Low-power holmium laser for the management of urinary tract calculi, structures, and tumors

Comparison of high and low pulse energy dusting protocols using holmium: YAG laser in flexible ureteroscopy for treatment of renal stones

Objectives

The management of renal stones, particularly those less than 2 cm in diameter, has changed with the development of endourological techniques, among which flexible ureteroscopy (FURS) using laser for lithotripsy has become a cornerstone. This study aims to compare the effectiveness of high pulse energy versus low pulse energy laser settings in renal stone dusting by Holmium YAG laser.

Patients and Methods

This prospective randomized study was conducted between September 2021 and November 2023 to compare the efficacy and safety of high energy versus low-energy pulse settings using a Holmium: YAG laser dusting of renal stones less than 2 cm in diameter. A total of 174 adult patients were included, divided equally into high- and low-pulse energy groups, based on the energy settings of the laser high energy (ranged from 1.2-2.5 Joules and frequency of 8 hz) and low energy (less than 0.5 Joules and frequency ≥ 15 hz) using the dusting ‎technique with non-touch non-stop approach. The study sought to evaluate the impact of these settings on stone fragmentation efficiency, operative time, laser energy consumption, and postoperative outcomes, including stone-free rates and complications.

Results

The study involved 174 patients who underwent renal stone lithotripsy and showed that using high pulse energy laser dusting settings significantly reduced operative times and more rapid dusting compared to low pulse energy settings, without affecting the stone-free rate. The study observed no significant differences in stone size or location between both groups. Minor postoperative complications were similar between both groups, indicating high pulse energy settings for lithotripsy dusting.

Conclusion

The efficacy of high pulse energy dusting in enhancing stone removal during surgery, potentially reducing operative time. Further validation through larger-scale studies is needed to solidify these findings. This technique presents a promising solution, particularly in regions with limited resources where acquiring expensive laser equipment is challenging.

Multicentric evaluation of high and low power lasers on RIRS success using propensity score analysis

In this study, we aimed to evaluate the effect of HPL on different parameters by different centers and urologists. While doing this, we evaluated different parameters by comparing HPL(High Power laser) and LPL(Low-power laser). This is an observational, retrospective, comparative, multicentric study of prospectively organised database. A total of 217 patients who underwent RIRS for kidney stones smaller than 2 cm in three different centers were included in the study. The patients were divided into two groups; LPL used (Group1, n:121 patients) and HPL used (Group2, n:96). Propensity score matching was done in the data analysis part. After matching, a total of 192 patients, 96 patients in both groups, were evaluated. There was no difference between the groups regarding age, gender, stone side, and stone location. The stone-free rate on the first day was 80.3% in Group 1, it was 78.1% in Group 2 (p = 0.9). In the third month, it was 90.7% in Group 1 and 87.5% in Group 2 (p:0.7).Hospitalization duration was significantly higher in Group 1. (2.35 ± 2.27 days vs. 1.42 ± 1.10 days; p < 0.001).The operation duration was 88.70 ± 29.72 min in Group1 and 66.17 ± 41.02 min in Group2 (p < 0.001). The fluoroscopy time (FT) was 90.73 ± 4.79 s in Group 1 and 50.78 ± 5.64 s in Group 2 (p < 0.001). Complications according to Clavien Classification, were similar between the groups(p > 0.05). According to our study similar SFR and complication rates were found with HPL and LPL. In addition, patients who used HPL had lower operation time, hospital stay, and fluoroscopy time than the LPL group. Although high-power lasers are expensive in terms of cost, they affect many parameters and strengthen the hand of urologists thanks to the wide energy and frequency range they offer.

Comparison of Low-Power vs High-Power Holmium lasers in pediatric RIRS outcomes

OBJECTIVES

to compare the outcomes of using low-power (up to 30W) vs high-power (up to 120W) holmium lasers in retrograde intrarenal surgery (RIRS) in children and to analyse if lasering techniques and the use of access sheath have any influence on the outcomes.

METHODS

We retrospectively reviewed data from 9 centres of children who underwent RIRS with holmium laser for the treatment of kidney stones between January 2015 and December 2020. Patients were divided into two groups: high-power and low-power holmium laser. Clinical, perioperative variables and complications were analysed. Outcomes were compared between groups using Student's T-test for continuous variables, and Chi-square and Fisher's exact test for categorical variables. A multivariable logistic regression analysis model was also performed.

RESULTS

314 patients were included. A high-power and low-power holmium laser was used in 97 and 217 patients, respectively. Clinical and demographic variables were comparable between both groups, except for stone size where the low-power group treated larger stones (mean 11.11 mm vs 9.70 mm; p 0.018). In the high-power laser group, a reduction in surgical time was found (mean 64.29 min vs 75.27 min; p 0.018) with a significantly higher stone-free rate (SFR) (mean 81.4% vs 59%; p <0.001). We found no statistical differences in complication rates. The multivariate logistic regression model showed lower SFR in the low-power holmium group, especially with larger (p = 0.011) and multiple stones (p < 0.001).

CONCLUSION

Our real-world pediatric multicenter study favours high-power holmium laser and establishes its safety and efficacy in children.  .

The Feasibility of Pop-Dusting Using High-Power Laser (2 J × 50 Hz) in Retrograde Intrarenal Surgery for Renal Stones: Retrospective Single-Center Experience

Objective: Recently, retrograde intrarenal surgery (RIRS) using laser lithotripsy has become popular. However, the optimal laser energy setting for pop-dusting has not been established. In this study, we report our experiences of RIRS using the high-power (up to 100 W) pop-dusting (HPPD) technique. Methods: This study retrospectively assessed 82 cases with RIRS using HPPD. Patients who underwent abdominal CT or mercaptoacetyltriglycine (MAG3) diuretic renal scan at 3 months postoperatively were included in this study. Patient and stone characteristics and perioperative and postoperative outcomes were evaluated. Results: The average number of renal stones was 3.67 ± 4.11, and the average length of the largest stones was 13.30 ± 6.41 mm. The mean Hounsfield units was 959.99 ± 384.73. The operation time was 58.10 ± 26.67 minutes. The mean HPPD time was 11.93 ± 9.48 minutes, with settings of 1.97 ± 0.25 J and 48.78 ± 3.29 Hz. The stone-free rate was 89%. The mean hospital stay was 1.68 ± 1.29 days. Pelvicaliceal and ureter injuries were observed in 9.8% and 32.9% of the study population, respectively. However, there was no transfusion, subcapsular hematoma, persistent urinary leakage, ureteral or infundibular stricture, or renal functional deterioration. There was transient postoperative fever in 12.2% of the study population. Conclusions: HPPD could be performed safely during RIRS for renal stones without significant complications such as collecting system injury or bleeding. High-power laser mode (up to 100 W) can be a safe and effective choice for pop-dusting during RIRS, especially for large and hard stones.

Minimally invasive management of ureteral strictures: a 5-year retrospective study

Introduction

Ureteric strictures are well-documented complications related to surgery or radiation therapy. Minimally invasive treatment using endoscopic dilatation or laser incision is the standard practice. There are no existing guidelines on which techniques to use in the treatment of different stricture types and a paucity of data regarding long-term results.

Purpose

Our study aimed to retrospectively assess the long-term efficacy of minimally invasive treatment in benign and malignant ureteric strictures.

Materials and methods

Over a 5-year period, 2007–2012, we analyzed the data of 59 consecutive patients undergoing minimally invasive treatment for symptomatic ureteric strictures. We excluded 16 patients from final analysis due to failed access or loss to follow-up. All patients but one were treated with antegrade, retrograde balloon or catheter dilatations. Successful outcome was defined as an asymptomatic, completely catheter free patient, with stable renal function.

Results

43 patients were eligible for retrospective final analysis. The largest proportion of strictures occurred following surgery combined with radiotherapy 8/43 (19%). Preoperative decompression was required in 30/43 (70%). We identified 32/43 (75%) balloon dilatations, 10/43 (23%) catheter dilatations and 1/43 (2%) laser incision. Overall success rate was 31/43 (72%). All 6 recurrences occurred within 36 months, 4 within the first 12 months. 3/6 patients were successfully re-dilated.

Conclusion

Minimally invasive treatment is a worthwhile alternative in strictures due to previous radiation and/or surgical treatment of malignancies. Most recurrences occurred within the first year. However, late recurrences arise; therefore, patients should be subject to long-term follow-up. Moreover, re-dilatation may be required.

[European Association of Urology guidelines on laser technologies]

CONTEXT

The European Association of Urology (EAU) Guidelines Office has set up a guideline working panel to analyse the scientific evidence published in the world literature on lasers in urologic practice.

OBJECTIVE

Review the physical background and physiologic and technical aspects of the use of lasers in urology, as well as current clinical results from these new and evolving technologies, together with recommendations for the application of lasers in urology. The primary objective of this structured presentation of the current evidence base in this area is to assist clinicians in making informed choices regarding the use of lasers in their practice.

EVIDENCE ACQUISITION

Structured literature searches using an expert consultant were designed for each section of this document. Searches were carried out in the Cochrane Database of Systematic Reviews, the Cochrane Central Register of Controlled Trials, and Medline and Embase on the Dialog/DataStar platform. The controlled terminology of the respective databases was used, and both Medical Subject Headings and EMTREE were analysed for relevant entry terms. One Cochrane review was identified.

EVIDENCE SYNTHESIS

Depending on the date of publication, the evidence for different laser treatments is heterogeneous. The available evidence allows treatments to be classified as safe alternatives for the treatment of bladder outlet obstruction in different clinical scenarios, such as refractory urinary retention, anticoagulation, and antiplatelet medication. Laser treatment for bladder cancer should only be used in a clinical trial setting or for patients who are not suitable for conventional treatment due to comorbidities or other complications. For the treatment of urinary stones and retrograde endoureterotomy, lasers provide a standard tool to augment the endourologic procedure.

CONCLUSIONS

In benign prostatic obstruction (BPO), laser vaporisation, resection, or enucleation are alternative treatment options. The standard treatment for BPO remains transurethral resection of the prostate for small to moderate size prostates and open prostatectomy for large prostates. Laser energy is an optimal treatment method for disintegrating urinary stones. The use of lasers to treat bladder tumours and in laparoscopy remains investigational.

EAU guidelines on laser technologies

CONTEXT

The European Association of Urology (EAU) Guidelines Office has set up a guideline working panel to analyse the scientific evidence published in the world literature on lasers in urologic practice.

OBJECTIVE

Review the physical background and physiologic and technical aspects of the use of lasers in urology, as well as current clinical results from these new and evolving technologies, together with recommendations for the application of lasers in urology. The primary objective of this structured presentation of the current evidence base in this area is to assist clinicians in making informed choices regarding the use of lasers in their practice.

EVIDENCE ACQUISITION

Structured literature searches using an expert consultant were designed for each section of this document. Searches were carried out in the Cochrane Database of Systematic Reviews, the Cochrane Central Register of Controlled Trials, and Medline and Embase on the Dialog/DataStar platform. The controlled terminology of the respective databases was used, and both Medical Subject Headings and EMTREE were analysed for relevant entry terms. One Cochrane review was identified.

EVIDENCE SYNTHESIS

Depending on the date of publication, the evidence for different laser treatments is heterogeneous. The available evidence allows treatments to be classified as safe alternatives for the treatment of bladder outlet obstruction in different clinical scenarios, such as refractory urinary retention, anticoagulation, and antiplatelet medication. Laser treatment for bladder cancer should only be used in a clinical trial setting or for patients who are not suitable for conventional treatment due to comorbidities or other complications. For the treatment of urinary stones and retrograde endoureterotomy, lasers provide a standard tool to augment the endourologic procedure.

CONCLUSIONS

In benign prostatic obstruction (BPO), laser vaporisation, resection, or enucleation are alternative treatment options. The standard treatment for BPO remains transurethral resection of the prostate for small to moderate size prostates and open prostatectomy for large prostates. Laser energy is an optimal treatment method for disintegrating urinary stones. The use of lasers to treat bladder tumours and in laparoscopy remains investigational.

[Quantong Recipe integrated with ureteroscopic laser lithotripsy for ureteral calculi]

BACKGROUND

Endoscopic surgery of Western medicine has developed rapidly in treating ureteral calculi while traditional Chinese medicine (TCM) therapy also has its advantage, thus the integrated traditional Chinese and Western medicine therapy may have an even better efficacy in dealing with this problem.

OBJECTIVE

To observe the clinical effects of sequential therapy of Quantong Recipe, a compound traditional Chinese herbal medicine, combined with ureteroscopic laser lithotripsy on ureteral calculi.

DESIGN, SETTING, PARTICIPANTS AND INTERVENTIONS

A total of 151 patients with ureteral calculi (stone diameter of 3 to 21 mm) from Department of Urology, Yueyang Hospital of Integrated Traditional Chinese and Western Medicine, Shanghai University of Traditional Chinese Medicine were included, of which 106 patients with stone diameter of 3 to 10 mm were treated with Quantong Recipe for the first two weeks. Twenty patients with unexpelled stones and 45 patients with stone diameter of more than 10 mm were treated with ureteroscopic laser lithotripsy. The 65 patients except one open operation were divided into regular treatment group (32 cases) and regular treatment combined with Quantong Recipe group (32 cases) after lithotripsy. The efficacy was assessed after one week.

MAIN OUTCOME MEASURES

Cure rate in the patients with stone diameter of less than 10 mm after two-week Quantong Recipe treatment was calculated, and clearance rate in the patients with residual stone for ureteroscopic laser lithotripsy after one-week Quantong Recipe treatment was also observed.

RESULTS

After taking Quantong Recipe for two weeks, the stones in 86 patients were completely discharged, and the stones in 6 patients were not completely discharged, but the unexpelled stones had moved down more than one segment of ureteral stenosis; the total response rate was 86.79% (92/106). The 64 patients with stones unexpelled or with stone diameter of more than 10 mm were treated with ureteroscopic laser lithotripsy, and the clearance rate of residual stone was 93.8% in regular treatment combined with Quantong Recipe group, and was 71.9% in regular treatment group, and there was a significant difference between the two groups (P<0.05).

CONCLUSION

Sequential therapy of Quantong Recipe integrated with ureteroscopic laser lithotripsy demonstrates a significant advantage of integrated traditional Chinese and Western medicine therapy in treating ureteral calculi.

Percutaneous nephroscopic with holmium laser and ultrasound lithotripsy for complicated renal calculi

The aim of this work is to validate the clinical efficacy of the high-power holmium:YAG laser with percutaneous nephrolithotripsy (PCNL) in combination with ultrasound lithotripsy for complicated renal calculi. From November 2006 to December 2007, 60 patients with complicated renal calculi were treated with PCNL, where an F24 standard renal access tract was established by percutaneous renal puncture under the guidance of B-mode ultrasound, and stones were fragmented and cleared by high-power holmium laser in combination with ultrasound under an F20.8 nephroscope. Of the 60 patients with complicated renal calculi, 20 were complete staghorn calculi and 30 were partial staghorn calculi, of which six patients were accompanied with renal insufficiency; two were solitary calculi, and eight were caliceal diverticular calculi. Calculi were removed by one attempt in 49 patients and by two attempts in 11 patients; through one tract in 50 patients and through two and three tracts in ten patients. The stone-free rate was 81.7%. No injury to the pleura and abdominal organs occurred during the intraoperative puncture. No postoperative blood transfusion was needed in any patient, nor did fever and secondary hemorrhage occur. The mean operation duration was 98 min (range, 60-150 min), and the mean lithotripsy time was 45 min (range, 30-85 min). Additional postoperative extracorporeal shock wave lithotripsy (ESWL) was performed on six patients. High-power holmium laser PCNL in combination with ultrasound lithotripsy is safe, effective, and minimally invasive, with a high stone-free rate, especially for complicated renal calculi.

Success of laser endoureterotomy of ureteral strictures associated with ureteral stones is related to stone impaction

PURPOSE

Since the holmium:yttrium-aluminum-garnet (Ho:YAG) laser is the flexible lithotrite of choice for ureteral stones, its application to ureteral strictures associated with ureteral calculi is convenient. The results of Ho:YAG laser endoureterotomy in this specific setting have not been defined. We report our experience with Ho:YAG laser endoureterotomy of ureteral strictures associated with ureteral stone treatment, with or without a history of stone impaction.

METHODS

We reviewed the medical records of 13 patients with ureteral stricture related to stone treatment, with (n = 9) or without (n = 4) a history of impacted ureteral stones, who were managed with Ho:YAG laser endoureterotomy. Follow-up was obtained with radiographic imaging and renal scans.

RESULTS

The overall success rate was 62%, with a mean follow-up of 21 months in successful cases and a mean recurrence time of 1.6 months in failures. Outcome was not associated with length or location of the stricture. Among the nine strictures associated with impacted stones, treatment was successful in only 5 (56%). Of the four strictures that occurred after stone removal but without history of impaction, the success rate was 75%. Success was also greater for strictures managed with post-procedure stents >or=8 Fr (75%), compared to stents <or=7 Fr. (56%).

CONCLUSIONS

Our results suggest that laser endoureterotomy of ureteral strictures due to ureteral stone treatment without a history of impaction is associated with a reasonable success rate (75%), but that laser endoureterotomy for strictures related to impacted stones is associated with a success rate of only 56%. Larger caliber stents might be preferred in this setting.

The future of lasers in urology

The use of laser applications in urology has undergone significant advances over the past 20 years. Laser technology is now used in a wide variety of procedures, and has become the primary treatment modality or standard of care for many urologic conditions. Despite these advances, a number of challenges still face laser utilization in urologic practice. Recent work has illuminated the potential improvement and further optimization of this field. Improvements in types of lasers, the wavelength of energy used, optical fiber delivery systems, precision of laser application and cost reduction have served to further improve laser technology and extend the potential applications.

Holmium laser for stone management

The efficiency and safety profile of the holmium laser has made this tool a versatile multi-purpose instrument for use in the endoscopic treatment of a wide variety of urologic disorders, in particular urinary calculi. Herein we review holmium laser physics, current endourologic laser lithotripsy applications, and the performance of new low power holmium laser devices.

High-power holmium:yttrium-aluminum-garnet laser for percutaneous treatment of large renal stones

OBJECTIVES

To assess the efficacy and safety of high-power holmium-yttrium-aluminum-garnet (YAG) laser lithotripsy for percutaneous nephrolithotomy in patients with large renal stones.

METHODS

We retrospectively reviewed the charts of 87 patients who underwent 91 percutaneous nephrolithotomy procedures at our hospital from April 2004 to June 2005, during which a holmium-YAG laser with a self-made fiber guider was used for lithotripsy. Of the 91 procedures, 51 were performed with the maximal power output set at 3.0 J in patients with a renal stone size of 3 cm or larger (group 1). The other 40 procedures were performed with the maximal power set at 2.0 J in patients with a renal stone size of less than 3 cm or with ureteral stones (group 2).

RESULTS

The average stone size was 5.4 cm in group 1, and the stone-free rate was 61.4% after a single procedure. The average operation time was 108 minutes in group 1 and 93 minutes in group 2. The average postoperative hospital stay was 5.7 days in group 1 and 5.9 days in group 2. Two patients in group 1 and one in group 2 required blood transfusions after the procedure. Seven patients (13.7%) in group 1 and two (5.0%) in group 2 experienced a urinary tract infection after the procedure. No statistically significant difference in procedure time, postoperative hospital stay, blood transfusion rate, or postoperative urinary tract infection rate was found between the two groups.

CONCLUSIONS

The results of our study have shown that using a high-power holmium-YAG laser is safe and effective in the treatment of large renal stones.

Urinary calculus fragmentation during Ho: YAG and Er:YAG lithotripsy

BACKGROUND AND OBJECTIVES

We tested Ho:YAG and Er:YAG laser ablation of human urinary calculi to determine if Er:YAG is a more efficient lithotripsy device.

STUDY DESIGN/MATERIALS AND METHODS

Ablation efficiency of Ho:YAG and Er:YAG lasers was tested at varying energy settings, ranging from the damage threshold to clinical energy setting associated with Ho:YAG laser. Stones of known composition (calcium oxalate monohydrate (COM), cystine, and uric acid (UA)) were irradiated. Crater width, depth, and ablation volumes were determined using an optical coherence tomography (OCT).

RESULTS

For all stones and energy settings, the Er:YAG laser produced deeper craters and larger ablation volumes than Ho:YAG laser. The Ho:YAG laser created wider craters during the multiple pulse process and the shape of craters was irregular.

CONCLUSIONS

The Er:YAG laser is more efficient than the Ho:YAG laser for lithotripsy. The deeper craters produced by the Er:YAG laser is attributed to the high absorption of energy at its wavelength.

High-power laser vaporization of the canine prostate using a 110 W Thulium fiber laser at 1.91 microm

INTRODUCTION

The Thulium fiber laser may have several advantages over current urology lasers, including smaller size, more efficient operation, improved spatial beam quality, more precise tissue incision, and operation in pulsed or continuous-wave modes. Previous laser-tissue interaction studies utilizing the Thulium fiber laser have been limited to laser powers of less than 5 W, restricting potential medical applications. This study describes the preliminary testing of a high-power Thulium fiber laser for vaporization of the canine prostate, ex vivo.

STUDY DESIGN/MATERIALS AND METHODS

A continuous-wave, 110-W Thulium fiber laser operating at a wavelength of 1.91 microm, delivered 88.5+/-2.3 W of power through a 600-microm-core silica fiber for non-contact vaporization of canine prostates (n = 6).

RESULTS

The Thulium fiber laser vaporized prostate tissue at a rate of 0.83+/-0.11 g/minute. The thermal coagulation zone measured 500-2,000 microm, demonstrating the potential for hemostasis.

CONCLUSIONS

The high-power Thulium fiber laser is capable of rapid vaporization and coagulation of the prostate. In vivo animal studies are currently being planned for evaluation of the Thulium fiber laser for potential treatment of benign prostate hyperplasia (BPH).

Percutaneous nephrolithotomy with holmium: Yttrium-aluminum-garnet laser and fiber guider—report of 349 cases

OBJECTIVES

To assess the efficacy and safety of holmium:yttrium-aluminum-garnet (YAG) laser lithotripsy for percutaneous nephrolithotomy in a cohort of 349 consecutive procedures.

METHODS

We retrospectively reviewed the charts of 334 patients who had undergone 349 percutaneous nephrolithotomy (PCNL) procedures conducted at our hospital from January 2001 to March 2004 in which the holmium:YAG laser with a self-made fiber guider was used for lithotripsy.

RESULTS

The average patient age was 54.1 years, and the average stone size was 3.3 +/- 1.8 cm. The average operative time was 99 +/- 38 minutes, and the average postoperative hospital stay was 4.0 +/- 2.3 days. The overall stone-free rate was 83.7%. The postoperative urinary tract infection rate was 7.2%. The postoperative transfusion rate was 2.0%. The holmium:YAG laser was effective against all kinds of stones, but sometimes it was time consuming to use the holmium:YAG laser to disintegrate a very large stone. Thirteen PCNLs (3.7%) to treat large complete staghorn stones were performed in combination with a pneumatic lithotriptor. Of the 349 procedures, 152 (43.6%) had bloodless tracts afterward, and all 152 procedures had been performed with the nephrostomy tube-free modification.

CONCLUSIONS

The holmium:YAG laser is an effective and safe lithotriptor for most percutaneous stone surgery. However, in patients with a very large stone burden, the combination of this technology with another, more powerful, intracorporeal lithotriptor may be necessary.

Thulium fiber laser lithotripsy: An in vitro analysis of stone fragmentation using a modulated 110-watt Thulium fiber laser at 1.94 µm

BACKGROUND AND OBJECTIVES

The high-power Thulium fiber laser has previously been shown to rapidly vaporize and coagulate soft urinary tissues (e.g., prostate). This is the first preliminary study of a high-power Thulium fiber laser for fragmentation of urinary stones.

STUDY DESIGN/MATERIALS AND METHODS

A continuous-wave, high-power Thulium fiber laser operating at a wavelength of 1.94 microm, was modulated to operate in pulsed mode with an output pulse energy of 1 J through a 300-microm-core silica fiber at a 20 milliseconds pulse length and repetition rate of 10 Hz. The fragmentation time to reduce uric acid (UA) (n = 13) and calcium oxalate monohydrate (COM) (n = 6) stones into particles < 2 mm was measured.

RESULTS

Mean initial mass of the UA and COM stones measured 860+/-211 and 763 +/- 204 mg. Fragmentation rates measured 388 +/- 49 and 25 +/- 2 mg/minute. Average time needed to fragment the UA and COM stones into particles < 2 mm was 2.25 +/- 0.63 and 30.7 +/- 8.4 minutes, respectively.

CONCLUSIONS

The high-power Thulium fiber laser, when operated in pulsed mode, is capable of fragmenting both soft (UA) and hard (COM) urinary stones. The Thulium fiber laser may be useful as a single laser system for use in multiple soft and hard tissue laser ablation applications in urology.

Use of the holmium:YAG laser for ureterolithotripsy in children

OBJECTIVE

To review our experience with rigid ureteroscopy and holmium:YAG laser for treating ureteric calculi in children.

PATIENTS AND METHODS

The study included 35 children who were treated with rigid ureteroscopy for ureteric calculi between November 1997 and June 2003 (15 boys and 20 girls; mean age 6.2 years, range 1-14). The mean (range) stone size was 8 (4-15) mm and the duration of anaesthesia 46.6 (15-90) min. The stone was in the distal third of the ureter in 33 children and in the proximal third in two. We used a 7.5/8/10 F rigid ureteroscopes with routine dilatation of the ureteric orifice. For lower ureteric stones, lithotripsy was carried out with holmium:YAG laser in 29 cases, a pneumatic impactor in two and forceps extraction in two. Both stones in the proximal ureter were pushed back into the collecting system. All the ureters were stented using JJ stents in 31 and ureteric catheters in four cases. The mean postoperative follow-up was 12 (2-30) months.

RESULTS

Excluding the two stones pushed back, the stone-free rate after a one-stage procedure was 82% (27/33). With repeated procedures in the six (ESWL in two) remaining cases the success rate was 97% (32/33). The ureter was perforated in two patients within the first five in the series. There was no pyelonephritis or gross haematuria after surgery.

CONCLUSION

Ureteroscopy and lithotripsy using the holmium:YAG laser is effective and safe for treating ureteric stones in children, in experienced hands. The results would be even better using smaller and flexible ureteroscopes.

Optimization of the Erbium:YAG laser for precise incision of ureteral and urethral tissues: in vitro and in vivo results

BACKGROUND AND OBJECTIVES

Tissue damage during endoscopic treatment of urethral and ureteral strictures may result in stricture recurrence. The Erbium:YAG laser ablates soft tissues with minimal peripheral damage and may be a promising alternative to cold knife and Holmium:YAG laser for precise incision of urological strictures.

STUDY DESIGN/MATERIALS AND METHODS

Optimization of the Er:YAG laser was conducted using ex vivo porcine ureteral and canine urethral tissues. Preliminary in vivo studies were also performed in a laparoscopic porcine ureteral model with exposed ureter. Laser radiation with a wavelength of 2.94 microm, pulse lengths of 8, 70, and 220 microseconds, output energies of 2-35 mJ, fluences of 1-25 J/cm2, and pulse repetition rates of 5-30 Hz, was delivered through 250-microm and 425-microm core germanium oxide optical fibers in direct contact with tissue.

RESULTS

Ex vivo perforation thresholds measured 2-4 J/cm2, with ablation rates of 50 microm/pulse at fluences of 6-11 J/cm2. In vivo perforation thresholds were approximately 1.8 J/cm2, with the ureter perforated in less than 20 pulses at fluences greater than 3.6 J/cm2. Peripheral thermal damage in tissue decreased from 30 to 60 microm to 10-20 microm as the laser pulse length decreased from 220 to 8 microseconds. Mechanical tissue damage was observed at the 8 microseconds pulse duration.

CONCLUSIONS

The Er:YAG laser, operating at a pulse duration of approximately 70 microseconds, a fluence greater than approximately 4 J/cm2, and a repetition rate less than 20 Hz, is capable of rapidly incising urethral and ureteral tissues with minimal thermal and mechanical side-effects.

Assessment of stricture formation with the ureteral access sheath

OBJECTIVES

To analyze the long-term incidence of ureteral stricture formation in a series of patients in whom a new-generation ureteral access sheath was used. A new generation of ureteral access sheaths has been developed to facilitate ureteroscopic procedures. However, some have questioned their safety and whether the device might cause significant ureteral trauma.

METHODS

Between September 1999 and July 2001, 150 consecutive ureteroscopic procedures with adjunctive use of an access sheath were performed. A retrospective chart review to April 2002 was done. Of the 150 patients, 130 underwent ureteroscopy for ureteral stones. Patients who underwent endoureterotomy or treatment of transitional cell carcinoma were excluded from this analysis. Sixty-two patients had follow-up greater than 3 months and were included in the analysis. Overall, 71 ureteroscopic procedures were performed, with 9 patients undergoing multiple procedures. Ninety-two percent of the patients had pathologic findings above the iliac vessels. The average patient age was 45.3 years (range 17 to 76), and 70% and 30% of the patients were male and female, respectively. The mean clinical follow-up was 332 days (range 95 to 821), and follow-up imaging was performed within 3 months after ureteroscopy in all patients.

RESULTS

The 10/12F access sheath was used in 8 ureteroscopic procedures (11.2%), the 12/14F access sheath in 56 (78.9%), and the 14/16F access sheath in 7 (9.8%). One stricture was identified on follow-up imaging of 71 procedures performed, for an incidence of 1.4%. The patient developed the stricture at the ureteropelvic junction after multiple ureteroscopic procedures to manage recurrent struvite calculi. The access sheath did not appear to be a contributing factor.

CONCLUSIONS

The results of our series indicate that the ureteral access sheath is safe and beneficial for routine use to facilitate flexible ureteroscopy. However, awareness of the potential ischemic effects with the use of unnecessarily large sheaths for long periods in patients at risk of ischemic injury should be considered. We advocate the routine use of the device for most flexible ureteroscopic procedures proximal to the iliac vessels.

Surgical management of urolithiasis

The surgical management of urinary calculus disease has changed dramatically in the past two decades. Minimally invasive options have made open stone surgery nearly obsolete. The development of shock wave lithotripsy, percutaneous nephrostolithotomy techniques and intracorporeal lithotripsy devices has conferred unprecedented management tools for upper tract stones. Moreover, transfusion rates, hospital costs, and convalescence periods have been markedly reduced when compared to open surgery. Likewise, the advent of fiberoptic technology has resulted in miniaturization of ureteroscopes making access to the entire collecting system possible from either a retrograde or antegrade approach. With experience, successful stone retrieval has occurred in upwards of 90% of cases, again with minimal complications. The subspecialty of Endourology has emerged over the past 20 years and significantly changed the management of urinary tract calculi within this short period of time. Further advancements in shock wave and laser technology, training modules and the development of more durable endoscopes may prove beneficial in providing even better stone treatments with a reduction in morbidity.

Laser lithotripsy

PURPOSE OF REVIEW

All literature related to laser lithotripsy published within the past year was reviewed. Salient articles have been reviewed and grouped according to safety issues, efficacy, comparison studies, biliary applications or future directions.

RECENT FINDINGS

There is no evidence of renal deterioration after holmium:yttrium-aluminium-garnet lithotripsy. Laser-related complications occur in less than 1%. Stone-free rates from holmium:yttrium-aluminium-garnet lithotripsy are greater than 90% for ureteral calculi, and 67-84% for renal calculi. This method of lithotripsy is effective for ureteral and renal calculi in morbidly obese patients who are not suitable candidates for shock-wave lithotripsy or percutaneous nephrolithotomy. Holmium:yttrium-aluminium-garnet lithotripsy is more effective than pneumatic lithotripsy for ureteral calculi, but no more effective than shock-wave lithotripsy (Dornier HM-3) for distal ureteral calculi. Holmium:yttrium-aluminium-garnet lithotripsy of biliary calculi is uniformly effective. Preliminary data showed the erbium:yttrium-aluminium-garnet laser to be more efficient than holmium:yttrium-aluminium-garnet energy, but current erbium:yttrium-aluminium-garnet fibers are impractical.

SUMMARY

The holmium:yttrium-aluminium-garnet laser is safe and effective. It is the lithotrite of choice for endoscopic ureteral and ureterorenoscopic lithotripsy.