Comparison of laser fiber passage in ureteroscopic maximum deflection and their influence on deflection and irrigation: Do we really need the ball tip concept?

Single-Use Flexible Ureteroscopes: How Difficult Is It Today to Stay Up to Date? A Pictorial Review of Instruments Available in Europe in 2023

The invention of the flexible ureteroscope (fURS) and its subsequent spread have revolutionized the surgical management of urolithiasis and upper tract urothelial carcinoma (UTUC). During the last few years, single-use flexible ureteroscopes (su-fURSs) have been developed to improve the limitations of reusable fURSs, namely their cost, durability and risk of device contamination. Since the introduction of the first fully disposable digital fURS, several su-fURSs have been developed by various manufacturers. In this pictorial review, we combined the different physical and technical features of su-fURSs currently available on the market with Food and Drug Administration (FDA) and European Conformity (CE) approval, in order to help surgeons choose the appropriate device according to each case requirement and personal preferences. To the best of our knowledge, 17 su-fURSs with CE and FDA approval have been developed to date.

Flexible ureteroscopy for lower pole calculus: is it still a challenge?

PURPOSE

Flexible ureteroscopy (fURS) is steadily gaining popularity in the management of renal calculi, including those located in the lower pole (LP). Due to difficulty in accessing to the LP of kidney in minority of cases with fURS and reports of lower stone-free rate (SFR), it is still considered as a challenge in selected cases. The purpose of the review was to analyze the various aspects of fURS for LP stones.

METHODS

An extensive review of the recent literature was done including different factors such as anatomy, preoperative stenting, stone size, flexible scopes, types of lasers, laser fibers, suction, relocation, stone-free rates, and complications.

RESULTS

The significance of various lower pole anatomical measurements remain a subject of debate and requires standardization. Recent improvements in fURS such as single-use digital scopes with better vision and flexibility, high power laser, thulium fiber laser, smaller laser fiber, and accessories have significantly contributed to make flexible ureteroscopy  more effective and safer in the management of LP stone. The utilization of thulium fiber lasers in conjunction with various suction devices is being recognized and can significantly improve SFR.

CONCLUSIONS

With the significant advancement of various aspects of fURS, this treatment modality has shown remarkable efficacy and gaining widespread acceptance in management of LP kidney stones. These developments have made the fURS of LP stones less challenging.

Laser accessories: surgical fibers, strippers, cleavers, and protective glasses

PURPOSE OF REVIEW

This review provides most recent findings and developments relating to surgical laser fibers, strippers, cleavers, and protective glasses.

RECENT FINDINGS

The smallest core diameter that can be used with Holmium:YAG lasers is 200 μm. Smaller core diameter fibers can be used with the Thulium fiber laser and offer better flexibility and lower risk of fracture, at the risk of greater burnback effect. Misleading discrepancies between the true diameter of laser fibers and their packaging labels must be considered. Fiber tip degradation from the burnback occurs within few minutes, thus questioning the need for time-consuming fiber tip reprocessing with fiber strippers and special cleaving tools. This shortcoming also applies to instrument-protecting ball-tip fibers. Cleavage of fiber tips through their protective jackets ('coated tips') is a cheaper alternative for instrument protection, additionally offering better visual control of the fiber tip. Third-generation side-firing greenlight laser fibers are still prone to rapid deterioration. Laser eyewear does not seem necessary for Holmium:YAG applications, whereas laser-specific protective glasses should be worn for greenlight laser applications.

SUMMARY

With better understanding of laser accessories, practicing urologists may tailor their practice to reach optimal efficacy and safety for Holmium:YAG, Thulium fiber laser and Greenlight laser applications.

How to evaluate a flexible ureterorenoscope? Systematic mapping of existing evaluation methods

Objectives

The objective of this study was to identify, map and review scope‐related and user‐related parameters used to evaluate the quality of flexible ureterorenoscopes. Thereby identifying key items and variability in grading systems.

Methods

A literature search of four databases (MEDLINE [Ovid], EMBASE [Ovid], Web of Science, Google scholar and the Cochrane Library) was performed according to the Preferred Reporting Items for Systematic Reviews and Meta‐Analyses guidelines encompassing articles published up to August 2020. A total of 2386 articles were screened.

Results

A total of 48 articles were included in this systematic scoping review. All studies had a prospective design. Five key items in the assessment of flexible ureterorenoscopy were distinguished: ‘Manoeuvrability’ (87.5%), ‘Optics’ (64.6%), ‘Irrigation’ (56.3%), ‘Handling’ (39.6%) and ‘Durability’ (35.4%). After regrouping, every key item could be divided into specific subcategories. However, the quality assessment showed a wide variation in denomination, method of measurement, circumstances of measurement, tools used during measurements, number of measurements performed, number of observers, and units of outcomes.

Conclusion

The research field regarding quality assessment of ureterorenoscopes is heterogeneous. In this systematic scoping review we identified five key parameters: Manoeuvrability, Optics, Irrigation, Handling and Durability, used to grade flexible ureterorenoscopes. However, within these categories we found a wide variety in terms of method of measurements. A standardised, uniform grading tool is required to assess and compare the quality of flexible ureterorenoscopes in the future.

Basic and advanced technological evolution of laser lithotripsy over the past decade: An educational review by the European Society of Urotechnology Section of the European Association of Urology

Laser disintegration of urinary stones is a cornerstone of urolithiasis treatment in the modern era. Despite the wide clinical use of stone lasers, basic and advanced technological achievements and developments are difficult to comprehend and interpret by the average urologist. A descriptive analysis of laser production and stone disintegration mechanisms was performed. We focused on physics of modern types of lithotripters, the construction of laser fibers, laser parameters, new modes, settings, and lithotripsy techniques. The main principle of laser emission remains the same since the first emitting laser was produced. Peak power density and short interaction time lead to photothermal effects responsible for stone disintegration. Modern lithotripters such as Holmium: YAG (low/high power, Moses technology) and thulium fiber laser show basic construction differences with the physical properties of the latter being superior, at least in in vitro studies. By adjusting lasing parameters, a wide spectrum of stone ablation from fragmentation to dusting can be achieved. New technology allows for the production of real dust. Knowledge of laser fiber construction and physical properties are useful in marketing and clinical use. Urologists should understand the physical and physiological background of the lasers used in their everyday practice for stone fragmentation.

Device profile of the LithoVue single-use digital flexible ureteroscope in the removal of kidney stones: overview of safety and efficacy

Introduction: Flexible ureteroscopy is a commonly performed urologic procedure for visualization and treatment of the upper urinary tracts. Traditionally, ureteroscopy has been performed with reusable scopes, which have large initial purchasing costs. LithoVue was the first widely adopted single-use flexible ureteroscope clinically available in 2016 and has caused reevaluation of this paradigm. Areas covered: This review is an objective assessment of the LithoVue single-use ureteroscope based on available studies at the time of publication. The authors searched major databases for papers that included the term 'LithoVue' and included relevant papers. The state of the market, technical specifications, results from clinical studies and cost analyses, and competitors are discussed. Expert opinion: The LithoVue single-use flexible ureteroscope has comparable clinical performance to existing reusable ureteroscopes based on available data. Direct clinical comparisons to competing single-use ureteroscopes, many of which are relatively new, are limited. In numerous pre-clinical studies LithoVue performed favorably compared to available competitors. Cost analyses suggest that benefit of single-use ureteroscopes is institution-specific, and will likely be favorable at a low volume of cases and with high local costs for repairs of reusable scopes.

Consultation on kidney stones, Copenhagen 2019: aspects of intracorporeal lithotripsy in flexible ureterorenoscopy

Purpose

To summarize current knowledge on intracorporeal laser lithotripsy in flexible ureterorenoscopy (fURS), regarding basics of laser lithotripsy, technical aspects, stone clearance, lithotripsy strategies, laser technologies, endoscopes, and safety.

Methods

A scoping review approach was applied to search literature in PubMed, EMBASE, and Web of Science. Consensus was reached through discussions at the Consultation on Kidney Stones held in September 2019 in Copenhagen, Denmark.

Results and conclusions

Lasers are widely used for lithotripsy during fURS. The Holmium laser is still the predominant technology, and specific settings for dusting and fragmenting have evolved, which has expanded the role of fURS in stone management. Pulse modulation can increase stone ablation efficacy, possibly by minimizing stone retropulsion. Thulium fibre laser was recently introduced, and this technology may improve laser lithotripsy efficiency. Small fibres give better irrigation, accessibility, and efficiency. To achieve optimal results, laser settings should be adjusted for the individual stone. There is no consensus whether the fragmentation and basketing strategy is preferable to the dusting strategy for increasing stone-free rate. On the contrary, different stone scenarios call for different lithotripsy approaches. Furthermore, for large stone burdens, all laser settings and lithotripsy strategies must be applied to achieve optimal results. Technology for removing dust from the kidney should be in focus in future research and development. Safety concerns about fURS laser lithotripsy include high intrarenal pressures and temperatures, and measures to reduce both those aspects must be taken to avoid complications. Technology to control these parameters should be targeted in further studies.

Pressurized-Bag Irrigation Versus Hand-Operated Irrigation Pumps During Ureteroscopic Laser Lithotripsy: Comparison of Infectious Complications

Introduction and Objectives: A variety of irrigation systems are available during ureteroscopy. We sought to compare gravity-driven pressure bags with hand-operated irrigation pumps in terms of postoperative complications after ureteroscopy with lithotripsy. Methods: A retrospective analysis of 234 patients undergoing flexible ureteropyeloscopy with laser lithotripsy by 24 supervised trainees over 4 years at a single teaching institution. Patients were divided into those who had procedures performed by using gravity-driven pressure bags fixed at 60 to 204 cm H₂O, vs those who had procedures performed by using a hand-operated irrigation pump capable of delivering 1 to 10 mL per flush. Variables including surgical duration, hypotension, fever, sepsis, and hematuria were extracted from the charts, along with the surgical techniques utilized. Statistical analyses included chi-squared tests and Student's t-tests. Results: There were no differences in gender, age, indication, or stone size in the two groups. Postoperative systemic inflammatory response syndrome was significantly greater in the hand-assisted n = 11/144 (7.6%) compared with the fixed irrigation group n = 1/90 (1.1%); p = 0.032. Emergency room presentations were greater in the hand irrigation group, n = 46/144 (32%) vs n = 12/90 (13%) in the pressure-bag irrigation, p = 0.002. Postoperative fever was also greater in the hand pump irrigation cohort compared with the continuous pressure cohort (13/144 [9%] vs 1/90 [1%], p = 0.011). No statistical difference was found between the two groups with respect to stone clearance and subsequent procedures required (p = 0.123). Conclusions: This analysis suggests that using continuous flow irrigation at a fixed maximum pressure of 150 mmHg (204 cm H₂O) or less may result in decreased pain, infection, and sepsis compared with handheld pressure irrigation.

Are We Cutting Ourselves Short? Laser Lithotripsy Performance Based on Differences in Fiber-tip Preparation

OBJECTIVE

To better understand the impact of laser fiber-tip configuration on lithotripsy performance, we undertook an in vitro study comparing 3 fiber-tip configurations: (1) new (single-use), (2) cleaved (reusable), and (3) coated (cut with scissors).

METHODS

Lithotripsy was performed using a Ho:YAG laser utilizing fragmentation (1 J × 10 Hz) and dusting (0.5 J × 20 Hz) settings. BegoStones were fragmented with a laser fiber advancing at a speed of 1 mm/s (220 seconds of activation). Three fiber-tip configurations were tested: new single-use standard (242 μm core) and cleaved (272 μm core), compared to the same fiber-tip coated/cut flush with scissors, respectively. Study outcome was difference in stone mass before and after each experiment. Power output was measured using a power meter.

RESULTS

Fragmentation for new or cleaved fibers was greater than the coated/cut flush fiber-tip (P <.05). For 1 J × 10 Hz and 0.5 J × 20 Hz settings, fragmentation was 59% and 75% higher with new fiber-tip compared to the coated/cut flush fiber-tip, respectively. For 1J × 10 Hz and 0.5 J × 20 Hz settings, fragmentation was 51% and 45% higher with cleaved fiber-tip compared to the coated/cut flush fiber-tip, respectively. Power output at the end of laser activation was higher for new and cleaved fiber-tips.

CONCLUSION

New and cleaved laser fibers demonstrated superior lithotripsy performance compared to fibers that were coated/cut flush with scissors. Cutting single-use laser fibers risks damaging the fiber-tip which can disperse the energy and reduce lithotripsy efficiency.

Clinical efficacy and safety of flexible ureteroscopic lithotripsy using 365 μm holmium laser for nephrolithiasis: a prospective, randomized, controlled trial

PURPOSE

To compare the clinical efficacy and safety between the FURL with 365 μm and 200 μm holmium laser for treating nephrolithiasis.

MATERIALS AND METHODS

A prospective randomized controlled trial was performed including analysis of data from 200 patients with nephrolithiasis. A total of 180 patients were randomized into two groups according to 1:1 ratio. In the 365 μm holmium laser group, kidney stones were disintegrated into less than 2 mm fragments with a 365 µm holmium laser fiber with the settings of 30-45 W under direct visualization; in the control group, the conventional 200 μm holmium laser was used. Descriptive statistics and logistic regression analyses tested the association among operation time, stone-free rate (SFR) and incidence of complications.

RESULTS

Operation time in the FURL with 365 μm laser was significantly shortened and no significance was observed in the complication rate. Stone size and location were identified as two major confounding factors for the operation time and SFR. Moreover, the FURL using 365 μm laser showed less operation time for renal stones with the diameter between 1 and 2 cm, stones located in lower calyx and multiple calculi; stones larger than 2 cm and/or located in lower pole inclined to present better SFR using the FURL with 365 μm laser.

CONCLUSIONS

The FURL combined with 365 μm holmium laser is safer and highly efficacious for the management of nephrolithiasis when compared to conventional FURL procedures, especially for those located in lower pole and larger than 2 cm.

Let's Get to the Point: Comparing Insertion Characteristics and Scope Damage of Flat-Tip and Ball-Tip Holmium Laser Fibers

INTRODUCTION

A ball-tip holmium laser fiber (TracTip; Boston Scientific) has been developed to theoretically reduce damaging friction forces generated within a ureteroscope working channel. We compared the insertional forces and damage with a ureteroscope inner lining when inserting standard flat-tip and ball-tip laser fibers.

MATERIALS AND METHODS

A standard ureteroscope channel liner was placed in a 3D-printed plastic mold. Molds were created at four angles of deflection (30°, 45°, 90°, and 180°) with a 1 cm radius of curvature. New 200 μm ball-tip (TracTip; Boston Scientific) and 200 μm flat-tip (Flexiva; Boston Scientific) laser fibers were advanced through the liner using a stage controller. A strain gauge was used to measure force required for insertion. Each fiber was passed 600 times at each angle of deflection. The ureteroscope liner was changed every 150 passes. Leak testing was performed every 50 passes or when the insertional force increased significantly to assess damage to the liner.

RESULTS

At all deflection angles, the average insertional force was significantly lower with the ball-tip laser fibers compared with flat-tip laser fibers (p < 0.001). All trials with the ball-tip lasers were completed at each angle without any leaks. Two of four trials using flat-tip fibers at 45° deflection caused liner leaks (at 91 and 114 passes). At 90° deflection, all flat-tip trials caused liner leaks on first pass. The 180° trials could not physically be completed with the flat-tip laser fiber. Within the flat- and ball-tip groups, an increasing amount of force was needed to pass the fiber as the degree of deflection increased (p < 0.001).

CONCLUSIONS

The ball-tip holmium laser fiber can be safely passed through a deflected ureteroscope without causing liner perforation. The standard flat-tip fiber requires greater insertion force at all angles and can cause the ureteroscope liner to leak if it is deflected 45° or more.

Advances in Lasers for the Treatment of Stones-a Systematic Review

PURPOSE OF REVIEW

Laser lithotripsy is increasingly used worldwide and is a continuously evolving field with new and extensive research being published every year.

RECENT FINDINGS

Variable pulse length Ho:YAG lithotripters allow new lithotripsy parameters to be manipulated, and there is an effort to integrate new technologies into lithotripters. Pulsed thulium lasers seem to be a viable alternative to holmium lasers. The performance of similar laser fibers varies from manufacturer to manufacturer. Special laser fibers and "cleaving only" fiber tip preparation can be beneficial for the lithotripsy procedure. Different laser settings and the surgical technique employed can have significant impact on the success of laser lithotripsy. When safely done, complications of laser lithotripsy are rare and concern the endoscopic nature of procedure, not the technology itself, making laser lithotripsy one of the safest tools in urology. Laser lithotripsy has had several new developments and more insight has been gained in recent years with many more advances expected in the future.

First clinical evaluation of the new single-use flexible and semirigid Pusen ureteroscopes

Introduction

The purpose of the present study was to clinically evaluate two new single-use Pusen ureteroscopes, one semirigid with a flexible tip (srURS) and one flexible (fURS).

Materials and methods

During ten consecutive procedures (five srURS and five fURS), we subjectively evaluated on a scale from 0 (poor) to 10 (excellent), the scope's deflection, image quality, and maneuverability prior to, during and after the surgery. Patient demographics, complications with the devices, and troubleshooting were recorded.

Results

There were a total of ten patients, five of which were female while the other five were male. Mean age was 58.9 years. Seven patients had a single kidney stone with mean size of 9.6 mm (1.6-20 mm). Half of the patients were pre-stented. For the fURS, the preoperative image quality rating was 8.4 (8-10), compared with 6.8 (4-9) during surgery. The preoperative deflection rating was 9.6+ 0.9 (8-10), while during surgery this decreased to 8.0 (6-10) and to 6.0 (4-8) when using a laser fiber. The srURS had a preoperative image quality rating of 9.2 (8-10), which decreased to 7.6 (6-9) while using the scope. The deflection rating decreased from 9.4 (7-10) preoperatively to 7.0 (1-10) postoperatively, and a similar reduction was observed in the maneuverability rating, from 9.6 (8-10) to 7.4 (1-10). Ureteroscopy was considered as a standard in four of the fURS and three of the srURS procedures. The mean overall satisfaction rating was 6.

Conclusions

The two new single-use ureteroscopes, one flexible and one semirigid, were considered to have allowed standard ureteroscopy in four and three out of the five procedures for each scope, respectively. The image quality, deflection, and maneuverability ratings decreased during the procedure for both scopes.

Flexible ureteroscopy: technique, tips and tricks

During the last decades, the surgical management of kidney stones benefited of many technological advances and one of them is the development of flexible ureteroscopy (fURS). This tool, ancillary equipment such as graspers and baskets, and lithotripsy technique with Holmium:YAG laser underwent many improvements leading to a widening of its indications with diagnostic and therapeutic management of upper urinary tract pathologies such as urolithiasis and urothelial tumors. The objective of this review is to describe the surgical technique for fURS as well as tips and tricks for the treatment of renal stones.

Intracorporeal lithotripsy

Since the introduction of ESWL, PNL and URS during the early 1980s the application rate of ESWL has declined while those of PNL and URS have increased. This is mainly due to the facts that instruments and techniques for Intracorporeal Lithotripsy (IL) have made a continuous progress. This review shows that today an array of options for IL within the entire urinary tract is available to treat stones in a perfect minimal invasive way. At the same time further improvements of IL are already visible.