Single-use flexible ureteroscope provides an alternative treatment for upper urinary calculi: A systematic review and meta-analysis.

OBJECTIVE: This study aimed to evaluate the efficacy and safety of single-use flexible ureteroscope and reusable flexible ureteroscope for upper urinary calculi. METHODS: We conducted a meta-analysis that had a comprehensive search in PubMed, Embase, Cochrane Library, Web of Science, and WanFang databases from 2000/01/01 to 2023/06/01 for available randomized controlled trials. "Ureteroscopes," "Flexible Ureteroscope," "Single-use," and "Upper Urinary Calculi" were used as the major keywords for the search. Review Manager 5.0 and STATA 12.0 were used for calculation and statistical analysis. RESULTS: A total of 9 randomized controlled trials comprising 1293 participants were included in our meta-analysis. Single use-FURS had better results in stone-free rate (relative risk: 1.08, 95% confidence interval: [1.02, 1.15], P = .02) and postoperative infection (relative risk: 0.41, 95% confidence interval: [0.23, 0.72], P = .002). Operative time, hemoglobin decline, postoperative serum creatinine, postoperative hospital stay, and overall complication after surgery showed no significant differences between the 2 procedures (P > .05). CONCLUSION: Single-use flexible ureteroscope provides a valuable alternative to reusable flexible ureteroscope in upper urinary calculi with its better visual field performance and manipulation, opening a new technological revolution for kidney stone treatment.

Exploring ureteroscope design with computational fluid dynamics for improved intra-pelvic pressure.

High intra-pelvic pressure (IPP) during ureteroscopy can lead to complications including pyelovenous backflow, bleeding, and infection. Our primary goal was to identify the best cross-section and orientation of a ureteroscope within a Ureteral Access Sheath (UAS) to minimize IPP and maximize outflow. Our secondary goal was to validate our findings with a UAS prototype. To determine the optimal ureteroscope cross-section within a UAS, four ureteroscopes of equivalent cross-sectional area were simulated within a 10 Fr UAS using computational fluid dynamics software COMSOL. We then created a corresponding prototype by securing a 3-0 monofilament suture at the inferior aspect of the 12 Fr outer UAS, inducing an offset to the ureteroscope. Mean flow volumes through a 10/12 Fr UAS occupied by a 9.5-Fr single-use flexible ureteroscope were compared (17 iterations) to those through our prototype UAS. During the simulation, the lowest IPP and highest outflow were seen with an offset circular ureteroscope (41% resistance) compared to a ureteroscope centered in the UAS. The unmodified UAS had an average volume of 30.0 mL/min (SD ± 0.35) compared to 33.76 mL/min (SD ± 0.90) for the modified UAS (p < 0.05). We found that using a circular ureteroscope positioned along the sidewall maximizes outflow through a circular UAS. We made a prototype UAS to offset the ureteroscope and observed a 12.5% increase in outflow. This approach can potentially decrease IPP during ureteroscopy without impacting inflow or the working channel. Although modifying a ureteroscope is more difficult, it could create an offset without reducing UAS cross-section.

Predicting Urinary Stone Composition in Single-Use Flexible Ureteroscopic Images with a Convolutional Neural Network.

Background and Objectives: Analysis of urine stone composition is one of the most important factors in urolithiasis treatment. This study investigated whether a convolutional neural network (CNN) can show decent results in predicting urinary stone composition even in single-use flexible ureterorenoscopic (fURS) images with relatively low resolution. Materials and Methods: This study retrospectively used surgical images from fURS lithotripsy performed by a single surgeon between January 2018 and December 2021. The ureterorenoscope was a single-use flexible ureteroscope (LithoVue, Boston Scientific). Among the images taken during surgery, a single image satisfying the inclusion and exclusion criteria was selected for each stone. Cases were divided into two groups according to whether they contained any calcium oxalate (the Calcium group) or none (the Non-calcium group). From 506 total cases, 207 stone surface images were finally included in the study. In the CNN model, the transfer learning method using Resnet-18 as a pre-trained model was used, and only endoscopic digital images and stone classification data were input to achieve minimally supervised learning. Results: There were 175 cases in the Calcium group and 32 in the Non-calcium group. After training and validation, the model was tested using the test set, and the total accuracy was 81.8%. Recall and precision of the test results were 88.2% and 88.2% in the Calcium group and 60.0% and 60.0% in the Non-calcium group, respectively. The area under the receiver operating characteristic curve of the model, which represents its classification performance, was 0.82. Conclusions: Single-use flexible ureteroscopes have financial benefits but low vision quality compared with reusable digital flexible ureteroscopes. As far as we know, this is the first artificial intelligence study using single-use fURS images. It is meaningful that the CNN performed well even under these difficult conditions because these results can further expand the possibilities of its use.

Optimal placement of flexible ureteral access sheath in retrograde intrarenal surgery.

This study aims to explore the optimal location of flexible ureteral access sheath (f-UAS) in retrograde intrarenal lithotripsy (RIRS). RIRS model was built by AutoCAD 2011 software, and imported COMSOL 5.6 software to computer simulation. An RIRS model was constructed in vitro to analyze the distribution pattern of stone fragments and compare the weight of stone fragments carried out by the irrigation fluid when the f-UAS is in different positions. Computer simulation showed that the highest flow of irrigation fluid was in the channel of flexible ureteroscopy (f-URS) and in the lumen of f-UAS. From the f-URS to the renal collection system and then to the f-UAS, the velocity of irrigation fluid changes gradually from high-flow to low-flow and then to high-flow. When the f-URS and the f-UAS are at the same level, the irrigation fluid is always at a state of high flow during the process from f-URS to f-UAS. When the f-URS and the f-UAS are at the same level, it can increase the local intrarenal pressure (IRP) at the front of f-URS. The stone fragments are mainly sediment in the low-flow region of irrigation fluid. More stone fragments could follow the irrigation fluid out of the body when the tip of f-URS and the tip of f-UAS are at the same level (P < 0.001). The f-UAS should be brought closer to the stone in RIRS. And more stone fragments can be taken out of the body by the effect of irrigation fluid.

Residual fragment size following retrograde intrarenal surgery: a critical evaluation of related variables.

Given the limited data on the predictive factors of residual kidney stone size after flexible ureteroscopy (fURS), this study aims to investigate the variables affecting residual stone size. The medical records of 642 patients without complications being treated for kidney stones with fURS between July 2014 and May 2022 were reviewed retrospectively, and the information of the 170 patients in whom residual stones were found was recorded. In addition to patient-specific factors and stone characteristics, length of postoperative hospital stay, postoperative fever, and preoperative antiaggregant use were evaluated. Of the 170 patients ultimately included in the study. The mean age was 51.56 (± 14.70). The mean stone size was 14.01 mm (± 5.75), the mean residual stone size was 7.04 mm (± 2.51), and the mean stone density was 829 Hounsfield units (± 395.06). The mean infundibulopelvic angle (IPA) was 49.37º (± 15.37), and 41.2% of the stones were non-opaque. The mean parenchymal thickness was 22.88 mm (± 5.55). 34 patients were on antiaggregant therapy. Preoperative stone size increases in stone density and decreases in IPA were found to be correlated with increase residual stone size (p < 0.001, p < 0.001, and p < 0.001, respectively). In addition, larger residual stones were observed after the fURS procedure in patients using anticoagulants and those without hydronephrosis (p = 0.02 and p = 0.016, respectively). Use of reliable predictive factors to forecast residual stone size after fURS may help to inform those treated and enable urologists to design rational surgical strategies.

Evaluation of ultrathin semirigid ureteroscopy in terms of efficiency and cost compared to flexible ureteroscopy in treating proximal ureteric stones: a prospective randomized multicenter study.

PURPOSE: To investigate the outcome and cost-effectiveness of ultrathin 6-7.5-Fr semirigid ureteroscopy in treating proximal ureteric stones compared to flexible ureteroscopy. METHODS: Two hundred and twenty patients with a solitary proximal ureteric stone were eligible for ureteroscopy (stone size = 1-2 cm). Patients were randomly subdivided into two groups: Group I included 105 patients who underwent ultrathin semirigid ureteroscopy and group II included 115 patients who underwent flexible ureteroscopy. Both groups were compared regarding successful stone access, operation time, reoperation rates, the financial cost to stone-free, complications, and stone clearance at 4 and 8 weeks. RESULTS: Groups I and II had no significant differences regarding patient demographics, stone criteria, and hospitalization time. In contrast, the mean operative time was significantly longer in group II (p < 0.001). The overall scope-to-stone access rate was 89.5%. It was 87.6% compared to 91.3% (p = 0.32), while the stone-free rate was 81.9% versus 87.8% (p = 0.22) for groups I and II, respectively. Intraoperative and postoperative complications were statistically insignificant between the study groups. The cost/person in Egyptian pounds was 8619 ± 350 in group I, compared to 17,620 ± 280 in group II (p < 0.001); similarly, the cost to attain the stone-free rate was 8950 ± 720 in group I compared to 17,950 ± 500 in group II. CONCLUSION: Ultrathin semirigid ureteroscopy is safe, durable, and considered a cost-effective method for treating upper ureteric calculi compared to the flexible ureteroscopy and could be considered a first treatment option in developing countries.

Effect of outflow resistance on intrarenal pressure at different irrigation rates during ureteroscopy: in vivo evaluation.

To maintain visualization and control temperature elevation during ureteroscopy, higher irrigation rates are necessary, but this can increase intrarenal pressure (IRP) and lead to adverse effects like sepsis. The IRP is also dependent on outflow resistance but this has not been quantitatively evaluated in a biological system. In this study, we sought to characterize the IRP as a function of irrigation rate in an in vivo porcine model at different outflow resistances. Ureteroscopy was performed in a porcine model with a 9.5 Fr prototype ureteroscope containing a pressure sensor. A modified ureteral access sheath (UAS) (11/13 Fr, 36 cm) was configured to adjust outflow resistance. IRP-irrigation rate curves were generated at four different outlet resistances representing different outflow scenarios. At lower irrigation rates, the pressure change in response to increased irrigation was gradual and non-linear, likely reflecting a "compliant" phase of the renal collecting system. Once IRP reached the range of 35-50 cm H2O, the pressure increased in a linear fashion with irrigation rate, suggesting that the distensibility of the collecting system had become saturated. The relationship between IRP and irrigation rate becomes linear during in vivo porcine studies once the initial compliance of the system is saturated. IRP is more sensitive to changes in irrigation rate in systems with higher outflow resistance. The modified UAS is a novel research tool which allows variance of outflow resistance to mimic different clinical scenarios. Knowledge of outflow resistance may simplify the decision to use an UAS.

Using vacuum-assisted ureteral access sheath in the treatment of complex steinstrasse.

Steinstrasse is an iatrogenic condition resulting from upper urinary tract lithotripsy. Uncomplicated steinstrasse can be managed expectantly. Complex steinstrasse can pose a therapeutic challenge. The vacuum-assisted ureteral access sheath (vaUAS) is similar to a conventional ureteral access sheath but has a side branch that can be connected to vacuum apparatus. This device seemed to be useful in the management of complex steinstrasse. 35 patients with complex steinstrasse, defined as steinstrasse containing ≥ 4 stones or with an aggregate length of ≥ 1.5 cm, were treated in four tertiary medical centers using the vaUAS in this prospective and non-randomized study. The vaUAS was inserted into the ureter over a guidewire until the tip of the vaUAS was in contact with the lowermost stone fragment. A 7 Fr./8.4 Fr. semirigid ureteroscope and a holmium laser were used to pulverize the obstructing stone. All the stone fragments were aspirated either in the space between the scope and the sheath, or through the channel of the sheath by withdrawing the scope to the proximal of the aspiration port. All patients were steinstrasse-free at end of the procedure, as assessed visually and by KUB. At the 3-month follow-up, 94.3% of patients were stone-free with or without a supplementary procedure. There were no perioperative complications. Five patients experienced postoperative fever and/or significant hematuria, and one patient had transient sepsis, a grade I and IV Clavien complication, respectively. vaUAS can be an effective adjunctive device in the management of complex steinstrasse.

Development of an Automated Composite Ureteroscopic Efficiency Score Through Simulated Ureteroscopic Skills Assessment.

Introduction: Flexible ureteroscopy (fURS) is the most common procedure for treatment of urolithiasis. We previously utilized kinematic evaluations of simulated fURS to demonstrate that certain body movements are associated with efficient ureteroscopic manipulation for complex tasks. In this study, we incorporated computer vision to create an efficiency score using the ureteroscope travel distance (DIST), task time (TIME), spectral arc length (SPARC), and percentage of purposeful wall collisions (COLL). The goal is a simulation-based system that can abstract these automated performance metrics (APMs) to differentiate between novice and expert ureteroscope handling. Methods: A ureteroscopic simulation box was used. Body kinematics, task time, and ureteroscopic movements were analyzed using a motion capture system and video camera. Optical flow computer vision was used to track the ureteroscope. DIST, TIME, and SPARC were automatically calculated. Wall collisions were automatically captured and independently judged by two authors; an algorithm was developed to automatically determine the COLL variable. A mixed-effects model was used to aggregate these variables and distinguish between surgeons' first and final task attempts. Normalized values of these metrics were added to create a composite ureteroscopic efficiency score (CUES). Results: Twelve urologists completed the simulated tasks. The COLL assessment algorithm determined beneficial wall collisions with an accuracy of 77%. Normalized values of TIME, DIST, SPARC, and COLL were combined to create a composite ureteroscopic efficiency score (CUES). Compared with the first attempt, both the second and third attempts showed statistically significant improvements in CUES. The ROC-AUC score reached 0.86, suggesting excellent discrimination between attempts. There was also a statistically significant difference in CUES when comparing resident and attending performance. Conclusions: APMs can be abstracted using computer vision and artificial intelligence; an aggregate composite score (CUES) may be a promising method for evaluation of ureteroscopic efficiency.

Comparison of commonly utilized ureteral access sheaths: A prospective randomized trial.

OBJECTIVE: We aimed to evaluate and compare the functional characteristics, safety profile and effectiveness of two commonly used ureteral access sheaths (UAS) during flexible ureteroscopy. METHODS: After institutional review board approval, patients with proximal ureteral or kidney stones requiring flexible ureteroscopy and UAS were prospectively randomized to group I or group II according to the type of access sheath used. Primary outcome was incidence of intraoperative complications. RESULTS: Eighty-eight patients were enrolled in the study, 44 patients in each group. Sheath size 12/14 FR was used in both cohorts. Median (IQR) stone size was 10 mm (7-13.5) and 10.5 mm (7.37-14) in group I and II respectively (p = 0.915). Nineteen and twenty patients, in group I and II respectively, were pre-stented. Subjective resistance with insertion of the UAS was observed in 9 and 11 patients in group I and II respectively (p = 0.61) while failed insertion was encountered in one patient in group I. Traxer grade 1 ureteral injury was noted in 5 and 6 patients in group I and II respectively while grade 3 injury was seen in 1 patient for both cohorts (p = 0.338). There was less resistance for UAS placement in pre-stented patients (p = 0.0202) but without significant difference in ureteric injury incidence (p = 0.175). Emergency department visits were encountered in 7 (group I) and 5 patients (group II) (p = 0.534). CONCLUSIONS: The studied UASs were comparable regarding safety and efficacy in the current study. Pre-stented and dilated ureters had less resistance to insertion although this was not reflected on incidence of ureteric injury.

A robotic system for solo surgery in flexible ureteroscopy: development and evaluation with clinical users.

PURPOSE: The robotic system CoFlex for kidney stone removal via flexible ureteroscopy (fURS) by a single surgeon (solo surgery, abbreviated SSU) is introduced. It combines a versatile robotic arm and a commercially available ureteroscope to enable gravity compensation and safety functions like virtual walls. The haptic feedback from the operation site is comparable to manual fURS, as the surgeon actuates all ureteroscope DoF manually. METHODS: The system hardware and software as well as the design of an exploratory user study on the simulator model with non-medical participants and urology surgeons are described. For each user study task both objective measurements (e.g., completion time) and subjective user ratings of workload (using the NASA-TLX) and usability (using the System Usability Scale SUS) were obtained. RESULTS: CoFlex enabled SSU in fURS. The implemented setup procedure resulted in an average added setup time of 341.7 ± 71.6 s, a NASA-TLX value of 25.2 ± 13.3 and a SUS value of 82.9 ± 14.4. The ratio of inspected kidney calyces remained similar for robotic (93.68 %) and manual endoscope guidance (94.74 %), but the NASA-TLX values were higher (58.1 ± 16.0 vs. 48.9 ± 20.1) and the SUS values lower (51.5 ± 19.9 vs. 63.6 ± 15.3) in the robotic scenario. SSU in the fURS procedure increased the overall operation time from 1173.5 ± 355.7 s to 2131.0 ± 338.0 s, but reduced the number of required surgeons from two to one. CONCLUSIONS: The evaluation of CoFlex in a user study covering a complete fURS intervention confirmed the technical feasibility of the concept and its potential to reduce surgeon working time. Future development steps will enhance the system ergonomics, minimize the users' physical load while interacting with the robot and exploit the logged data from the user study to optimize the current fURS workflow.

Device Failure and Adverse Events Related to Single-use and Reusable Flexible Ureteroscopes: Findings and New Insights From an 11-Year Analysis of the Manufacturer and User Facility Device Experience Database.

OBJECTIVE: To catalog and characterize device failures and adverse events related to flexible ureteroscopes from a national database. METHODS: Search of the Manufacturer User and Facility Device Experience database was performed for all recorded events related to flexible ureteroscopes between 2012 and 2022. The following information was collected: Problem and cause, timing, complications and injury, prolonged anesthesia, and early termination of procedure. Event severity was graded using a validated tool. RESULTS: A total of 206 events were identified (reusable/single use ratio, 2.5:1). There were 20 different problem categories reported, which included image loss (26.7%), difficulty removing scope (13.6%), scope damage from basket (4.4%), detachment of scope tip (5.8%) and contamination (4.9%). Faulty device was the predominant cause for an event related to single-use scopes (86.4%); this was seldom the case for reusable (2%). Patient injury occurred in 21.8%, but these were all in reusable scopes. No deaths were reported, but major complications included complete avulsion of the ureter (3.4%) and fully entrapped scope necessitating open surgery (2.9%). While the safety profile for single-use scopes was superior, they were significantly more likely to result in early termination (71.1% vs 37.3%, P < .001). This was related to 76.3% of the single-use scopes experiencing sudden image loss. CONCLUSION: Flexible ureteroscopes are fragile, and a multitude of problems can occur. Many of these can be avoided through correct surgeon technique and robust maintenance services.

Innovations in Endourologic Stone Surgery: Contemporary Practice Patterns from a Global Survey.

Objective: The purpose of this study is to evaluate the current availability of technology for urolithiasis treatment and ureteroscopy (URS). Perioperative practice patterns, availability of ureteroscopic technologies, pre- and poststenting practices, and methods to alleviate stent-related symptoms (SRS) were assessed via a survey of members of the Endourological Society. Methods: We distributed a 43-question survey online via the Qualtrics platform to members of the Endourological Society. The survey consisted of questions pertaining to the following topics: general (6), equipment (17), preoperative URS (9), intraoperative URS (2), and postoperative URS (9). Results: A total of 191 urologists responded to the survey and 126 completed all questions of the survey (66%). Fifty-one percent (65/127) of urologists were fellowship trained and dedicated an average of 58% of their practice to stone management. In terms of procedures, most urologists performed URS most commonly (68%), followed by percutaneous nephrolithotomy (23%) and extracorporeal shockwave lithotripsy (11%). Ninety percent (120/133) of respondent urologists purchased a new ureteroscope within the last 5 years (16% single-use scopes, 53% reusable, and 31% purchased both). Fifty-three percent (70/132) of the respondents stated that they would be interested in a ureteroscope that can sense intrarenal pressure, with an additional 28% (37/132) stating they would be interested depending on the cost. Seventy-four percent (98/133) of responders purchased a new laser within the last 5 years, and 59% (57/97) changed their lasering technique due to the new laser. Urologists are performing primary ureteroscopy for obstructing stones in 70% of cases, and prefer prestenting patients for subsequent URS in 30% (on average after 21 days). Seventy-one percent (90/126) of responders insert a ureteral stent after uncomplicated URS, which is removed, on average, after 8 days in uncomplicated cases and 21 days after complicated URS. Most urologists give analgesics, alpha-blockers, and anticholinergics for SRS and <10% prescribe opioids. Conclusion: Our survey revealed urologists' eagerness for the early adoption of novel technologies and adherence to conservative practice patterns focused on patient safety.

Efficacy and feasibility of self-made negative pressure reflux system combined with rigid ureteroscope in the treatment of upper ureteral calculi in exercise-minded patients

Objective: To explore the efficacy and feasibility of self-made negative pressure reflux system combined with rigid ureteroscopy in the treatment of upper ureteral calculi.Methods: The clinical data of 379 Exercise-minded patients with upper ureteral calculi treated in our hospital from January 2018 to August 2022 were analyzed retrospectively. F8.0/9.8STORZ ureteroscope was used to explore the ureteral opening on the affected side, and then the 200μm wavelength holmium laser fiber and F4 ureteral catheter were inserted into the stone incarceration site through the rigid ureteroscope, and the residual stone fragments which were clinically meaningless (the maximum diameter of the stone < 2mm) were completely sucked out by negative pressure reflux system.Results: A total of 379 Exercise-minded patients were included in this study, with a one-time success rate of 97.1% (368/379), aged 26 to 76 years, with an average of (47.5) years. Most of the Exercise-minded patients (63.2%) had low back pain and hematuria before operation. The average diameter of stone was 0.8cm~2.8cm, the mean diameter of the stone was 1.8±1.0 cm.The operation time ranged from 18min to 52min, with an average of (37.86±25.64)min.The average length of hospital stay was (2.7±1.7) days (range, 1-8 days). On the first day after operation, the stone clearance rate was 84.43% (320/379), and the stone clearance rate was 90.77% (344/379) 3 months after operation. Among them, 4 Exercise-minded patients developed fever and 6 Exercise-minded patients had mild urinary fistula or renal pelvis perforation. Stone composition analysis was mainly ammonium phosphate stones and calcium oxalate stones.Conclusion: The treatment of upper ureteral calculi with self-made negative pressure reflux system combined with hard ureteroscope has the advantages of high stone clearance rate, low complications and greatly reducing the utilization rate of soft lens，and had high clinical promotion value. (AU)

Application of Flexible Holmium Laser Sheath in Rigid Ureteroscopy for the Treatment of Impacted Upper Ureteral Stones.

OBJECTIVE: By comparing with rigid ureteroscopy (r-URS), we explored the application value of flexible holmium laser sheath combined with r-URS in treating impacted upper ureteral stones. We also verified its effectiveness, safety and economy and investigated its application prospects at community or primary hospitals. METHODS: From December 2018 to November 2021, 158 patients with impacted upper ureteral stones were selected from Yongchuan Hospital of Chongqing Medical University. Seventy-five patients in the control group were treated with r-URS, and 83 patients in the experimental group were treated with r-URS combined with a flexible holmium laser sheath if necessary. The operation time, postoperative hospital stay, hospitalization expenses, stone clearance rate after r-URS, auxiliary extracorporeal shock wave lithotripsy (ESWL) ratio, auxiliary flexible ureteroscope, the incidence of postoperative complications and the stone clearance rate after one month were observed. RESULTS: The postoperative hospital stay, stone clearance rate after r-URS, the ratio of auxiliary ESWL, the ratio of the auxiliary flexible ureteroscope, and total hospitalization expenses in the experimental group were significantly less than those in the control group (p < 0.05). There was no significant difference in operation time, postoperative complications, and stone clearance rate after one month between the two groups (p > 0.05). CONCLUSIONS: r-URS combined with flexible holmium laser sheath in treating impacted upper ureteral stones can improve the stone clearance rate and reduce hospitalization expenses. Therefore, it has a certain application value in community or primary hospitals.

Percutaneous management of caliceal diverticula: a narrative review.

PURPOSE OF REVIEW: Caliceal diverticula are relatively uncommon within urologic practice and may be difficult to diagnose and treat. We aim to highlight contemporary studies examining surgical interventions for patients with caliceal diverticula, with a focus on percutaneous intervention, and provide updated practical recommendations for the management of these patients. RECENT FINDINGS: Studies within the last 3 years examining surgical treatment options for caliceal diverticular calculi are limited. When flexible ureteroscopy (f-URS) and percutaneous nephrolithotomy (PCNL) are examined within the same observational cohorts, PCNL is associated with improved stone-free rates (SFRs), lower requirement for re-intervention, and longer lengths of stay (LOS). Retrograde f-URS for the treatment of caliceal diverticula and diverticular calculi is associated with satisfactory safety and efficacy outcomes. There are no studies in the last 3 years that provide supporting evidence to use shock wave lithotripsy to treat caliceal diverticular calculi. SUMMARY: Recent studies examining surgical interventions for patients with caliceal diverticula are limited to small observational studies. Heterogeneity in LOS and follow-up protocol limits comparisons between series. Despite technological advancements in f-URS, PCNL appears to be associated with more favorable and definitive outcomes. PCNL continues to be the preferred treatment strategy for patients with symptomatic caliceal diverticula when deemed technically feasible.

Single-use versus conventional reusable flexible ureteroscopes - an evaluation of the functional parameters.

The purpose of single-use flexible ureteroscopes (su-fURS) was to overcome the limitations of conventional reusable ureteroscopes in terms of maneuverability and maintenance. We aimed to perform a systematic literature review on available su-fURS performance versus conventional reusable fURS focusing on clinical data. A systematic research using Pubmed was performed evaluating single-use fURS and reusable fURS in urinary tract stone disease, including prospective assessments and case series. This review aimed to provide an overview of single-use and disposable flexible ureteroscopes and to examine and compare their capabilities (deflection, irrigation, optical properties). We included 11 studies, where the single-use fURS were compared to the reusable fURS. The studies with single-use ureteroscopes included data on LithoVue (Boston Scientific), The Uscope UE3022 (Pusen, Zhuhai, China), NeoFlex-Flexible, (Neoscope Inc San Jose, CA), 23 YC-FR-A (Shaogang). For reusable ureteroscopes, data were included on three models, two digital (Karl Storz Flex-XC and Olympus URF-Vo) and one fiber optic (Wolf-Cobra). There were no significant differences in stone-free rate, procedure duration, or functional capabilities between single-use fURS and reusable fURS. The systematic literature review analyzed operative time, functional capabilities, stone-free rates, and postoperative complications of the ureteroscopes, and a special chapter about renal abnormalities to emphasize that they are a good choice having a high proportion of stone-free rates and few risks, particularly in treating difficult-to-access calculi. Single-use fURS demonstrate a comparable efficacy with reusable fURS in resolving renal lithiasis. Further studies on clinical efficacy are needed to determine whether single-use fURS will reliably replace its reusable counterpart.

Laparoscopic Ureterolithotomy and Single-Use Digital Flexible Ureteroscope For Unilateral Large Ureteral Stone and Small Renal Stone.

BACKGROUND The removal of concurrent ureteral and renal stones within a single procedure has always been a challenge for urological surgeons. The incorporation of single-use digital flexible ureteroscopes into laparoscopic ureterolithotomy procedures has demonstrated effective removal of concurrent stones with a good clearance rate and decreased risk of bleeding and trauma. We report the successful removal of a unilateral upper ureteral stone and a smaller renal stone with this procedure. CASE REPORT A 60-year-old man visited the outpatient clinic with an ultrasonography report that revealed a large proximal ureteral stone with moderate hydronephrosis, accompanied by bilateral renal stones and prostatic hyperplasia. He had been experiencing urinary urgency for a year and was determined to undergo lithotomy. Due to his longstanding history of coronary artery disease and myocardial ischemia, the urologists decided that concurrent stone removal within an operation would be the best treatment. A preoperative computed tomography urogram measured the left ureteral and renal stones to be 2.0×0.8 cm and 0.6 cm, respectively. Both stones were successfully removed by laparoscopic ureterolithotomy using a single-use digital flexible ureteroscope. The patient had an uneventful recovery and remained well 1 month post-operation. CONCLUSIONS The application of single-use digital flexible ureteroscopes for laparoscopic ureterolithotomy has demonstrated safety, efficiency, and cost-effectiveness. The authors believe that it is a safe alternative for the removal of concurrent ureteral and renal stones, especially in patients with multiple comorbidities.

What is the appropriate gravel size during ureteroscopy lithotripsy? An in vitro evaluation.

To propose the suitable diameter of calculus debris produced during flexible ureteroscopy lithotripsy (fURL). A glass tube was used to simulate the stone excretion process during Furl. Different stone diameters (0.50-1.00 mm, 0.25-0.50 mm, and 0.10-0.25 mm) with three sizes of flexible ureteroscopy (fURS) (7.5Fr, 8.7Fr, and 9.9Fr) and ureteral access sheath (UAS) (12/14Fr) with or without negative pressure suction were employed in the experiment. The intraoperative calculi excretion (ICE) was recorded according to the stones discharged from the gap between fURS and UAS. The ICE raised significantly in thinner fURS and UAS due to the smaller Ratio of Endoscope-Sheath Diameter (RESD). The gravel size ≤ 0.25 mm was conducive to drainage with traditional UAS, while using fURS with negative-pressure UAS could significantly improve ICE. The gravel size ≤ 0.5 mm was conducive to expulsion. We clarify that ICE during ureteroscopy relates to RESD and negative pressure suction. The proper size of the stone fragment is critical in ensuring the expulsion during fURL, ≤ 0.25 mm in traditional UAS and ≤ 0.50 mm in negative-pressure UAS, respectively.

Initial Experience of Simultaneous Combined use of Percutaneous Nephrolithotomy and Flexible Ureteroscopy in Complex Renal Calculi: A Novel Surgical Technique of 'Through-Through' Approach.

BACKGROUND: For complex branched renal calculi, the endoscopic combined intrarenal surgery (ECIRS) is worldwide prevalent. This study aimed to present a novel surgical technique of percutaneous nephrolithotomy combined with antegrade flexible ureteroscopy which is named 'Through-through' approach. METHODS: We retrospectively analyzed the data of 68 patients with complex renal calculi who underwent combined PNL and flexible ureteroscopy surgery using 'Through-through' approach at our center between August 2019 and December 2021. The 'Through-through' approach to surgery was indicated in residual calyceal calculi that neither rigid nephroscope nor retrograde flexible ureteroscope could reach. The brief procedure of this technique involved determining the direction of targeted calyces with the nephroscope first, followed by putting flexible ureteroscope into the targeted calyx through the nephroscope instrument channel and basketing or dusting residual calculi through the flexible ureteroscope instrument channel. RESULTS: The mean maximum stone diameter was 4.0 ± 0.4 cm. The mean operative duration was 100.1 ± 18.0 minutes, and mean hemoglobin loss was 21.4 ± 5.1 g/L. In all 68 patients, calculi were cleared in 62 patients, and the stone free rate was 91.2%. Five patients underwent further surgery after 2 weeks because of significant residual calculi. One patient that had a 6 mm residual stone chose observational follow-up. Ten patients emerged with postoperative fever but did not progress to uroseptic shock. There were no Clavien grade ≥ III complications, and none of the patients required blood transfusion. CONCLUSION: The 'Through-through' approach is safe, feasible and effective for complex renal calculi patients. It is a complementary solution to the failed endoscopic combined intrarenal surgery.