An update on ureteroscopic instrumentation for the treatment of urolithiasis

Ureteral inflammatory edema grading clinical application

Purpose

To evaluate the relationship between endoscopic ureteral inflammatory edema (UIE) and ureteral lumen, formulate a preliminary grading method for the severity of UIE, and analyze the impact of different grades of UIE on endoscopic ureteral calculi surgery and prognosis.

Materials and methods

We retrospectively analyzed 185 patients who underwent ureteroscopic lithotripsy (URSL) for upper urinary tract stones between January 2021 and November 2021. The UIE grade and lumen conditions were assessed by endoscopic observation. The effect of UIE grade on URSL and on patient prognosis were analyzed by multiple linear regression and binary logistic regression.

Results

A total of 185 patients were included in the study. UIE grade showed a significant correlation with age, hydronephrosis grading (HG), ureteroscope placement time (UPT), surgery time (ST), hemoglobin disparity value (HDV), and postoperative ureteral stenosis (PUS) (P < 0.05). Logistics regression analysis showed a gradual increase in intraoperative UPT and ST with increase in UIE grade. The severity of UIE showed a negative correlation with improvement of postoperative hydronephrosis (IPH) and the appearance of PUS. HDV was significantly increased in patients with UIE grade 3.

Conclusions

UIE grading can be used as an adjunctive clinical guide for endoscopic treatment of upper urinary tract stones. The postoperative management measures proposed in this study can help inform treatment strategy for ureteral stones.

Sheathed flexible retrograde intrarenal surgery without safety guide wire for upper urinary tract stones

OBJECTIVES

To assess the success rate and intraoperative complications of flexible ureterorenoscopy (f-URS) in patients with upper urinary tract (UUT) stones using a ureteral access sheath (UAS) without a safety guide wire (SGW).

PATIENTS AND METHODS

Between April 2010 and March 2022, 464 renal units in patients with renal stones with and without concomitant ureteral stones (UUT), underwent ureterorenoscopy by one surgeon, and UAS was used in all of them. The primary endpoint was the stone-free rate (SFR). SFR was defined as no residual fragments at all. The following characteristics were examined: age, sex, laterality, renal/ureteral stones, stone diameter, SFR, Hounsfield unit, auxiliary procedures, double-J stent insertion, and intraoperative complications. This study was retrospective, with all the data recorded prospectively. Patients with residual stones were scheduled for the 2nd RIRS. The Clavien-Dindo classification was used to report complications.

RESULTS

The mean patient age was 52.9 years. The mean stone size was 13.1 mm. Lower pole, upper and middle calyces, renal pelvis and ureteral stones were found in 51.5% (239), 34.9% (162), 18.3% (85) and 46.9% (218) of cases, respectively. The mean diameter was 8.1 mm, 8 mm, 12.5 mm and 8.1 mm for the lower pole, upper and middle calyces, renal pelvis and ureteral stones, respectively. The single- and second-session SFRs were 90% and 100%, respectively. The mean number of procedures per renal unit was 1.1. Ureteral double-J stents were inserted in 45.7% (212) of patients. In 96 cases, a stent was placed before surgery. Postoperative complications were minor, with no avulsion or perforation of the ureters; readmission and insertion of a DJ stent occurred in one patient. Ureteral stricture developed in one patient (0.2%) and needed treatment with laser ureterotomy.

CONCLUSIONS

f-URS is a safe and effective mode of surgical management of renal and simultaneous renal and ureteral calculi using the ureteral access sheath without a safety guide wire. A guide wire should not be routinely used in these cases.

Efficiency and Clinical Outcomes of Moses Technology with Flexible Ureteroscopic Laser Lithotripsy for Treatment of Renal Calculus

OBJECTIVE

The aim of the study was to compare the efficiency and clinical outcomes of Moses contact mode (MCM) and regular dusting mode (RDM) during flexible ureteroscopic lithotripsy (FURL) for treatment of renal calculus.

METHODS

This retrospective analysis examined 216 patients with renal calculus who underwent FURL with MCM or RDM between March 2015 and January 2020. Stone characteristics, including size, volume, and density, were collected. Laser parameters, including laser type, laser working time, laser pause time, and foot-pedal use, were automatically recorded by the lithotripter work panel. The percentages of laser working time and laser pause time, stone fragmentation efficiency (SFE; volume/laser working time), postoperative complications, including fever and acute renal failure (ARF), stone-free rate (SFR), and the need for auxiliary procedures were determined.

RESULTS

There were no significant differences in preoperative demographic and stone characteristics between the MCM group and the RDM group. The MCM group had a shorter laser working time (4.99 ± 1.06 vs. 5.94 ± 0.96 min, p < 0.001) and a greater SFE (137.86 [163.78-114.38] versus 114.94 [132.06-101.34] mm3/min, p < 0.001), which shortened the overall operative time (18.39 ± 5.13 vs. 21.17 ± 6.78 min, p = 0.001). There were no differences in postoperative complications, including fever and ARF, SFR (86.8 vs. 85.3%, p = 0.743), and auxiliary procedures between the 2 groups.

CONCLUSIONS

Using Moses laser technology with FURL significantly reduced laser working time and increased SFE, which shortened overall operative time. Urologists should consider this new instrument for the clinical management of renal calculus.

Risk factors for ureteroscopic lithotripsy: a case-control study and analysis of 385 cases of holmium laser ureterolithotripsy

Introduction

Ureteroscopic lithotripsy has become the first choice for the treatment of middle and lower ureteral stones, but it still has a certain rate of surgical failure. Here we aimed to determine the factors that may affect the success rate of holmium laser ureterolithotripsy (HLU) and provide the basis and guidance for its future use.

Aim

To evaluate the risk factors for HLU failure.

Material and methods

The clinical data of 385 patients undergoing holmium laser ureterolithotripsy from 2009 to 2012 were retrospectively reviewed to analyze the impact of gender, age, stone side, stone size, stone location, stone number, degree of hydronephrosis, stone impaction, previous extracorporeal shock lithotripsy (ESWL), and associated urinary tract infection (UTI) on the success or failure of surgery.

Results

Surgical success was achieved in 338 (87.8%) patients versus surgical failure in 47 (12.2%) patients. Univariate analysis revealed that the degree of hydronephrosis (p = 0.024), stone impaction (p = 0.003), stone location (p = 0.012), and previous ESWL (p = 0.037) were risk factors for surgical failure. Multivariate logistic regression revealed that stone impaction (odds ratio (OR) = 2.66; p = 0.018) and stone location (OR = 2.11; p = 0.013) were significantly associated with surgical failure. Since some cases of ureterostenosis developed postoperatively, we continued follow-up. The patients had the stent for a year and underwent regular follow-up checks until 5 years. No cases of ureterostenosis recurred.

Conclusions

Ureteroscopic lithotripsy is a safe procedure with few complications. Stone impaction and proximal location are the risk factors for its failure.

Is a safety guidewire needed for retrograde ureteroscopy?

INTRODUCTION

It is generally advised to have a safety guidewire (SGW) present during ureteroscopy (URS) to manage possible complications. However, it increases the strenght needed to insert and retract the endoscope during the procedure, and, currently, there is a lack of solid data supporting the need for SGW in all procedures. We reviewed the literature about SGW utilization during URS.

METHOD

A review of the literature was conducted through April 2017 using PubMed, Ovid, and The Cochrane Library databases to identify relevant studies. The primary outcome was to report stone-free rates, feasibility, contraindications to and complications of performing intrarenal retrograde flexible and semi-rigid URS without the use of a SGW.

RESULTS

Six studies were identified and selected for this review, and overall they included 1,886 patients where either semi-rigid or flexible URS was performed without the use of a SGW for the treatment of urinary calculi disease. Only one study reported stone-free rates with or without SGW at 77.1 and 85.9%, respectively (p=0.001). None of the studies showed increased rates of complications in the absence of SGW and one of them showed more post-endoscopic ureteral stenosis whenever SGW was routinely used. All studies recommended utilization of SGW in complicated cases, such as ureteral stones associated with significant edema, ureteral stricture, abnormal anatomy or difficult visualization.

CONCLUSION

Our review showed a lack of relevant data supporting the use of SGW during retrograde URS. A well-designed prospective randomized trial is in order.

Clinical factors associated with postoperative hydronephrosis after ureteroscopic lithotripsy

Purpose

This study aimed to determine the predictors of ipsilateral hydronephrosis after ureteroscopic lithotripsy for ureteral calculi.

Materials and Methods

From January 2010 to December 2014, a total of 204 patients with ureteral calculi who underwent ureteroscopic lithotripsy were reviewed. Patients with lack of clinical data, presence of ureteral rupture, and who underwent simultaneous percutaneous nephrolithotomy (PNL) were excluded. Postoperative hydronephrosis was determined via computed tomographic scan or renal ultrasonography, at 6 months after ureteroscopic lithotripsy. Multivariable analysis was performed to determine clinical factors associated with ipsilateral hydronephrosis.

Results

A total of 137 patients were enrolled in this study. The mean age of the patients was 58.8±14.2 years and the mean stone size was 10.0±4.6 mm. The stone-free rate was 85.4%. Overall, 44 of the 137 patients (32.1%) had postoperative hydronephrosis. Significant differences between the hydronephrosis and nonhydronephrosis groups were noted in terms of stone location, preoperative hydronephrosis, impacted stone, operation time, and ureteral stent duration (all, p<0.05). On multivariable analysis, increasing preoperative diameter of the hydronephrotic kidney (adjusted odds ratio [OR], 1.21; 95% confidence interval [CI], 1.12–1.31; p=0.001) and impacted stone (adjusted OR, 3.01; 95% CI, 1.15–7.61; p=0.031) independently predicted the occurrence of postoperative hydronpehrosis.

Conclusions

Large preoperative diameter of the hydronephrotic kidney and presence of impacted stones were associated with hydronephrosis after ureteroscopic stone removal. Therefore, patients with these predictive factors undergo more intensive imaging follow-up in order to prevent renal deterioration due to postoperative hydronephrosis.

EAU Guidelines on Interventional Treatment for Urolithiasis

CONTEXT

Management of urinary stones is a major issue for most urologists. Treatment modalities are minimally invasive and include extracorporeal shockwave lithotripsy (SWL), ureteroscopy (URS), and percutaneous nephrolithotomy (PNL). Technological advances and changing treatment patterns have had an impact on current treatment recommendations, which have clearly shifted towards endourologic procedures. These guidelines describe recent recommendations on treatment indications and the choice of modality for ureteral and renal calculi.

OBJECTIVE

To evaluate the optimal measures for treatment of urinary stone disease.

EVIDENCE ACQUISITION

Several databases were searched to identify studies on interventional treatment of urolithiasis, with special attention to the level of evidence.

EVIDENCE SYNTHESIS

Treatment decisions are made individually according to stone size, location, and (if known) composition, as well as patient preference and local expertise. Treatment recommendations have shifted to endourologic procedures such as URS and PNL, and SWL has lost its place as the first-line modality for many indications despite its proven efficacy. Open and laparoscopic techniques are restricted to limited indications. Best clinical practice standards have been established for all treatments, making all options minimally invasive with low complication rates.

CONCLUSION

Active treatment of urolithiasis is currently a minimally invasive intervention, with preference for endourologic techniques.

PATIENT SUMMARY

For active removal of stones from the kidney or ureter, technological advances have made it possible to use less invasive surgical techniques. These interventions are safe and are generally associated with shorter recovery times and less discomfort for the patient.

Management of lower ureteric stones: a prospective study

Objective

To discuss the current concepts in lower ureteric stone management.

Material and methods

Between October 2008 and November 2010, 190 patients of both sexes and of different age groups with lower ureteric stones, underwent in situ extracorporeal shock wave lithotripsy (ESWL) (48 cases), ureterorenoscopy (URS) (120 cases) and open stone surgery (OSS) (22 cases).

The patients’ clinical and radiological findings, as well as stone characteristics, were reviewed and correlated with the stone–free status.

Results

In the ESWL group, the operative time was 43.13 +22.5 min; the average number of sessions/patients was 1.5 sessions; the average number of SW/patients was 4500 SW/patients; the average energy was 16.5 kV; the average stone burden was 7.8/mm; the overall stone–free rate was 75% (36/48); and the average radiation exposure time was 3.5 min.

In the URS group, the operative time was 49.21 +16.09 min; the average stone burden was 10.81mm; the overall stone–free rate was 97.5% (117/120); the average hospital stay was 3.99 days; and the average radiation exposure time was 0.75 min.

In the OSS group, the operative time was 112.38 +37.1 min; the overall stone–free rate was 100% (22/22); and the average hospital stay was 9.74 days.

Conclusion

In the management of patients with lower ureteral stones, URS, SWL and OSS were considered acceptable treatment options.

This recommendation was based on the stone–free results, morbidity and retreatment rates for each therapy.

Ureteroscopy with and without safety guide wire: should the safety wire still be mandatory?

BACKGROUND AND PURPOSE

Although the evidence is sparse, most urologists advise the insertion of a safety guide wire (SGW) alongside the ureteroscope whenever performing ureteroscopy (URS). The aim of the study was to compare the results of ureteroscopic treatment for ureteral stones at the Oslo University Hospital (OUH), where the SGW is routinely used, with the results at the Haukeland University Hospital (HUH), where the SGW is routinely omitted. The primary goal was to evaluate the success rates of passing the ureteroscope through the orifice, the ability to access the ureteral stone, and the ability to place a ureteral stent when needed after the endoscopy. The secondary goals were to compare the perioperative complication rates and stone-free rates at the two hospitals.

MATERIALS AND METHODS

A retrospective review of 500 URS for ureteral calculi at each of the two hospitals, during 2004-2010, was performed. Relevant data were extracted from the medical records. The exact chi-squared, Mann-Whitney U, and independent-samples t-tests were used comparing the results at the two hospitals.

RESULTS

An SGW was used in 480 (96.2%) of the URS procedures at OUH and in 7 (1.4%) at HUH. No significant differences were found between the two hospitals in the success rates of passing the ureteroscope through the orifice, in the ability to access the ureteral calculus, or in the ability to place a ureteral stent when needed after the endoscopy. There were no significant differences in the number of intraoperative complications, but postendoscopic ureteral stenosis occurred more often at OUH (3.4%) than at HUH (1.2%), p=0.039. The overall stone-free rate was higher at HUH (85.9%) compared to OUH (77.1%), p=0.001.

CONCLUSION

No superior results were found at the hospital with the routine use of an SGW. It may be questioned if the SGW still should be considered mandatory.

A safety guidewire influences the pushing and pulling forces needed to move the ureteroscope in the ureter: a clinical randomized, crossover study

BACKGROUND AND PURPOSE

It is generally advised to keep a safety guidewire (SGW) in the ureter alongside the ureteroscope during endoscopy of the upper urinary tract, but little is known of how the SGW influences the forces exerted on the ureteroscope in the ureter. The purpose of this study was to investigate whether the presence of an SGW during ureteroscopy (URS) in a normal clinical setting will influence the pushing and pulling forces exerted on a semirigid ureteroscope.

PATIENTS AND METHODS

In a 1-year period (2010-2011), 40 patients admitted to Haukeland University Hospital for endoscopic treatment of renal pelvic stone disease were included in a clinical randomized crossover trial measuring the forces needed to move a semirigid ureteroscope during URS. A digital force meter was connected to the ureteroscope to perform the force measurements. The pushing and pulling forces were measured at four locations during URS with and without an SGW. The patients were randomized to whether the first series of force measurements should be with or without SGW. Paired-samples t tests were used comparing the forces in the two series.

RESULTS

Significantly higher forces were found both when inserting and retracting the semirigid endoscope when an SGW was used compared with times when an SGW was omitted. The mean percentage increase in the forces with an SGW in place varied between 51.8% and 112.5% across locations and directions. A limitation is that the study has been performed with a semirigid ureteroscope only.

CONCLUSION

An SGW substantially increased the resistance against moving a semirigid ureteroscope up and down the ureter. The SGW may thus be an obstacle to the ureteroscopic procedure and may even increase the risk of harming the ureter in some patients.

Ureteroscopic Holmium:YAG laser lithotripsy is effective for ureteral steinstrasse post-SWL

OBJECTIVE

To evaluate the efficacy of Holmium: YAG laser lithotripsy for ureteral steinstrasse after extracorporeal shock lithotripsy (SWL).

MATERIAL AND METHODS

Holmium: YAG laser lithotripsy was performed on 21 patients who had developed ureteral steinstrasse post-SWL.

RESULTS

Nineteen cases had successful treatment. The ureteral steinstrasse was cleared within one month after the treatment (success rate of 90.48%). Upper ureteral steinstrasse shifted to the renal pelvis was noted in one patient, who underwent a second SWL treatment. Another patient had a severely kinking ureter and underwent open surgery after ureteroscopy failed.

CONCLUSION

Holmium: YAG laser lithotripsy of ureteral steinstrasse post-SWL is an effective clinical modality due to its high success rate, short lithotripsy time, high safety and reliability, and easy feasibility.

Extracorporeal shockwave lithotripsy vs. percutaneous nephrolithotomy vs. flexible ureterorenoscopy for lower-pole stones

Objectives

To review previous reports and discuss current trends in extracorporeal shockwave lithotripsy (ESWL), percutaneous nephrolithotomy (PCNL) and ureterorenoscopy (URS). ESWL was recommended as the first-line treatment for small and intermediate-sized stones in the lower pole, while it is the standard treatment for large stones. However, the stone clearance rate after ESWL seems to be lower than that of stones in other locations. This seems to result from a lower rate of fragment passage, due to anatomical factors.

Methods

Reports on urinary stone disease were reviewed, assessing only publications in peer-reviewed, Medline-listed journals in the English language (publication years 1990–2011).

Results

Recent experience with flexible URS (fURS) for intrarenal stones showed that excellent stone-free rates can be achieved. With increasing experience and technically improved equipment, fURS has become an alternative to ESWL for small and intermediate-sized renal stones. Furthermore, several authors reported successful retrograde treatment for large renal stones, proposing fURS as an alternative to PCNL. However, the major drawbacks are long operating times and commonly, staged procedures, which is why PCNL remains the method of choice for such stones.

Conclusions

Considering the currents trends and evidence, the 2012 update of the European Association of Urology Guidelines on Urolithiasis has upgraded the endourological treatment of kidney stones. Individual factors such as body habitus, renal anatomy, costs and patient preference must be considered.

Emergency ureteroscopic removal of ureteral calculi after first colic attack: is there any advantage?

OBJECTIVE

To comparatively evaluate the efficacy of ureteroscopic stone treatment immediately after the first colic attack and in an electively planned manner.

METHODS

A total of 145 patients underwent semirigid ureteroscopic removal of obstructive ureteral calculi using 2 different approaches (group 1, 69 patients, and group 2, 76 patients). The 69 patients in group 1 were treated with appropriate medical therapy for a period of ≥7 days for colic pain and subsequently underwent either semirigid ureteroscopy or pneumatic lithotripsy in a planned manner. The 76 patients in group 2 underwent semirigid ureteroscopy after the first colic attack. The stone-free status, auxiliary procedures, and complications were evaluated between the 2 groups using the Mann-Whitney U test; for qualitative data, Fisher's exact test was used.

RESULTS

Of the 145 patients who underwent semirigid ureteroscopy, the mean stone size was 11.80±3.95 mm and 8.32±2.08 mm in the 2 groups. No patient experienced a major complication during or after the procedure. The stone-free rate was 87% and 90.7% in groups 1 and 2, respectively. The mean readmission rate to the emergency department for the management of a colic attack was 3.03±2.84 in group 1; no patient in group 2 required readmission.

CONCLUSION

Ureteroscopic stone removal immediately after the first colic attack in the cases of obstructive ureteral stones proved to be safe and effective. It has the main advantage of offering both immediate stone fragmentation and the relief of acute onset colic pain causing extreme discomfort.

Update on ureteroscopy instrumentation

The authors present an objective review of what is new in endourology instrumentation, based on up-to-date scientific data gathered from meetings, state-of-art lectures and current literature. The main scope of this review is to highlight the most recommended device options for each step of an ureteroscopy, in order to offer best care to patients.

Semirigid ureteroscopy for ureteral stones: a multivariate analysis of unfavorable results

PURPOSE

We determined the factors predicting unfavorable results of semirigid ureteroscopy for ureteral calculi.

MATERIALS AND METHODS

We reviewed the computerized files of 841 patients who underwent a total of 908 ureteroscopic procedures for ureteral stones from January 2003 through December 2006. A semirigid 6/7.5Fr ureteroscope was used in pediatric patients and an 8/10Fr or 8.5/11.5Fr ureteroscope was used in adults. Patients with favorable results were those who became stone-free after a single ureteroscopic procedure without any complications. They were compared with patients who had unfavorable results using univariate (chi-square and t tests) and multivariate (logistic regression) statistical tests to identify risk factors for unfavorable results.

RESULTS

The study included 567 males and 274 females with a mean age of 48.5 years (range 2 to 81). The complication rate was 6.7% (61 procedures). The stone-free rate after a single ureteroscopic intervention was 87% (791 procedures). Favorable results were documented in 751 procedures (82.7%). Significant factors for unfavorable results were proximal ureteral stones, ureteroscopy done by surgeons other than experienced endourologists, stone impaction and stone width (relative risk 4, 2.5, 1.8 and 1.2, respectively).

CONCLUSIONS

Semirigid ureteroscopy is a safe and highly effective treatment modality for ureteral stones.

Evaluation of the impact and need for use of a safety guidewire during ureteroscopy

BACKGROUND AND PURPOSE

The routine use of a "safety" guidewire adjacent to the ureteroscope during upper tract endoscopy is advocated in surgical texts and by many endourologists. Our experience has led us to theorize that a safety guidewire complicates ureteroscopy by providing resistance to introduction of the endoscope and by creating an obstruction to ureteroscopic instrumentation. To examine our theory, we developed a porcine animal model to evaluate the impact of the presence of a safety guidewire and reviewed our clinical experience, which routinely does not use a safety guidewire during ureteroscopy.

PATIENTS AND METHODS

An ex vivo model was created using the excised urinary tract of freshly slaughtered pigs. The forces needed to advance both a semirigid and flexible ureteroscope in the ureter were measured with and without the presence of a 0.035-inch safety guidewire. The clinical records of all patients undergoing ureteroscopy over a 4-year period were reviewed.

RESULTS

On average, an additional 12 and 20 g of force were needed to introduce the semirigid and flexible ureteroscope when a guidewire was present. For the chosen study period, 361 patients underwent ureteroscopic procedures without the placement of a safety guidewire. No patient experienced an intraoperative complication related to the absence of a safety wire.

CONCLUSIONS

The presence of a safety guidewire adjacent to the endoscope inhibits passage of the ureteroscope in an in vitro animal model. Technologic advancements in ureteroscope design and use of the holmium laser lithotrite minimize ureteral trauma and obviate the need for routine use of a safety wire during ureteroscopy.

Emergency ureteroscopic management of ureteral stones: why not?

OBJECTIVES

To describe a single-center experience in the emergency ureteroscopic management of ureteral stones.

METHODS

We retrospectively considered the data from 144 patients (mean age 49.6 years, range 23 to 82) who had had obstructive ureteral stones and had undergone emergency ureteroscopy with stone retrieval. Intracorporeal pneumatic lithotripsy was performed when necessary. At the end of the procedure, a ureteral catheter was systematically left in place in 100 patients (69.4%) and removed within 24 hours. In the remaining 44 patients, a double-J stent was preferred and was removed within 30 days, depending on the clinical course. Stone-free status was defined as the complete absence of fragments at 1 month of follow-up.

RESULTS

The calculi were more frequently localized in the distal ureter than in the proximal one (90.3% versus 9.7%, respectively). The overall mean stone diameter was 9.1 mm (range 5 to 20). The overall stone-free rate was 92.4%. A greater stone-free rate was obtained in those with stones less than 10 mm (95.8%) than in those with stones larger than 10 mm (89%, P = 0.002). Similarly, a significantly better outcome occurred for those with stones located in the distal ureter (94.6%) than for those with stones in the proximal one (71.4%, P = 0.004). The overall complication rate was 4.2%. The mean hospital stay was 2.5 days (range 1 to 7).

CONCLUSIONS

In our experience, emergency ureteroscopy in cases of obstructive ureteral stones proved to be safe and effective. It has the main advantage of offering both immediate relief from pain and stone fragmentation. Additional extensive studies are warranted to corroborate these findings.

Long-term efficacy of holmium laser endoureterotomy for benign ureteral strictures

OBJECTIVES

To determine the long-term clinical and radiographic success of holmium laser endoureterotomy for nonobliterative benign ureteral strictures.

METHODS

A total of 19 patients (12 women and 7 men, mean age 47.5 years) underwent holmium laser endoureterotomy for iatrogenic ureteral strictures (seven proximal, seven mid, and five distal) using semirigid ureteroscopy and a 360-microm fiber at 1 J and 10 Hz.

RESULTS

Success was strictly defined as both relief of symptoms and radiographic resolution of obstruction by intravenous pyelography or diuretic renography, or both. With a median follow-up of 3.0 years, success was achieved in 13 (68.4%) of 19 patients.

CONCLUSIONS

Our results have shown that holmium laser endoureterotomy is associated with a long-term success rate equivalent to, or better than, other currently available minimally invasive treatment options. Also, failure was uniformly evident within the first 3 months after treatment.

Ureterorenoskopie (URS) bei Harnsteinen

Distal ureteral calculi (<5 mm) usually pass the ureter spontaneously. Ureteroscopic lithotripsy of distal ureteral calculi shows high stone-free rates with a low complication rate (4%) and is equal to extracorporeal shock wave lithotripsy (ESWL), while ESWL is the primary choice for proximal ureteric stones. Flexible endoscopes are more difficult to handle and should be used only under fluoroscopic control. They are generally used in combination with the holmium:YAG laser and the flexible Lithoclast in the proximal ureter or the renal collecting system. Overall the complication rate of URS is 9-11% with avulsion of the ureteric urothelium being the most common complication. Ureteral perforation, stricture (<1%), impaction of the instrument in the ureter with consequent ureteral laceration, extravasation of stones, and bleeding in the urogenital tract are complications of URS but are minimal in the hands of a well-trained and skilled surgeon.

Performance and Safety of Holmium: YAG Laser Optical Fibers

BACKGROUND AND PURPOSE

Lower-pole ureteronephroscopy requires transmission of holmium:YAG energy along a deflected fiber. Current ureteroscopes are capable of high degrees of deflection, which may stress laser fibers beyond safe limits during lower-pole use. We hypothesized that optical fiber and safety measures differ among manufacturers.

MATERIALS AND METHODS

Small (200-273-microm) and medium-diameter (300-400-microm) Ho:YAG fibers were tested in a straight and 180 degrees bent configuration. Energy transmission was measured by an energy detector. Fiber durability was assessed by firing the laser in sequentially tighter bending diameters. The fibers were bent to 180 degrees with a diameter of 6 cm and run at 200- to 4000-mJ pulse energy to determine the minimum energy required to fracture the fiber. The bending diameter was decreased by 1-cm increments and testing repeated until a bending diameter of 1 cm was reached. The maximum deflection of the ACMI DUR-8E ureteroscope with each fiber in the working channel was recorded. The flow rate through the working channel of the DUR-8E was measured for each fiber.

RESULTS

The mean energy transmission differed among fibers (P < 0.001). The Lumenis SL 200 and the InnovaQuartz 400 were the best small and medium-diameter fibers, respectively, in resisting thermal breakdown (P < 0.01). The Dornier Lightguide Super 200 fractured repeatedly at a bend diameter of 2 cm and with the lowest energy (200 mJ). The other small fibers fractured only at a bend diameter of 1 cm. The Sharplan 200 and InnovaQuartz Sureflex 273T were the most flexible fibers, the Lumenis SL 365 the least. The flow rate was inversely proportional to four times the power of the diameter of the fiber.

CONCLUSIONS

Optical performance and safety differ among fibers. Fibers transmit various amounts of energy to their cladding when bent. During lower-pole nephroscopy with the fiber deflected, there is a risk of fiber fracture from thermal breakdown and laser-energy transmission to the endoscope. Some available laser fibers carry a risk of ureteroscope damage.

Novel endourologic applications for holmium laser

The holmium laser is used routinely during endoscopic procedures to treat stones, strictures, and tumors of the urinary tract. We report two successful novel endourologic applications of a holmium laser: division and removal of a synthetic urethral sling mesh in one patient and fragmentation of a tempered stainless steel surgical needle in another.