Ureteroscopy for proximal ureteral calculi: prevention of stone migration

The effect of stone size on the results of extracorporeal shockwave lithotripsy versus semi-rigid ureteroscopic lithotripsy in the management of upper ureteric stones

Objectives

Patients and methods

Results

Conclusion

Inadvertent Stone Migration During Pneumatic Lithotripsy: Still a Conundrum in the 21st Century

Currently, an ideal gadget to stop retrograde stone migration remains a holy grail, and the hunt for such a device is still ongoing in the 21st century. The quest for an ideal instrument is driven by the need to reduce cost, minimize ancillary procedure rates, reduce the device's operative time, and improve the stone-free rate. The purpose of the present review is to provide an update on the use of preventive measures that are used to stop retrograde stone migration during pneumatic lithotripsy for ureteric stone management.

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

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

Dual usage of a stone basket: Stone capture and retropulsion prevention

INTRODUCTION

Stone migration during ureteroscopy (URS) for proximal ureteric calculi is a constant challenge. Several retropulsion prevention devices have been developed to optimize URS outcomes. Our technique involves capturing the stone within a four-wire Nitinol stone basket and then performing laser lithotripsy to dust the stone while it is engaged in the basket. The dusted fragments wash out with the irrigation fluid and once small enough, the remaining stone is removed intact.

METHODS

A retrospective chart review was performed of all proximal semi-rigid URS procedures for a solitary calculus (2000-2016). We compared our new technique introduced in 2010 to URS control procedures that did not use retropulsion prevention techniques or devices.

RESULTS

One hundred and forty patients underwent URS for proximal ureteric calculi. Mean stone diameter was 9.3±3.4 mm, with similar impaction rate between both groups (44.1% vs. 43.1% control; p=n/s). The mean surgical procedure time was 53.3±17.9 minutes for the new technique and 65.2±29.2 minutes for the control group (p=0.005). Compared to the new technique, the control group had a higher rate of retropulsion (33.3% vs. 14.7%; p=0.01) and required flexible URS more often to exclude or remove residual fragments (24.1% vs. 59.1%; p=0.001). Using the new technique, stone-free rates were higher (79.1% vs. 69.4%; p=n/s) and there was a lower likelihood of leaving residual fragments both <3 mm and ≥3 mm (p=0.001).

CONCLUSIONS

Our novel technique results in shorter operative times, lower retropulsion rates, and decreases postoperative residual stone fragments.

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

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

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

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

In vitro investigations of propulsion during laser lithotripsy using video tracking

OBJECTIVES

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

MATERIALS AND METHODS

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

RESULTS

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

CONCLUSION

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

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.

Does a retropulsion prevention device equalize the surgical success of Ho:YAG laser and pneumatic lithotripters for upper ureteral stones? A prospective randomized study

To establish if a retropulsion prevention device for ureteral stones equalizes surgical success and push-back rates of Ho:YAG laser and pneumatic lithotripters for upper ureteral stones. Patients with upper ureteral stones (n = 267) were treated endoscopically at the Department of Urology between April 2014 and December 2015. Patients were randomly assigned to pneumatic and Ho:YAG laser lithotripters as group-1 and group-2, respectively. Lithotripsy was performed with Stone Cone^TM in both groups. The surgical success rate on the first postoperative day was 81.5 % (n = 106) and 90.6 % (n = 116) for group-1 and group-2, respectively, and the difference between the groups was statistically significant (p < 0.05). The relation between stone size and surgical success was statistically significant for both groups (p < 0.01). Surgical success for the stones closer than 2 cm to the UPJ was 23.1 % for the pneumatic group versus 64 % for the laser group (p < 0.01). Lithotripsy time was significantly longer in group-2 (16.48 ± 4.74 min) than group-1 (12.24 ± 3.95 min) (p < 0.01). Ho:YAG laser lithotripsy is more successful than pneumatic lithotripsy for upper ureteral stones and a retropulsion prevention device does not equalize the surgical success of Ho:YAG laser and pneumatic lithotripters for upper ureteral stones on the first postoperative day and one month after surgery. Although the success rate of the first month after surgery is higher in group-2, the difference is not statistically significant.

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.

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.

Efficacy of percutaneous nephrostomy tube during ureteroscopy for upper ureter stone management

OBJECTIVE

Preoperative percutaneous nephrostomy (PCN) has been commonly performed for patients with urinary stones complicated with pyelonephritis or obstructive uropathy; in fact, a considerable number of patients undergo ureteroscopic removal of stone (URS) in the presence of a PCN. We assessed the effectiveness of PCN during URS in the management of upper ureteral stones.

PATIENTS AND METHODS

We retrospectively analyzed 140 patients who underwent URS for upper ureteral stones between January 2008 and December 2011. All URS were performed by a single experienced surgeon. The subjects were divided into two groups depending on the presence of a PCN at the time of the surgery (PCN group: 42 and non-PCN group: 98). The PCN group was subdivided into two groups depending on the performance of external fluid irrigation through PCN during the surgery (irrigation group: 21 and non-irrigation group: 21). To evaluate operative outcomes, we compared operative times, auxiliary procedures required, and success and complication rates.

RESULTS

The PCN group showed significantly better outcomes in terms of the operative time (57.4 minute vs. 68.1 minute) and success rate (92.9% vs. 78.6%) without increasing the complication rate. In the PCN group, the irrigation group showed a shorter operative time compared to the non-irrigation group, although statistical significance was not observed. Other perioperative outcomes, such as the success rate, auxiliary procedures, and complication rates, were not significantly different between the two groups.

CONCLUSION

URS for upper ureteral stones in patients with PCN produced superior surgical outcomes in terms of the success rate, operative time, and auxiliary procedure rate without increasing the complication rate. The presence of PCN with/without external irrigation during URS can be a beneficial factor to produce better outcomes of URS for the management of upper ureteral stones.

Comparing of different methods for prevention stone migration during ureteroscopic lithotripsy

AIM

To compare the effectiveness of Stone Cone™, PercSys and lidocaine jelly instillation to prevent stone migration during ureterorenoscopy (URS).

MATERIALS AND METHODS

One hundred patients who underwent URS for proximal ureteral stones between 2007 and 2012 were evaluated prospectively. The patients were divided into four groups consecutively. The control group (Group I) consisted of the 25 consecutive patients, in whom no device or method was used to prevent stone migration. Group II consisted of 25 patients treated with the Stone Cone, group III consisted of 25 patients treated with PercSys, and group IV consisted of 25 patients treated with lidocaine jelly instillation.

RESULTS

The migration rates were 4.5% in group II, 8.7% in group III, 21.7% in group IV, and 31.8% in group I. The migration rate was found to be statistically significantly lower in the groups treated with the Stone Cone and PercSys compared to the control group (p = 0.014, p = 0.048). However, there was no statistically significant difference between the lidocaine jelly group and the control group in terms of migration rates (p = 0.444).

CONCLUSIONS

Our results suggested that the Stone Cone and PercSys were the most successful methods with significantly low migration rates (4.5 and 8.7%, respectively).

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.

Stone Cone® in ureteroscopic ballistic lithotripsy of proximal ureteral stones

Stone Cone® (Microvasive-Boston Scientific Corp, USA) is a device which prevents retrograde calculus migration during endoscopic ureterolithotripsy. We have studied the safety and efficacy of this device in endoscopic ureterolithotripsy with ballistic energy in proximal ureteral stones.

Materials and Methods.

From 01/02/2006 to 01/02/2008 we carried out 36 ureterorenoscopies (URS) for proximal ureteral stones (average age: 46, range: 15–73). A ballistic energy was used for stones fragmentation. In 18 patients (Group A) we carried out URS with the aid of Stone Cone®, which was not used in the other 18 patients (Group B). Semirigid 8 Ch or 10 Ch Storz ureteroscope and ballistic lithotriptor Swiss Lithoclast Master EMS® were used. In cases of migration, edema, and ureteral damage, a ureteral stent was used.

Results.

In Group B patients (URS performed without Stone Cone®) the migration of the whole stone, or of clinically significant fragments, occurred 8 times (45%). All of these patients underwent external shockwave lithotripsy (ESWL) at a center equipped with a lithotriptor. A ureteral stent was placed in 14 cases (78%). In Group A, the migration of a stone requiring ESWL treatment occurred only once (5%). The ureteral stent was placed 8 times (45%). We had no significant complications during the procedure.

Conclusions.

The Stone Cone® is a safe and easy-to-use device. The cost of this device can be balanced by the reduction of postoperative ESWL treatments for lithiasic fragments pushing up into the kidneys (p<0.01), and of ureteral stent applications at the end of the procedure (p<0.05).

Minimally invasive management of urolithiasis

The management of urolithiasis has radically changed over the last two decades. Open surgery has been almost completely replaced by minimally invasive procedures, mainly extracorporeal shock wave lithotripsy (ESWL) and ureteroscopy (URS). Although these treatment modalities have been proven to be very safe and effective, serious complications can occur. Prompt diagnosis is often essential and may even be lifesaving. Radiologists play an important role in this setting, since many of these complications can be readily diagnosed by imaging. Awareness of the wide spectrum of complications may be crucial in interpreting imaging studies of patients who have undergone one of these procedures. This article reviews the contemporary management of ureteric stones with ESWL and URS and illustrates the radiological findings of complications of these procedures.

The evolution of ureteroscopy: a modern single-institution series

OBJECTIVES

To evaluate a modern ureteroscopy series, including the use of new technological advances, operative procedures, and potential complications, at a single institution and to compare our current experience with our prior published series and the current literature.

MATERIAL AND METHODS

We retrospectively reviewed 1000 consecutive ureteroscopies performed in 961 patients from December 1999 to February 2003 at our institution.

RESULTS

Semirigid and flexible ureteroscopes were used in 60.3% and 37.0% of the cases, respectively. In 2.6% of cases, a combination of both rigid and flexible ureteroscopes was required. The most common indications for ureteroscopy were as follows: stone, 57.9%; diagnostic, 20.6%; and urothelial carcinoma, 12.6%. Of the stones treated, 31.8% were proximal or middle and 59.1% distal. The overall, proximal, and distal stone-free rates were 91.7%, 87.3%, and 94.2%, respectively. Average operative time was 81 minutes (range, 5-280 minutes). Average follow-up was 2.36 months (range, 1-24 months). The overall complication rate was 1.9% (18/961), including a 0.2% (2/961) incidence of ureteral strictures.

CONCLUSION

Current practice trends have shifted to an increased use of flexible ureteroscopes and more frequent ureteroscopic treatment of proximal calculi. Our single treatment stone-free rates are competitive with quoted shock wave lithotripsy success. In addition, there has been a decrease in ureteroscopic-associated complications in our series, with no ureteral avulsions. The improvements in treatment success and decrease in complications may be secondary to advances in ureteroscopic technology.

Assessment of Novel Ureteral Occlusion Device and Comparison with Stone Cone in Prevention of Stone Fragment Migration during Lithotripsy

PURPOSE

To present the initial ex-vivo results of a new ureteral-occlusion device (Cook Urological, Spencer, IN) for preventing the retrograde migration of particles during ureteroscopy and its comparison with the Stone Cone (Microvasive-Boston Scientific Corp., Spencer, IN).

MATERIALS AND METHODS

We designed an ex-vivo model using a porcine kidney with an intact ureter. Standardized plastic beads were placed in the proximal ureter. Each device was deployed proximal to the beads during ureteroscopy, and the number of beads impeded by each device was recorded.

RESULTS

The new device was successful at preventing retrograde migration of beads > or = 1.5 mm. Furthermore, 1.0-mm beads were impeded by the center of the device, although they passed through the periphery. The Stone Cone blocked the retrograde migration of beads > or = 2.5 mm.

CONCLUSION

The new occlusion device was efficacious in an ex-vivo model. It appears to prevent the migration of smaller particles than are blocked by the Stone Cone.

Prevention of retrograde calculus migration with the Stone Cone

Retrograde calculus migration during ureteroscopic lithotripsy remains a problem in 5-40% of cases. We assessed the safety and efficacy of the Stone Cone device, in comparison with the standard flat wire basket. A total of 56 consecutive patients with ureteral calculi, suitable for ureteroscopic extraction and/or lithotripsy, where included in this prospective study. Patients were randomly allocated into two groups. In group A (30 patients), we used the Stone Cone, while in group B (26 patients) we used the standard flat wire basket. The Stone Cone was placed through a cystoscope under fluoroscopic guidance, or when necessary under direct ureteroscopic control. Whenever necessary, intracorporeal electrohydraulic lithotripsy took place in both groups. Statistical significance was assessed by the paired t-test. The mean operative time was 48.5 min in group A, and 42.4 min in group B. Intact calculus extraction was possible in 16.6% in group A, and in 7.6% in group B (P < 0.01). Retrograde stone migration was revealed in 23% in group B only (P < 0.001). Also, residual fragments > 3 mm were recorded in 30.7% in group B only (P < 0.001). None of the patients in group A required auxiliary procedures, in contrary to 23% in group B (P < 0.001). No major complications were recorded in group A, while in group B a case of major ureteral mucosal abrasion was recorded. The Stone Cone is safe and efficient in preventing retrograde stone migration and in minimizing residual fragments during ureteroscopic lithotripsy in comparison with the flat wire basket.

Efficacy of the Stone Cone for Treatment of Proximal Ureteral Stones

BACKGROUND AND PURPOSE

Whereas ureteroscopic lithotripsy is more efficacious than SWL in treating lower-ureteral stones, the same has not been universally said of its ability to treat proximal ureteral stones. Because failed proximal lithotripsy is often attributable to the complications associated with stone migration into the renal pelvis and calices, an instrument that can prevent this migration is a potentially important tool in the ureteroscopic armamentarium. This study sought to assess the role of just such an instrument, the Stone Cone, in proximal-ureteral lithotripsy.

PATIENTS AND METHODS

We treated 19 consecutive patients having proximal-ureteral stones using semirigid ureteroscopy, a Stone Cone Nitinol urologic retrieval coil, and holmium:YAG laser lithotripsy with a 200- or 365-microm fiber. In all patients, both the Stone Cone and the laser fiber were utilized under direct visual guidance through the working channel(s) of the ureteroscope.

RESULTS

All 19 patients were rendered stone free after Ho:YAG laser lithotripsy in conjunction with a Stone Cone. No stone fragments were noted to migrate into the renal pelvis, and the Stone Cone did not break or become entrapped in any of the 19 cases.

CONCLUSION

The Stone Cone is a powerful new tool for proximal-ureteral lithotripsy and will likely revolutionize the treatment of proximal-ureteral stones. The savings in morbidity, time, and money associated with not having to chase stone fragments using flexible ureteroscopy are considerable.