Laser Ablation Efficiency, Laser Ablation Speed, and Laser Energy Consumption During Lithotripsy: What Are They and How Are They Defined? A Systematic Review and Proposal for a Standardized Terminology

Stone dust in endourology: a systematic review of its definition, management, and clinical impact

OBJECTIVE

To evaluate and synthesise the existing literature on stone dust (DUST) in endourology, focusing on its definition, creation methods, and removal techniques.

METHODS

A comprehensive electronic literature search was conducted using the PubMed/Medline, Web Of Science, and Embase databases to identify reports published until October 2024. The Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines were followed to identify eligible studies. The outcomes assessed included the definition of DUST, the method by which DUST was created, and how it was removed, evaluating both in vitro and in vivo studies. The review also assessed the efficacy of different laser technologies, including holmium-yttrium-aluminium-garnet (Ho:YAG) laser, thulium fibre laser (TFL), and pulsed thulium-YAG laser (p-Tm:YAG) laser, in generating DUST and their clinical relevance in stone management.

RESULTS

The systematic review identified 43 eligible studies, revealing significant variability in the definition and evaluation of DUST. Criteria for DUST ranged from sub-millimetre particle sizes to functional properties like floatability and aspiration capability. While Ho:YAG lasers remain widely used for stone dusting, emerging technologies such as TFL and p-Tm:YAG lasers have shown superior efficiency in producing finer particles and reducing retropulsion. No consensus emerged regarding the settings used by surgeons and the pre-settings provided by laser manufacturers.

CONCLUSIONS

Despite the widespread use of dusting techniques in endourology, a standardised definition of DUST remains lacking, with significant variability in laser settings, particle sizes, and evacuation methods. It must be clarified whether DUST should be defined as a noun-representing a distinct entity with a precise definition-or as the result of the dusting process, in which case clear criteria are needed to characterise it accurately. Establishing standardised definitions and protocols through international consensus is crucial to optimising clinical outcomes and ensuring consistency in future research.

Assessment of a novel bendable-tip ureteral access sheath with integrated suction: an in vitro study

Surgical management of urinary stones has significantly evolved with the advent of extracorporeal shockwave lithotripsy, flexible ureterorenoscopy (fURS), and percutaneous nephrolithotomy. For lower pole stones larger than 1 cm, the choice between fURS and miniaturized percutaneous nephrolithotomy remains debated. fURS with ureteric access sheaths (UAS) is a widely utilized technique, but fragment clearance is challenging in unfavorable anatomical conditions and/or lower pole stones. This study compares a novel flexible suction UAS (FANS) with a standard UAS in an in vitro model of lower pole stones. An in vitro experiment was conducted using an anatomical model of the urinary tract with artificial stones simulating complex 1-cm lower pole stones. Fourteen procedures were performed using either a 12/14 Fr diameter standard UAS or FANS. Every experiment was performed by a single surgeon using a 8.4 Fr single-use digital flexible ureteroscope and holmium:YAG laser set at 0.5 J, 25 Hz, and short pulse with a 272 μm fiber. Operative times, stone clearance rates, lasering times, were recorded and the residual stone masses (> 2 mm) was quantified. Complete stone clearance was achieved in 5 out of 7 procedures using FANS while no complete stone clearance was achieved using the standard UAS. The median laser time [27:33 (26:06-28:24) vs 24:02 (21:25-25:04) mm:ss, p = 0.017] and total energy output energy [20663 (19,575-21,325) vs 18,270 (16,069-18,931) J, p = 0.017] were significantly lower in the FANS group (p = 0.017), and the operative time was comparable. This in vitro experiment suggests that fURS with novel FANS may improve stone clearance and improve laser efficiency when compared to the standard UAS, without increasing operative times. Further clinical trials are warranted to confirm these findings.

Early clinical outcomes using a 6.3 Fr single use ureteroscope compared to a 7.5 Fr device

Flexible ureteroscopy is a cornerstone in minimally invasive urology, providing effective management of kidney stones and other urological conditions. The emergence of single-use ureteroscopes addresses challenges associated with reusable devices, such as cross-contamination, maintenance costs, and degradation over time. This prospective, single-center study compared the performance of the 6.3 Fr single-use flexible ureteroscope to the 7.5 Fr model in the treatment of kidney stones ≤ 2 cm. Forty patients were divided into two groups of 20, with preoperative assessments including CT scans and urine cultures. All patients underwent flexible ureteroscopy with thulium fiber laser lithotripsy under general anesthesia, and stone-free rates (SFRs) were assessed via CT at one month postoperatively. The 6.3 Fr ureteroscope achieved a significantly higher SFR of 95% compared to 92.9% with the 7.5 Fr model (p = 0.042). Mean operative times were 58 min (6.3 Fr) vs. 62.5 min (7.5 Fr), with no statistically significant differences in laser time or total energy used. Energy efficiency was 0.047 mm3/J (6.3 Fr) vs. 0.035 mm3/J (7.5 Fr), while energy consumption was 20.89 J/mm3 vs. 28.34 J/mm3, respectively. Both devices exhibited low complication rates, with only minor complications (Clavien-Dindo grades 1 and 2) reported. Postoperative ureteral mucosal injury was assessed intraoperatively, and no cases exceeded Grade 1. This study highlights the safety and efficacy of the 6.3 Fr ureteroscope, demonstrating comparable or superior outcomes to the 7.5 Fr model in terms of SFR and operative time. While economic and sterility benefits were not evaluated, the findings support the adoption of smaller-diameter devices for minimally invasive procedures, though further studies are warranted to validate their broader clinical impact.

Comparison of Measurement Methods for Stone Volume Estimation: An In Vitro Study

Introduction: Urolithiasis guidelines still rely on the maximum stone diameter to propose treatment strategy, although this measure is known to have many pitfalls. Stone volume (SV) could represent a more accurate measurement, helping to plan the treatment or follow-up. Various methods to measure SV have been proposed. We aimed to compare different methods to estimate SV. Methods: Fifteen stones (human and artificial) were assessed. Real SV was measured using the water displacement method. Volume estimation included three diameter-based formulas (Ackerman, 4/3 Pi r3 and r3/2) and two 3D segmentation methods (Horos and Kidney Stone Calculator [KSC]). All measurements were done by a single operator. Spearman correlation test and comparative analyses were conducted between the real and the estimated SV. Results: Compared with real SVs, Ackerman and r3/2 formulas estimated volume accurately in 2/15 (13%) of stones each. No accurate measurement was reported using the sphere formula. KSC did estimate volume accurately in 4/15 (27%) stones compared with the reference SV; Horos did it in 7/15 (47%) stones. Both segmentation methods presented strong correlation coefficients (r = 0.9642 and 0.9659, p < 0.0001), while formula correlation was moderate (r = 0.7531, p < 0.0001). Conclusion: Formulas and segmentation methods for SV estimation resulted in divergent outcomes. Segmentation methods (Horos and KSC) presented higher accuracies in SV estimation, compared with real SV. Formulas were the least accurate.

With great power comes great risk: High ureteral stricture rate after high-power, high-frequency Thulium fiber laser lithotripsy in ureteroscopy

PURPOSE

To compare the safety and efficacy of Thulium Fiber Laser (TFL) using either manufacturer presets (MP) or individualized presets (IP) in ureteroscopy.

METHODS

Multi-institutional, retrospective analysis on the first patients treated with SOLTIVE® Premium (Olympus Medical Systems®) TFL in Switzerland in 2020. MP were used at the University Hospital of Geneva, while IP were used at the University Hospital of Zurich. Patient demographics, stone characteristics, and procedural details were collected. Primary outcome was postoperative ureteral stricture (US). Secondary outcome was stone-free rate (SFR).

RESULTS

A total of 158 patients were analyzed, 79 in each group. Demographics were similar between the two groups, except for a lower pre-stenting rate in the MP group (56% vs. 91%; p < 0.001) and a higher rate of ureteral access sheath use in the MP group (65% vs. 44%; p = 0.011). No significant differences in stone burden (median stone diameter 9 mm, median stone volume 267 mm3), nor in the rate of impacted ureteral stones (29% vs. 34%; p = 0.49). Mean power, maximal power, frequency settings, and energy consumption were significantly higher in the MP group. US rate was 11% in MP group compared to 1% in IP group (p = 0.009). MP were a significant predictor of US on multivariable analysis (OR 12.4; p = 0.02), independently from impacted ureteral stones. No difference in SFR between groups (85% and 84%; p = 0.67).

CONCLUSION

High-power, high-frequency laser settings from manufacturer laser presets increase the risk of US, without improving SFR. Future studies shall further evaluate optimal laser settings depending on patient characteristics and intraoperative situation.

Is the ablation stone efficacy and efficiency better with a flexible and navigable suction ureteric access sheath?

OBJECTIVE

To compare the ablation efficacy and efficiency of flexible and navigable suction ureteric access sheath (FANS) and conventional ureteral access sheath (c-UAS) in retrograde intrarenal surgery (RIRS) for kidney stones treatment.

MATERIALS AND METHODS

A retrospective study of 96 patients who underwent RIRS using thulium fiber laser was performed. We divided the patients into Group 1: FANS and Group 2: c-UAS. We assessed the lithotripsy efficiency (mm3/Joules), ablation efficacy (mm3/min), and laser energy consumption (Joules/mm3). The stone-free rate (SFR) was defined as the absence of stone fragments in a non-contrast abdominal computed tomography 4-weeks after the procedure.

RESULTS

Both groups presented comparable stone volume (mm3) and stone density. RIRS with FANS presented a significantly lower surgical time and laser energy consumption (10.9 vs. 12.1 Joules/mm3, p < 0.001). In addition, FANS presented higher ablation efficiency (0.22 vs. 0.09 mm3/Joules, p < 0.001) and ablation efficacy (26.1 vs. 19.9 mm3/min, p < 0.001). SFR was significantly higher in the FANS group (93.7% vs. 75%, p < 0.001).

CONCLUSION

Compared to c-UAS, RIRS with FANS was associated with decreased total operative time and laser energy consumption and presented a significantly higher ablation efficacy and efficiency. Additionally, SFR was significantly higher in the FANS group.

Optimal stone density for ablation lithotripsy with vapor tunnel Ho:YAG pulse modality

INTRODUCTION

Vapor-Tunnel™ (VT) consists of a very long pulse that uses the minimum peak power, causing the energy to pass through a previously created vapor channel or tunnel. There are studies that have shown acceptable ablation lithotripsy efficiency. Nevertheless, there are no in-vivo studies that have compared the VT performance according to the stone density.

METHODS

A retrospective study of 152 patients who underwent RIRS using VT Ho:YAG laser was performed. We divided the patients according to the stone density (Group 1: < 1000UH vs. Group 2: > 1000UH). We assessed the lithotripsy efficiency (mm3/JJ) and the laser-energy consumption (JJ/mm3). The stone-free rate (SFR) was defined as the absence of stone fragments in a non-contrast abdominal computed tomography 4 weeks after the procedure.

RESULTS

Ninety three patients were included in Group 1 and 59 in Group 2. Body mass index was higher in Group 1 and the median stone volume was higher in Group 2 (846 vs. 672 mm3, p = 0.03). Total energy used (11.9 vs. 24 kj, p < 0.001), the laser emission time (19 vs. 30 min, p < 0.001), and the total operative time (60 vs. 85 min, p < 0.001) were lower in the Group 1. SFR was higher in Group 1 (96.7% vs. 57.6%, p < 0.001) with a global SFR of 81.6%. The ablation lithotripsy efficiency was higher in Group 1 (0.053 mm3/JJ vs. 0.035 mm3/JJ, p < 0.001).

CONCLUSIONS

VT Ho:YAG was associated with decreased laser time, operative time and laser-energy consumption in Group 1 than Group 2. Similarly, VT Ho:YAG increased lithotripsy efficiency and the SFR compared to hard stones with the same laser settings and pulse modality.

Direct-in-scope suction with a 5.1Fr large working channel ureteroscope: what stone dust size for effective evacuation during laser lithotripsy? An in vitro analysis by PEARLS and section of EAU Endourology

PURPOSE

A novel larger 5.1Fr working channel flexible ureteroscope for Direct-In-Scope Suction (DISS) has recently been introduced. However, the optimal stone dust size for successful evacuation without working channel blockage is currently unknown.

METHODS

In vitro assessment of the PU400A 9.2Fr ureteroscope (Zhuhai Pusen Medical Technology Co., Ltd, China) was performed with BegoStone particle sizes ≤ 2000 μm (size range 1000-2000 μm), ≤ 1000 μm (500-1000 μm), ≤ 500 μm (250-500 μm), ≤ 250 μm (125-250 μm) and ≤ 125 μm (63-125 μm), in a kidney calyx model. This was conducted with an empty working channel, and with occupancy by 150 μm Olympus, 200 μm Quanta, 270 μm Dornier laser fibers. Primary outcome was complete suction-evacuation without working channel blockage. Secondary outcome was evacuation speed for particle sizes that did not have blockage.

RESULTS

A stone particle size upper limit of 250 μm was found to achieve complete suction-evacuation without blockage, across all working channel occupancy situations. For stone particle size of range 125-250 μm, evacuation speeds were 35, 26, 13, 11 mm3/s across empty, 150 μm Olympus, 200 μm Quanta, 270 μm Dornier laser fiber occupancy, respectively (ANOVA = p < 0.001). For stone particle size range 63-125 μm, evacuation speeds were 19, 14, 9, 8 mm3/s respectively (ANOVA = p < 0.001).

CONCLUSION

The 5.1Fr working channel DISS ureteroscope allows a stone particle size limit of 250 μm to be suction-evacuated without blockage, even with laser fiber occupancy. With a laser fiber, a smaller 150 μm fiber size allows better particle evacuation speeds. Urologists should therefore aim for a dust particle size of ≤ 250 μm in routine DISS with the 5.1Fr working channel ureteroscope, for effective intraoperative stone evacuation.

Innovative use of the new pulsed-thulium: YAG laser for ureteroscopic lithotripsy: can the "kidney stone calculator" predict lithotripsy duration?

To assess the accuracy of Kidney Stone Calculator(KSC), a software designed for surgical planning, in predicting the duration of lithotripsy during flexible ureteroscopy(FURS) when using the novel pulsed-Thulium: YAG(p-Tm: YAG) laser. From February to August 2023, a single-center prospective study was conducted, including patients with kidney or ureteral stones through non-contrast computed tomography(NCCT), who underwent FURS with p-Tm: YAG laser lithotripsy. KSC used three-dimensional segmentation of the stones from NCCT images, along with an interactive user interface for laser settings, to estimate the stone volume(SV) and the lithotripsy duration(LD). The correlation between the estimated(esLD) and effective(efLD) lithotripsy duration was evaluated. A multiple linear regression analysis was conducted to identify preoperative and intraoperative factors affecting discrepancies between esLD and efLD. Twenty-eight patients were included with a median age of 55(48-74) years and 71% of men. Stone were located in the renal cavities(71%), ureter(21%) or both locations(8%). Median maximum stone diameter(MSD) and SV were respectively 14(11-30)mm and 1239(294, 2000)mm3. Nine patients had a SV equal to or greater than 2000mm3. EsLD and efLD did not differ(28 vs. 32 min, p = 0.8892), and were highly and positively correlated(r = + 0.90,p-value = < 0.001). Multivariate analysis indicated that the difference between estimated and effective lithotripsy were correlated with the stone volume(> 2000mm3), the use of ureteral access sheath and for struvite stones. "Kidney Stone Calculator" can accurately estimate LD during FURS with the p-Tm: YAG laser. Variables such as stone volumes over 2000mm3 and stone composition could be integrated the estimation. KSC is the only software that estimates LD with Holmium: YAG, Thulium Fiber and p-Tm: YAG lasers.

Harnessing magnetism: evaluation of safety, tolerance and feasibility of magnetic kidney stone retrieval in vivo in porcine models

The primary objective of urolithiasis therapy is complete stone removal and highest stone-clearance rates possible to minimize recurrence. A novel approach that employs a magnetic suspension and a magnetic probe for the passive collection and removal of small residual fragments was developed. This study assessed the feasibility of this system in porcine models. Five female domestic pigs underwent retrograde intrarenal surgery under general anaesthesia to assess the new magnetic system. Pre-analysed human calculi were endoscopically inserted and comminuted using lithotripsy. The magnetic suspension was applied, and the magnetic-stone fragment complex was extracted. After nephrectomy, independent blinded pathologists evaluated all the kidneys. Safety and tolerance assessments revealed no adverse events (i.e. no complications on the Clavien-Dindo scale > 1) or complications associated with treatment. This study revealed superficial urothelial damage in all animals, characterized by desquamation and inflammation, caused primarily by the insertion of access sheaths and laser lithotripsy. Residual magnetic particles were observed in the renal pelvis but did not show signs of toxicity even though this study is limited to the acute treatment. No pathological indicators were observed in the hemogram and urinalysis. Overall, the treatment did not cause any significant pathological changes. Preclinical in vivo evaluation of magnetic extraction of small rest fragments in porcine kidneys presents a promising, atraumatic approach for fragments removal. It demonstrated safety, tolerance, and feasibility that warrants clinical investigation. This method has the potential to increase stone-clearance rates with shorter extraction times, offering a possibility for addressing the challenge of urolithiasis in clinical practice.

Thulium fiber laser versus pulsed Thulium:YAG for laser lithotripsy during flexible ureteroscopy

To compare the pulsed-Thulium: YAG(p-Tm: YAG) and Thulium Fiber(TFL) lasers in terms of efficiency and safety profiles during flexible ureteroscopy(fURS) and endocorporeal laser lithotripsy(ELL). A prospective single-center open-label comparative study included consecutive patients with ureteral and renal stones who underwent fURS using Thulio(p-Tm: YAG, Dornier©,Germany) or TFL Drive(TFL, Coloplast©,Danemark), with 270 μm and 150/200μm laser fibers(LF), respectively. fURS were performed by a single operator in each group. Demographics, stone size, stone density, laser-on time(LOT) and laser settings were recorded. Ablation speed(mm3/s), energy consumption(J/mm3) values for each procedure were also assessed. Stone-free rate(SFR, <3 mm fragments) and zero fragment rate(ZFR) on non-contrast computed tomography within 3 months postoperatively were also recorded. 36 and 39 patients were included in p-Tm: YAG and TFL group, respectively. Groups presented similar demographics but for high blood pressure(53vs23%,p = 0,005), anatomical abnormalities(8vs33%,p = 0,03), lower pole(8vs26%,p = 0,04) and pelvic stones(25vs13%,p = 0,04) for p-Tm: YAG and TFL, respectively. The median stone maximum diameter was higher in the p-Tm: YAG group(17.3vs13.8 mm, p = 0,001) but stone volume was similar among groups(1514vs1347mm3,p = 0,6). Laser settings were similar among groups(0,6-15 Hz,10-12 W). Shorter LOT(< 0,001) and lower UAS insertion(0,01) rates were reported for TFL compared to p-Tm: YAG. The median J/mm3 was similar(14vs17,p = 0,2) but p-Tm: YAG presented higher ablation speed(0,91vs0,73mm3/s, p = 0,04). SFR were similar among groups(75vs77%,p = 0,8) but ZFR was higher in TFL group(39vs64%,p = 0,008). No difference in complications was reported. Both p-Tm: YAG and TFL are safe and effective for ELL during fURS. SFR were similar between TFL and p-Tm: YAG but the latter presented lower ZFR, traducing its lower ability to dust. Using 200 μm laser fibers with p-Tm: YAG could nuance these findings.

Multicenter outcome analysis of different sheath sizes for Flexible and Navigable Suction ureteral access sheath (FANS) ureteroscopy: an EAU Endourology collaboration with the global FANS study group

Flexible and navigable suction ureteral access sheath (FANS) is a potential game changer in flexible ureteroscopy (FURS). The influence of sheath size on outcomes needs research. The primary aim was to analyze 30-day single stage stone free status (SFS), zero fragment rate (ZFR) and complications when using 10/12Fr sheaths vis a vis other sheath sizes. The global FANS research group published the 30-day outcomes in patients who underwent FANS and reasoned this can be a potential game changer. We included 295 patients from this anonymized dataset with division into two groups: Group 1 (Smaller sheath) - 10/12Fr FANS, and Group 2 (Larger sheath) - 11/13Fr or 12/14Fr sheaths. Stone volume was similar between both groups (median 1320 mm3, p = 0.88). Ureteroscopy and total operative time was longer in the smaller sheath group (35 vs. 32 min, p = 0.02 and 50 vs. 45 min, p = 0.001, respectively). While 30-day computed tomography SFS (100% stone free or single residual fragment ≤ 2 mm) were not significantly different (96% vs. 95%, p > 0.99), ZFR (100% stone-free) was better with smaller sheaths (68% vs. 53%, p = 0.02). There was no difference in postoperative complication rates, and no sepsis in both groups. Urologists should consider individualizing appropriate sheath size in normal adult kidneys. Sheath size did not affect complication rates, risk of perioperative injury to the pelvicalyceal system or ureteric injury, but smaller FANS sheaths had similar high SFS. The ZFR with smaller sheaths was better, but this needs to be validated. These smaller sheath outcomes need to be balanced with longer ureteroscopy time, operative time, reach to the lower pole, ease of suction and visibility during lithotripsy. Large volume studies in different types of pelvicalyceal anatomy can determine if indeed smaller FANS is the best choice in FURS.

Flexible Ureteroscopic Lithotripsy with the Pulsed Thulium:Yttrium Aluminum Garnet Laser Thulio: Preliminary Results from a Prospective Study

Background and objective

Recently, the new pulsed thulium:yttrium aluminum garnet (p-Tm:YAG) laser technology has been introduced in endourology for lithotripsy. The aim of this study was to assess and validate the clinical laser performance and safety profile of p-Tm:YAG laser in a series of patients with renal and ureteral stones who underwent flexible ureteroscopy (fURS).

Methods

Prospective data were collected for patients who underwent fURS with the p-Tm:YAG laser Thulio (Dornier MedTech Systems GmbH, Wessling, Germany) at our institution by using two different laser fiber core diameters (270 and 200 μm). The primary endpoint of the study was stone-free rate (SFR), and the secondary endpoints were Clavien-Dindo complications grade ≥1 and the comparison between laser fibers of different diameters in all the parameters analyzed. Descriptive statistics relied on medians and interquartile ranges for continuous covariates, and on frequencies and percentages for categorical covariates. After stratification according to fiber types, differences between groups were tested with Wilcoxon and chi-square tests as appropriate. All the analyses and graphics were performed using R software (version 4.2.2).

Key findings and limitations

The SFR was 82% at 1-mo follow-up. In six out of 50 procedures (12%), Clavien-Dindo grade I-II complications were recorded. There were no differences regarding all the laser parameters considered between patients who were treated with 270 or 200 μm laser fibers (p > 0.05). Limitations of the study include small sample size in a single center and the lack of comparative groups.

Conclusions and clinical implications

In this prospective study of 50 patients who underwent fURS for ureteral and renal stones, the p-Tm:YAG laser Thulio was both effective and safe in a short-term follow-up. More prospective randomized studies in larger populations using different laser sources are required to confirm the clinical laser performance and safety of p-Tm:YAG laser for urinary stones treatment.

Patient summary

In this report, we looked at the outcomes for the pulsed thulium:yttrium aluminum garnet laser Dornier Thulio in patients who underwent flexible ureteroscopy for ureteral and renal stones. We found that this new laser technology is effective and safe, representing a good alternative to the other laser machines available for stone lithotripsy. We need more studies with larger populations to establish the superiority of this laser technology over the others.

Rethinking Stone-free Rates and Surgical Outcomes in Endourology: A Point of View from PEARLS Members

There is a lack of consensus on definitions for the success of endourological stone treatments. The zero-fragment rate (residual fragments [RFs] <1 mm) is now considered more accurate than the stone-free rate (RFs ≤4 mm). As stone volume may be adopted as the recommended method for preoperative estimation of the stone burden, the volumetric stone-free rate may be superior to standard linear RF measurements in defining success.

Steady-state versus burst lasing techniques for thulium fiber laser

OBJECTIVE

To evaluate the stone ablation rate and direct thermal damage from thulium fiber laser (TFL) lithotripsy using continuous (C) and burst (B) lasing techniques on an in vitro ureteral model.

METHODS

The TFL Drive (Coloplast, Humlebaek, Denmark) was used in an in vitro saline-submerged ureteral model. Ten participants, including five junior and five experienced urologists, conducted the experimental setup with 7 different settings comparing two lasing techniques: steady-state lasing (0.5 J/10 Hz = 5W for 300 s and 0.5 J/20 Hz = 10W for 150 s) and burst, intermittent 5 s on/off lasing (0.5 J/20 Hz, 0.5 J/30 Hz, 0.5 J/60 Hz, 0.1 J/200 Hz, and 0.05 J/400 Hz) with a target cumulative energy of 1500 J using cubic 125 mm3 phantom BegoStonesTM. Ureteral damage was graded 1-3 based on the severity of burns and holes observed on the surface of the ureteral model.

RESULTS

The were no significant differences in stone ablation mass neither between C and B lasing techniques, nor between expertise levels. At C lasing technique had only mild ureteral lesions with no significant differences between expertise levels (p: 0.97) or laser settings (p: 0.71). At B lasing technique, different types of thermal lesions were found with no expertise (p: 0.11) or setting (p: 0.83) differences. However, B laser setting had higher grade direct thermal lesions than C (p: 0.048).

CONCLUSION

Regarding efficacy, C and B lasing techniques achieve comparable stone ablation rates. Safety-wise, B lasing mode showed higher grade of direct thermal lesions. These results should be further investigated to verify which of the lasing mode is the safest in vivo. Until then and unless proven otherwise, a C mode with low frequency should be recommended to avoid ureteral wall lesions.