The evolution of ureteroscopy: a modern single-institution series

The Safety and Efficacy of Endoscopic Combined Intrarenal Surgery (ECIRS) versus Percutaneous Nephrolithotomy (PCNL): A Systematic Review and Meta-Analysis

Purpose

Our aim is to evaluate the safety and efficacy of endoscopic combined intrarenal surgery compared to percutaneous nephrolithotomy to guide practitioners and inform guidelines.

Materials and Methods

A detailed database search was performed in PubMed, OVID, Scopus, and Web of Science in October 2021 to identify articles pertaining to ECIRS published between 2001 and 2021.

Results

Four nonrandomized comparative studies and one RCT were identified, yielding five studies with a total of 546 patients (ECIRS/mini-ECIRS, n = 277; PCNL/mini-PCNL, n = 269). Subjects in these five studies met the predefined inclusion criteria established by two reviewers (J.E.A. and R.L.S.) and were therefore eligible for analysis. The results demonstrated that ECIRS was associated with a higher SFR (OR: 4.20; 95% CI: 2.79, 6.33; p < 0.00001), fewer complications (OR: 0.63; 95% CI: 0.41, 0.97; p=0.04), and a shorter hospital stay (WMD: −1.27; 95% CI: −1.55, −0.98; p < 0.00001) when compared to PCNL. There were no statistically significant differences in blood transfusions (OR: 0.45; 95% CI: 0.12, 1.68; p=0.24), operative time (SMD: −1.05; 95% CI: −2.42, 0.31; p=0.13), or blood loss (SMD: −1.10; 95% CI: −2.46, 0.26; p=0.11) between ECIRS and PCNL.

Conclusions

ECIRS may be a more suitable approach for the surgical management of large and complex kidney stones currently indicating PCNL due to its superior efficacy with comparable surgical time and complication rate, though it is thought that a lack of resources and properly trained personnel may preclude ECIRS from becoming the standard. It is our impression that ECIRS may become the preferred technique in the endourologic community corresponding to the evolutionary sequence of percutaneous stone surgery.

Complications Associated With Ureteroscopic Management of Upper Tract Urothelial Carcinoma

OBJECTIVES

To compile and examine safety data from clinical studies of endoscopic management of patients with low-grade upper tract urothelial carcinoma (UTUC) to identify rates and factors associated with reported complications.

METHODS

Ovid Medline and Ovid Medline Daily (with Embase as secondary search) including citations from 1946-2018 were queried using the following terms: ureteroscopy, ureter, catheter, endoscopy, complication, adverse events, morbidity, ablation, laser, upper tract urothelial carcinoma, ureteral stricture, ureteral stenosis, and ureteral injury. Abstracts were reviewed for relevance; diagnostic studies, case studies, and reviews were excluded.

RESULTS

Thirty-eight publications (7 prospective, 31 retrospective) representing >1100 patients were identified. Ureteral stricture was the most frequently reported complication (studies; rates) (26/38; 0-27%), with incidence associated with number of procedures and treatment method. Bleeding, infection, and fever were most common with adjuvant treatment (BCG or mitomycin). Serious and fatal complications were rare.

CONCLUSIONS

Ureteral stricture is the most frequent complication of endoscopic UTUC management but can be managed successfully in most cases. Most complications were minor. Although additional prospective studies are needed, these results support the safety of ureteroscopic management of UTUC in appropriately selected patients.

Case Report: An occurrence of steinstrasse in retrograde intra renal surgery (RIRS) for large staghorn kidney stone: a difficult experience in managing surgical outcomes

Immediate removal of staghorn kidney stones is important to prevent life-threatening complications. With the advancement of endoscopic technology, retrograde intrarenal surgery (RIRS) is now an alternate treatment to the standard percutaneous nephrolithotomy (PCNL) for stones removal. However, when used to treat large stones (>3cm), RIRS can cause the formation steinstrasse (SS). Here, we present the case of a 68-year-old man with multiple stones in the collecting system of the right kidney after initial treatment with RIRS. After two years of multiple interventions, the SS was completely removed. To prevent this complication in patients, a detailed assessment of the stone (size, location) and renal anatomy should be completed before RIRS is performed.

Simulation of Laser Lithotripsy-Induced Heating in the Urinary Tract

PURPOSE

Holmium laser lithotripsy is a common modality used to fragment urinary stones during ureteroscopy. Laser energy deposited during activation produces heat and potentially causes thermal bioeffects. We aimed to characterize laser-induced heating through a computational simulation.

MATERIALS AND METHODS

A finite-element model was developed and used to estimate temperature in the urinary tract. Axisymmetric models of laser lithotripsy in a renal calyx, the renal pelvis, and proximal ureter were created. Heat generation by laser and heat transfer were simulated under different laser powers between 5 and 40 W. Irrigation fluid flow was introduced at rates between 0 and 40 mL/min. The model was validated by comparison with previous in vitro temperature data in a test tube, then used to calculate heating and thermal dose in the three tissue models.

RESULTS

Simulated temperature rises agreed well with most in vitro experimental measurements. In tissue models, temperature rises depended strongly on laser power and irrigation rate, and to a lesser extent on location. Injurious temperatures were reached for 5-40 W laser power without irrigation, >10 W with 5 mL/min irrigation, 40 W with 15 mL/min irrigation, and were not found at 40 mL/min irrigation. Tissue injury volumes up to 2.3 cm³ were calculated from thermal dose.

CONCLUSIONS

The results suggest a numerical model can accurately simulate the thermal profile of laser lithotripsy. Laser heating is strongly dependent on parameters and may cause a substantial temperature rise in the fluid in the urinary tract and surrounding tissue under clinically relevant conditions.

Evaluation of risk factors and treatment options in patients with ureteral stricture disease at a single institution

INTRODUCTION

Ureteral strictures are a significant cause of morbidity and mortality, resulting in potential kidney damage requiring several surgical procedures. Non-malignant causes include radiation, trauma from calculi impaction, pelvic surgery, or ureteroscopy (URS). We identified risk factors in our patients with ureteral strictures and the success of their treatment outcomes.

METHODS

A retrospective chart review of 25 patients with 29 ureteral strictures was performed to determine the success of their treatment.

RESULTS

Twenty-five (25) patients with 29 benign ureteral strictures were identified. Most cases (60%) were caused by impacted stones where the median stone size was 1.15 cm (0.37-1.8 cm). Intervention for stones prior to stricture development included shockwave lithotripsy, URS, and percutaneous nephrolithotomy. Five patients with strictures from impacted stones had ureteric complications during stone treatment including perforation +/- urinoma (n=3), fractured guidewire left in situ (n=1), and ureteric orifice resection (n=1). Other stricture etiologies included radiation (28%) and endometriosis (4%). Treatment modalities used included ureteroureterostomy (n=2), ureteral re-implant (n=3), urinary diversion (n=3), autotrasplant (n=1), laser endoureterotomy +/- balloon dilation (n=8), nephrectomy (n=2), balloon dilation +/- stent (n=3), ureterovesical junction (UVJ) resection + stent (n=1), chronic stent changes (n=4), or surveillance (n=3).

CONCLUSIONS

Our evaluation highlights important principles. Patients with complicated ureteroscopies or severely impacted calculi warrant close followup with imaging after stone treatment due to possibility of rapid renal deterioration from stricture formation. Radiation-induced strictures are difficult to manage, possibly requiring subsequent urinary diversion. Finally, endoscopic management of benign ureteral strictures via balloon dilation and laser endoureterotomy is an excellent choice in properly selected patients, with opportunity for subsequent salvage treatments if needed.

Evaluation of the tensile strength of the human ureter--preliminary results

BACKGROUND AND PURPOSE

Ureteral injuries such as avulsion are directly related to mechanical damage of the ureter. Understanding the tensile strength of this tissue may assist in prevention of iatrogenic injuries. Few published studies have looked at the mechanical properties of the animal ureter and, of those, none has determined the tensile strength of the human ureter. Therefore, the purpose of this work was to determine the tensile strength of the human ureter.

METHODS

We harvested 11 human proximal ureters from patients who were undergoing nephrectomy for either kidney tumors or nonfunctioning kidney. The specimens were then cut into multiple circumferentially and longitudinally oriented tissue strips for tensile testing. Strips were uniaxially stretched to failure in a tensile testing machine. The corresponding force and displacement were recorded. Finally, stress at failure was noted as the tensile strength of the sample. Circumferential tensile strength was also compared in the proximal and distal regions of the specimens.

RESULTS

The tensile strength of the ureter in circumferential and longitudinal orientations was found to be 457.52±33.74 Ncm(-2) and 902.43±122.08 Ncm(-2), respectively (P<0.001). The circumferential strength in the proximal portion of the ureter was 409.89±35.13 Ncm(-2) in comparison with 502.89±55.85 Ncm(-2) in the distal portion (P=0.08).

CONCLUSIONS

The circumferential tensile strength of the ureter was found to be significantly lower than the longitudinal strength. Circumferential tensile strength was also lower with more proximal parts of the ureter. This information may be important for the design of "intelligent" devices and simulators to prevent complications.

Incidence and Predictors for Ipsilateral Hydronephrosis Following Ureteroscopic Lithotripsy

OBJECTIVE

To review our experience in using ureteroscopy (URS) with lithotripsy for renal or ureteral calculi to determine the incidence and predictors of postprocedural ipsilateral hydronephrosis.

PATIENTS AND METHODS

Records of 324 URS cases for renal or ureteral calculi with imaging performed 4-12 weeks postprocedure were reviewed. Ipsilateral hydronephrosis was determined by computed tomography scan or renal ultrasound. Univariate and multivariate analyses determined the factors associated with hydronephrosis.

RESULTS

176 men and 148 women with a median age of 50 years were included. Median stone size was 6 mm and operative duration was 60 minutes; 30% of patients had multiple calculi; and 35% had undergone a prior ipsilateral URS. Overall, 49 of 324 patients (15%) had evidence of hydronephrosis, with 65% of these patients having symptoms and 40% requiring ancillary procedures. On multivariate analysis, increasing stone diameter (odds ratio [OR] 8.9, 95% confidence interval [CI] 1.9-23.8, P = .03), prior ipsilateral URS (OR 7.7, 95% CI 1.8-28.2, P = .006), longer operative duration (OR 6.5, 95% CI 1.8-16.3, P = .02), and renal colic symptoms (OR 48.3, 95% CI 14.7-71.4, P <.001) independently predicted hydronephrosis. Conversely, other factors including stone impaction at procedure, ureteral dilation, use of an access sheath, intraoperative perforation, or use of a stent did not associate with ipsilateral hydronephrosis.

CONCLUSION

In this contemporary cohort study, 15% of patients undergoing URS had evidence of ipsilateral hydronephrosis. Larger stone size, longer OR duration, prior ipsilateral URS, and recurrent colic were associated with an increased likelihood for this observation. Patients and stone cases with such characteristics likely warrant imaging modalities beyond plain radiography.

The surgical management of kidney stone disease: a population based time series analysis

PURPOSE

We evaluate population based trends in the use of extracorporeal shock wave lithotripsy, ureteroscopy and percutaneous nephrolithotomy during the last 20 years, as well as assess the re-treatment rate and morbidity from treatment over time.

MATERIALS AND METHODS

Using administrative databases in the province of Ontario, Canada, a population based cross-sectional time series analysis was performed between July 1, 1991 and December 31, 2010. All extracorporeal shock wave lithotripsy, ureteroscopy and percutaneous nephrolithotomy procedures were identified, along with all hospital readmissions and emergency department visits within 7 days of treatment. The primary outcome was treatment use, and secondary outcomes were the need for ancillary treatment and hospital readmission or emergency department visit after treatment. Exponential smoothing and autoregressive integrated moving average (ARIMA) models were used to assess trends over time.

RESULTS

We identified 194,781 kidney stone treatments performed during the study period. Time series modeling revealed a significant increase in the use of ureteroscopy over time (25% to 59% of all procedures, p <0.0001) and a reciprocal decrease in the use of extracorporeal shock wave lithotripsy (69% to 34% of all procedures, p <0.0001). A corresponding significant decrease in the need for ancillary treatment over time (23% to 15%, p <0.0001) and increase in the need for hospital readmission (7% to 11%, p <0.0001) or emergency department visit (7% to 11%, p=0.0024) after treatment were also demonstrated.

CONCLUSIONS

Our population based study demonstrates a shift in the treatment paradigm with increased use of ureteroscopy over time and a reciprocal decrease in the use of extracorporeal shock wave lithotripsy. We also observed a corresponding decrease in ancillary treatment and increase in posttreatment morbidity over time.

Ureteroscopic lithotripsy in Trendelenburg position for proximal ureteral calculi: a prospective, randomized, comparative study

PURPOSE

We conducted a prospective, randomized, comparative study to compare the clinical outcome between the Trendelenburg position ureteroscopic lithotripsy (tURSL) and the conventional position ureteroscopic lithotripsy (cURSL) for the management of single proximal ureteral stone.

METHODS

From January 2012 to September 2013, consecutive patients with single proximal ureteral calculi less than 2 cm and planned for ureteroscopic lithotripsy at our institution were enrolled in this study. The eligible patients were randomized into cURSL group and tURSL group according to sequence of random numbers generated by computer. In tURSL group, patients were turned into a Trendelenburg lithotomy position with head down 30° while the conventional lithotomy position was applied in cURSL group. URSL was performed using a 6/7.5F semi-rigid ureteroscope with holmium laser. When retropulsion occurred, the stones fragments were followed by semi-rigid ureteroscope up to the renal collecting system. The Olympus P5 flexible ureteroscope was used if there was any suspicion of stone migration into lower calices or incomplete stone fragmentation by semi-rigid ureteroscope. Patients' demographics between the two groups, perioperative course, clinical outcome and complication rates were compared. Data were analyzed using Chi-square test, Fisher's exact test or Student's t test. Binary logistic regression analysis was applied to estimate the effects of surgical position and stone size on stone migration.

RESULTS

A total of 355 cases were finally analyzed in this study (176 in cURSL group and 179 in tURSL group). The mean operative time was significantly prolonged in cURSL group than in tURSL group, while the stone-free rate (SFR) at 4 weeks was significantly higher in tURSL group. A statistically significant difference was found in stone migration rate between the two groups (26.7 vs. 43.6 %, P = 0.001). In the stone migration subsetting, less stones fragments were found to migrate into lower calices in tURSL stone migration subgroup (P = 0.000). Also, the flexible ureteroscope utilization as well as the operative time was significantly decreased in tURSL stone migration subgroup (25.5 vs. 72.3 %, P = 0.000), (44.96 ± 11.0 min vs. 59.17 ± 9.2 min, P = 0.000) with higher SFR after retrograde intrarenal surgery (RIRS) (96.2 vs. 74.5 %, P = 0.000).

CONCLUSION

The tURSL was safe and highly efficacious for the management of proximal ureteral calculus, especially in nonobese patient. Even with important stone migration risk, it rendered higher SFR and less operative time compared with cURSL. Moreover, less utilization of flexible ureteroscope and decreased deflection time in tURSL could potentially reduce the medical cost.

Hydrophilic guidewires: evaluation and comparison of their properties and safety

OBJECTIVE

To compare physical and mechanical properties of 10 commercially available hydrophilic guidewires.

METHODS

In vitro testing was performed to evaluate 10 different straight hydrophilic guidewires (5 regular and 5 stiff wires): Glidewire, NiCore, EZ Glider, Hiwire, and Zipwire. The forces required for tip perforation, tip bending, shaft bending, and friction during movement were measured for all 10 wires. The tip contour was measured using high power light microscopy.

RESULTS

The Glidewire required the greatest force to perforate our model (P = .01). The EZ Glider, Zipwire, and Glidewire had the lowest tip bending forces (P <.001). The Glidewire had the stiffest shaft (P <.001). The EZ Glider and Glidewire required the greatest forces in the friction test (P <.001). Regarding the stiff guidewires, the GlidewireS required the greatest force in the perforation test (P ≤.05). The GlidewireS and EZ GliderS required the lowest tip bending force (P ≤.004). The ZipwireS and NiCoreS had the stiffest shafts (P ≤.01). The GlidewireS required the greatest force in the friction test (P <.001). Measurement of the tip contour showed the Zipwire, HiwireS, and EZ GliderS had the roundest tips.

CONCLUSION

Each wire has unique properties with advantages and disadvantages. The Glidewires (both stiff and regular) have the lowest potential for perforation, although they are less slippery. The Glidewire and EZ Glider required the least tip force to bend around a point of obstruction.

Semi-rigid ureteroscopy for ureteric and renal pelvic calculi: Predictive factors for complications and success

OBJECTIVE

To analyse and compare the effect of stone site and size, method of lithotripsy, and level of experience on the results and complications of semi-rigid ureteroscopy for ureteric and renal pelvic stones.

PATIENTS AND METHODS

Between April 2010 and May 2011, 90 patients underwent 95 ureteroscopies, using 7.5- and 9-F semi-rigid ureteroscopes, with or without pneumatic or laser lithotripsy. The peri-operative findings were analysed and compared.

RESULTS

The mean (SD) longest diameter of the stones was 11.8 (4.5) mm. Laser lithotripsy was used in 32 cases and pneumatic lithotripsy in 26. There were complications in 35 procedures in the form of colicky pain (2%), haematuria (1%), stone migration (7%), equipment failure (5%), access failure (8%), mucosal injury (7%), fever (2%) and extravasation (3%).The calculi were successfully retrieved in 75 patients (83%). The success rate was 95%, 77%, 85%, and 53% in the lower, middle, upper ureter and renal pelvis, respectively.

CONCLUSIONS

Upper ureteric stones can be managed safely with the semi-rigid ureteroscope. Renal pelvic stones are associated with a lower success rate, and thus they were not a primary indication for ureteroscopic intervention. The secondary ureteroscopic management of renal pelvic stones improved the results of subsequent alkalinisation or shock-wave lithotripsy if they could not be eradicated completely. The failure rate was significantly small in lower ureteric stones and stones of <10 mm. Less experience, a stone size of >15 mm and patients ⩽2 years old were associated with more complications or a lower success rate. There was no significant difference in the success or complication rate between laser and pneumatic lithotripsy.

Advances in ureteroscopy

Recent innovations in imaging equipment and novel instrumentation have helped ureteroscopy evolve from a diagnostic to a therapeutic tool. In this review, the authors highlight several of the most recent advances in ureteroscopy that have helped allow unprecedented access, visualization, and treatment of upper urinary tract pathologic conditions.

The emerging role of robotics and laparoscopy in stone disease

The surgical management of urolithiasis has undergone a remarkable clinical evolution over the past three decades. The once common practice of open stone surgery has nearly been relegated to historical interest by modern technology. The introduction of minimally invasive techniques, laparoscopy and robot-assisted surgery, have emerged to complete the urologist's armamentarium. The benefits to patients when other endourologic procedures have failed include less pain, shorter hospitalization and convalescence, and improved cosmesis. This chapter explores the historical shift from open to minimally invasive management for stone disease and the unique risks and outcomes associated with these procedures in modern urology.

Full-length ureteral avulsion caused by ureteroscopy: report of one case cured by pyeloureterostomy, greater omentum investment, and ureterovesical anastomosis

The aim of this report was to look for a good solution to full-length ureteral avulsion. This report retrospectively analyzed the data of the patient. The patient underwent ureteroscopic management. Full-length avulsion of ureter occurred during ureteroscopy. Pyeloureterostomy plus greater omentum investment outside the avulsed ureter and ureterovesical anastomosis were performed immediately. The patient was followed-up 25 months. After the first operation, the patient developed hydronephrosis because of press of fibrosis tissue outside ureter and anastomotic atresia of ureter-bladder. When we finished the second operation, the renal function recovered well. Full-length avulsion of ureter is a severe complication. Pyeloureterostomy plus greater omentum investment outside the avulsed ureter and ureterovesical anastomosis are probably a good choice.

The ureteroscope as a safety wire for ureteronephroscopy

BACKGROUND AND PURPOSE

The recent technologic advances in the newer generation of flexible ureteroscopes have significantly enhanced the therapeutic and diagnostic efficacy of ureteroscopy. The purpose of our study was to assess ureteroscopy and lithotripsy of renal calculi without a safety wire, using the ureteroscope as the safety device.

PATIENTS AND METHODS

Medical records for patients undergoing ureteroscopy by a single surgeon were retrospectively reviewed from December 2006 to December 2009. Inclusion criteria for our study included all adult patients who underwent wireless flexible ureteroscopy for the management of renal calculi and had 1 month follow-up data.

RESULTS

Of the 568 patients who underwent ureteroscopy during this period, 268 patients met our study inclusion criteria. The mean age of the patients undergoing wireless ureteroscopy was 33 years, and the mean body mass index was 33.1 kg/m(2). Mean stone diameter of the renal calculi treated was 12.0±5.9 mm. Fifteen percent of the patients had a ureteral stent in place before the procedure, and 84% of the patients had a stent placed after ureteroscopy. Twenty percent of the patients needed ureteral dilation, and 15% of the patients had a ureteral access sheath placed intraoperatively. The overall complication rate was 2.6% (major=0.7%, minor=1.9%). Complications included: Four urinary tract infections, two patients with urosepsis, and one patient with urinary retention. No patients had ureteral perforation or ureteral avulsion.

CONCLUSIONS

Using the ureteroscope as the safety mechanism, ureteroscopy is safe with regard to maintaining renal access and control. Routine safety wires during ureteronephroscopy are not necessary assuring the ureteroscope is in the kidney.

Contemporary management of ureteral stones

CONTEXT

Ureteral calculi represent a common condition that urologists encounter in everyday practice. Several treatment options are available for calculi that do not pass spontaneously or are unlikely to do so.

OBJECTIVE

In this nonsystematic review, we summarize the existing data on contemporary management of ureteral stones focusing on medical expulsive therapy (MET) and different treatment modalities.

EVIDENCE ACQUISITION

A PubMed search was performed. We reviewed the recent literature on the management of ureteral calculi. Articles were considered between 1997 and 2011. Older studies were included selectively if historically relevant.

EVIDENCE SYNTHESIS

For stones that do not pass spontaneously or with MET, shock wave lithotripsy (SWL) and ureteroscopy (URS) are the most common and efficient treatment modalities. Both techniques have obvious advantages and disadvantages as well as different patterns of complications. For select cases or patients, other modalities may be useful.

CONCLUSIONS

Ureteral stones of up to 10mm and eligible for observation may be offered MET. For most ureteral calculi that require treatment, advances in SWL and URS allow urologists to take a minimally invasive approach. Other more invasive treatments are reserved for select "nonstandard" cases.

Case Report: Successful Staged Ureteroscopic Treatment of a 5 cm Staghorn Renal Calculus

It is widely accepted that percutaneous nephrostolithotorny (PCNL) is the standard of choice for the removal of large staghorn renal calculi. Although data exists supporting a stagad ureteroscopic as an alternate treatment for stones up to 3 cm in select patients, little data exists to support a ureteroscopic approach for stones as large as 5 cm. We present a case of a 68 year old female with a 5 cm staghorn renal calculus managed successfully with a staged ureteroscopic approach. A staged ureteroscopic approach can be effective in treating stones as large as 5 cm.

Systematic evaluation of hybrid guidewires: shaft stiffness, lubricity, and tip configuration

OBJECTIVE

To conduct a comparison of physical and mechanical properties for 5 commonly used guidewires to assess advantages of wires for specific applications.

METHODS

Tests on guidewires (0.035" diameter; straight, flexible tip) included tip bending, shaft buckling, lubricity, and tip puncture measurements. Guidewires included 2 hybrid wires: the U-Nite (Bard Urological, Covington, GA) and the Sensor (Boston Scientific, Natick, MA). Our aim was to compare the stiffness of these hybrid wires with the standard Amplatz SuperStiff (Boston Scientific). Our second aim was to compare the hydrophilic tip of the hybrid wires with 2 traditional hydrophilic guidewires: the NiCore (Bard Urological) and RadiFocus glidewire (Boston Scientific).

RESULTS

The Amplatz SuperStiff had a significantly stiffer shaft than either hybrid wire, with a buckling force of 1.81 ± 0.91 N compared with the Sensor (0.80 ± 0.29 N, P = .0002) and the U-Nite (0.77 ± 0.29 N, P < .0001). The Boston Scientific guidewire tips were less stiff than the Bard guidewires, requiring up to 48% less force to bend when encountering resistance (P < .0001). The U-Nite had the highest lubricity (0.09 ± 0.03 N, P < .0001) and roundest tip of all the guidewires tested. The RadiFocus required the greatest puncture force (1.80 ± 0.27 N, P < .0001) of all the guidewires tested.

CONCLUSION

Hybrid wires offer a combination of a stiffer shaft and hydrophilic tip. The Amplatz SuperStiff remains the stiffest wire and as such is best suited for placement of ureteral access sheaths or larger stents. The Boston Scientific wires require less force to "bend" around a point of obstruction compared with the Bard wires. The Boston Scientific RadiFocus requires the greatest force to puncture aluminum foil.

Successful outcome of flexible ureteroscopy with holmium laser lithotripsy for renal stones 2 cm or greater

Although percutaneous nephrolithotomy has been recommended as the first-line treatment for renal stones larger than 2 cm, its major complication rate is not negligible and less invasive approaches are to be explored. Thanks to the recent advances in endoscopic technology, flexible ureteroscopy has become another option in this setting. Herein we report our most recent experience with flexible ureteroscopy for large renal stones. Between September 2008 and May 2011, 20 patients with renal stones ≥ 2 cm underwent a total of 28 procedures of ureteroscopy with holmium laser lithotripsy, using the Olympus URF-P5 and a ureteral access sheath. The number of procedures, operative time, stone-free rates, stone compositions and complications were evaluated. Stone-free status was defined as the absence of fragments or fragments of ≤ 4 mm. Mean stone size was 3.1 cm (range 2.0-5.0). The average number of procedures was 1.4. One, two and three procedures were required in 13, six and one patients, respectively. Overall, the stone-free rate was 90%. The stone-free rate for preoperative stone size of 2 to ≤ 4 cm and >4 cm was 100% (14/14) and 67% (4/6), respectively. No major intraoperative complications were identified. Postoperative high-grade fever was observed in three patients, including one patient who developed sepsis. All these patients were successfully treated conservatively. Our findings suggest that ureteroscopy represents a favorable option for selected patients with renal stones, especially those 2 to ≤ 4 cm in size.

Ureteral avulsion during contemporary ureteroscopic stone management: "the scabbard avulsion"

Ureteral avulsion during ureteroscopic stone management is extremely rare. To date, many publications reporting avulsion have been associated with "blind basket extraction" under fluoroscopy and the use of the Dormia stone basket. Fortunately, despite the significant rise in the numbers of ureteroscopic cases being performed, the rate of ureteral avulsion remains low. This is likely in part because of improvements in ureteroscope technology and stone manipulation devices. We present three recent cases of ureteral avulsion referred to our center for further management. To our knowledge, these cases represent the first published description of avulsion where the ureteroscope became wedged in the intramural ureter, resulting in full-length avulsion of the ureter. The avulsion occurs both proximally and distally with a resultant length of ureter left attached to the ureteroscope. We dub this mechanism the "scabbard" avulsion. We describe the most likely mechanism of this injury, with suggestions on how to prevent it and how to release the ureteroscope should it become wedged in the intramural ureter.

Lower pole calculi larger than one centimeter: Retrograde intrarenal surgery

Controversy remains on how to treat lower pole calculi between 1 and 2 cm of size. Treatment options like shock wave lithotripsy (SWL) or percutaneous stone treatment (PCNL) are associated with poor stone-free rates or high morbidity.

Due to the ongoing development in endourologic technology, especially in flexible renoscopy, laser technique and grasping devices (tipless Nitinol baskets) retrograde intrarenal surgery (RIRS) has become an option in treating these patients.

Based on personal experience and an overview of the published literature we discuss RIRS as a valuable alternative to PCNL in treating patients with larger calculi of the lower pole.

The technical developments in laser technology as well as significant improvement in flexible renoscopes have made RIRS for larger lower pole stones possible. The low complication rate gives RIRS for lower pole stones superiority over the invasive percutaneous approach, which is associated with significant morbidity, even in experienced hands.

Contralateral ureteroscopy performed at percutaneous nephrolithotomy: a unique evaluation of stone-free rates

PURPOSE

Immediate stone-free rates of ureteroscopy are rarely reported. To establish accurate stone-free rates after ureteroscopy we assessed the safety and success of ureteroscopy for patients undergoing the procedure at contralateral percutaneous nephrolithotomy.

MATERIALS AND METHODS

From our prospectively collected, institutional review board approved, percutaneous nephrolithotomy database we identified patients who underwent contralateral ureteroscopy for urolithiasis at percutaneous nephrolithotomy from December 2001 to December 2008. Stone-free status was assessed with noncontrast computerized tomography on postoperative day 1.

RESULTS

A total of 65 patients underwent ureteroscopy for urolithiasis at contralateral percutaneous nephrolithotomy. There were 63 patients available for review who had noncontrast computerized tomography on postoperative day 1. Immediate stone-free status was achieved after ureteroscopy in 37 of 63 patients (58.7%). The remaining 26 patients (41.3%) demonstrated a residual stone burden. Of these patients with residual stones after ureteroscopy 65.4% (17 of 26) had residual fragments of 1 to 3 mm and 34.6% (9 of 26) had residual stones larger than 3 mm. Three patients (4.8%) underwent repeat ureteroscopy at secondary percutaneous nephrolithotomy. There was no association of stone composition, patient age, stone location, gender or surgical complications with residual fragments (p>0.05).

CONCLUSIONS

Based on noncontrast computerized tomography 58.7% of patients who underwent ureteroscopy were rendered immediately stone-free. When residual passable stone fragments less than 3 mm were included the success rate increased to 85.7%. We found no association between characteristics of patients, stones or procedures and residual fragments.

Failure after shockwave lithotripsy: is outcome machine dependent?

AIM

To investigate the issue of shockwave lithotripsy failure by studying the effect of machine crossover to the Technomed Sonolith Vision (TSV) lithotriptor in patients with previously unsuccessfully treated renal stones with the Dornier Compact Delta (DCD). Records were examined for the period between 1998 and 2006. Parameters analysed were: size, multiple/single stones, location, treatments/stone.

RESULTS

Seventy-six patients fulfilled the inclusion criteria. Following lithotripsy with the TSV, the stone-free rate (SFR) at 3 months was 56.7%, and the success rate (stone-free and fragments < or = 4 mm, SR) 86.7%. Twenty-two patients had multiple stones and the majority of the stones were located in the lower calyx (59.2%). Mean size was 8.9 mm prior to treatment with the TSV machine (10.2 mm for DCD). Further analysis followed in a subgroup of 42 patients of the same stone size (+/-2 mm) before and after DCD sessions. Mean stone size was 7 mm. The SFR was 61.9% (62.9% vs. 40.9% for single and multiple stones), and the SR was 88.1%. No difference in SFR was found for single or multiple stones in any of the two groups.

CONCLUSIONS

The term 'extracorporeal shockwave lithotripsy (ESWL)-resistant stones' needs to be re-examined, as treatment with a different lithotriptor was successful in a group of stones where another machine had failed. Lithotripters with different shock wave characteristics may result in difference in the results of ESWL. Future research in ESWL should focus on stone characteristics and development of machines with the ability to adapt to specific stone features.

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.

Is routine ureteral stenting necessary after uncomplicated ureteroscopic lithotripsy for lower ureteral stones larger than 1 cm?

We evaluated the need for routine ureteral stenting after uncomplicated ureteroscopic lithotripsy (URSL) without dilation for lower ureteral stones larger than 1 cm. A total of 43 patients underwent URSL for lower ureteral stones larger than 10 mm. They were randomized into a stented (21) or an unstented (22) group. URSL was performed by using a semirigid ureteroscope and pneumatic lithotripter without ureteral dilation. Additional forceps application (AFA) was used to remove fragments > or =4 mm. Patients in each group were assessed for stone-free rate, stone size, operative time, AFA, hospitalization time, postoperative pain, irritative voiding symptoms, hematuria, re-hospitalization and stricture formation. The stone-free rate was 100% in each group. There were no statistical differences in the two groups regarding stone size, operative time, AFA, postoperative pain, hematuria and hospitalization time. However, irritative voiding symptoms of the stented group were significantly higher than those in the unstented group (P < 0.05). One patient (4.5%) in the unstented group required re-hospitalization for severe flank pain with fever (>38 degrees C) compared to one patient (4.7%) in the stented group for proximal stent migration (P > 0.05). Stricture formation was not demonstrated in either group at 3 months follow-up excretory urography (EXU). Our results demonstrate that ureteral stenting after uncomplicated URSL without dilation for lower ureteral stones larger than 1 cm does not appear to be necessary if AFA is used to remove fragments > or =4 mm, thereby reducing morbidity of patients and risk of re-hospitalization.

Flexible ureteroscopy and laser lithotripsy for single intrarenal stones 2 cm or greater--is this the new frontier?

PURPOSE

Percutaneous nephrolithotomy has been the standard of care for intrarenal calculi greater than 2 cm. Flexible ureteroscopy with holmium laser lithotripsy is a minimally invasive treatment modality that is able to treat large intrarenal calculi with the potential to decrease morbidity, while maintaining a high level of efficacy.

MATERIALS AND METHODS

A total of 15 patients with a single intrarenal calculus 2 cm or greater were treated with retrograde ureteroscopic nephrolithotripsy. Lithotripsy was performed with a 7.2Fr flexible ureteroscope and 200 micron laser fiber. The stone-free rate was defined as the absence of any stones in the kidney or residual stone fragments less than 1 mm, which is too small to be extracted with a basket or a grasper. All patients underwent followup ureteroscopy within 15 days after the last procedure and renal ultrasound 30 days after the last treatment.

RESULTS

There were a total of 15 intrarenal calculi 20 to 25 mm (mean 22) in diameter. The mean number of procedures was 2.3 (range 2 to 4). The overall stone-free rate was 93.3%. One patient (6.6%) had a residual 5 mm stone fragment in the lower pole of the kidney, which was followed expectantly for 2 years with no change in size. There were no major complications. There were 3 minor complications (20%), including 1 emergency room visit for fever and pain, and 2 cases of gross hematuria. All cases were performed on an outpatient basis.

CONCLUSIONS

In select patients with a single intrarenal calculus 2 cm or greater small diameter flexible ureteroscopy with holmium laser lithotripsy may represent an alternative therapy to standard percutaneous nephrolithotomy with acceptable efficacy and low morbidity.

Advances in ureterorenoscopy

There has been a shift toward minimally invasive surgery in all surgical subspecialties in recent decades. Ureterorenoscopy represents an area in which there have been numerous advances that have resulted in excellent patient outcomes with low morbidity. Technologic advances such as miniaturization of ureteroscopes and improved video imaging have expanded the indications for ureteroscopy. The entire upper urinary tract can now be accessed for diagnosis and treatment of many common urologic conditions. Technologic research and development will continue to drive future improvements in the technique and applications for ureteroscopy.

In Vitro Evaluation of Ureteral Perforation Forces

OBJECTIVES

Ureteroscopy has become a very effective treatment option for ureteral and upper tract abnormalities. The reported complication rates have ranged from 1.5% to 13% for perforations and have been less than 1% for avulsions. We present a study that quantified the ureteral avulsion force in porcine ureters and ureteral perforation forces in human and porcine ureters.

METHODS

The avulsion force was measured in six porcine kidneys. A 2.4F stainless steel flat-wire basket was advanced through an incision made in the renal pelvis, and a 10-mm stone was placed in the extraction basket. The external end of the basket (handle) was attached to a miniature, low-force load cell and slowly pulled with increasing force until the ureter avulsed. The ureteral perforation forces were measured in 10 fresh porcine and 9 human ureters. Perpendicular perforation with either the blunt end of a CT-1 needle (0.038 in.) or the back end of a stiff guidewire (0.035 in.) was measured using the miniature, low-force load cell.

RESULTS

The average maximal force to avulse the pig ureter was 2.21 +/- 0.43 pound-mass (lb(m)). The force required to perforate the porcine ureter was significantly greater than that required to perforate the human ureter, irrespective of whether a needle (1.70 +/- 0.26 lb(m) versus 1.05 +/- 0.29 lb(m), P = 0.019) or guidewire (1.30 +/- 0.25 lb(m) versus 0.79 +/- 0.25 lb(m), P = 0.013) was used. Greater force was required to perforate with the needle than with the guidewire in both the porcine (P = 0.037) and the human (P = 0.26) ureter.

CONCLUSIONS

Quantifying the ureteral perforation forces will facilitate the design of endourologic devices, open the door for "smart devices" that sense forces and provide feedback, provide information critical to the design of endourologic and suturing simulators, and, finally, establish competency parameters for professionals in training.