiologists (ASA) score, diabetes mellitus, positive end-expiratory pressure (PEEP), FiO2, stone size, stone location, procedural type, position, procedure duration, PaO2, SaO2, PaCO2, pH, and dynamic compliance. PaO2, SaO2, PaCO2, pH, and dynamic compliance were recorded at the beginning of the procedure, 5 min later, 15 min later, and at the end of the procedure. Results: Thirty patients in prone position and 30 in lithotomy position were included in this study. Patients in prone position underwent percutaneous nephrolithotomy, and patients in supine/lithotomy underwent retrograde intrarenal surgery or ureteroscopy. Statistically significant differences were found in PEEP, duration, PaO2 at the beginning, SaO2 at the beginning and at the end of the procedure, PaCO2 at the beginning and at minute 5 and pH at the beginning of the surgery. The saturation PaO2 increased significantly on prone position and was statistically significantly better at the end of the surgery. Conclusions: Both prone and supine positions were safe regarding anesthesiologic risk and had no clinically relevant differences in terms of individual comparisons in arterial blood gas parameters in static moments of the procedure. Prone position was related to an increase in PaO2 and a drop in PaCO2 gradually from the beginning to the end of the surgery.

New Technologies in Endourology and Laser Lithotripsy: The Need for Evidence in Comprehensive Clinical Settings.

Flexible ureteroscopy (fURS) with laser lithotripsy is currently the gold standard surgical treatment for ureteral and kidney stones with a maximum diameter of 2 cm [...].

The effect of percutaneous tract dilation technique on renal parenchymal trauma: An experimental in vivo study on a porcine model.

Purpose: The purpose of this study was to evaluate renal parenchymal trauma of two-step dilation compared to the conventional Amplatz gradual dilation during percutaneous nephrolithotomy on a porcine model. Materials and Methods: A nonpapillary percutaneous access tract was established under fluoroscopic guidance in both kidneys of four female pigs. On the right kidney of each pig, gradual dilation was performed using an Amplatz dilator set with a gradual dilation to 30 Fr, whereas on the left, a two-step dilation was utilized using only 16 Fr and 30 Fr dilators. Two of the animals were euthanized immediately after the procedure and the remaining two 1 month later. The pigs that were kept alive underwent a contrast-enhanced computed tomography immediately, 15, and 30 days postoperatively. A dimercaptosuccinic acid (DMSA) scintigraphy and single-photon emission computed tomography-computed tomography (CT) were also performed after the last CT and afterward, the pigs were sacrificed. All kidneys were harvested for pathohistological examination. Results: The follow-up radiologic imaging showed similar parenchymal damage caused by the compared dilation techniques and an expected reduction in scar size in the later scans. No scar was identified by DMSA in any kidney. Gross and microscopic examinations conducted both on the kidneys that were harvested immediately after the procedure and the ones from the animals that were left to heal, revealed no significant differences in tissue damage, grade of fibrosis, or inflammation depending on the dilation method. Conclusions: Our study showed no inferior outcomes caused by two-step dilation compared to gradual dilation regarding renal parenchymal damage following a nonpapillary puncture. In fact, postoperative imaging findings suggested a trend toward better healing and less scar tissue when the two-step method was used.

Holmium: Yttrium-aluminum-garnet laser lithotripsy: Is there a difference in ablation rates between short and long pulse duration?

Introduction: The high-power holmium: yttrium-aluminum-garnet lasers provide a wide variety of settings for stone disintegration. The aim of this in vitro study is to evaluate the effect of short and long pulse duration on ablation rates on urinary stones. Materials and Methods: Two types of artificial stones were created by BegoStone™ with different compositions (15:3 and 15:6, stone/water ratio). Stones with a 15:3 and 15:6 powder-to-water ratio were defined as hard and soft stones, respectively. Lithotripsy was performed with different laser settings using a custom-made in vitro model consisting of a 60 cm long and 19 mm diameter tube. The ablation rate is defined as the final total mass subtracted from the initial total mass and divided to the time of treatment. Stone ablation rates were measured according to different laser settings with total power of 10W (0,5J-20 Hz, 1J-10 Hz, 2J-5 Hz) and 60W (1J-60 Hz, 1,5J-40 Hz, 2J-30 Hz). Results: Higher pulse rates and higher total power settings were related to higher ablation rates. Short pulse duration was more effective on soft stones, whereas long pulse duration was more effective on hard stones. For the same power settings, the highest energy-lowest frequency combination resulted in higher ablation rate in comparison to the lowest energy-higher frequency combination. Finally, short and long pulse average ablation rates do not differ so much. Conclusion: Regardless of the stone type and pulse duration, utilization of higher power settings with higher energies increased the ablation rates. Higher ablation rates were demonstrated for hard stones using long pulse duration, and for soft stones with short pulse duration.

High-power laser lithotripsy - do we treat or harm? Histological evaluation of temperature effects in an in vivo study with thulium fiber laser.

Introduction: The aim of this study was to evaluate the possible histopathological alterations that occur in the kidneys due to a continuous temperature increase above 43°C for one hour of lithotripsy using a newly introduced thulium fiber laser (TFL). Material and methods: Two female pigs were used. After the insertion of a 9.5/11.5 ureteral access sheath, flexible ureteroscopy and laser lithotripsy for one hour were conducted. A TFL laser with a 200-µm fiber was used. The power setting used was 8 W (0.5 J × 16 Hz). A K-type thermocouple was inserted and fixed in the upper calyx of the right porcine kidney to record the temperature in the pelvicalyceal system during the laser activation. Second-look flexible nephroscopy followed by nephrectomy and pathohistological evaluation of the operated kidney was performed one week after the procedure in the first pig and 2 weeks after the surgery in the second pig. Results: Flexible nephroscopy did not reveal significant differences between the 2 porcine kidneys. Nevertheless, the histopathological report demonstrated severe alterations in the kidney of the first pig. Mild changes were reported in the kidney of the second pig. A significant improvement in inflammation and haemorrhagic lesions was demonstrated when comparing the 2 kidneys. Conclusions: The difference demonstrated between the 2 kidneys based on the histopathological report shows that the healing process is capable of improving severe to mild alterations within a one-week time frame. Two weeks after the surgery, only minor changes were observed, suggesting that even temperature increases above the threshold can be tolerated regarding renal damage.

Endoscopic management of encrusted ureteral stents: outcomes and tips and tricks.

PURPOSE: To report our experience in the management of encrusted ureteral stents (EUS) and provide technical insight of our endourological approaches for difficult scenarios posed by this entity. MATERIALS AND METHODS: A retrospective evaluation of a longitudinally collected database of 58 patients with encrusted US between December 2012 and May 2022 was performed. The ureteral stents were initially inserted due to obstructive uropathy, pyelonephritis or after a successful endoscopic procedure for urolithiasis. A combination of antegrade/retrograde treatment in single or multiple sessions took place for the retrieval of the encrusted stents. Non-contrast enhanced computer tomography was used for the follow-up of the patients at 1-month after the removal of the encrusted stent. RESULTS: Overall 58 patients, 39 males and 19 females with a median age of 51 years old were included in the study. Indwelling time was < 6 months, 6-12 months and > 12 months in 22%, 57% and 21% of the cases, respectively. All US were successfully removed. Semi-rigid ureteroscopy (URS) and flexible ureteroscopy (fURS) were used in 90% of the cases. In 10% of the cases, a second-stage percutaneous nephrolithotomy (PCNL) or endoscopic combined intrarenal surgery (ECIRS) was performed. All US were successfully released. Stone-free rate was 84% at 1-month. Overall complication rate was 10.5% (mostly postoperative fevers, 5.4%). CONCLUSION: Removal of the encrusted US is a challenging procedure. Appropriate decision-making and knowledge of specific tricks may result in safe and successful management of significant EUS.