The Use of a Novel Reverse Thermosensitive Polymer to Prevent Ureteral Stone Retropulsion During Intracorporeal Lithotripsy: A Randomized, Controlled Trial

Clinical Efficacy Evaluation of a Novel Negative Pressure Ureteroscopic Lithotripsy for Ureteral Stones

OBJECTIVE

To evaluate the clinical efficacy of a novel negative pressure ureteroscopic lithotripsy (NP-URL) compared to standard ureteroscopic lithotripsy (S-URL) for treating ureteral stones.

METHODS

A total of 284 patients diagnosed with ureteral stones and who underwent ureteroscopic lithotripsy between December 2020 and May 2022 at our hospital were included in the study. Among them, 146 cases underwent NP-URL and 138 cases underwent S-URL. The negative pressure device used in NP-URL consists of a 5F ureteric catheter and a tee joint. We evaluated the operative duration, stone-free rate, incidence of postoperative complications, stone retropulsion rate, and adjunct procedure rate between the two groups.

RESULTS

The mean operative duration was significantly shorter in the NP-URL group compared to the S-URL group (30.17 ± 5.84 minutes vs 34.84 ± 6.62 minutes; P＜.05). Additionally, the NP-URL group had a lower incidence of postoperative fever (1.4% vs 8.7%; P＜.05), reduced stone retropulsion rate (3.4% vs 11.6%; P＜.05), and a statistically lower rate of adjunct procedures (5.5% vs 14.5%, P＜.05). The NP-URL group also demonstrated a higher primary stone-free rate (91.8% vs 81.9%; P＜.05). However, there was no significant difference in the final stone-free rate between the NP-URL and S-URL groups (P＞.05).

CONCLUSION

NP-URL potentially reduces operative duration, significantly decreases the incidence of postoperative complications, and achieves better primary stone-free rates compared to S-URL.

2022 Recommendations of the AFU Lithiasis Committee: Summary of indications

The spontaneous elimination rate of ureteral stones decreases with their size, but also in function of their location. The objectives of stone surveillance are to detect the occurrence of a complication (e.g., fever, clinical tolerance) and to verify the potential stone migration/elimination. The use of urological procedures and the choice of technique are based on many different factors. Kidney stone surveillance is proposed mainly to people with low risk of progression or complications (size<4mm and/or lower calyx location and non-infection stone). Surveillance may be extended to patients with larger stones, in function of the clinical context and comorbidities. Conversely, a urological procedure may also be proposed to patients with stones<4mm for professional (e.g., soldier, pilot, expatriate) or social reasons or if travelling is planned. The choice of technique is based on the stone composition (if already known) and density, the advantages and limitations of each technique, and also the clinical context, while trying to choose the least invasive procedure for a stone-free objective. METHODOLOGY: These recommendations were developed using two methods: the Clinical Practice Recommendations method (CPR) and the ADAPTE method, depending on whether the question was considered in the European Association of Urology (EAU) recommendations (https://uroweb.org/guidelines/urolithiasis) [EAU 2022] and their adaptability to the French context. This chapter is based on the references used in the chapters on the different techniques (extracorporeal shock wave therapy, ureteroscopy, percutaneous nephrolithotomy, medical expulsive therapy, postural therapy, chemolysis by alkalinization) as well as the American Urological Association (AUA) and EAU recommendations.

2022 recommendations of the AFU Lithiasis Committee: Objectives, results, residual stones and fragments

The main objectives of interventional stone treatment are stone removal, symptom elimination, and kidney function preservation. After treatment of kidney stones (extracorporeal shock wave lithotripsy [ESWL], or endoscopy), fragments may remain in the kidney, either deliberately left in place or due to treatment failure (i.e. residual stone [RS], resistant to ESWL, left or inaccessible by endoscopy), or due to failure to eliminate the obtained fragments (i.e. residual fragments [RF]). Their management may differ. The most commonly used definition of RF in the literature is based on a size cut-off (≤4mm) and on three criteria: spontaneous clearance rate, secondary intervention rate, and disease progression rate. RF may be spontaneously eliminated (42%), persist and increase in size (32%), or become complicated and require a secondary urological procedure (36%). Like for the initial treatment, it is important to consider the stone composition for the treatment decision-making concerning RS/RF. METHODOLOGY: These recommendations were developed using two methods: the Clinical Practice Recommendation (CPR) method and the ADAPTE method, depending on whether the question was considered in the European Association of Urology (EAU) recommendations (https://uroweb.org/guidelines/urolithiasis) (EAU, 2022) and their adaptability to the French context.

Reverse Trendelenburg Lithotomy with Certain Inclination Angles Reduces Stone Retropulsion during Ureteroscopic Lithotripsy for Proximal Ureteral Stone

The objective of this study is to investigate how different inclination angles of reverse Trendelenburg lithotomy affect stone retropulsion and stone-free rates during ureteroscopic lithotripsy for proximal ureteral stones. Patients with proximal ureteral stones undergoing ureteroscopic lithotripsy in our institution between January 2019 and December 2020 were included according to predefined criteria. The rigid ureteroscope and Holmium: YAG laser were utilized to perform lithotripsy, and a stone basket was used to keep the stone in place and to avoid retropulsion. Before initiating lithotripsy, the upper part of the patient’s body was tilted up to establish a reverse Trendelenburg posture with appropriate inclination angles. To quantify the stone-free rate, computed tomography was used to evaluate the residual stones in the kidney one month following surgery. Patients’ clinical data were obtained retrospectively, including age, gender, the largest diameter of stone, stone density on computed tomography, and the distance between stone and ureteral pelvic junction, etc. Patients were divided into four groups based on the inclination angles of reverse Trendelenburg lithotomy: 0°, 10°, 20°, and 30°. The chi-square test was used to compare stone retropulsion and stone-free rates between groups. To discover possible determinants of the stone-free rate, logistic regression analyses were used. There were 189 patients that qualified. There were no differences in clinical characteristics between groups (p > 0.05). Multiple comparisons between groups revealed that the 20° and 30° groups had less retropulsion and a greater stone-free rate than the 0° and 10° groups (p < 0.05), whereas there were no significant differences in stone retropulsion or stone-free rates between the 20° and 30° groups or between the 0° and 10° groups (p > 0.05). The inclination angles as well as distance between the stone and ureteral pelvic junction were identified by using logistic regression analyses as the related factors for the stone-free rate. According to our results, the appropriate inclination angles of reverse Trendelenburg lithotomy during ureteroscopic lithotripsy for proximal ureteral stones would help preclude stone retropulsion and increase the stone-free rate.

Comparison of vacuum suction ureteroscopic laser lithotripsy and traditional ureteroscopic laser lithotripsy for impacted upper ureteral stones

PURPOSE

To compare a novel vacuum suction ureteroscopic laser lithotripsy (VS-URS) with traditional ureteroscopic laser lithotripsy (T-URS) for impacted upper ureteral stones and to better define the potential benefits of VS-URS.

METHODS

Between May 2019 and March 2021, 158 patients with impacted upper ureteral stones underwent ureteroscopic holmium-YAG laser lithotripsy. Of these, 76 underwent VS-URS and 82 underwent T-URS. In VS-URS procedures, the vacuum suction device is composed of a 5F ureteral catheter and a tee joint. The ureteral catheter is linked to the vacuum aspirator by the sidearm of the tee joint, and a 200 μm fiber is inserted through the tee joint and the ureteral catheter into the stone site for lithotripsy.

RESULTS

When compared to the T-URS group, the VS-URS group had a shorter mean operation time (38.18 ± 6.37 min vs. 46.65 ± 5.66 min; P = 0.000), lower fever rate (3.9% vs. 14.6%; P < 0.022), less stone retropulsion (5.3% vs. 18.3%; P = 0.012), lower extra management rate (6.58% vs. 21.95%; P = 0.006), and a higher stone-free rate of the first postoperative day (88.2% vs. 72.0%; P = 0.011). There were no significant differences in stone-free rates 1 month after surgery between groups (94.7% vs. 92.7%; P = 0.748).

CONCLUSIONS

VS-URS is an effective modality for impacted upper ureteral stones, and has a shorter operating time, lower fever rate, less stone retropulsion, and a higher primary stone-free rate compared with T-URS.

In Situ Generated Medical Devices

Medical devices play a major role in all areas of modern medicine, largely contributing to the success of clinical procedures and to the health of patients worldwide. They span from simple commodity products such as gauzes and catheters, to highly advanced implants, e.g., heart valves and vascular grafts. In situ generated devices are an important family of devices that are formed at their site of clinical function that have distinct advantages. Among them, since they are formed within the body, they only require minimally invasive procedures, avoiding the pain and risks associated with open surgery. These devices also display enhanced conformability to local tissues and can reach sites that otherwise are inaccessible. This review aims at shedding light on the unique features of in situ generated devices and to underscore leading trends in the field, as they are reflected by key developments recently in the field over the last several years. Since the uniqueness of these devices stems from their in situ generation, the way they are formed is crucial. It is because of this fact that in this review, the medical devices are classified depending on whether their in situ generation entails chemical or physical phenomena.

Devices to help combat stone retropulsion during ureteroscopic lithotripsy in 2016

Proximal migration of stones during ureteroscopic lithotripsy is a common problem that faces many urologists and reduces stone-free rates, which translates into higher costs and longer operative times. In a bid to increase stone-free rates, there are several anti-retropulsion devices on the market, to help urologists during ureteroscopic lithotripsy. We previously reviewed these anti-retropulsion devices and wish to update what is currently available on the market.

The "Guidewire-Coil"-Technique to prevent retrograde stone migration of ureteric calculi during intracorporeal lithothripsy

Background

Stone retropulsion represents a challenge for intracorporeal lithotripsy of ureteral calculi. The consequences are an increased duration and cost of surgery as well as decreased stone-free rates. The use of additional tools to prevent proximal stone migration entails further costs and risks for ureteral injuries. We present the simple technique of using a coil of the routinely used guidewire to prevent stone retropulsion.

Methods

We retrospectively evaluated all patients with mid-to-proximal ureteral stones in 2014, which were treated by ureteroscopic lithotripsy (Ho: YAG and/or pneumatic lithotripsy). The preoperative stone burden was routinely assessed using low dose CT scan (if available) and/or intravenous pyelogram.

Results

The study population consisted of 55 patients with 61 mid-to-proximal calculi. Twentyseven patients underwent semirigid ureterorenoscopy using the “Guidewire-Coil-Technique”, the second group (n = 28) served as control group using the guidewire as usual. There has been a statistically significant reduction of accidental stone retropulsion (2/27 vs. 8/28, p < 0.05) as well as a decreased use of auxiliary procedures (p < 0.05) compared to the control group. No difference was observed in operative time. One ureteral injury in the control group required a prolonged ureteral stenting.

Conclusion

The “Guidewire-Coil-Technique” is a simple and safe procedure that may help to prevent proximal calculus migration and therefore may increase stone-free rates without causing additional costs.

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

OBJECTIVE

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

MATERIALS AND METHODS

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

RESULTS

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

CONCLUSIONS

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

The Future of Intravesical Drug Delivery for Non-Muscle Invasive Bladder Cancer

Despite being the fifth most common cancer in the United States, minimal progress has been made in the treatment of bladder cancer in over a decade. Intravesical instillation of Bacillus Calmette-Guerin (BCG) for the treatment of non-muscle invasive bladder cancer (NMIBC) has been in use for over 30 years and remains the standard treatment in cases of intermediate and high risk disease. Despite the relative success of intravesical BCG, unmet needs in the treatment of NMIBC persist. These challenges include disease recurrence and progression even with treatment with BCG, as well as issues regarding its availability and patient tolerability. The inherent properties of the bladder pose the biggest obstacle to developing effective intravesical treatments for NMIBC. Current research is now focusing on methods to improve the delivery of intravesical therapies. The objective of this review is to discuss novel intravesical drug delivery systems and how they are addressing these challenges in the treatment of NMIBC.

Protein-surface interactions on stimuli-responsive polymeric biomaterials

Responsive surfaces: a review of the dependence of protein adsorption on the reversible volume phase transition in stimuli-responsive polymers. Specifically addressed are a widely studied subset: thermoresponsive polymers. Findings are also generalizable to other materials which undergo a similarly reversible volume phase transition. As of 2015, over 100,000 articles have been published on stimuli-responsive polymers and many more on protein-biomaterial interactions. Significantly, fewer than 100 of these have focused specifically on protein interactions with stimuli-responsive polymers. These report a clear trend of increased protein adsorption in the collapsed state compared to the swollen state. This control over protein interactions makes stimuli-responsive polymers highly useful in biomedical applications such as wound repair scaffolds, on-demand drug delivery, and antifouling surfaces. Outstanding questions are whether the protein adsorption is reversible with the volume phase transition and whether there is a time-dependence. A clear understanding of protein interactions with stimuli-responsive polymers will advance theoretical models, experimental results, and biomedical applications.

Non-compliance with randomised allocation and missing outcome data in randomised controlled trials evaluating surgical interventions: a systematic review

Background

Randomised controlled trials are widely acknowledged as the gold standard in medical research although their validity can be undermined by non-compliance with the randomly allocated treatment and missing data. Due to the nature of the intervention, surgical trials face particular threat to compliance and data collection. For example, ineligibility for the intervention may only become apparent once the operation has commenced. It is unclear how such cases are reported and handled.

Objective

The objective was to assess non-compliance and missing data in reports of trials of surgical interventions.

Methods

Searches for reports of trials involving at least one surgical procedure and published in 2010 were carried out in the Medical Literature Analysis and Retrieval System Online (MEDLINE^®). Data on missing data, non-compliance and methods of handling missing data were extracted from full texts. Descriptive data analyses were carried out on the data.

Results

Forty-five (55 %) studies reported non-compliance with treatment allocation and 52 (63 %) reported primary outcome missing data. The median levels of non-compliance and missing data were 2 % [IQR (0, 5), range (0–29)] and 6 % [IQR (0, 15), range (0–57)], respectively. Fifty-two (63 %) studies analysed as randomised, 17 (21 %) analysed per protocol and 3 (4 %) analysed as treated. Complete case analysis was the most common method used to deal with missing data, 35/52 (67 %).

Conclusions

The reporting of non-compliance to allocation and the handling of missing data were typically suboptimal. There is still room for improvement on the use of the CONSORT statement particularly in accounting for study participants. Transparency in reporting would facilitate evidence synthesis.

Electronic supplementary material

The online version of this article (doi:10.1186/s13104-015-1364-9) contains supplementary material, which is available to authorized users.

Antiretropulsion devices

PURPOSE OF REVIEW

Stone migration during the treatment of ureteral stones can prove frustrating and increases both healthcare cost and patient morbidity. Antiretropulsion devices have been engineered to prevent stone migration.

RECENT FINDINGS

Improvements in antiretropulsion devices allow for efficient prevention of stone migration during ureteroscopic lithotripsy with minimal adverse effects or complications. Multiple devices are now available each with advantages and disadvantages. New devices are currently engineered to prevent stone migration and maintain ureteral access. Antiretropulsion devices appear to be cost-effective to prevent stone migration during intracorporeal lithotripsy.

SUMMARY

Antiretropulsion devices have been safely and effectively used during ureteroscopic procedures. These tools increase stone-free rates, decrease morbidity and new studies have demonstrated their cost-effectiveness.

Advances in ureteroscopy

Ureteroscopy (URS) is a procedure which has been constantly evolving since the development of first generation devices 40 years ago. Progress towards smaller and more sophisticated equipment has been particularly rapid in the last decade. We review the significant steps that have been made toward improving outcomes and limiting morbidity with this procedure which is central to the management of urolithiasis and other upper urinary tract pathology.

Clinical efficacy, safety, and costs of percutaneous occlusive balloon catheter-assisted ureteroscopic lithotripsy for large impacted proximal ureteral calculi: a prospective, randomized study

PURPOSE

To evaluate the clinical efficacy, safety, and costs of percutaneous occlusive balloon catheter-assisted ureteroscopic lithotripsy (POBC-URSL) for large impacted proximal ureteral calculi.

PATIENTS AND METHODS

156 patients with impacted proximal ureteral stones ≥1.5 cm in size were randomized to ureteroscopic lithotripsy (URSL), POBC-URSL, and percutaneous nephrolithotomy (PNL) group between May 2010 and May 2013. For URSL, the calculi were disintegrated with the assistance of anti-retropulsion devices. POBC-URSL was performed with the assistance of an 8F percutaneous occlusive balloon catheter. PNL was finished with the combination of an ultrasonic and a pneumatic lithotripter. A flexible ureteroscope and a 200 μm laser fiber were used to achieve stone-free status to a large extent for each group. Variables studied were mean operative time, auxiliary procedure, postoperative hospital stay, operation-related complications, stone clearance rate, and treatment costs.

RESULTS

The mean lithotripsy time for POBC-URSL was shorter than URSL, but longer than PNL (42.6±8.9 minutes vs 66.7±15.3 minutes vs 28.1±6.3 minutes, p=0.014). The auxiliary procedure rate and postoperative fever rate for POBC-URSL were significantly lower than URSL and comparable to PNL (p<0.01, p=0.034). POBC-URSL was superior to URSL with regard to the stone clearance rate at 3 days postoperatively, and as good as PNL (98.1% vs 75.0% vs 96.2%, p<0.01). The postoperative hospital stay and hematuria rate were lower in POBC-URSL group than PNL group and similar to URSL group (p=0.016, p<0.01). The treatment costs were lowest in POBC-URSL group ($1205.0±$113.9 vs $1731.7±$208.1 vs $2446.4±$166.4, p=0.004).

CONCLUSIONS

For large impacted proximal ureteral calculi, POBC-URSL was associated with a higher stone clearance rate, fewer complications and costs. POBC-URSL combined the advantages of URSL and PNL.

In vivo evaluation of a reverse thermosensitive polymer for ureteroscopy with laser lithotripsy: porcine model

PURPOSE

To evaluate the effects of a reverse thermosensitive polymer during ureteroscopy with laser lithotripsy in an in vivo porcine model.

MATERIALS AND METHODS

Six pigs underwent general anesthesia followed by bilateral ureteroscopy with laser lithotripsy of stone phantoms while measuring intrapelvic renal pressures through bilateral nephrostomy tubes. The procedures were performed in one ureter with the reverse thermosensitive polymer and in the contralateral, control ureter without the reverse thermosensitive polymer. Stone migration lengths, operative times, laser times, laser energy usage, intrapelvic pressures, and postnecropsy histologic examinations of the ureters were compared between the two groups.

RESULTS

Bilateral ureteroscopy with lithotripsy was successfully performed in five of six pigs. In one pig, only the unilateral control was performed, because the ureter was too narrow to complete the contralateral side. The mean laser time was 12.8 minutes shorter with the use of the reverse thermosensitive polymer group than in the controls (P=0.021). The procedure time, laser energy usage, and retropulsion length was shorter in the reverse thermosensitive polymer group, but did not reach significance. Between the two groups, there was no difference in mean renal pelvic pressures, peak renal pelvic pressures, or postprocedure histologic examinations of the ureters.

CONCLUSIONS

The use of a reverse thermosensitive polymer during ureteroscopy with lithotripsy may have greater advantages beyond preventing stone retropulsion. Here, the use of a reverse thermosensitive polymer during ureteroscopy with lithotripsy resulted in a significant decrease in laser times. Further clinical investigations could further delineate the advantages of using a reverse thermosensitive polymer during intracorporeal lithotripsy.

The clinical research office of the endourological society ureteroscopy global study: indications, complications, and outcomes in 11,885 patients

PURPOSE

To assess the current indications for ureteroscopy (URS) treatment, outcome in terms of stone-free rate, and intra- and postoperative complications using the modified Clavien grading system.

PATIENTS AND METHODS

The Clinical Research Office of the Endourological Society collected prospective data as part of the URS Global Study for consecutive patients treated with URS at centers around the world for 1 year. URS was performed according to study protocol and local clinical practice guidelines. The stone size and location were recorded and postoperative outcome and complications, graded according to the modified Clavien grading system, reported.

RESULTS

Between January 2010 and October 2012, 11,885 patients received URS at 114 centers in 32 countries; 1852 had only renal stones, 8676 had only ureteral stones, and 1145 patients had both types of stone. Fragmentation was performed principally using a laser device (49.0%) or a pneumatic device (30.3%); no device was used in 17.9% of the patients. A high stone-free rate (85.6%) was achieved. The large majority of patients did not receive any further treatment for renal or ureter stones (89.4%). The postoperative complication rate was low (3.5%). The most frequent complication was fever (1.8%); a blood transfusion was required in 0.2% of patients. The majority of complications were Clavien grade I or II (2.8% of patients).

CONCLUSION

URS is an established minimal invasive treatment for urinary stones with a high success rate and low morbidity. Recent advances have expanded the indication for urinary stones, which now ranges from treatment of smaller sized distal ureter stones by semirigid URS to larger sized renal pelvis stones treated by flexible URS.

[Use of a polymeric gel to prevent retropulsion during intracorporeal lithotripsy]

INTRODUCTION

Stone retropulsion during ureteroscopic lithotripsy may lead to additional procedures needed for residual calculi. Several devices have been introduced in an attempt to reduce retropulsion. We set out to report our initial experience utilizing the new polymeric gel, BackStop.

MATERIAL AND METHODS

We prospectively collected data on 7 ureteroscopy procedures with distal ureteral calculi treated with BackStop. Perioperative data including stone size, location, operative time, stone free rate, the presence or absence of retropulsion was collected. Success was defined as no residual fragments, no retropulsion, and no additional procedures required.

RESULTS

All of the patients were rendered stone free after URS and no retropulsion occurred. There were no intraoperative complications nor gel migration or problems with dissolving the gel.

CONCLUSIONS

BackStop is a new promising therapy to prevent retropulsion during ureteral intracorporeal lithotripsy. It is safe, easy to apply and very effective in preventing stone fragment migration. BackStop has the potential to reduce operative time.

Increasing dwell time of mitomycin C in the upper tract with a reverse thermosensitive polymer

Abstract Background and Purpose: Topical chemotherapy for urothelial cancer is dependent on adequate contact time of the chemotherapeutic agent with the urothelium. To date, there has not been a reliable method of maintaining this contact for renal or ureteral urothelial carcinoma. We evaluated the safety and feasibility of using a reverse thermosensitive polymer to improve dwell times of mitomycin C (MMC) in the upper tract.

MATERIALS AND METHODS

Using a porcine model, four animals were treated ureteroscopically with both upper urinary tracts receiving MMC mixed with iodinated contrast. One additional animal received MMC percutaneously. The treatment side had ureteral outflow blocked with a reverse thermosensitive polymer plug. MMC dwell time was monitored fluoroscopically and intrarenal pressures measured. Two animals were euthanized immediately, and three animals were euthanized 5 days afterward.

RESULTS

In control kidneys, drainage occurred at a mean of 5.3±0.58 minutes. Intrarenal pressures stayed fairly stable: 9.7±14.0 cm H20. In treatment kidneys, dwell time was extended to 60 minutes, when the polymer was washed out. Intrarenal pressures in the treatment kidneys peaked at 75.0±14.7 cm H20 and reached steady state at 60 cm H20. Pressures normalized after washout of the polymer with cool saline. Average washout time was 11.8±9.6 minutes. No histopathologic differences were seen between the control and treatment kidneys, or with immediate compared with delayed euthanasia.

CONCLUSIONS

A reverse thermosensitive polymer can retain MMC in the upper urinary tract and appears to be safe from our examination of intrarenal pressures and histopathology. This technique may improve the efficacy of topical chemotherapy in the management of upper tract urothelial carcinoma.

Optimal power settings for Holmium:YAG lithotripsy

PURPOSE

We determined the optimal Ho:YAG lithotripsy power settings to achieve maximal fragmentation, minimal fragment size and minimal retropulsion.

MATERIALS AND METHODS

Stone phantoms were irradiated in water with a Ho:YAG laser using a 365 μm optical fiber. Six distinct power settings were tested, including 0.2 to 2.0 J and 10 to 40 Hz. For all cohorts 500 J total radiant energy were delivered. A seventh cohort (0.2 J 40 Hz) was tested post hoc to a total energy of 1,250 J. Two experimental conditions were tested, including with and without phantom stabilization. Total fragmentation, fragment size and retropulsion were characterized. In mechanism experiments using human calculi we measured crater volume by optical coherence tomography and pressure transients by needle hydrophone across similar power settings.

RESULTS

Without stabilization increased pulse energy settings produced increased total fragmentation and increased retropulsion (each p <0.0001). Fragment size was smallest for the 0.2 J cohorts (p <0.02). With stabilization increased pulse energy settings produced increased total fragmentation and increased retropulsion but also increased fragment size (each p <0.0001). Craters remained symmetrical and volume increased as pulse energy increased. Pressure transients remained modest at less than 30 bars even at 2.0 J pulse energy.

CONCLUSIONS

Holmium:YAG lithotripsy varies as pulse energy settings vary. At low pulse energy (0.2 J) less fragmentation and retropulsion occur and small fragments are produced. At high pulse energy (2.0 J) more fragmentation and retropulsion occur with larger fragments. Anti-retropulsion devices produce more efficient lithotripsy, particularly at high pulse energy. Optimal lithotripsy laser dosimetry depends on the desired outcome.

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.

A comparison of Stone Cone versus lidocaine jelly in the prevention of ureteral stone migration during ureteroscopic lithotripsy

BACKGROUND

Intracorporeal lithotripsy modalities and stone removal devices have been created to facilitate endoscopic management of ureteral stones. These devices, along with improved techniques, have resulted in stone-free rates greater than 95% with low morbidity. However, problems remain that preclude consistent 100% stone-free rates with endoscopic treatment of ureteral calculi. Retrograde migration during ureteroscopic procedures remains a significant problem.

OBJECTIVES

The aim of this study was to compare the Stone Cone device and instillation of lubricating lidocaine jelly as two methods to prevent retrograde stone migration during ureteroscopic lithotripsy.

PATIENTS AND METHODS

This study included patients suffering from ureteral stones that were treated with intracorporeal lithotripsy using the pneumatic Lithoclast. These patients were divided into two groups. In group I, the Stone Cone device was used, while in group II, lidocaine jelly 2% concentration was used.

RESULTS

This study included 40 patients with a mean age of 38.6 ± 9.3 years (20 patients in each group). There was no significant difference between the groups with regards to stone site, size or state of the upper urinary tract by excretory urography. The pneumatic Lithoclast allowed successful fragmentation of all calculi into small fragments. Upward stone migration did not occur in patients in the Stone Cone group, while in the lidocaine jelly group it occurred in three patients (15%). The operative time in the Stone Cone group ranged between 30 and 55 minutes (mean, 41.8 ± 5.3), while in the lidocaine jelly group it ranged between 40 and 71 minutes (mean, 51.4 ± 3.4), and this difference was statistically significant (p < 0.05).

CONCLUSION

The Stone Cone is safe and efficient in preventing proximal stone migration during ureteroscopic pneumatic lithotripsy. It maintained continuous ureteral access and demonstrated a statistically significant advantage over the lidocaine jelly in terms of proximal stone migration, operative time, and the need for auxiliary procedures.

The Use of Reverse Thermosensitive Polymer (LeGoo) for Temporary Vessel Occlusion in Clampless Peripheral Vascular Surgery

Introduction: There is a need to develop methods of vascular hemostasis, which limit vessel trauma. LeGoo is a reverse thermosensitive polymer (poloxamer) which is a viscous liquid at room temperature, becoming a firm plug at body temperature. We aimed to describe early single center experience in clampless peripheral vascular surgery. Methods: Single surgeon experience using LeGoo during peripheral vascular surgery between February and October 2010 was analyzed. Results: LeGoo was used in 13 anastomoses in 11 patients. A satisfactory bloodless field without the use of conventional occlusion devices was achieved in 92% of anastomoses. At a median of 36 weeks follow-up, total conduit patency was 91%. Conclusions: In this small series, LeGoo was seen to be safe and effective in the provision of a clamp-free bloodless field in the context of peripheral vascular surgery. Prospective comparative study is necessary to determine performance against conventional vascular clamps.

Instrumentation in endourology

Success with endourological procedures requires expertise and instrumentation. This review focuses on the instrumentation required for ureteroscopy and percutaneous nephrolithotomy, and provides a critical assessment of in vitro and clinical studies that have evaluated the comparative effectiveness of these medical devices.