Background and Purpose: Flexible ureterorenoscopy (F-URS) plays a major role in the management of kidney stones. Ureteral access sheaths (UAS) are important tools for F-URS. In this study, we aimed to evaluate the difference in intrarenal pressures between different flexible ureteroscopes while using the same UAS and to calculate the irrigation flow variance. Materials and Methods: Eight different flexible ureteroscopes were tested with five different UAS on an artificial kidney model to measure intrarenal pressures and irrigation flow. Irrigation at 60 cmH₂O pressure was performed; the pressure and the irrigation flow amount were recorded with different states of the operator channel: Free, with the laser fiber (272 μm), and with the nitinol basket (1.9F) inside. Results: The highest pressure recorded was 46.68 cmH₂O with Wolf Boa and 9.5/11.5F Cook Medical UAS. All the ureteroscopes that fit inside the 10/12F Coloplast ReTrace provided pressures below 40 cmH₂O. The inner diameter of the 10/12F Rocamed Bi-Flex is actually 11F, so intrarenal pressures were lower and irrigation flow was higher. With the 11/13F Boston Scientific Navigator HD and 12/14F Coloplast ReTrace, the pressures were very low. The irrigation flow measurements were in concordance with pressure measurements. Conclusion: The ureteroscope sizes diminished with advancements in technology. Small-sized ureteroscopes can provide low intrarenal pressures with good irrigation flow when used with convenient small-sized access sheaths. The compatibility between the ureteroscopes and UASs should be anticipated by all endourologists and considered during F-URS. The advantages of 10/12 UASs in terms of intrarenal pressure and irrigational flow should make these access sheaths an interesting first-line choice.

Ureteral access sheaths (UASs) are part of urologist’s armamentarium when performing retrograde intrarenal surgery (RIRS). Recently, the world of RIRS has changed dramatically with the development of three game-changers: thulium fiber laser (TFL), smaller size single use digital flexible ureterosopes and intraoperative intrarenal pressure (IRP) measurement devices. We aimed to clarify the impact of UASs on IRP, complications and SFRs and put its indications in perspective of these three major technological improvements. A systematic review of the literature using the Medline, Scopus and Web of Science databases was performed by two authors and relevant studies were selected according to PRISMA guidelines. Recent studies showed that using a UAS lowers IRP and intrarenal temperature by increasing irrigation outflow during RIRS. Data on the impact of a UAS on SFRs, postoperative pain, risk of infectious complications, risk of ureteral strictures and risk of bladder recurrence of urothelial carcinoma after diagnostic RIRS were inconclusive. Prestenting for at least one week resulted in ureteral enlargement, while the influence of pre-operative administration of alpha-blockers was unclear. Since TFL, smaller single use digital ureteroscopes and devices with integrated pressure-measuring and aspiration technology seemed to increase SFRs and decrease pressure and temperature related complications, indications on the use of a UAS may decrease in the near future.

Introduction: With the rise in the use of ureteroscopy and laser stone lithotripsy (URSL), a proportionate increase in the risk of post-procedural urosepsis has also been observed. The aims of our paper were to analyse the predictors for severe urosepsis using a machine learning model (ML) in patients that needed intensive care unit (ICU) admission and to make comparisons with a matched cohort. Methods: A retrospective study was conducted across nine high-volume endourology European centres for all patients who underwent URSL and subsequently needed ICU admission for urosepsis (Group A). This was matched by patients with URSL without urosepsis (Group B). Statistical analysis was performed with ‘R statistical software’ using the ‘randomforests’ package. The data were segregated at random into a 70% training set and a 30% test set using the ‘sample’ command. A random forests ML model was then built with n = 300 trees, with the test set used for internal validation. Diagnostic accuracy statistics were generated using the ‘caret’ package. Results: A total of 114 patients were included (57 in each group) with a mean age of 60 ± 16 years and a male:female ratio of 1:1.19. The ML model correctly predicted risk of sepsis in 14/17 (82%) cases (Group A) and predicted those without urosepsis for 12/15 (80%) controls (Group B), whilst overall it also discriminated between the two groups predicting both those with and without sepsis. Our model accuracy was 81.3% (95%, CI: 63.7–92.8%), sensitivity = 0.80, specificity = 0.82 and area under the curve = 0.89. Predictive values most commonly accounting for nodal points in the trees were a large proximal stone location, long stent time, large stone size and long operative time. Conclusion: Urosepsis after endourological procedures remains one of the main reasons for ICU admission. Risk factors for urosepsis are reasonably accurately predicted by our innovative ML model. Focusing on these risk factors can allow one to create predictive strategies to minimise post-operative morbidity.

Introduction: The improvements in flexible ureteroscopes provide efficient access to the upper urinary tract and advancements in laser technology strengthens the endourologists' armamentarium. The endourologists must be aware of the advantages and the potential complications of these powerful technological equipments. Our aim is to demonstrate temperature evolution during laser use inside an artificial kidney model. Materials and Methods: We created a bench model using K-Box ^® immersed into a saline-filled heating tank, which was used to obtain the needed temperature inside the cavity to provide different real-time situations. An endotracheal thermometer was placed inside. We used Olympus URF-P6 ureteroscope and Rocamed Holmium:yttrium-aluminium-garnet laser with two different fibers; 200 and 272 μm, at five different settings. Irrigation at room (24.5°C) and body (36.5°C) temperatures was used. We measured temperatures at 15th, 30th, and 45th seconds and 1st, 2nd, and 5th minutes of laser use with and without irrigation. We stopped measurements when temperature reached the upper limit of the endotracheal thermometer. Results: When irrigation was closed, with 272-μm laser fiber, we reached the temperature limit more rapidly with saline tank at 36.5°C than the tank at 24.5°C. When irrigation was closed, with both fibers and regardless of tank temperature and laser settings, the system surpassed the maximum temperature limit. With 272-μm laser fiber, the limit was reached as early as the 30th second. When the irrigation was open, we did not reach the maximum temperature limit regardless of tank temperature and laser setting. When two laser fibers were compared, the temperature increase was more pronounced with 272-μm fiber, but the difference was not statistically significant. Conclusion: Laser use during flexible ureteroscopy may cause increased intrarenal temperatures. Rapid increases should be kept in mind when irrigation is closed. The irrigation seems to limit the temperature increase when used with any laser setting.