Advances in ureterorenoscopy

The Saudi urological association guidelines on urolithiasis

Aims

The Saudi Urolithiasis Guidelines are a set of recommendations for diagnosing, evaluating, and treating urolithiasis in the Saudi population. These guidelines are based on the latest evidence and expert consensus to improve patient outcomes and optimize care delivery. They cover the various aspects of urolithiasis, including risk factors, diagnosis, medical and surgical treatments, and prevention strategies. By following these guidelines, health-care professionals can improve care quality for individuals with urolithiasis in Saudi Arabia.

Panel

The Saudi Urolithiasis Guidelines Panel consists of urologists specialized in endourology with expertise in urolithiasis and consultation with a guideline methodologist. All panelists involved in this document have submitted statements disclosing any potential conflicts of interest.

Methods

The Saudi Guidelines on Urolithiasis were developed by relying primarily on established international guidelines to adopt or adapt the most appropriate guidance for the Saudi context. When necessary, the panel modified the phrasing of recommendations from different sources to ensure consistency within the document. To address areas less well covered in existing guidelines, the panel conducted a directed literature search for high quality evidence published in English, including meta analyses, randomized controlled trials, and prospective nonrandomized comparative studies. The panel also searched for locally relevant studies containing information unique to the Saudi Arabian population. The recommendations are formulated with a direction and strength of recommendation based on GRADE terminology and interpretation while relying on existing summaries of evidence from the existing guidelines.

Two-shift operation mode can improve the efficiency and comfort of flexible ureteroscopic holmium laser lithotripsy for the treatment of renal calculi larger than 1.5cm

Purpose:

To compare two-shift operation mode and single player mode different impact on surgical results and operator comfort in flexible ureteroscopic holmium laser lithotripsy for renal calculi larger than 1.5cm.

Materials and Methods:

From december 2017 to december 2018, 92 patients with renal calculi admitted to Qilu Hospital and were treated through flexible ureteroscopy. They were randomized in two-shift group (n=50) and single player group (n=42). The operative time, blood loss, hospitalization stay after operation, residual fragments (≥4mm) rate, fragmentation speed, postoperative complications and operator's fatigue score were compared.

Results:

There was no significant difference between two groups regarding age, gender, illness side, stone size, blood loss, operative time, postoperative hospitalization stay, complications, etc (p >0.05). The fragmentation speed was 44.5±20.0mm3/min in two-shift group compared with 34.2±17.3mm3/min in single player group (p=0.037). Residual fragments (≥4mm) rate after first surgery was 18% in two-shift group, while the residual fragments (≥4mm) rate was 40.5% after first surgery in single player group (p=0.017). The total fatigue score of two-shift group was 8.4 compared to 29.9 in single player group (p <0.001).

Conclusion:

In flexible ureteroscopic holmium laser lithotripsy for the treatment of renal calculi larger than 1.5cm, two-shift operation mode can raise the fragmentation speed and stone clearance rate, as well as significantly lower operator's fatigue level and improve operator's comfort.

Sheathless and fluoroscopy-free retrograde intrarenal surgery: An attractive way of renal stone management in high-volume stone centers

Objective

To evaluate the efficacy and safety of sheathless and fluoroscopy-free flexible ureterorenoscopic laser lithotripsy (FURSL) for treating renal stones.

Methods

Between May 2015 and May 2017, 135 patients with renal stones treated with sheathless and fluoroscopy-free FURSL were prospectively evaluated. Our technique involved a semi-rigid ureteroscopic assessment of the ureter, and the guidewire was left in situ to railroad the flexible ureteroscope. A holmium laser was used to fragment and dust the stones; fragments were neither grasped nor collected.

Results

The study population consisted of 135 patients including 85 males (62.96%) and 50 females (37.04%) with a mean age of 40.65 years (range: 3–70 years) were evaluated. The mean stone size was 17.23 mm (range: 8–41 mm). Complete stone-free status was achieved in 122 (90.37%) patients and clinically insignificant residual fragments (CIRF) in two (1.48%), while residual stones were still present in 11 (8.15%) patients. Postoperative complications occurred in 23 (17.4%) cases and were mostly minor, including fever in 17 (12.6%), pyelonephritis in four (3.0%), subcapsular hematoma in one (0.7%) and steinstrasse in one (0.7%). These complications were Clavien I-II, GI in 17 (12.6%) patients, GII in five (3.7%), and Clavien IIIb in one (0.7%). No major complications were observed. Stone size ≥2 cm, operative time ≥30 min, and lasing time ≥20 min were significantly associated with a higher rate of complications and lower stone-free rates upon univariate analysis (p<0.05).

Conclusion

Sheathless and fluoroscopy-free FURSL are effective and safe for renal stone management, especially for stones under 2 cm in diameter. This process is a feasible option for avoiding sheath complications, which can protect surgeons from the negative effects of radiation.

Retrograde intrarenal surgery technique without using fluoroscopy and access sheet in the treatment of kidney stones

Background/aim

In this study, we aimed to present our results on single-guidewire flexible ureteroscopy and retrograde intrarenal surgery without fluoroscopy and an access sheet, and to evaluate the efficacy and safety of this procedure retrospectively.

Material and methods

Our routine technique can be described as the evaluation of the ureter using a semirigid ureterorenoscope (URS), leading in the guidewire through the semirigid URS, pulling the semirigid URS back, inserting the flexible URS with the aid of the guidewire, inserting the laser probe through the flexible URS, and performing laser lithotripsy.

Results

Our study included 400 male and 198 female patients with a mean age of 36.8 ± 16 (14–80) years. The mean stone size was 8.7 ± 4 (8–20) mm, and the mean operation time was 56 (32–106) min. Postoperative fever was observed in 24 (4%) of the patients, and 30 (5%) patients had hematuria as a minor complication. A stone-free status was observed in 466 (78%) patients, while 102 (17%) patients had clinically insignificant minor stone fragments and 30 patients had clinically significant stone residue.

Conclusion

The retrograde intrarenal surgery procedure using only a guidewire without fluoroscopy and an access sheet in the treatment of kidney stones is technically safe and effective.

In Vitro Evaluation of Single-Use Digital Flexible Ureteroscopes: A Practical Comparison for a Patient-Centered Approach

OBJECTIVE

To compare the manufacturing and in vitro performance characteristics of two single-use flexible ureteroscopes with a permanent optical flexible ureteroscope.

MATERIALS AND METHODS

Two single-use flexible ureteroscopes, LithoVue (Boston Scientific) and Pusen (1rs. generation; Zhuhai Pusen Medical Technology Company Limited, China), were tested and compared with a permanent Flex-X² ureteroscope (Karl Storz, Germany) in terms of technical characteristics, optics, deflection mechanism, and additional parameters which could potentially affect surgical technique.

RESULTS

Pusen was the lightest ureteroscope while the LithoVue had the longest working length. LithoVue had a higher resolution power than the other two ureteroscopes at all distances tested (p < 0.001). Pusen showed higher resolution than Flex-X² (p < 0.01). Field of view was wider for LithoVue (87°), followed by Flex-X² (85°) and Pusen (75°). Color representation was superior for Flex-X² than LithoVue and then Pusen. LithoVue outperformed Pusen and Flex-X² for all settings with instruments in terms of deflection loss (p < 0.01). Pusen had the highest irrigation flow (52 mL/min) with an empty working channel (p < 0.01). LithoVue and Pusen showed similar flow rates with a 200 μm (21 mL/min) and 365 μm laser fiber (7 mL/min) and 1.3F basket (18 mL/min), being superior to Flex-X² (p < 0.01). With the 1.9F basket, LithoVue had superior flow rate (7 mL/min) than Pusen (3.5 mL/min) and Flex-X² (4 mL/min; p = 0.01).

CONCLUSION

LithoVue outperformed the other ureteroscopes in terms of optical resolution, field of view, deflection capacity, and irrigation flow with larger instruments. Pusen is the lighter scope and showed better results in terms of irrigation when no instruments are in place. Flex-X² was superior in terms of color representation.

Ureteroscopy from the recent past to the near future

Stone surgery is one of oldest surgical practices undertaken by man. Hippocrates refused to let his followers "cut for the stone" and it was only in February 1980, when the first human trial of shock wave therapy on a renal stone was performed with success that a new era in minimally invasive treatment (surgery) for stones was opened up and this condemnation was finally resolved in the Hippocratic Oath. Endoscopy, using natural orifices, supported by anaesthesia, incremented by technology and with access to all points along the urinary tract, began by competing with ESWL, but is now the treatment of choice in most cases. As far as we know humans have always had stones. First, lithiasis was endemic bladder stones in children, now it is renal in general. Added to this a number of well-known risk factors, a rapid increase in obesity in the population, as well as bariatric surgery for its treatment, are causing an increase in the prevalence and recurrence of lithiasis everywhere. A short history of the advances made with the introduction and development of the ureteroscope, along with auxiliary devices, will show why this is the preferred technique at the moment for treating lithiasis in general and for treating stones in pregnant women, children and the obese in particular. Being a minimally invasive surgery, with a low morbidity and a very high efficiency and stonefree rate, has become established as a clear future technique for both adults and children. This development is not only due to technological advancements, but also to the routine use of the Holmium: YAG LASER for intracorporeal lithotripsy, capable of destroying any stone regardless of its composition or location, surpassing the ability of any other lithotripter. It is also due to the development of devices that allow access to the ureter and all parts of the kidney, as well as auxiliary aids to assist in the handling of stones during treatment. New LASERs, robotic control of the fdURS and digital imaging, as well as disposable devices, have had and, indeed, continue to have a unique impact on future development in this field. However, success will continue to depend on the careful choice of fURS, energy source and ancillary instruments obtained by the urologist during both real life and virtual training in human simulators.

Robot-assisted flexible ureteroscopy: an update

The role of flexible ureteroscopy (FURS) in the management of nephrolithiasis has increased due to the improved armamentarium. However, FURS still represents a challenging technique limiting its diffusion. Similar to previous experiences in laparoscopy, recently developed robotic devices may significantly compensate for the ergonomic deficiencies of FURS. Based on a short description of the history of robotic devices for laparoscopy, this article summarizes all current developments of robotic FURS. In 2008, robotic FURS was first reported using the Sensei-Magellan system designed for interventional cardiology. However, with this device the ureteroscope was only passively manipulated, which represented the main reason why this project has been discontinued after 18 clinical cases. Avicenna Roboflex™ was especially developed for FURS. It consists of a surgeon's console and manipulator of a flexible ureterorenoscope. The console provides an adjustable seat with armrests and two manipulators of the endoscope: the right wheel enables deflection and the left horizontal joystick allows rotation as well as advancing and retracting the instrument. The speed of rotation and advancement can be regulated at the screen of the console. Using the IDEAL system for evaluation of new robotic devices, safety and efficacy of the system could be demonstrated in two multi-centric studies providing significant improved ergonomics for the surgeon (IDEAL stage 1 and 2). Future studies are necessary to determine the final role of robotic FURS.

Flouroscopy-free technique is safe and feasible in retrograde intrarenal surgery for renal stones

OBJECTIVE

The aim of this study was to present outcomes of our patients who had undergone retrograde intrarenal surgery (RIRS) with fluoroscopy-free technique and evaluate the efficacy and safety of the technique.

MATERIAL AND METHODS

Between January 2013 and June 2015 the outcomes of 93 patients who had undergone RIRS with fluoroscopy-free technique were retrospectively evaluated. Our RIRS technique involved preoperative assessment of ureter by semi-rigid ureteroscope, inserting guidewire through semi-rigid ureteroscope, inserting ureteral access sheath over the guidewire with the visiual guidance of semi-rigid ureteroscope, passing flexible ureteroscope through the sheath, dusting the stone with holmium laser, rechecking the ureter with semi-rigid ureteroscope and inserting double J stent through semi-rigid ureteroscope. Low-dose computerized tomography scan was performed to all patients in postoperative first month and the results were classified as stone-free (absence of any fragment), clinically insignificant residual fragments (CIRF) (≤4 mm) and residual stone.

RESULTS

Study population consisted of 62 (66.6%) male and 31 (33.3%) female patients with a mean age of 47.8±14 (range 14-93) years. Mean stone size was 14.7±5 (7-32) mm. Median operative time was 72 (30-125) minutes. Stone-free rate was achieved in 65 (69.9%) patients while CIRF was achieved in 13 (13.9%) and residual stones were detected in 15 (16.1%) patients. Five patients (5.37%) had minor complications, including hematuria and fever. No major complications were observed.

CONCLUSION

Fluoroscopy-free technique is effective and safe technique in management of renal stone. Furthermore fluoroscopy-free technique can protect the surgeon from the negative effects of radiation.

Intraluminal pressure profiles during flexible ureterorenoscopy

Background

Irrigation and instrumentation during ureterorenoscopic procedures may cause increased pressure in the renal pelvis (PP) with potential harmful adverse effects. In order to assess the pressure increases during ureterorenoscopy, we measured the intraluminal renal pelvic pressure during retrograde intrarenal stone surgery (RIRS).

Methods

Twelve patients admitted for RIRS were included. Irrigation rate was standardized to 8 ml/min. A ureteral catheter was retrogradely placed in the renal pelvis for PP measurements. PP was measured one time per second during insertion of the Storz Flex-X2 ureteroscope and during stone treatment.

Results

Baseline PP was mean 10(±4.0) mmHg. During simple ureterorenoscopy, PP was mean 35(±10) mmHg. During stone management the average PP was 54(±18) mmHg and pelvic pressure peaks up to 328 mmHg occurred. In a 5-min standardized period of simple ureterorenoscopy, 83 pressure peaks >50 mmHg were measured in average per patient (range 2–238). Forced irrigation with a 20 ml syringe resulted in pressure peaks up to 288 mmHg.

Conclusion

Very high pelvic pressures are obtained during flexible ureterorenoscopy. Taking into consideration that the threshold for pyelovenous backflow is around 30 mmHg, it is concerning that PPs >300 mmHg are not uncommon during these procedures. Methods to monitor and lower the PP during ureterorenoscopy, therefore, are considered of importance.

Retrograde intrarenal surgery for the treatment of renal stones: is fluoroscopy-free technique achievable?

The aim of this study was to present the safety and efficacy of retrograde intrarenal surgery (RIRS) procedures that minimize the intraoperative radiation exposure. The totally endoscopy-guided RIRS technique included the following steps: (a) preoperative assessment of pelvicaliceal system anatomy and stone characteristics, (b) thorough evaluation of the ureters by rigid ureteroscopy, (c) a step-wise approach of introducing the ureteral sheath, (d) gathering stones in the more accessible renal calyx before fragmenting them, and (e) a modified holmium laser technique. The RIRS procedures performed by a single surgeon between October 2012 and October 2013 in consecutive patients with renal stones were retrospectively reviewed. The mean stone size was 1.4 ± 0.4 (range 0.8-2.0) cm. The median operative time was 74.5 min. Fluoroscopy was only used in one patient who had a double collecting system with two ureters. The stone-free status was achieved in 134 (95.7%) patients one month after surgery. Five (3.6%) patients had minor complications, including hematuria and fever. No major intraoperative complication was observed. We believe that with appropriate preparation, RIRS without fluoroscopic guidance can be safely and efficiently performed by experienced urologists in selected patients with renal stones.

Invasive treatment trends in urinary calculi in a third level hospital

OBJECTIVE

In the following study, we observe the progress of various invasive calculi treatments that have taken place in our hospital in the last 15 years.

MATERIAL AND METHOD

We extracted data from our hospital database on patients who underwent extracorporeal shock wave lithotripsy (ESWL), endoscopic surgery and open surgery. We analyzed how the incidence of these treatments has evolved over the last 15 years. We also studied the number of publications in PubMed that reference invasive calculi treatments.

RESULTS

From January 1998 to December 2012, a total of 10,947 patients were treated instrumentally for lithiasis, 9,695 of whom (90.4%) underwent ESWL and 1,034 of whom underwent endoscopic or open surgery (9.6%). The incidence of lithotripsy treatments reached its maximum in 2006, with a progressive reduction thereafter. The incidence of endoscopic surgery increased progressively until 2009 and then leveled off. We can see how in recent years there has been a clear increase in the number of studies that have covered endoscopic surgery, with a decreasing number covering ESWL.

CONCLUSIONS

In our community, ESWL remains the most widely used invasive treatment for calculi. In recent years, there has been a reduction in the number of ESWL treatments and an increase in the number of endoscopic treatments, with open surgery showing a clearly decreasing trend.

Ureteroscopy and stones: Current status and future expectations

Urolithaisis is becoming an ever increasing urological, nephrological and primary care problem. With a lifetime prevalence approaching 10% and increasing morbidity due to stone disease, the role of ureteroscopy and stone removal is becoming more important. We discuss the current status of stone disease and review the ever increasing role that ureteroscopy has to play in its management. We discuss technological advances that have been made in stone management and give you an overview of when, how and why ureteroscopy is the most common treatment option for stone management. We touch on the role of robotic ureteroscopy and the future of ureteroscopy in the next 10 years.

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.

A new robot for flexible ureteroscopy: development and early clinical results (IDEAL stage 1-2b)

BACKGROUND

An improved armamentarium has had a significant impact on the emerging role of flexible ureteroscopy (FURS) for the management of nephrolithiasis; however, FURS still represents a challenging technique.

OBJECTIVE

To examine a robotic device designed for FURS for its impact on ergonomics and outcome of the procedure based on the IDEAL (idea, development, evaluation, assessment, long-term study) framework.

DESIGN, SETTING, AND PARTICIPANTS

Roboflex Avicenna consists of a surgeon's console and a manipulator for the flexible ureterorenoscope. Following experimental evaluation of the prototype (IDEAL stage 1) and receipt of ethical approval, seven surgeons treated 81 patients (mean age: 42 yr [range: 6-68]) with renal calculi (mean volume: 1296±544 mm(3) [range: 432-3100 mm3]) in an observational study (IDEAL stage 2).

SURGICAL PROCEDURE

Robotic FURS was performed with the Roboflex Avicenna robotic device.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Numerical data were analysed with the Mann-Whitney test, and categorical variables were analysed using the chi-square test or Fisher exact test. P values <0.05 were considered statistically significant.

RESULTS AND LIMITATIONS

Mean robot docking time was 59.6±45 s. Mean operative time was 74min (range: 40-182). Mean fragmentation speed was 29.1±6.1 mm3/min. Ergonomics based on a validated questionnaire showed significant advantage for robotic FURS (total score: 5.6 vs 31.3; p<0.01). A 10/12F-access sheath was used in 72 patients. Two cases required secondary FURS, one because of malfunction of the flexible digital ureteroscope and another because of larger residual fragments. In the remaining 79 cases, complete stone disintegration was accomplished.

CONCLUSIONS

Roboflex Avicenna provides a suitable and safe platform for robotic FURS with significant improvement of ergonomics. Future studies should evaluate its impact on the clinical outcome of FURS.

PATIENT SUMMARY

Robotic flexible ureteroscopy (FURS) was performed with the Roboflex Avicenna robotic device. Results showed that Roboflex Avicenna provides a suitable and safe platform for robotic FURS with significant improvement of ergonomics.

Flexible ureterorenoscopy: Tips and tricks

With advancement in technology, improvement in endoscope and ancillary equipment, more complex procedures can be performed using flexible ureterorenoscopy. In this review article we provide a summary of flexible ureterorenoscopic procedures with “tips and tricks” for success for each type of procedure. It looks at the disposables used with flexible ureterorenoscopic procedures, set up and patient positioning for gaining access, insertion and handling of scope and the use of urethral access sheath. We also provide techniques for various flexible ureterorenoscopic procedures including management of renal stones, calyceal diverticula and upper tract urothelial tumours.

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.

Hand problems among endourologists

BACKGROUND AND PURPOSE

Endourology has evolved rapidly for the management of both benign and malignant disease of the upper urinary tract. Limited data exist, however, on the occupational hazards posed by complex endourologic procedures. The aim of this study was to determine the prevalence and possible causes of hand problems among endourologists who routinely perform flexible ureteroscopy compared with controls.

MATERIALS AND METHODS

An online computer survey targeted members of the Endourological Society and psychiatrists in academic and community settings. A total of 600 endourologists and 578 psychiatrists were contacted by e-mail. Invited physicians were queried regarding their practice settings and symptoms of hand pain, neuropathy, and/or discomfort.

RESULTS

Survey responses were obtained from 122 (20.3%) endourologists and 74 (12.8%) psychiatrists. Of endourologists, 61% were in an academic setting and 70% devoted their practice to endourology. Endourologists were in practice for a mean 13 years, performing 4.5 ureteroscopic cases per week with a mean operative time of 50 minutes. Hand/wrist problems were reported by 39 (32%) endourologists compared with 14 (19%) psychiatrists (P=0.0486, relative risk [RR]=1.69). Surgeons who preferred counterintuitive ureteroscope deflection were significantly more likely to have problems (56%) compared with intuitive users (27%) (RR 2.07, P=0.0139) or those with no preference (26%) (RR 2.15, P=0.0451). Overall, most respondents (85%) with hand/wrist problems needed either medical or surgical intervention.

CONCLUSIONS

Hand and wrist problems are very common among endourologists. Future studies are needed to develop more ergonomic platforms and thereby reduce the endourologist's exposure to these occupational hazards.

Subcapsular renal haematoma after holmium:yttrium-aluminum-garnet laser ureterolithotripsy

OBJECTIVE

To report the incidence, risk factors, and outcomes of subcapsular renal haematoma (SRH) after ureteroscopic lithotripsy (URSL) using holmium:yttrium-aluminum-garnet (Ho:YAG) laser to treat ureteric stones.

PATIENTS AND METHODS

Prospective data from 2848 URSLs performed between January 2003 and September 2010 were retrospectively analysed. In all 11 patients were identified as having a SRH after URSL if they had persistent severe ipsilateral flank pain or a palpable mass within a day of surgery, or presented with radiographic evidence of a SRH. Risk factors for the development and course of the SRH were reported.

RESULTS

Of the 2848 consecutive patients treated with URSL using Ho:YAG laser, 11 (0.4%) developed a SRH after surgery. Patients who developed a SRH had larger stones (1.4 vs 0.9 cm, P < 0.001), more severe ipsilateral hydronephrosis (P < 0.001), longer operation duration (41 vs 33 min, P < 0.001), and higher perfusion pressure of hydraulic irrigation (176.8 vs 170.2 mmHg, P < 0.001) than patients who did not develop a SRH. Patient age, sex, body mass index, presence of diabetes mellitus, history of urolithiasis and hypertension, presence of multiple stones, stone location and flow rate of hydraulic irrigation were not statistically different in patients who did or did not develop a SRH. Most patients were managed conservatively, with no further intervention or with a flank drain, until the SRH resolved. Overall, in three patients the SRH resolved with no further intervention, six patients were treated with a drain only, and two patients had open surgery within a day of presenting with SRH.

CONCLUSIONS

The rate of development of SRH after URSL is very low. Most patients who present with a SRH after URSL, can be treated conservatively with no intervention or with a drain only.

Effect of pulse energy, frequency and length on holmium:yttrium-aluminum-garnet laser fragmentation efficiency in non-floating artificial urinary calculi

BACKGROUND AND PURPOSE

Holmium:yttrium-aluminum-garnet (Ho:YAG) laser lithotripsy is the standard lithotrite in ureteroscopy. We investigated the influence of pulse frequency, energy and length on the fragmentation efficiency of Ho:YAG laser lithotripsy in non-floating artificial stones in vitro.

MATERIALS AND METHODS

Stone fragmentation efficiency of three different Ho:YAG laser devices were evaluated in vitro at different pulse energy (1.0 and 2.0 J) and frequency settings (5 and 10 Hz), resulting in a standardized output power of 10W, respectively. Where possible, pulse length was modified (350 vs 700 microsec). Each setting was performed with a 273 microm and a 365 microm fiber. Lithotripsy was conducted using non-repulsive stones consisting of soft stone (plaster of Paris) and hard stone composition (Fujirock type 4).

RESULTS

Our results showed an increased stone disintegration efficiency at higher pulse energy (2.0 J/5 Hz vs 1.0 J/10 Hz) independently of two fiber diameters and stone types applied in this study (P < 0.05 in 18 of 20 groups). Similarly, reduction of the pulse length from 700 to 350 microsec resulted in a higher stone disintegration (P < 0.05 in 13 of 16 groups). This effect was most prominent when applied to soft stones. Higher fiber diameter was not constantly associated with an increase in stone disintegration.

CONCLUSION

We demonstrate that an increase of pulse energy and a reduction of pulse length at a standardized output power of 10W can improve Ho:YAG laser fragmentation efficiency in vitro in nonfloating stones. These results may potentially affect clinical practice of Ho:YAG laser lithotripsy in impacted or large stones, when retropulsion is excluded.

Clinical application of percutaneous nephrostomy in some urologic diseases

Percutaneous nephrostomy was applied in some other urologic diseases and the efficacy was evaluated. Percutaneous nephrostomy for percutaneous nephrolithotomy (PNL) was performed in patients with various renal, perinephric and bladder diseases (n=79). The tract establishment, operation duration and complications were observed and the efficacy was assessed. The results showed that the tracts were successfully established in 79 cases. The operation lasted 4-20 min. 12F-16F single tract was established in nephrohydrop patients and 16F-20F single or multiple tracts were established in patients with pyonephrosis, renal cortical abscess, renal cyst and perinephric abscess. During dilation, no leakage of liquor puris was noted. Establishment of 18F single tract was achieved in one urinoma patient. In two patients with foreign body in kidney, the foreign bodies were removed via established 14F single tract. 18F tracts were established in 2 patients with bladder contracture, which was followed by the placement of 16F balloon urethral catheter for drainage. No complications, such as massive bleeding, intestinal injury and spreading of infection took place in our series. All the patients were followed up for 2-12 months. No long-term complications such as dropping of drainage tube occurred. It is concluded that as a minimally invasive technique, percutaneous nephrostomy has the advantages of convenience, simplicity and causing less complications and can be used for various urologic diseases.