Holmium:YAG laser lithotripsy for upper urinary tract calculi in 598 patients

Stone-event-free survival after retrograde intrarenal surgery: is the stone-free-status so relevant for the future outcomes?

INTRODUCTION

The primary aim of stone treatment is to achieve stone-free status. Residual fragments can cause stone growth, recurrence, urinary tract infections, and ureteric obstruction. Our goal was to describe the natural history of stone burden after retrograde intrarenal surgery (RIRS) based on stone-free status (SFS), evaluating stone growth and stone-events.

METHODS

We retrospectively reviewed data from patients who underwent RIRS at a tertiary care center between October 2014 and September 2019. The stone burden was assessed by measuring the maximum diameter (mm) and volume (mm3). Patients were divided into four groups according to SFS-(A) absolute stone-free, no stones on non-contrast-enhanced computed tomography (NCCT); (B) relative stone-free with ≤ 2 mm fragments, (C) relative stone-free with 2.1-4 mm fragments, and (D) residual fragments > 4 mm. Our main outcomes were stone growth over time (defined as an increase in diameter compared to first postoperative measurement) and incidence of stone-related events (pain or additional intervention to treat symptoms, obstruction, or removing fragments).

RESULTS

A total of 98 patients were included in the study-42 were classified as absolute stone-free (Group A), 20 were categorized as relatively stone-free (Groups B and C), and 36 had a residual stone burden with fragments larger than 4 mm (Group D) on postoperative NCCT. There was a significant difference in the number of stones among the groups (p < 0.001). The pre-operative stone volume differed significantly among the groups (p = 0.003). Group A had the lowest median total stone volume (551.3 mm3). Twenty patients (20.4%) developed stone-events during a mean follow-up period of 62.3 months (± 26.0). Stone-event-free survival differed significantly between the groups (p = 0.028), with Group D demonstrating a higher incidence of stone-related events post-RIRS compared to the other groups. Sixteen patients (16.3%) had renal colic requiring a hospital visit across all groups. Thirteen patients (13.3%) required re-intervention (3 patients belonged to Group A, 1 to Group B, 2 to Group C, and 7 to Group D).

CONCLUSIONS

Group D shows a higher rate of stone-related events post-RIRS. Ensuring complete stone-free status after RIRS is crucial for treatment success. Other factors should be considered in the management, including ensuring compliance with general preventive measures and stone-specific pharmacological treatments to prevent recurrence.

In Vitro Comparison of Pulsed-Thulium:YAG, Holmium:YAG, and Thulium Fiber Laser

Objective: To characterize the pulse characteristics and risk of fiber fracture (ROF) of the pulsed-Thulium:YAG (p-Tm:YAG) laser and to compare its ablation volumes (AVs) against Holmium:Yttrium-Aluminium-Garnet (Ho:YAG) laser and Thulium fiber laser (TFL). Materials and Methods: p-Tm:YAG (100 W-Thulio, Dornier-Medtech©, Germany) was characterized using single-use 272 μm core-diameter-fibers. p-Tm:YAG characterization included pulse shape, duration, and peak power (PP) studies. ROF was assessed after 5 minutes of continuous laser activation (CLA) at five decreasing fiber bend radii (1, 0.9, 0.75, 0.6, and 0.45 cm). p-Tm:YAG, Ho:YAG (120 W-Cyber-Ho, Quanta®, USA), and TFL (60 W-TFLDrive, Coloplast®, Denmark) AVs were compared using a 20-mm linear CLA at 2 mm/second velocity in contact with 20 mm3 hard stone phantoms (HSP) and soft stone phantoms (SSP) (15:3 and 15:5 water to powder ratio, respectively) fully submerged in saline at 0.5 J-20 Hz or 1 J-10 Hz. After CLA, phantoms underwent three-dimensional (3D) micro-scanning (CT) and subsequent 3D segmentation to estimate the AVs, using 3DSlicer©. Each experiment was performed in triplicate. Results: p-Tm:YAG presents a uniform pulse profile in all of the available preset modes. PP ranged from 564 to 2199 W depending on pulse mode. No laser fiber fracture occurred at any bend radius. p-Tm:YAG achieved similar mean AVs to TFL and Ho:YAG for HSP (8.96 ± 3.1 vs 9.78 ± 1.1 vs 8.8 ± 2.8 mm3, p = 0.67) but TFL was associated with higher AVs compared with p-Tm:YAG and Ho:YAG (12.86 ± 1.85 vs 10.12 ± 1.89 vs 7.56 ± 2.21 mm3, p = 0.002) against SSP. AVs for HSP increased with pulse energy for p-Tm:YAG and Ho:YAG and (11.56 ± 1.8 vs 6.36 ± 0.84 mm3 and 11.27 ± 1.98 vs 6.34 ± 0.55 mm3, p = 0.03 and p = 0.02), whereas AVs for SSP were similar across laser settings for all laser sources. AVs with TFL were similar across laser settings for both phantom types. Conclusion: p-Tm:YAG combines intermediate PP between Ho:YAG and TFL, a uniform pulse profile, no ROF with increasing deflection and effective ablation rates. Further clinical studies are needed to confirm these in vitro results.

For upper ureteral stone, semirigid ureteroscopy or flexible ureteroscopy? Strengths and weaknesses

BACKGROUND

Flexible and semirigid ureteroscopy are two often used modalities in treating for upper ureteral stone. How about the outcome of each procedure?

METHODS

A retrospective cohort study among 167 patients who underwent flexible or semirigid ureteroscopic lithotripsy was performed. The pre-, intra-, postoperative and one-year follow-up outcomes were taken into comparison.

RESULTS

Significantly higher instant stone-clearance rate (81.3% vs. 92.4%, p = .032) and less operative time (62.1 ± 27.6 min vs. 44.1 ± 24.6 min, p<.001) were found in semirigid ureteroscopy. However, the stone-clearance rate at one month (90.7% vs. 93.5%, p = .500) was similar. Baseline characteristics including patient demographics, stone characteristics, duration of stone symptoms, hospital stay, expense, and complications between groups were approximately same. Three cases of stricture were found in the flexible ureteroscopy, and two in the semirigid ureteroscopy. Outcomes showed no significant difference. Further analysis showed that flexible ureteroscopy was likely more negatively affected by hydronephrosis and stone size, and semirigid ureteroscopy was more affected by stone location.

CONCLUSION

flexible ureteroscopy and semirigid ureteroscopy both had high stone clearance rate in the treatment for upper ureteral stones. They had similar outcomes and follow-up results. However, they also had their each most suitable application object.

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.

Dynamic renal scans as a modality for follow-up of flexible ureteroscopy

OBJECTIVE

To determine whether dynamic renal scans - DTPA or MAG3 - routinely performed after flexible ureteroscopies (f-URS) could detect the development of an obstruction and thus promote prompt early intervention for kidney preservation.

PATIENTS AND METHODS

In this retrospective study, with all the data recorded prospectively between April 2010 and October 2023, 250 renal units in 242 patients with upper urinary tract stones (UUTS) who underwent ureterorenoscopy by one surgeon in the same medical center were evaluated. Stone-free rate (SFR) was defined as no residual fragments at all using an intraoperative "triple test". The following characteristics were examined: gender, BMI, age, Hounsfield unit, stone diameter, laterality, renal/ureteral stones, stone-free rate, and auxiliary procedures per renal unit. The Clavien-Dindo classification was used to report complications. Renal units with residual stones were scheduled for a 2nd f-URS. Post- flexible ureteroscopy ureteral obstruction and renal function were detected using renal scan DTPA or MAG-3. The primary outcome was renal/ ureteral obstruction.

RESULTS

The mean patient age was 53 years. The mean stone size was 12.3 mm. Stones in renal pelvis, upper, middle and lower calyces were treated in 9.2% (23), 27.6% (69), and 30.8% (77) of cases, respectively; 44% (110) ureteral stones were also treated. The single- and second-session SFRs were 94.8% and 99.7%, respectively. A third auxiliary procedure was needed in one renal unit (0.4%). The mean number of procedures per renal unit was 1.06 (264/250). Ureteral double-J stents were inserted in 53.6% (134) of the cases. In 37 (14.8%) cases, a stent was placed before surgery. Post-operative complications were minor, with readmission and pain control needed in only two patients (0.8%). No avulsion or perforation of the ureters was observed. In six patients with t1/2 between 10-20 minutes, a second renal scan revealed spontaneous improvement and no obstruction in five patients. One patient with large stones and a history of prior ureteroscopy developed a ureteral stricture (0.4%) and needed treatment with laser endoureterotomy.

CONCLUSIONS

Post-flexible ureteroscopy obstruction due to ureteral stricture is very rare. A routine renal scan post-operatively may be used in potentially high-risk patients.

Analyzing global research trends and focal points in the utilization of laser techniques for the treatment of urolithiasis from 1978 to 2022: visualization and bibliometric analysis

Laser lithotripsy is gaining global prominence and is a dynamically progressing field marked by a continual influx of new and comprehensive research each year. Recently, there has been a noticeable shift toward the adoption of various kinds of lasers, such as holmium: yttrium-aluminum-garnet (Ho:YAG) and thulium fiber (TFL) lasers. Consequently, we aim to conduct a bibliometric analysis to analyze key areas of research activity within scientific publications that center on the utilization of laser techniques in urolithiasis. A search of the literature spanning from 1978 to 2022 was carried out on 25 December 2023 using the Scopus database to explore research related to the application of laser techniques for urolithiasis treatment. Visualization analysis was performed using VOSviewer software (version 1.6.20). We examined 962 publications that met the specified criteria, 791 (82.22%) of which were original articles. The analysis of the retrieved publications indicated a consistent increase in research output from 1978 to 2022; a particularly noteworthy surge occurred after 2003. In particular, the U.S. claimed the leading position as the most productive country, contributing 211 articles (21.93%). However, India had the highest research productivity according to the adjustment index of 19.08. In the European region, 324 publications (33.68% of the total) originated from 25 countries. The Journal of Endourology contributed the most between 1978 and 2022 (n = 96, 9.98%). The most cited paper examined the effectiveness of holmium: yttrium-aluminum-garnet (Ho:YAG) lasers, while a subsequent study focused on the use of a thulium fiber laser (TFL), an emerging laser technology that has gained increased recognition. Co-occurrence analysis revealed three distinct clusters focusing on the types of laser technology, minimally invasive approaches, and success rate/postoperative complications. This comprehensive investigation delves into the global landscape of laser use for the treatment of urolithiasis. This review supports the emerging clinical concept of using various types of laser technology for urolithiasis treatment. Moreover, the hot issues that researchers should focus on based on the findings of this study are the use of different types of laser lithotripsy in view of the surgical approach, success rate and complications.

Ureteral stricture rate after endoscopic treatments for urolithiasis and related risk factors: systematic review and meta-analysis

PURPOSE

We aimed to accurately determine ureteral stricture (US) rates following urolithiasis treatments and their related risk factors.

METHODS

We conducted a systematic review and meta-analysis following the PRISMA guidelines using databases from inception to November 2023. Studies were deemed eligible for analysis if they included ≥ 18 years old patients with urinary lithiasis (Patients) who were subjected to endoscopic treatment (Intervention) with ureteroscopy (URS), percutaneous nephrolithotomy (PCNL), or shock wave lithotripsy (SWL) (Comparator) to assess the incidence of US (Outcome) in prospective and retrospective studies (Study design).

RESULTS

A total of 43 studies were included. The pooled US rate was 1.3% post-SWL and 2.1% post-PCNL. The pooled rate of US post-URS was 1.9% but raised to 2.7% considering the last five years' studies and 4.9% if the stone was impacted. Moreover, the pooled US rate differed if follow-ups were under or over six months. Patients with proximal ureteral stone, preoperative hydronephrosis, intraoperative ureteral perforation, and impacted stones showed higher US risk post-endoscopic intervention with odds ratio of 1.6 (P = 0.05), 2.6 (P = 0.009), 7.1 (P < 0.001), and 7.47 (P = 0.003), respectively.

CONCLUSIONS

The overall US rate ranges from 0.3 to 4.9%, with an increasing trend in the last few years. It is influenced by type of treatment, stone location and impaction, preoperative hydronephrosis and intraoperative perforation. Future standardized reporting and prospective and more extended follow-up studies might contribute to a better understanding of US risks related to calculi treatment.

To Evaluate the Impact of Ho:YAG Laser Lithotripsy for Ureteroscopic Removal of Proximal and Distal Ureter Calculi

Background Urinary calculus illness is a prevalent clinical issue encountered by the medical community, particularly urologists, in contemporary society. Laser technologies have been widely accepted as standard modalities for lithotripsy applications. Using the Ho:YAG laser has expanded the range of applications for ureteroscopic stone management (URS), enabling the treatment of bigger stones in all regions of the upper urinary tract. It is noteworthy that ureteroscopy (URS) demonstrates superior rates of stone clearance for distal stones, regardless of their size, with a success rate of 94.5% compared to 74% for other treatment modalities. Significant variation exists in the reported results and problems associated with Ho:YAG laser lithotripsy across different trials, as documented in the literature. The procedure's outcome might vary based on factors such as the size of the stone, the length of impaction, the presence of ureteral damage and granulation, the kind and size of endoscopes used, and the specific energy settings employed by various operators. The present study aimed to evaluate the impact of Ho:YAG laser lithotripsy for ureteroscopic removal of proximal and distal ureter calculi. Methods This prospective observational study was carried out in the Department of Urology at DY Patil Medical College and Hospital, Pune, from March 2021 to March 2023. Patients diagnosed with a case of ureteric stone who opted for URSL during the study period were included. A total of 50 patients who underwent URSL in the urology department were included in this study. These were then grouped into those with proximal ureteral stones and distal ureteral stones. (25 each) Results The study observed that patients diagnosed with proximal ureteral stones had bigger calculi, with a mean stone size of 15mm, in comparison to patients with distal ureteral stones, with a mean stone size of 10mm (P=0.010). The stone burden was significantly higher for proximal ureteral stone patients than those with distal ureteric stones (P=0.010). The average duration of the operating procedure for upper ureter stones was 70 minutes, but for lower stones, the mean operative time was 45 minutes (P<0.001). No statistical significance was seen in the median age of patients between the two groups (P=0.89). The maximum number of cases in the upper stone group were in the age group of 16-30 years, and in the lower stone group was in the age group of 31-45 years. The prevalence of DJ stents at the time of presentation was higher among patients diagnosed with proximal ureteric stones than those with distal ureteric stones, with rates of 28% and 20%, respectively (P=0.508). Full fragmentation was successfully accomplished in all patients within the distal calculus group, accounting for 100% of the cases. At the same time, for proximal ureteric stones, a single laser lithotripsy session resulted in 92% (23 patients) achieving a stone-free status after two weeks.  Conclusion The study observed that stone size, burden, and procedure duration were statistically significant among other criteria. Mean age, stone HU, prior DJ stent, and stone-free rate were statistically insignificant. The procedure indicated that Ho:YAG laser lithotripsy has efficacy in treating both proximal and distal ureteral stones, with minimal intraoperative and postoperative complications. None of the complications were due to laser energy.

Impact of retrograde intrarenal surgery on biomarkers that are associated with renal parenchyma injury, a preliminary study

PURPOSE

The primary objective of this preliminary study was to assess the changes in concentration of biomarkers, which indicate renal injury, after RIRS.

MATERIALS AND METHODS

Within this prospective study, we included 21 patients with nephrolithiasis requiring treatment with RIRS. From each patient, blood and urine samples were taken at fixed intervals before and after RIRS. Kidney injury molecule-1 (KIM-1), monocyte chemoattractant protein 1 (MCP-1), neutrophil gelatinase-associated lipocalin (NGAL), interleukin-18 (IL-18), calbindin, albumin, clusterin, gluthation S-transferase-π (GST-π), beta-2-microglobulin (B2M), osteopontin, cystatin c, and trefoil-factor-3 (TFF3) were measured in urine. Creatinine, cystatin c and uric acid were analyzed in the blood samples.

RESULTS

A significant increase of the biomarkers clusterin, GST-π, B2M, NGAL and cystatin c was observed after RIRS. However, the biomarkers gradually normalized during the first 14 postoperative days. The parameters surgery time, cumulative stone volume, and BMI did not significantly influence the biomarker concentrations. In the case of GST-π and NGAL a significant positive, yet minuscule effect of age was observed.

CONCLUSIONS

With our study, we identified 5 out of 12 assessed renal injury biomarkers that showed a significant increase after RIRS. The increase was only temporary and all markers normalized within 14 days. Further studies are needed to determine the clinical value of these identified markers to assess the long-term impact of intrarenal pressure elevation during RIRS.

A Systematic Review of Elective Laser Therapy during Pregnancy

Introduction: Currently, lasers are used to treat many diseases and their complications. However, the use of lasers in pregnant patients is still controversial. Methods: In this review, the application of lasers in the fields of urology, surgery, obstetrics, dermatology, and musculoskeletal disorders is evaluated. The following keywords were used to search through PubMed, Google Scholar, and Scopus: pregnancy, laser, urolithiasis, endovenous laser ablation (EVLA) or treatment, leg edema, varicose vein, venous insufficiencies, hair removal, pigmentation, telangiectasia, vascular lesions, Q switch laser, diode laser, holmium, holmium-YAG laser, erbium laser and Pulsed dye laser, low-level laser therapy, high-intensity laser therapy, pain, musculoskeletal disorders, twin to twin transfusion syndrome (TTTS), amnioreduction, and safety. Results: Totally, 147 articles were found, and their abstracts were evaluated; out of 53 articles extracted, 14 articles were about dermatology, 24 articles were about urology, 12 articles were about obstetrics and gynecology, 10 articles were about musculoskeletal disorders and three articles were related to surgery. Conclusion: Laser therapy can be used as a safe treatment for urolithiasis, skin diseases, TTTS and varicose veins of the lower extremities. However, the use of laser therapy for musculoskeletal disorders during pregnancy is not recommended due to lack of evidence, and also we cannot recommend endovenous ablation.

Optical fibers for endoscopic high-power Er:YAG laserosteotomy

SIGNIFICANCE

The highest absorption peaks of the main components of bone are in the mid-infrared region, making Er:YAG and CO2 lasers the most efficient lasers for cutting bone. Yet, studies of deep bone ablation in minimally invasive settings are very limited, as finding suitable materials for coupling high-power laser light with low attenuation beyond 2  μm is not trivial.

AIM

The first aim of this study was to compare the performance of different optical fibers in terms of transmitting Er:YAG laser light with a 2.94-μm wavelength at high pulse energy close to 1 J. The second aim was to achieve deep bone ablation using the best-performing fiber, as determined by our experiments.

APPROACH

In our study, various optical fibers with low attenuation (λ  =  2.94  μm) were used to couple the Er:YAG laser. The fibers were made of germanium oxide, sapphire, zirconium fluoride, and hollow-core silica, respectively. We compared the fibers in terms of transmission efficiency, resistance to high Er:YAG laser energy, and bending flexibility. The best-performing fiber was used to achieve deep bone ablation in a minimally invasive setting. To do this, we adapted the optimal settings for free-space deep bone ablation with an Er:YAG laser found in a previous study.

RESULTS

Three of the fibers endured energy per pulse as high as 820 mJ at a repetition rate of 10 Hz. The best-performing fiber, made of germanium oxide, provided higher transmission efficiency and greater bending flexibility than the other fibers. With an output energy of 370 mJ per pulse at 10 Hz repetition rate, we reached a cutting depth of 6.82  ±  0.99  mm in sheep bone. Histology image analysis was performed on the bone tissue adjacent to the laser ablation crater; the images did not show any structural damage.

CONCLUSIONS

The findings suggest that our prototype could be used in future generations of endoscopic devices for minimally invasive laserosteotomy.

Retrograde intrarenal surgery: Past, present, and future

With the recent technological advancements in endourology, retrograde intrarenal surgery has become a more popular procedure for treatment of urolithiasis. Furthermore, since the introduction of new laser systems and advanced flexible ureteroscopy with miniaturized ureteroscopes, the treatment indications for retrograde intrarenal surgery have expanded to include not only larger renal stones of >2 cm but also upper urinary tract urothelial carcinoma, ureteral stricture, and idiopathic renal hematuria. Clinicians must keep up with these trends and make good use of these technologies in the rapidly changing field of endourology. Simultaneously, we must consider the risk of various complications including thermal injury due to laser use, ureteral injury caused by the ureteral access sheath, and radiation exposure during retrograde intrarenal surgery with fluoroscopic guidance. This review focuses on the past, present, and future of retrograde intrarenal surgery and provides many topics and clinical options for urologists to consider.

Retrograde ureteroscopy in the management of distal ureteric stones: A retrospective analysis of outcome and complications

Background

Urinary stones affect 8%-15% of the world population. In Nigeria, contemporary reports have shown that the incidence of urinary stones is rising. The distal ureter has been described as the most common location of ureteric stones. This study seeks to review our experience in the ureteroscopic management of distal ureteric stones with a view to appraising the stone clearance rate and the complications seen in our patients.

Patients and Methods

This descriptive study reviewed the record of 21 patients, who had semirigid ureteroscopy and pneumatic lithotripsy for distal ureteric stone between October 2015 and September 2018. All patients had computed tomography urography preoperatively to locate the stone. Data on patients' demographics, indication for the surgery, location and size of stone, preoperative double-J (DJ) placement, postoperative DJ stent placement, intraoperative and postoperative complications, and status of stone clearance were retrieved and subjected to statistical analysis.

Results

The mean age of the patients was 37.95 ± 11.09 (range, 21-67) years. The mean stone size was 8.06 ± 2.87 mm with a range of 4.8 mm-15.0 mm. Out of the 21 patients, 20 (95.2%) had the procedure for recurrent ureteric colic and 1 (48%) was for hematuria. Four (19.0%) patients had DJ stent preoperatively, whereas 17 (81.0%) patients did not have. Fourteen (66.7%) patients had intraoperative ureteric dilatation. Postoperative DJ stent was placed in 17 (81.0%) patients, whereas 4 (19.0%) patients did not have. Three (14.3%) patients had mucosal flap, 6 (14.3%) had mucosal abrasion, 2 (9.5%) had bleeding, 1 (4.8%) patient had transient hematuria postoperatively, and 2 (9.5%) patients had urinary tract infection. Nineteen (90.5%) patients had complete clearance in a single surgery. Two (9.5%) patients had symptomatic residual fragments that required repeat ureteroscopy.

Conclusion

Our study has shown that ureteroscopy is a useful and safe technique in the removal of stones in distal ureter.

Laser-guided real-time automatic target identification for endoscopic stone lithotripsy: a two-arm in vivo porcine comparison study

Introduction and objective

Thermal injuries associated with Holmium laser lithotripsy of the urinary tract are an underestimated problem in stone therapy. Surgical precision relies exclusively on visual target identification when applying laser energy for stone disintegration. This study evaluates a laser system that enables target identification automatically during bladder stone lithotripsy, URS, and PCNL in a porcine animal model.

Methods

Holmium laser lithotripsy was performed on two domestic pigs by an experienced endourology surgeon in vivo. Human stone fragments (4–6 mm) were inserted in both ureters, renal pelvises, and bladders. Ho:YAG laser lithotripsy was conducted as a two-arm comparison study, evaluating the target identification system against common lithotripsy. We assessed the ureters’ lesions according to PULS and the other locations descriptively. Post-mortem nephroureterectomy and cystectomy specimens were examined by a pathologist.

Results

The sufficient disintegration of stone samples was achieved in both setups. Endoscopic examination revealed numerous lesions in the urinary tract after the commercial Holmium laser system. The extent of lesions with the feedback system was semi-quantitatively and qualitatively lower. The energy applied was significantly less, with a mean reduction of more than 30% (URS 27.1%, PCNL 52.2%, bladder stone lithotripsy 17.1%). Pathology examination revealed only superficial lesions in both animals. There was no evidence of organ perforation in either study arm.

Conclusions

Our study provides proof-of-concept for a laser system enabling automatic real-time target identification during lithotripsy on human urinary stones. Further studies in humans are necessary, and to objectively quantify this new system’s advantages, investigations involving a large number of cases are mandatory.

Electronic supplementary material

The online version of this article (10.1007/s00345-020-03452-0) contains supplementary material, which is available to authorized users.

Retrograde intrarenal surgery of renal stones: a critical multi-aspect evaluation of the outcomes by the Turkish Academy of Urology Prospective Study Group (ACUP Study)

AIMS

To outline and evaluate the incidence, management and follow-up of the residual fragments (RFs) following retrograde intrarenal surgery (RIRS) of renal stones by the Turkish Academy of Urology Prospective Study Group (ACUP Study).

METHODS

Following the ethical committee approval, 15 centers providing data regarding the incidence, management, and follow-up of RFs after RIRS were included and all relevant information was recorded into the same electronic database program ( https://acup.uroturk.org.tr/ ) created by Turkish Urology Academy for Residual Stone Study.

RESULTS

A total of 1112 cases underwent RIRS for renal calculi and RFs were observed in 276 cases (24.8%). Of all the parameters evaluated, our results demonstrated no statistically significant relation between preoperative DJ stenting and the presence of RFs (χ2 (1) = 158.418; p = 0.099). RFs were significantly higher in patients treated with UAS (82 patients, 29.3%) during the procedure compared to the cases who did not receive UAS (194 patients, 23.3%) (χ2 (1) = 3.999; p = 0.046). The mean period for a secondary intervention after RIRS was 28.39 (± 12.52) days. Regarding the procedures applied for RF removal, re-RIRS was the most commonly performed approach (56%).

CONCLUSIONS

Despite the reported safe and successful outcomes, the incidence of RFs is higher, after the RIRS procedure particularly in cases with relatively larger calculi. Such cases need to be followed in a close manner and although a second flexible ureteroscopy is the treatment of choice for fragment removal in the majority of these patients, shock wave lithotripsy and percutaneous nephrolithotomy may also be preferred in selected cases.

Microultrasonic Probe Combined with Ultrasound-Guided Minipercutaneous Nephrolithotomy in the Treatment of Upper Ureteral and Renal Stones: A Consecutive Cohort Study

Objectives: We conduct a study to assess the outcome of microultrasonic probe combined with ultrasound (US)-guided minipercutaneous nephrolithotomy (PCNL) for upper ureteral and renal stones. Patients and Methods: Data of 119 patients (123 kidney units) who underwent microultrasonic lithotripsy combined with mini-PCNL were retrospectively reviewed. The group included 96 men and 23 women. All procedure of puncture and dilatation were guided by US solely. Data were analyzed by SPSS. Results: The mean operation time was 32.6 minutes (range, 10-110 minutes). The mean time of lithotripsy and stone removal was 14.5 minutes (3-100 minutes). The mean postoperative length of stay was 2.7 days (1-7 days). Besides, stone-free rate (SFR) at discharge was 95.9% (118/123). The mean hemoglobin drop was 11.6 mg/dL (range 1-26 mg/dL). Grades I, II, and IIIa complications were observed in four, one, and one patients, respectively. Subgroup analysis was done to compare the outcomes of 20 mm or less vs 21 mm or more calculi. There was a longer operation duration (40 vs 29 minutes) and lower SFR in the 21 mm or more calculi subgroup. Conclusions: Microultrasonic probe combined with US-guided mini-PCNL is an effective and safe procedure to treat patients with upper ureteral and renal stones with higher SFR but lower complications.

Post ureteroscopic stone surgery ureteral strictures management: a retrospective study

PURPOSE

To share experience in managing ureteral strictures following ureteroscopic lithotripsy.

METHODS

Ninety five patients diagnosed as ureteral strictures after ureteroscopic lithotripsy between January 2013 and January 2018 were included. 53 received endourological treatment, 34 underwent reconstruction, 6 underwent nephrectomy for severe renal impairment, and 2 chose routine ureteral stent replacement. Therapeutic success was defined as absence of clinical symptoms and radiologic relief of obstruction.

RESULTS

The follow-up time ranged from 13 to 57 months, with a median time of 24. It lasted more than 13 months in all patients, exception for 2 nephrectomies. Two patient groups including 69 endourological procedures and 37 reconstructions were used to compare therapeutic effects and complications. The overall success rate was 60.9% (42/69) in endourological intervention vs. 97.3% (36/37) in reconstruction (p < 0.001), while 74.4% (29/39) patients with stricture less than 1 cm and 68.8% (33/48) patients with mild-to-moderate hydronephrosis achieved success in endourological group. All except 1 failure appeared within the first year postoperatively. Subgroup analyses for endourological procedures revealed significant differences in the success rate of different stricture lengths and hydronephrosis (p = 0.004 and p = 0.043). Multivariate Cox regression analysis indicated that reconstruction was significantly related to a more successful outcome, compared with endourological procedures (HR 0.052, 95% CI 0.007-0.394, p = 0.004).

CONCLUSION

Reconstruction performs better than endourological procedures in surgical outcome. Endourological procedure provides an acceptable success rate in patients with stricture shorter than 1 cm and slight hydronephrosis. Most stricture recurrence appeared within the first year postoperatively.

Polymer-Mineral Composites Mimic Human Kidney Stones in Laser Lithotripsy Experiments

Despite the widespread use of laser lithotripsy to fragment kidney stones in vivo, there is a lack of robust artificial stone models to replicate the behavior of human stones during lithotripsy procedures. This need for accurate stone models is particularly important as novel laser technologies are introduced in the field of lithotripsy. In this work, we present a method to prepare composite materials that replicate the properties of human kidney stones during laser lithotripsy. Their behavior is understood through the lens of near-IR spectroscopy and helps to elucidate the mechanism of laser lithotripsy in kidney stone materials.

Advances in laser technology and fibre-optic delivery systems in lithotripsy

The flashlamp-pumped, solid-state holmium:yttrium-aluminium-garnet (YAG) laser has been the laser of choice for use in ureteroscopic lithotripsy for the past 20 years. However, although the holmium laser works well on all stone compositions and is cost-effective, this technology still has several fundamental limitations. Newer laser technologies, including the frequency-doubled, double-pulse YAG (FREDDY), erbium:YAG, femtosecond, and thulium fibre lasers, have all been explored as potential alternatives to the holmium:YAG laser for lithotripsy. Each of these laser technologies is associated with technical advantages and disadvantages, and the search continues for the next generation of laser lithotripsy systems that can provide rapid, safe, and efficient stone ablation. New fibre-optic approaches for safer and more efficient delivery of the laser energy inside the urinary tract include the use of smaller-core fibres and fibres that are tapered, spherical, detachable or hollow steel, or have muzzle brake distal fibre-optic tips. These specialty fibres might provide advantages, including improved flexibility for maximal ureteroscope deflection, reduced cross section for increased saline irrigation rates through the working channel of the ureteroscope, reduced stone retropulsion for improved stone ablation efficiency, and reduced fibre degradation and burnback for longer fibre life.

Sheathless and fluoroscopy-free retrograde intrarenal surgery: An attractive way of renal stone management in high-volume stone centers

Objective

To evaluate the efficacy and safety of sheathless and fluoroscopy-free flexible ureterorenoscopic laser lithotripsy (FURSL) for treating renal stones.

Methods

Between May 2015 and May 2017, 135 patients with renal stones treated with sheathless and fluoroscopy-free FURSL were prospectively evaluated. Our technique involved a semi-rigid ureteroscopic assessment of the ureter, and the guidewire was left in situ to railroad the flexible ureteroscope. A holmium laser was used to fragment and dust the stones; fragments were neither grasped nor collected.

Results

The study population consisted of 135 patients including 85 males (62.96%) and 50 females (37.04%) with a mean age of 40.65 years (range: 3–70 years) were evaluated. The mean stone size was 17.23 mm (range: 8–41 mm). Complete stone-free status was achieved in 122 (90.37%) patients and clinically insignificant residual fragments (CIRF) in two (1.48%), while residual stones were still present in 11 (8.15%) patients. Postoperative complications occurred in 23 (17.4%) cases and were mostly minor, including fever in 17 (12.6%), pyelonephritis in four (3.0%), subcapsular hematoma in one (0.7%) and steinstrasse in one (0.7%). These complications were Clavien I-II, GI in 17 (12.6%) patients, GII in five (3.7%), and Clavien IIIb in one (0.7%). No major complications were observed. Stone size ≥2 cm, operative time ≥30 min, and lasing time ≥20 min were significantly associated with a higher rate of complications and lower stone-free rates upon univariate analysis (p<0.05).

Conclusion

Sheathless and fluoroscopy-free FURSL are effective and safe for renal stone management, especially for stones under 2 cm in diameter. This process is a feasible option for avoiding sheath complications, which can protect surgeons from the negative effects of radiation.

The Rise and Fall of High Temperatures During Ureteroscopic Holmium Laser Lithotripsy

Introduction: Temperatures over 43°C-the threshold for cellular injury-may be achieved during ureteroscopic holmium laser lithotripsy. The time to reach and subsequently clear high temperatures at variable laser power settings and irrigation pressures has not been studied. Methods: A flexible or semirigid ureteroscope was placed within an 11/13 F ureteral access sheath inserted into a 250-mL saline bag simulating a normal-caliber ureter, renal pelvis reservoir, and antegrade irrigation flow. A thermocouple was placed adjacent to a 365 μm fiber fired for 45 seconds at 0.6 J/6 Hz, 0.8 J/8 Hz, 1 J/10 Hz, 1 J/20 Hz, and 0.2 J/80 Hz. Irrigation pressures of 200, 100, and 0 mm Hg were tested. Mean temperature changes were recorded with 6°C increase as a threshold for injury (as body temperature is 6°C below 43°C). Results: Semirigid scope: At 200 mm Hg no temperature changes >6°C were observed. At 100 mm Hg, changes >6°C occurred with 1 J/20 Hz within 1 second of activation and returned to ≤6°C within 1 second of cessation. At 0 mm Hg, changes >6°C occurred with all settings; within 1 second at power ≥10 W. Temperatures returned to ≤6°C within 5-10 seconds. Flexible scope: At 200 mm Hg, changes >6°C occurred at 1 J/10 Hz (15 seconds), 0.2 J/80 Hz (3 seconds), and 1 J/20 Hz (2 seconds). Temperatures returned within 6°C of baseline within 2 seconds. At 100 mm Hg, changes >6°C occurred in all but 0.6 J/6 Hz. Temperatures returned to ≤6°C in 5-10 seconds. At 0 mm Hg, all settings produced changes >6°C within 3 seconds, except 0.6 J/6 Hz (35 seconds). Temperatures returned to ≤6°C in under 10 seconds. Conclusions: High temperatures were achieved in our in vitro model in as little as 1 second at common irrigation pressures and laser settings, particularly with a flexible ureteroscope and power ≥10 W. However, with laser cessation, temperatures quickly returned to a safe level at each irrigation pressure.

Duodenal Ulceration following Holmium Laser Lithotripsy

The epidemiology of peptic ulcer disease (PUD) has changed considerably in the last several decades. Previously a chronic disease characterized by frequent recurrences with a high rate of surgical interventions, it is now largely a self-limited disease that is medically managed. The role of acid suppression was widely recognized as being important in the pathogenesis of PUD in the 19th century, while it was not until the 1980s and 1990s that the importance of Helicobacter pylori infection was identified. Today, PUD is largely caused by either H. pylori infection or nonsteroidal anti-inflammatory drug use. However, other less common etiologies of this disease are becoming more relevant as the prevalence of H. pylori decreases and proton pump inhibitor therapy is increasingly common. Here, we report a case of duodenal ulceration following bilateral rigid ureteroscopy with holmium laser lithotripsy.

Is the 4.5-F ureteroscope (Ultra-Thin) an alternative in the management of ureteric and renal pelvic stones?

Objectives

To compare the 7.5–9.5F ureteroscope (URS) with the 4.5–6.5F URS (Ultra-Thin) in terms of success and complication rates in adult patients with ureteric and renal pelvic stones.

Patients and methods

In all, 41 patients treated with 7.5–9.5F semi-rigid URS (Group 1) and 33 patients treated with the Ultra-Thin (Group 2) were prospectively included in the study. All patients underwent holmium laser ureteroscopic lithotripsy. In each group, when the selected ureteroscopic intervention failed to reach or disintegrate the stone, the URS was replaced with the other one. Outcome criteria were: success and complication rates, stone size and stone surface area, operative time, laser time, usage of guidewire, and postoperative JJ-catheter placement.

Results

The ureteroscopic lithotripsy in 36 of 41 (87.8%) and 24 of 33 (72.7%) patients was completed without a need to replace the URS with the other one in groups 1 and 2, respectively (P = 0.67). After replacement of the 7.5–9.5F URS with the Ultra-Thin for patients who failed in Group 1, the overall stone-free rate (SFR) improved to 97.5% (P = 0.014). In Group 2, after replacement of the Ultra-Thin with the 7.5–9.5F URS for the failed patients, the overall SFR improved to 96.9% (P = 0.02). There was no significant difference between the groups for complications. Postoperative JJ stenting was significantly less in Group 2 (21.2%) in comparison to Group 1 (46.3%) (P = 0.02).

Conclusions

The Ultra-Thin has a similar success rate as the 7.5–9.5F URS in the treatment of ureteric stones and is a feasible option in patients in whom a conventional URS cannot be advanced through any segment of the ureter.

Holmium:yttrium-aluminum-garnet laser induced lithotripsy: in-vitro investigations on fragmentation, dusting, propulsion and fluorescence

The fragmentation efficiency on Bego artificial stones during lithotripsy and the propulsive effect (via video tracking) was investigated for a variety of laser settings. A variation of the laser settings (pulse energy, pulse duration, repetition rate) altered the total application time required for stone fragmentation, the stone break up time, and the propulsion. The obtained results can be used to develop lithotripsy devices providing an optimal combination of low stone propulsion and high fragmentation efficacy, which can then be evaluated in a clinical setting. Additionally, the fluorescence of human kidney stones was inspected endoscopically in vivo. Fluorescence light can be used to detect stone-free areas or to clearly distinguish calculi from surrounding tissue or operation tools.

Toward Respiratory-Gated Retrograde Intrarenal Surgery: A Prospective Controlled Randomized Study

INTRODUCTION

We set out to investigate whether general anesthesia with low ventilation (LV, respiratory rate ≤8/minute and tidal volume <500 mL) could reduce renal mobility and thereby facilitate improved retrograde intrarenal surgery (RIRS) compared with general anesthesia with standard ventilation (SV).

MATERIALS AND METHODS

All 60 consecutive patients who presented for RIRS in our department from September 1, 2017 to December 31, 2017 were prospectively randomized 1:1 into one group that was selected to receive SV and another that received LV. Significant factors influencing the study endpoints considered fragmentation rate (FR), removal rate (RR), processing rate (PR), and operating rate (OR), were statistically analyzed for the whole group as well as for comparison by level of surgeon expertise.

RESULTS

Univariate analysis revealed that LV was a significant factor in improving all endpoints. Some endpoints were also affected by the stone's volume, number, and density as well as the surgeon expertise. LV remained the single independent factor for FR, RR, and PR in the multivariate analysis. LV significantly improved all four of the fellows' endpoints (p < 0.05 for each) and positively influenced the expert's RR (p = 0.04), PR (p = 0.02) and OR (p = 0.04). The performance gap between the fellows and the experts narrowed under LV. The end-tidal CO₂ was significantly higher in the LV group (50 vs 36 mm Hg; p < 0.0001), however, without any clinical significance. The overall stone-free rate (97%) and complication rate (5%) were not significantly different between the two groups. The patient's anesthesia-related safety was not affected by the mode of ventilation as evidenced by no need to convert from LV to SV during the procedures.

CONCLUSIONS

LV during RIRS has a significant positive impact on the overall improvement of surgical performance and effectiveness. It does not negatively affect the patient's anesthesia-related safety and may contribute to considerably improving the performance of in-training endourologists.

A clinical study of choledochoscopic holmium laser lithotripsy for multiple intrahepatic calculi within ERAS programs

OBJECTIVES

Multiple intrahepatic calculi, especially calculi in both sides of the liver, cannot be completely resolved by traditional surgery. In addition, morbidity after liver resection remains high. ERAS programs have been suggested that could relieve surgical stress and accelerate postoperative recovery. This study aimed to evaluate the safety and efficacy of choledocholithotomy combined with holmium laser lithotripsy in the treatment of multiple intrahepatic calculi within ERAS programs.

METHODS

In all, 109 patients with multiple intrahepatic calculi were enrolled between January 2012 and September 2016, 42 of whom received choledocholithotomy combined with holmium laser lithotripsy. The remaining 67 patients underwent choledocholithotomy combined with choledochoscopic mechanical lithotripsy. Perioperative outcomes were compared and analyzed.

RESULTS

Patient characteristics and preoperative details were similar between the groups (P > 0.05). The implementation of holmium laser lithotripsy could reduce the calculi residual rate (7.1% vs. 22.4%, P = 0.037), and even the liver resection rate (16.7% vs. 35.8%, P = 0.031). Additionally, holmium laser lithotripsy did not result in a higher morbidity (11.9% vs. 16.4%, P = 0.517), readmission rate (0% vs. 6%, P = 0.158), hospital stay (P = 0.189), hospital cost (P = 0.998), transfusion rate (P = 0.576), or operative time (P = 0.638).

CONCLUSIONS

Holmium laser lithotripsy is feasible and efficient for treating multiple intrahepatic calculi within ERAS programs, which could reduce the liver resection rate and render refractory hepatic calculi easy to eliminate. In addition, holmium laser lithotripsy could be well coupled to the ERAS program to relieve surgical stress and accelerate postoperative recovery. Lasers Surg. Med. 51:161-166, 2019. © 2018 Wiley Periodicals, Inc.

Miniature ureteroscope distal tip designs for potential use in thulium fiber laser lithotripsy

Thulium fiber laser lithotripsy using smaller optical fibers may enable development of miniature ureteroscopes. Two ureteroscope distal tip prototypes were built and characterized. The first design was 4.5-French (Fr) [1.5-mm outer diameter (OD)], five channel tip, housing 200-μm inner diameter (ID) dedicated central channel for insertion of 100-μm core fibers and four surrounding channels, each with 1.5 Fr (510-μm ID) for instrumentation, irrigation, imaging, and illumination, respectively. The second design was 6.0-Fr (2.0-mm OD), three-dimensional printed tip with larger, hemispherical common working channel and separate detection port integrated with ring lighting. Standard instruments, including optical fibers, guidewires, and stone baskets, were inserted through working channels to demonstrate feasibility. Gravitational and manual pump-assisted saline irrigation rates were measured. Luminous intensity distribution curves (LIDCs) were modeled for both ring and conventional lighting designs. Imaging was conducted using 3000, 6000, and 10,000 pixel, miniature, flexible endoscopes with 0.4-, 0.6-, and 0.9-mm OD, to differentiate between urinary stones and ureter wall, for potential clinical application. The multichannel ureteroscope tip with 1.5-Fr working channel yielded a gravitational saline flow rate of 3.9  ±  0.2  mL  /  min compared to 31.3  ±  0.6  mL  /  min for standard (3.6 Fr) ureteroscope channel. Manual, pump-assisted irrigation increased flow rate to 32.5  ±  3.0  mL  /  min. The 6000 pixel, 0.6-mm OD, flexible endoscope provided a balance of clear differentiation between stones and ureter wall and sufficiently small OD. A ring lighting configuration provided more uniform illumination than conventional cross-lighting geometry as demonstrated by LIDCs. With further development, these miniature ureteroscope tip designs may be integrated into a fully functional ureteroscope to permit ureteral access with minimal trauma and improved patient safety and comfort.

Rirs through Semi-Rigid Ureteroscope and Holmium Laser in the Treatment of Ureteral Stones Retropulsion

Retrograde displacement of ureteral stones into the renal cavities during ureteroscopic lithotripsy represents a frequent and adverse event that leads to additional procedures (ESWL, PCNL, Retrograde Intra-renal lithotripsy with flexible instruments, DJ stent placement and subsequent EWSL) to obtain full clearence of calculi. All these procedures require a further time of treatment.

Between 1/2008 and 3/2009, a total of 48 patients harbouring proximal (21 cases) and distal (27 cases) ureteral stones underwent Holmium Laser lithotripsy. In 3 patients previous percutaneous nephrostomy was performed to drain the excretory way. In 12 cases (25%) stone retropulsion occurred; in 3 patients in the upper calix and in 5 in the renal pelvis. Only in 4 cases the stone migrated in the lower or medium calix. In 8 cases we attempted the immediate treatment of intrarenal displaced stones by advancing the semi-rigid instrument into the renal cavities. In 2 cases the treatment aborted because of the shortness of ureteroscope. The instillation of lubricating lidocaine jelly prevented in 3 cases furher displacement of stone. Washing with saline solution through nephrostomic catheter allowed an effective mobilization of stone and an easy lasertripsy

RIRS was successful in 4 cases. When flexible devices or immediate ESWL are not available, rigid or semi-rigid retrograde lithotripsy with holmium laser immediately performed after ureteral stone displacement represents a safe and effective method to treat displaced stones. Several tricks are required to obtain a good stone-free rate.

Miniaturized percutaneous nephrolithotomy versus retrograde intrarenal surgery in the treatment of renal stones with a diameter <15 mm: A 3-year open-label prospective study

Aim

The aim of this study is to compare the outcomes of miniaturized percutaneous nephrolithotomy (mini-perc) and retrograde intrarenal surgery (RIRS) in management of renal stones with a diameter <15 mm.

Materials and Methods

This was an open-label prospective study that included a total of 80 cases underwent mini-perc (n = 40) and RIRS (n = 40) between July 2014 and August 2017. The primary outcome objective was stone-free rate, retreatment rate, complications, hospital stay, operative time, and reduction in hemoglobin level. Data were analyzed using SPSS version 16.0 Software.

Results

Overall, 80 patients were enrolled in this study. The mean age was 40.12 and 38.20 years, and the mean stone size was 1.15 and 1.30 cm in mini-perc and RIRS group, respectively. Majority of the study participants were males. Overall, mini-perc and RIRS had stone clearance rates of 100% and 95.4%, respectively. Two patients required retreatment in RIRS group. The duration of hospital stay and the rate of complication was similar in both the groups. Operative duration was more in RIRS group. Decrease in hemoglobin level was more in mini-perc group.

Conclusions

Results demonstrated that both modalities were associated with high stone clearance rates with minimal complications. RIRS was associated with less reduction in hemoglobin and could be used as standard treatment modality for small renal calculi.

In vitro investigations of propulsion during laser lithotripsy using video tracking

OBJECTIVES

Ureteroscopic laser lithotripsy is an important and widely used method for destroying ureter stones. It represents an alternative to ultrasonic and pneumatic lithotripsy techniques. Although these techniques have been thoroughly investigated, the influence of some physical parameters that may be relevant to further improve the treatment results is not fully understood. One crucial topic is the propulsive stone movement induced by the applied laser pulses. To simplify and speed up the optimization of laser parameters in this regard, a video tracking method was developed in connection with a vertical column setup that allows recording and subsequently analyzing the propulsive stone movement in dependence of different laser parameters in a particularly convenient and fast manner.

MATERIALS AND METHODS

Pulsed laser light was applied from below to a cubic BegoStone phantom loosely guided within a vertical column setup. The video tracking method uses an algorithm to determine the vertical stone position in each frame of the recorded scene. The time-dependence of the vertical stone position is characterized by an irregular series of peaks. By analyzing the slopes of the peaks in this signal it was possible to determine the mean upward stone velocity for a whole pulse train and to compare it for different laser settings. For a proof of principle of the video tracking method, a specific pulse energy setting (1 J/pulse) was used in combination with three different pulse durations: short pulse (0.3 ms), medium pulse (0.6 ms), and long pulse (1.0 ms). The three pulse durations were compared in terms of their influence on the propulsive stone movement in terms of upward velocity. Furthermore, the propulsions induced by two different pulse energy settings (0.8 J/pulse and 1.2 J/pulse) for a fixed pulse duration (0.3 ms) were compared. A pulse repetition rate of 10 Hz was chosen for all experiments, and for each laser setting, the experiment was repeated on 15 different freshly prepared stones. The latter set of experiments was compared with the results of previous propulsion measurements performed with a pendulum setup.

RESULTS

For a fixed pulse energy (1 J/pulse), the mean upward propulsion velocity increased (from 120.0 to 154.9 mm · s^-1 ) with decreasing pulse duration. For fixed pulse duration (0.3 ms), the mean upward propulsion velocity increased (from 91.9 to 123.3 mm · s^-1 ) with increasing pulse energy (0.8 J/pulse and 1.2 J/pulse). The latter result corresponds roughly to the one obtained with the pendulum setup (increase from 61 to 105 mm · s^-1 ). While the mean propulsion velocities for the two different pulse energies were found to differ significantly (P < 0.001) for the two experimental and analysis methods, the standard deviations of the measured mean propulsion velocities were considerably smaller in case of the vertical column method with video tracking (12% and 15% for n = 15 freshly prepared stones) than in case of the pendulum method (26% and 41% for n = 50 freshly prepared stones), in spite of the considerably smaller number of experiment repetitions ("sample size") in the first case.

CONCLUSION

The proposed vertical column method with video tracking appears advantageous compared to the pendulum method in terms of the statistical significance of the obtained results. This may partly be understood by the fact that the entire motion of the stones contributes to the data analysis, rather than just their maximum distance from the initial position. The key difference is, however, that the pendulum method involves only one single laser pulse in each experiment run, which renders this method rather tedious to perform. Furthermore, the video tracking method appears much better suited to model a clinical lithotripsy intervention that utilizes longer series of laser pulses at higher repetition rates. The proposed video tracking method can conveniently and quickly deliver results for a large number of laser pulses that can easily be averaged. An optimization of laser settings to achieve minimal propulsive stone movement should thus be more easily feasible with the video tracking method in connection with the vertical column setup. Lasers Surg. Med. 50:333-339, 2018. © 2017 Wiley Periodicals, Inc.

Jackets Off: The Impact of Laser Fiber Stripping on Power Output and Stone Degradation

PURPOSE

To investigate the effect of laser fiber stripping on stone fragmentation and laser fiber power output.

MATERIALS AND METHODS

In a benchtop simulation of laser lithotripsy, 20 BegoStone phantoms were positioned within a ureteral model and irradiated for 10 minutes at 8 Hz and 0.8 J. A freshly cleaved 365 μm laser fiber was used for all trials, with half of the fibers also undergoing stripping. Power output was measured at 1-minute intervals, beginning with an initial prelithotripsy recording at 0 minutes. Fiber tips were imaged with scanning electron microscopy. In a single-blinded manner, final masses of residual stone fragments were measured and used to quantify stone breakdown. Independent-sample Mann-Whitney U tests were performed with significance set at p < 0.05, comparing stripped and unstripped fiber tips with respect to power output and fraction of stone fragmentation.

RESULTS

Mean power output after 1 minute of lasing was significantly greater in unstripped laser fibers (p = 0.015), while fibers, whether stripped or not, demonstrated no significant output differences prelithotripsy or at any time from 2 to 10 minutes. However, stripped laser fibers achieved significantly increased stone breakdown compared to unstripped fibers (p = 0.004), fragmenting 63 mg (25%) more of the initial stone mass per trial.

CONCLUSIONS

Although unstripped laser fibers provided superior power output at 1 minute, output at all other time points was similar between stripped and unstripped fibers. However, despite similar optical output, stripped laser fibers achieved greater stone fragmentation, possibly due to improved contact between stone and fiber tip.

A prospective multicenter European study on flexible ureterorenoscopy for the management of renal stone

Purpose

The aim of this study was to describe the outcomes and the complications of retrograde intrarenal surgery (RIRS) for renal stones in a multi-institutional working group.

Materials and Methods

From 2012 to 2014, we conducted a prospective study including all RIRS performed for kidney stones in 4 European centers. Demographic information, disease characteristics, and perioperative and postoperative data were gathered. Patients and stone data, procedure characteristics, results and safety outcomes were analyzed and compared by descriptive statistics. Complications were reported using the standardized Clavien system.

Results

Three hundred and fifty-six patients underwent 377 RIRS with holmium laser lithotripsy for renal stones. The RIRS was completed in all patients with a mean operative time of 63.5 min. The stone-free status was confirmed endoscopically and through fluoroscopic imaging after the first procedure in 73.6%. The second procedure was performed in twenty patients (5.6%) achieving an overall stone free rate of 78.9%. The overall complication rate was 15.1%. Intra-operative and post-operative complications were seen in 24 (6.7%) and 30 (8.4%) cases, respectively.

Conclusions

RIRS is a minimally invasive procedure with good results in terms of stone-free and complications rate.

Retrospective comparative study of rigid and flexible ureteroscopy for treatment of proximal ureteral stones

BACKGROUND

We analyzed the outcome and complications of rigid (R-URS) and flexible (F-URS) ureteroscopic lithotripsy for treatment of proximal ureteric stone (PUS).

SUBJECTS AND METHODS

Retrospective data of 135 patients (93 males and 42 females) submitted to R-URS and F-URS for treatment of PUS in the period between July 2013 and January 2015 were investigated. (R-URS, group 1) was performed in 72 patients while 63 patients underwent (F-URS, group 2).We compared the 2 groups for success, stone characteristics, operative time, intraoperative and postoperative complications.

RESULTS

The overall stone free rate (SFRs) was 49/72 (68%) in group 1 and 57/63 (91%) patients in group 2, (P=0.005). The operative time was shorter in group 1 in comparison to group 2 with statistically significant difference (P=0.005). There was not any statistically significant difference between 2 groups in complication rate (P=0.2). Conclusıon: Both R-URS and F-URS could be a feasible option for treatment of PUS. R-URS is less successful for treatment of PUS and should be used cautiously and with availability of F-URS.

The Efficacy and Safety of Laser Lithotripsy in Pregnancy

Introduction: The aim of our study was to assess the efficacy and safety of laser lithotripsy in pregnant patients. Methods: In this retrospective study, we reviewed the 15 pregnant women who have been treated for ureteral stones with semi-rigid ureteroscope and holmium laser at our center between Januarys 2007and April 2015. Results: The mean age of patients and mean gestational age was 29.3 years old 27.3 weeks respectively. Mean size of stones was 7.84 mm. Twelve patients had renal colic, and hematuria was found in 3 cases. Irritative urinary symptoms such as frequency and urgency detected in 6 ones and 2 patients had fever. The stone of all patients were fragmented by using holmium laser lithotripter. In 5 patients stone residual fragments were removed by grasper while other 10 patients were left to pass fragments spontaneously. No intraoperative and postoperative urological or obstetric complication was seen. Conclusion: Laser lithotripsy is safe and efficacious in pregnant patients who have ureteral stone that does not respond to conservative management.

Light in diagnosis, therapy and surgery

Light and optical techniques have made profound impacts on modern medicine, with numerous lasers and optical devices being currently used in clinical practice to assess health and treat disease. Recent advances in biomedical optics have enabled increasingly sophisticated technologies — in particular those that integrate photonics with nanotechnology, biomaterials and genetic engineering. In this Review, we revisit the fundamentals of light–matter interactions, describe the applications of light in imaging, diagnosis, therapy and surgery, overview their clinical use, and discuss the promise of emerging light-based technologies.

Benchtop and Initial Clinical Evaluation of the ShockPulse Stone Eliminator in Percutaneous Nephrolithotomy

PURPOSE

Standardized bench testing of the new ShockPulse™ intracorporeal lithotripter was performed against three commercially available lithotripsy systems to determine differences and nuances in performance.

MATERIALS AND METHODS

The ShockPulse intracorporeal lithotripter was tested against the LUS-2™, CyberWand,™ and EMS LithoClast™ in a standardized bench setting using hard (Ultracal-30) and soft (plaster of Paris) stone phantoms. An in vitro kidney model was used to record the time needed to fragment stone samples into retrievable-sized pieces. The time needed to fully comminute and evacuate stone samples was also recorded. The efficacy of each device at various applied pressures was determined using a hands-free apparatus, which was used to apply 1.0, 1.5, and 2.0 pounds of fixed force.

RESULTS

For hard and soft stones, the time needed to create retrievable fragments was similar among all systems (p = 0.585). The ShockPulse was significantly faster than the LUS-2 and LithoClast at fully fragmenting and evacuating stone samples (p = 0.046), while the CyberWand was significantly slower than all three systems at this task (p = 0.001). When fixed forces were applied to a large stone phantom, the ShockPulse and CyberWand were significantly faster than the LUS-2 and LithoClast (p < 0.0001). When groups of smaller stones were tested, the ShockPulse was significantly faster at 1.0 pound (p < 0.001) and 1.5 pounds (p < 0.002) of force. At 2.0 pounds, no differences were observed (p = 0.09).

CONCLUSIONS

The ShockPulse is equally as effective and, in some circumstances, more effective than the three commercially available devices against which it was tested in an in vitro setting.

Stone/tissue differentiation for Holmium laser lithotripsy using autofluorescence: Clinical proof of concept study

BACKGROUND AND OBJECTIVES

Holmium laser lithotripsy is the gold standard for intracorporeal fragmentation of urinary calculi. Usually, a visible beam is superimposed on the IR treatment laser as an aiming beam to guide the surgeon. In vitro tests showed that this aiming beam (532 nm, power <1 mW) excites strong fluorescence on human calculi. Tissue, in contrast, emitted much weaker fluorescence. If this is verified in vivo, the fluorescence signal induced by the aiming beam could be used to implement a feedback loop, preventing the Holmium laser being fired on tissue.

MATERIALS AND METHODS

Fluorescence signals of 67 tissue and 68 stone spots were measured in a clinical proof of concept study with eight patients. For this, a modulated excitation/detection scheme (lock-in technique) was implemented. A frequency-doubled, diode-pumped solid-state laser module (532 nm, modulation frequency 66 Hz, average power 0.3 mW) was coupled via a dichroic mirror with the Holmium lithotripsy laser into the treatment fiber. The fluorescence signal entering the treatment fiber was detected via another dichroic mirror with a photodiode and a lock-in amplifier.

RESULTS

In most instances (94%), the calculus of a patient gave a signal which was at least twice the maximum signal of ureteral tissue.

CONCLUSION

The results of our proof of concept study indicate that measuring the fluorescence signal of a green aiming beam could be used to implement a feedback loop for Holmium laser lithotripsy. Preventing the laser being fired on tissue, this would increase the safety of the procedure. Lasers Surg. Med. 49:361-365, 2017. © 2016 Wiley Periodicals, Inc.

Comparison of the Nanopulse Lithotripter to the Holmium Laser: Stone Fragmentation Efficiency and Impact on Flexible Ureteroscope Deflection and Flow

INTRODUCTION

The Nanopulse Lithotripter (NPL; Lithotech Medical, Israel) is a novel intracorporeal device that uses a nanosecond duration electrical discharge through a reusable flexible coaxial probe to endoscopically fragment urinary stones. This device was compared with a holmium laser lithotripsy (HoL) with regard to stone fragmentation efficiency (SFE) and its impact on flexible ureteroscope (URS) deflection and flow of irrigation.

METHODS

Using a custom bench model, a 6 mm BegoStone cylindrical phantom (mixture 5:2) was confined under 0.9% saline atop sequential mesh sieves. The SFE of two NPL probe sizes (2.0F, 3.6F) and two HoL fibers (200, 365 μm) was evaluated using concordant settings of 1 J and 5 Hz. URS deflection and irrigation flow with NPL probes in the working channel were tested in five new fourth generation flexible URS and compared with other adjunct endourologic instruments.

RESULTS

The 2.0F NPL showed improved SFE compared with the 200 μm laser (86 mg/min vs 52 mg/min, p = 0.014) as did the 3.6F NPL vs the 365 μm laser (173 mg/min vs 80 mg/min, p = 0.05). The NPL created more 1 to 2 mm fragments; the laser created more dust. URS deflection reduced by 3.75° with the 2.0 NPL probe. URS irrigation flow reduced from 36.5 to 6.3 mL/min with the 2.0F NPL probe.

CONCLUSION

NPL shows improved SFE compared with HoL. Flow with the 2.0F probe is akin to a stone basket. NPL offers an effective alternative to HoL.

Evaluation of dusting versus basketing - can new technologies improve stone-free rates?

Over the past two decades, the management of upper-tract urinary stones has dramatically changed towards an increase in the use of ureteroscopic treatment. This change has been driven by technological advances such as the creation of flexible ureteroscopes with reduced calibre (which now have digital, disposable and dual flexion capability) and holmium lasers with increased power. Two basic principles exist when treating stones ureteroscopically: either creating stone dust and small fragments (<1-2 mm) to theoretically enable spontaneous passage of the small particles or stone fragmentation that enables safe extraction of the stone pieces with a basket or grasper in an efficient manner. Each method has unique advantages and disadvantages, but, ultimately, surgeon preference, stone size, composition, location and intrarenal and/or ureteral anatomy determine which technique is used. To date, clinical trials comparing these two techniques are lacking.

The surgical experience influences the safety of retrograde intrarenal surgery for kidney stones: a propensity score analysis

The aim of this study is to evaluate if surgical experience could influence the outcomes of retrograde intrarenal surgery (RIRS) in terms of stone clearance and complication rate. Patients from five institutions were included in this study. Patients were divided into two groups. Group 1: patients treated by three surgeons in the early phase of learning curve (surgical experience <100 procedures); Group 2: cases operated by two surgeons with great endourological experience (>400 procedures). Patients and stone characteristics, outcome and complications were analyzed. Multivariable regression model was used. Differences between groups were estimated using propensity scores to adjust for the bias inherent to the different characteristics. 381 RIRS were analyzed (Group 1: 150 RIRS; Group 2: 231 RIRS). Clinical data and stone parameters were comparable. The SFR was 70 % in Group 1 and 77.9 % in Group 2 (p = 0.082). Operative time was significantly shorter in the Group 2 (76.3 vs. 53.1 min, p = 0.001). The overall complication rate was significantly lower in Group 2 (20.7 vs. 8.7, p = 0.001). At unadjusted analysis, a non-significant difference was found between centers on SFR (OR 1.51 95 % CI 0.95-2.41). Conversely, a significant difference was found on overall complications (OR 0.36 95 %CI 0.20-0.67) with lower overall complication in Group 2. This study shows that surgeon experience influences the outcomes of RIRS mainly in terms of safety. Further studies will be needed to assess the exact number of procedures necessary to obtain a plateau in the rate of complications and success.

Modified Access Sheath for Continuous Flow Ureteroscopic Lithotripsy: A Preliminary Report of a Novel Concept and Technique

OBJECTIVE

To improve the safety and efficacy of ureteroscopic lithotripsy for the treatment of ureteral stone, we made a simple modification to the standard ureteral access sheath (mUAS) and developed a novel technique to overcome the deficiencies of the current procedure.

MATERIALS AND METHODS

We added an oblique suction-evacuation port with pressure regulating mechanism to the UAS to allow active egress of irrigation fluid and stone fragments. A pressure vent was placed on the egress port. Continuous negative pressure aspiration was connected to the egress port, whereas the continuous irrigation was delivered through the endoscope with a pressure pump. Stone fragmentation was performed using a holmium-YAG laser through a semirigid ureteroscope. Tiny stone fragments were evacuated in the space between the sheath and the scope. When larger fragments came into the sheath that were too large to exit between the scope and the sheath, the scope was withdrawn to just proximal to the bifurcation of the oblique port. This opened up an unimpeded egress channel for the larger fragments. We attempted this procedure in 104 consecutive patients.

RESULTS

Seventy-four patients had effective insertion of mUAS. Seven patients failed semirigid ureteroscopy despite effective placement of mUAS. Patient with effective semirigid ureteroscopic lithotripsy had 100% immediate stone clearance and no observed stone retropulsion. Patients who failed semirigid ureteroscopy were converted to flexible ureteroscopy. Five patients had completed stone clearance. The overall immediate stone-free rate was 97.3% and 100% at 1-month follow-up. Complications included two fevers and one minor ureteral false passage.

CONCLUSIONS

Our modification of UAS has reduced stone retropulsion, improved stone clearance, improved visual field, and probably reduced the intraluminal pressure.

Mini-percutaneous nephrolithotomy with high-power holmium YAG laser in pediatric patients with staghorn and complex calculi

INTRODUCTION

Shock wave lithotripsy (SWL) is the treatment of choice for most cases of renal lithiasis in children. Some cases, however, are refractory to SWL and may be associated with anatomic and metabolic changes or a large stone burden. In these circumstances, mini-percutaneous nephrolithotomy (mini-PCNL) is an option.

OBJECTIVE

The aim was to assess the safety and efficacy of high-power holmium YAG (Ho:YAG) laser in mini-PCNL for staghorn calculi.

PATIENTS AND METHODS

The clinical records relating to 35 mini-PCNLs (Table) performed between January 2008 and December 2012 in 33 patients (27 boys and 6 girls; mean age 7 years, range 2-18 years) were retrospectively reviewed. Twenty-two (66.7%) of the patients had undergone a previous SWL (28.6% three sessions). The mini-PCNL puncture technique used involved fluoroscopic guidance with the C arm at 0-90° in the supine position. An 18F tract was used. Stone fragmentation was performed with a high-power Ho:YAG laser (Lumenis 100 W).

RESULTS

Ten of the mini-PCNLs (28.6%) were right sided, and 25 were left sided (71.4%). Stones were located in the lower calyceal group in 64% of patients and in the renal pelvis in 50%. The mean stone size was 4.46 cm(2) (range 3-13.20 cm(2)). The number of stones varied between one and 20, and 83.3% were radiopaque. The laser was set at 70 W (range 50-100 W) (3.5 J/pulse with a frequency of 20 pulses/s). The mean surgical time was 150 min. In 78% of patients, complete stone clearance was achieved, and the overall stone-free rate rose to 85% when residual stones were treated with either SWL or retrograde intrarenal surgery. No perioperative complications were seen.

DISCUSSION

There are few reports in the literature concerning the use of a high-power laser for treatment of complex stones and the few that do exist relate to adults have similar results, showing it to be highly effective and safe, with low morbidity. Some limitations of the present study must be acknowledged. It was retrospective and a relatively small number of patients were included. However, randomized prospective studies are required to confirm our findings and conclusions.

CONCLUSION

In the pediatric population, mini-PCNL with high-power Ho:YAG laser is feasible and safe and represents the technique of choice for complex renal stones.

Fluoroscopy free flexible ureteroscopy with holmium: Yttrium-aluminium-garnet laser lithotripsy for removal of renal calculi

Objective

To evaluate the feasibility of access sheath insertion and ureteric stent placement without image guidance in flexible ureteroscopic lithotripsy with holmium:yttrium-aluminium-garnet laser for renal stones.

Patients and methods

Between March 2014 and October 2015, 80 patients with renal stones treated with flexible ureteroscopic laser lithotripsy were evaluated. Indications for surgery were renal obstruction, failed shockwave lithotripsy (SWL), stones in polycystic kidneys, and mal-rotated kidneys. A 6.5-F Cobra flexible ureteroscope was used in all cases with an access sheath of 12 F, 35/45 cm in length. Fluoroscopy was not intended for use in all cases and postoperative JJ stenting was optional. The perioperative complications were listed and the collected data were analysed.

Results

The study included 80 patients (66 male, 14 female), with a mean (SD; range) age of 48.2 (8; 28–54) years and a stone burden of 13 (3.5; range 6–23) mm. In all, 26 patients had a stone burden of >15 mm and 48 patients had lower calyceal stones. The mean (SD; range) operative time was 71.5 (20; 25–130) min. Overall, 76 (95%) access sheath insertions were performed successfully without the use of fluoroscopy. JJ stenting was used in 22 patients (27.5%). The mean (SD; range) hospital stay was 10 (8.5; 10–36) h. After one session, a stone-free rate (SFR) of 87.5% was achieved (93.3% for stones of <15 mm). A single session was successful in 87.9% of cases with lower calyceal stones, with a SFR of 91.7% for post-SWL failure cases. The perioperative complication rate was 15%.

Conclusion

Access sheath insertion without fluoroscopic guidance is feasible. This technique reduces radiation exposure in patients requiring flexible ureteroscopy.