The Clinical Research Office of the Endourological Society Ureteroscopy Global Study: Indications,Complications,and Outcomes in 11,885 Patients

Abstract

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.

Introduction

Nephrolithiasis is a common disease with the incidence peaking at the third to fourth decade of life.¹ Risk factors for the development of urinary stones include socioeconomic status, environmental factors, genetic predisposition, and certain metabolic disorders.² Management of the disease ranges from observation (active monitoring with or without expulsive treatment using different drugs) to extracorporeal shockwave lithotripsy (SWL) and surgical stone removal.^3

–6 Influencing the choice of treatment is a number of factors, including stone size, symptom severity, degree of obstruction, kidney function, stone location, and urinary tract infection status.^5,6

The European Association of Urology (EAU) guidelines on urolithiasis report that 95% of stones up to 4 mm pass within 40 days and recommend that, in patients with newly diagnosed ureteral stones <10 mm and if active removal is not indicated, then observation with periodic evaluation should be conducted.⁷ Appropriate medical therapy, such as an alpha-blocker, to facilitate stone removal should be offered.^7,8 The EAU guidelines state the indications for active removal of ureteral stones as being stones with a low likelihood of spontaneous passage, persistent pain despite adequate pain medication, persistent obstruction, and renal insufficiency.⁷ Indications for active removal of kidney stones include stone growth, stones in high-risk patients for stone formation, obstruction caused by stones, infection, symptomatic stones (e.g., pain, hematuria), stones >15 mm, stones <15 mm if observation is not the option of choice, patient preference, comorbidity, social situation of the patient (e.g., profession, travelling), and >2–3 years stone persistence.⁷

During the past 20 years, ureteroscopy (URS) has dramatically changed the management of ureteral calculi. Major technical improvements include endoscope miniaturization, enhanced optical quality and tools, and introduction of disposables. URS has had a great impact on active stone removal and is performed increasingly worldwide. The EAU guidelines specify that apart from general problems, for example, with general anesthesia or untreated urinary infections, URS can be performed in all patients without any specific contraindications.⁷ Specific problems such as ureteral strictures may prevent successful retrograde stone management. Specific recommendations are made with regard to stone size and location.⁷ The AUA/EAU joint guidelines describe that in patients for whom active stone removal is recommended, proximal stones <10 mm should be removed using SWL, while those >10 mm should be removed using URS or SWL. For distal ureter stones <10 mm, URS or SWL are recommended, while for stones >10 mm, URS is first choice treatment based on improved stone-free rates.⁹

There are some fundamental (institutional) differences concerning indication for URS surgery, equipment used, and possible outcomes.⁴ Moreover, specific factors may influence treatment-related morbidity. The clinical research office of the Endourological Society (CROES) initiated the URS Global Study to establish a prospective global database to examine these aspects. In this communication, we report the overall results for indications, complications, and outcomes in 11,885 patients reported by the centers participating in the CROES URS Global Study. This is the first in a series of articles that will be presented from the study.

Patients and Methods

This was a prospective, observational, international, multicenter study that involved the collection of data on consecutive patients treated at the participating centers over a 1-year period.

Study objectives

The primary study objectives were to assess the current indications for URS treatment, outcome in terms of stone-free rate, and intra- and postoperative complications using the modified Clavien grading system.

Study organization

CROES launched the URS Global Study in January 2010. CROES invited the authors to form an International Representative Steering Committee that would be responsible for managing the CROES URS Global Study. The authors were members of the Endourological Society and their selection for the Steering Committee was due to their recognition as experts in URS treatment. Centers, specifically urology departments that had expertise in URS, were invited to participate in this prospective study. The invitation to each center was to include all consecutive patients who were treated over a 1-year period; the treatment of the first patient indicated the start of the study period at each site. The overall study period was from January 2010 to October 2012.

Inclusion criteria and treatment protocol

Patients eligible for inclusion were those who were candidates for URS, for ureter stones and renal stones, as a primary treatment or after failure of a previous treatment. No specific exclusion criteria were applied. For semirigid URS, guidewire and occasionally dilatation were employed; stone disintegration was conducted using the equipment locally available and might include laser and/or ballistic devices. For flexible URS, guidewire and access sheath were used depending on the local protocol. Stone removal was conducted using stone retrieval devices, with insertion of an internal drain postremoval depending on local protocols.

Patient follow-up

Patients were assessed postprocedure according to the local protocol, which included the kidneys, ureter, and bladder and/or ultrasound or computed tomography scan of the abdomen. The classification of a patient being stone free was based on the absence of stones or fragments larger than 1 mm. Intraoperative details and postoperative outcome were assessed, including complications graded according to the modified Clavien system.¹⁰

Secondary treatment

Secondary treatment was considered necessary if significant remnant stones were present, if the upper urinary tract was obstructed by the remaining stones, or for other reasons, dependent on the clinical judgment of the treating physician. Secondary treatment involving repeated URS or SWL was selected based on clinical assessment.

Data collection

Data were collected electronically through a web-based website: www.croesoffice.org and held in a central database at the CROES office. Data were managed as reported previously.¹¹ Data included patient epidemiological characteristics, calculus specification, type of treatment, and postoperative outcomes and complications. Centers were asked to treat patients according to the local protocols. The database was censored for inclusion in October 2012. Audit took place according to the rules of CROES.¹² Subsequently, the database was locked, checked for consistency, and cleaned.

Data analysis

The data were analyzed using SPSS version 19.0. All data are descriptive and based on frequencies. The data collected did not represent 100% of patients. Where data were missing, the number of patients for whom the values were missing or not available was stated. Percentages were calculated based on the total cohort.

Results

Between January 2010 and October 2012, 11,885 patients received URS during a 1-year period at 114 centers in 32 countries. The number of participating centers and patients per country are shown in Table 1 and the Appendix.

Table 1.

Number of Centers and Cases Enrolled Per Country in the URS Global Study

	Centers (n)	Patients (n)
Argentina	3	342
Australia	1	59
Austria	1	50
Canada	2	163
Chile	5	203
China	3	318
Czech Republic	1	195
Denmark	2	194
Egypt	2	398
France	2	260
Germany	5	734
Greece	7	421
India	7	1521
Iran	2	1102
Israel	2	120
Italy	11	778
Japan	2	355
Lithuania	1	98
Mexico	2	39
Poland	1	43
Romania	5	1071
Russia	3	377
Serbia	1	50
Spain	6	371
Sweden	1	83
Switzerland	1	54
The Netherlands	3	309
Tunisia	1	40
Turkey	17	1295
USA	10	678
UK	3	142
Venezuela	1	22
Total	114	11,885

URS=ureteroscopy.

Patient characteristics

The distribution of the cases according to age, gender, body mass index (BMI), and clinical details are presented in Table 2. The peak distribution of patients was in the age range 51–60 years with a predominance of males in the entire cohort 64.9%. With a mean BMI of 26.8 recorded, the study group was on average of normal weight. Almost one-third of the patients had the significant comorbidity of cardiovascular disease and 10.7% were diagnosed with diabetes mellitus. For the majority of patients (67.6%), this was their first-line treatment of their stone disorder. Previous stone treatments undertaken included percutaneous nephrolithotomy (PCNL), SWL, URS, ureterolithotomy, pyelolithotomy, or ureteropelvic junction pyeloplasty. A doubleJ stent had been placed previously in 2341 (19.7%) cases and 471 (4.0%) cases had a previous nephrostomy. There was a low incidence of anatomic kidney abnormalities (3.4%). The majority of patients had an American Society of Anesthesiologists (ASA) score of I or II (84.2%). In 827 (7.0%) patients, a positive urine culture was found preoperatively.

Table 2.

Baseline Characteristics of Cases Enrolled in the URS Global Study

Characteristic	No. (%) (unless indicated)
No. cases	11,885
Age (years): mean (SD); median (range)	48.7 (15.8); 49.0 (1–97)
Age distribution (years)
0–10	91 (0.8)
11–20	214 (1.8)
21–30	1322 (11.1)
31–40	2179 (18.3)
41–50	2578 (21.7)
51–60	2671 (22.5)
61–70	1724 (14.5)
71–80	918 (7.7)
81–90	174 (1.5)
91–100	9 (0.1)
Missing	5 (0.1)
Gender
Male	7709 (64.9)
Female	4168 (35.1)
Missing	8 (0.04)
BMI: mean (SD); median (range)	26.8 (5.3); 26.2 (9.7–86.4)
Underweight	253 (2.1)
Normal weight	3558 (29.9)
Overweight	4311 (36.3)
Obese	1985 (16.7)
Missing	1778 (15)
Comorbidity
DM	1269 (10.7)
Cardiovascular disease	2994 (25.2)
Prednisone	106 (0.9)
Crohn's disease	59 (0.5)
Anticoagulation	702 (5.9)
Missing	179 (1.5)
Previous calculus treatment (in the same renal unit)^a
PCNL	611 (5.1)
SWL	2241 (18.9)
Ureterolithotomy	129 (1.1)
URS	1599 (13.5)
Pyelolithomy	152 (1.3)
UPJ pyeloplasty	31 (0.3)
None	8034 (67.6)
Not available	48 (0.4)
Missing	75 (0.6)
Solitary kidney	313 (2.6)
Renal congenital abnormality
Horse shoe	45 (0.4)
Ectopic	28 (0.2)
Malrotation	17 (0.1)
ASA score
n=11,087
I	6003 (50.5)
II	4000 (33.7)
III	1021 (8.6)
IV	63 (0.5)
Not available	738 (6.2)
Missing	60 (0.5)

More than one treatment feasible.

SD=standard deviation; BMI=body mass index; DM=diabetes mellitus; PCNL=percutaneous nephrolithotomy; SWL=extracorporeal shockwave lithotripsy; URS=ureteroscopic stone removal; UPJ=ureteropelvic junction; ASA=American Society of Anesthesiologists.

Intraoperative characteristics

Of the total population of 11,885 patients, 1852 (15.6%) had only renal stones, 8676 (73.0%) had only ureteral stones, 1145 (9.6%) patients had both types of stone, of 199 (1.7%) patients, the stone location could not be indicated and of 13 (0.1%), the stone location was missing. Renal stones were located in the upper pole in 713 patients (6.0%), in the middle pole in 876 patients (7.4%), in the lower pole in 1688 patients (14.2%), and in the renal pelvis in 882 (7.4%) patients. The ureteral stones were located proximal in 3101 (26.1%) patients, middle in 2390 (20.1%) patients, and distal in 5020 (42.2%) patients. Antibiotics were given in only 82.2% of the patients. The semirigid URS was primarily used (73.9%), followed by the flexible URS (15.0%) or a combination of both techniques (10.7%). The flexible URS was never used in a quarter of the centers (28/114), probably because the flexible URS was not available. Access techniques used were predominantly through guide wire (62.0%), followed by a dilation technique (33.7%). Once access was obtained, 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. Operative procedures were considered uneventful in the majority of patients (93.7%). There was a low incidence of significant bleeding (1.4%), perforation (1.0%), and failure to complete the operation (1.6%) (Table 3).

Table 3.

Intraoperative Characteristics of Cases Enrolled in the URS Global Study

Intraoperative characteristic	No. (%) (unless indicated)
Operation time (min): mean (SD); median (range)	48.6 (32.5); 40.0 (5–300)
Antibiotic use
Yes	9770 (82.2)
No	1981 (16.7)
Not available	134 (1.1)
Type of ureteroscope
Semirigid	8782 (73.9)
Flexible	1781 (15.0)
Both	1274 (10.7)
Not available	31 (0.3)
Missing	17 (0.1)
Access
Guide wire	7370 (62.0)
Dilation (e.g., balloon)	4004 (33.7)
None	486 (4.1)
Not available	12 (0.1)
Missing	13 (0.1)
Fragmentation device
Laser	5820 (49.0)
Pneumatic	3600 (30.3)
Ultrasonic device	138 (1.2)
Electrohydraulic lithotripsy	34 (0.3)
All combinations	47 (0.4)
None	2132 (17.9)
Not available	83 (0.7)
Missing	31 (0.3)
Intraoperative complication^a
Uneventful	11,131 (93.7)
Failed	188 (1.6)
Bleeding	166 (1.4)
Perforation	122 (1.0)
Other	153 (1.3)
Not available	158 (1.3)
Converted	11 (0.1)
Avulsion	12 (0.1)
Missing	25 (0.2)

More than one complication feasible.

Postoperative outcomes

A summary of postoperative outcomes is shown in Table 4. A high stone-free rate (85.6%) was achieved, but stones were impacted in 27.2% of patients and the intraoperative migration rate was 9.5%. Ureteral stents were inserted in the majority of patients (81.4%). 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). Five patients had a Clavien grade V; causes of death were sepsis, lung embolism, cardiac death, multiorgan dysfunction, and sudden death from arrhythmia. At 3 months, 8.4% of patients were readmitted to the hospital for a range of complications, including flank pain and ureteral stent discomfort.

Table 4.

Postoperative Characteristics of Cases Enrolled in the URS Global Study

Characteristic	No. (%)
Stone impaction	3231 (27.2)
Not available	244 (2.1)
Intraoperative migration	1131 (9.5)
Not available	186 (1.6)
Stone free	10,169 (85.6)
Not available	257 (2.2)
Ureteral stent inserted	9669 (81.4)
Not available	26 (0.2)
Stent type
DoubleJ	7984 (82.6)
Ureteric catheter	1515 (15.7)
SingleJ	148 (1.5)
Not available	8 (0.1)
Missing	14 (0.1)
Retreatment^a
None	10,629 (89.4)
URS	435 (3.7)
SWL	410 (3.4)
PCNL	100 (0.8)
Other	124 (1.0)
Not available	220 (1.9)
Missing	25 (0.2)
Blood transfusion	26 (0.2)
Patients experiencing any complication	420 (3.5)
Not available	50 (0.4)
Complications^a
Fever	210 (1.8)
Other	129 (1.1)
UTI	116 (1.0)
Bleeding	53 (0.4)
Bladder cramps	52 (0.4)
Sepsis	38 (0.3)
Acute abdomen	5 (0.04)
Lung embolism	2 (0.02)
CVA/TIA	2 (0.02)
Acute MI	1 (0.01)
Clavien grading score
0	11,415 (96.0)
I	169 (1.4)
II	159 (1.3)
III	61 (0.5)
IV	14 (0.1)
V	5 (0.02)
Missing	12 (0.04)
Antibiotics at discharge
Yes	8776 (73.8)
No	2989 (25.1)
Missing	120 (1.0)
Imaging for post-treatment evaluation^a
None	617 (5.2)
Ultrasound	5996 (50.5)
X-ray/KUB	5880 (49.5)
CT	1271 (10.7)
IVU	488 (4.1)
Retrograde pyelogram	289 (2.4)
Intraoperative confirmation	1684 (14.2)
Other	113 (1.0)
Not available	146 (1.2)
Missing	97 (0.8)
Readmission within 3 months	1002 (8.4)
Not available	685 (5.8)
Cause of readmission^a
Ureter obstruction	62 (0.5)
Ureteral stricture	36 (0.3)
Ureteral stent discomfort	102 (0.9)
Flank pain	127 (1.1)
Bleeding	26 (0.2)
Sepsis	50 (0.4)
Other	672 (5.7)
Not available	21 (0.2)
Missing	2 (0.02)

More than one option feasible.

UTI=urinary tract infection; CVA=cerebrovascular accident; TIA=transient ischemic attack; MI=myocardial infarction; KUB=kidneys, ureter, and bladder; CT=computed tomography; IVU=intravenous urogram.

Discussion

According to the EAU guidelines on urolithiasis, URS can be used in all patients without specific contraindications to treat renal and ureteral stones.⁷ Of the total population of 11,885 patients in the URS Global Study, 1852 (15.6%) had only renal stones, 8676 (73.0%) had only ureteral stones, and 1145 (9.6%) patients had both types of stone. In the case of renal stones, stones were evenly divided over all renal locations and similarly for the ureteral stones. The large majority of ureteroscopic procedures employed a semirigid device alone (73.9%) or with a flexible ureteroscope (10.7%), while a flexible ureteroscope alone was used in 15.0% of procedures. These figures mirror the data on stone location. These findings indicate that URS can be used with the semirigid and flexible ureteroscopes to treat stones in most locations for both ureteral and renal stones.

The mean and median values of BMI in treated patients in the study show that they were in the normal weight range. The high value of obese patients (16.7%) with an upper limit of range at 86.4 shows that URS was used in morbidly obese patients. Previous studies reveal successful treatment of such patients. Dash and colleagues¹³ reported on the use of URS in obese patients with renal calculi and compared outcome with normal weight patients and found no difference in success rates. Andreoni and colleagues¹⁴ also reported successful outcomes in obese and morbidly obese patients with renal stones up to 15 mm in size. Other patient characteristics in the current study indicate a high rate of morbidity due to diabetes mellitus (10.7%) and cardiovascular disease (25.2%); anticoagulant use was reported in 5.9% of patients. Previous stone treatment was reported in 31.4% of patients, which comprised primarily of SWL (18.9%) and URS (13.5%). The majority of patients had an ASA score of I and II (84.2%) and there was a low rate of renal abnormalities in the study cohort.

Stents were employed postoperatively in 84.1% of procedures. This contrasts with current literature, which reveals that for uncomplicated URS, there is no increased risk of obstruction or colic if the ureter is left unstented.^15

–18 A comprehensive review by Haleblian and colleagues¹⁹ also reported that stenting was not mandatory after uncomplicated URS, with more bladder and lower urinary tract symptoms being reported when stents were placed. Nevertheless, the review showed that in certain patients at increased risk of complications, such as pregnant women, stenting was beneficial. The EAU 2012 guidelines also recommend that stenting is optional after uncomplicated URS.⁷

The reported rate of intraoperative stone migration in the current study was 9.5%. A number of techniques have been introduced to reduce the rate of migration. These include the Accordion,^20,21 the Backstop,²² the Dretler stone cone,^23,24 the Escape basket,²⁵ and the Ntrap.²⁶ In general, these devices act as a backstop during lithotripsy once deployed within the ureter and are connected to a guide wire or catheter. They also assist in extracting significant fragments after fragmentation.

In the majority of patients, stone fragmentation was achieved using lasers (49%) or pneumatic disruption (30.3%). According to the EAU guidelines, for flexible URS, the Ho:YAG laser is preferred.⁷ The primary intraoperative complications reported were bleeding (1.4%) and perforation (1.0%); ureteral avulsion was reported in 0.1% of patients. Five patients died after URS. The perforation, avulsion, and bleeding rates are in line with those previously reported.^27,28 Antibiotics were administered at patient discharge in 73.8% of patients in accordance with the EAU guidelines, which recommend the administration of short-term antibiotic prophylaxis.⁷

A stone-free rate of 85.6% overall, for renal and ureteral stones, was reported in the URS Global Study. Stone-free rates for ureteral stones using URS range from 81% to 97% according to the location of the stone (distal, mid, or proximal ureter) and size (<10 and >10 mm).⁷ The highest rates reported were for stones in the distal ureter and sized <10 mm. For renal stones, evidence implies that no significant difference in stone-free rates exists between lower pole and nonlower pole renal stones.^29
–31 Again, with renal stones, the impact of large stone size on stone-free rates is well accepted with the stone size being inversely proportional to the stone-free rate.³² In the current study, the success of the treatment is reflected in the observation that 89.4% of patients did not require retreatment. A retreatment rate of 2.2% for ureteral stones treated with URS has been reported.³³

The postoperative complication rate was low at 3.5%; fever was reported in 1.8% of patients and was comparable to that in other studies.²⁷ The rate of bleeding at 0.4% was lower than the 2% rate of persistent hematuria previously published.²⁷ Notably, 96% of patients had no reported complications (Clavien grade 0). The Clavien classification of complications post-semirigid URS was reported by Mandal and colleagues,³⁴ who showed a 30% complication rate at a resident training center; 98% of these were grade 1–3 and <2% were grade 4. A stricture rate of 0.3% resulted in hospital readmission. Again, ureteral stricture has previously been reported as a late complication in 0%–4% of cases, with comparable rates of <1% in the more recent studies, and may be due to ureteral trauma from instrumentation or calculus impaction.²⁸

Very few centers participating in the study enrolled fewer than 50 patients. Evidence suggests that optimal outcomes can be achieved in centers that focus on URS and provide a dedicated center for the procedure.³⁵ A recent review also shows that predictive factors for success or complications of URS include technological advancement and surgeon experience.³⁶

Conclusion

In URS, for urinary stones, semirigid URS is the dominant form of treatment. Recent advances in flexible instruments, however, have expanded the indications for urinary stone treatment. At present, the indications include treatment of smaller sized distal ureter stones by semirigid URS to larger sized renal pelvis stones treated by flexible URS. Widening of the indication for URS is at the cost of PCNL and SWL, as URS is a minimal invasive treatment for urinary stones with a high success rate and low morbidity.

Footnotes

Acknowledgment

The URS Global Study was supported by an unrestricted educational grant from Boston Scientific.

Disclosure Statement

No competing financial interests exist.

Appendix. CROES URS Global Study

Country	Center	Principal investigator
Argentina	Centro de Urologia-CDU	Barusso
Argentina	Hospital Italiano de Buenos Aires	Daels
Argentina	Urosalud	Labate
Australia	Westmead Hospital and University of Sydney	Bariol
Austria	Medical University of Vienna	Klingler^a
Canada	McGill University Health Centre	Andonian
Canada	Western University, St. Joseph's Hospital	Razvi
Chile	Clinica Alemana de Santiago	Krebs
Chile	Clínica Las Condes Santiago	Zambrano
Chile	Hospital Militar de Santiago	Coz
Chile	Hospital San Borja Arriaran	Silva
Chile	University of Chili, Clinic Hospital Santiago	Marchant
China	Changhai Hospital	Sun
China	First Hospital of Tsinghua University	Li
China	Renji Hospital	Xue
Czech Republic	University Hospital Brno, Medical School Masaryk University	Pacik
Denmark	Århus University Hospital Skejby	Fuglsig
Denmark	Fredericia Hospital, University of Southern Denmark	Osther
Egypt	University of Tanta	El-Abd
Egypt	Urology and Nephrology Center, Mansoura University	EL-Nahas
France	Nouvel Hôpital Civil les Hôpitaux Universitaires	Saussine
France	University Pierre et Marie Curie Paris 6	Traxer
Germany	Academic Hospital Braunschweig	Hammerer
Germany	Asklepios Hospital Barmbek	Knipper
Germany	Sindelfingen-Boblingen Medical Center	Wendt-Nordahl
Germany	SLK-Klinikum am Gesundbrunnen	Klein
Germany	University Medical Center Marburg	Olbert
Greece	Aristotle University of Thessaloniki	Toutziaris
Greece	General Hospital Of Veria	Sountoulidis
Greece	Laiko Hospital, University of Athens Medical School	Stravodimos
Greece	Athens Medical School, Sismanoglio Hospital	Skolarikos
Greece	University Hospital of Heraklion	Mamoulakis
Greece	University Hospital of Thessaly	Melekos
Greece	University of Patras	Liatsikos
India	Fortis Raheja Hospital	Shah^b
India	Institute of Urology, Division of Tejnaksh Healthcare	Ashish Rawandale-Patil
India	Muljibhai Patel Urological Hospital	Desai
India	RG Stone Urology and Laparoscopy hospital Mumbai	Sodha
India	RG Stone Urology and Laparoscopy Hospital New Delhi	Varshney
India	Shyam Urosurgical Hospital	Parikh
India	Vedanayagam Hospital and Postgraduate Institute	Kandasami
Iran	Hasheminejad Hospital	Etemadian
Iran	Labbafinejad Hospital	Basiri
Israel	Hadassah Ein-Kerem University Hospital	Duvdevani
Israel	Rambam Medical Center	Meretyk
Italy	AOS Paolo Teaching Hospital, University of Milan	Montanari
Italy	Azienda Ospedaliero Universitaria di Parma	Frattini
Italy	Careggi Hospital, University of Florence	Crisci
Italy	Catholic University School of Medicine	D'Addessi
Italy	I.C. Humanitas, IRCCS	Giusti
Italy	San Bassiano Hospital	Celia
Italy	Second University Hospital Naples	De Sio
Italy	University of Cagliari	De Lisa
Italy	Vittorio Emanuele Hospital	Saita
Italy	University of Foggia	Cormio
Italy	University San Luigi Gonzaga	Scarpa
Japan	Hachinohe Heiwa Hospital	Miura
Japan	Kansai Medical University	Fukui
Lithuania	Vilnius university, Republic Vilnius University Hospital	Gaizauskas
Mexico	Centro Medico Puerta de Hierro and Nuevo Hospital Civil	Gutierrez-Aceves^c
Mexico	Hospital Regional de Alta Especialidad del Bajío	Negrete
Poland	Central Railway Hospital	Dobruch
Romania	Emergency County Hospital	Mitroi
Romania	Oncological Institute Cluj-Napoca	Petrut
Romania	Prof Dr Th Burghele Hospital	Jinga
Romania	Saint John Emergency Clinical Hospital	Geavlete
Romania	Timisoara Clinical Emergency Hospital	Bucuras
Russia	Moscow City Urological Hospital	Martov
Russia	First City Hospital	Zenkov
Russia	Yekaterinburg City Hospital	Frank
Serbia	Clinical Centre of Vojvodina	Marusic
Spain	Clinica La Luz	Perez-Castro
Spain	Hospital Clínico Universitario “Lozano Blesa”	Zalabardo
Spain	Hospital Galdakao-Usansolo	Palacios-Ramos
Spain	Hospital General Royo Villanova	Rioja Sanz
Spain	Hospital Mateu Orfila	Bercowsky
Spain	Hospital Miguel Servet de Zaragoza	Rioja Zuazu
Sweden	Orebro University hospital	Popiolek
Switzerland	University of Bern, Inselspital	Thalmann
The Netherlands	Hospital Rijnstate	Roelofs
The Netherlands	AMC University Hospital	de la Rosette
The Netherlands	Atrium Medisch Centrum	Strijbos
Tunisia	Charles Nicolle Hospital	Bouzouita
Turkey	Akdeniz University Hospital	Erdogru^d
Turkey	Cerahpasa School of Medicine Istanbul	Onal
Turkey	Ege University School of Medicine	Turna
Turkey	ESOGU Medical Faculty Urology	Baseskioglu
Turkey	Fatih University	Unal
Turkey	Gulhane Military Medical Academy	Ozgok
Turkey	Hacettepe University School of Medicine	Bilen
Turkey	Haseki Training and Research Hospital	Muslumanoğlu
Turkey	Istanbul Bilim University School Of Medicine	Kural^e
Turkey	Istanbul Goztepe Training Hospital	Erkan^f
Turkey	Kecioren Training and Research Hospital	Unsal
Turkey	Bahcesehir University, School of Medicine	Tefekli
Turkey	Necmettin Erbakan University, Meram School of Medicine	Guven
Turkey	Pamukkale University Faculty of Medicine	Tuncay
Turkey	Private Lokman Hekim Hospitals	Yildiz
Turkey	University of Cukurova	Aridogan
Turkey	Bülent Ecevit University School of Medicine	Mungan
UK	Barts and The London NHS Trust	Buchholz
UK	Forth Valley Royal Hospital	McIlhenny
UK	University Hospital Southampton NHS Trust	Somani
USA	Boston Medical Center, Boston University School of Medicine	Babayan
USA	Mayo Clinic	Krambeck
USA	Northwestern University Medical School	Nadler
USA	The University of Oklahoma Health Sciences Center	Wong^g and Culkin
USA	The University of Texas Southwestern Medical Center	Pearle
USA	University of Arkansas for Medical Sciences	Eltahawy
USA	University of Pittsburgh Medical Center	Averch
USA	Urological Institute of Northeastern New York/Albany Medical Center	White
USA	Vanderbilt University Medical Center	Miller
USA	Wake Forest University	Assimos^h
Venezuela	Instituto Medico La Floresta	Sotelo

^aDr. Klingler is currently affiliated to Wilhelminenspital Wiener KAV.

^bDr. Shah is currently affiliated to Urolap Superspeciality Clinic.

^cDr. Gutierrez-Aceves is currently affiliated to Wake Forest University.

^dDr. Erdogru is currently affiliated to Memorial Istanbul Atasehir Hospital.

^eDr. Kural is currently affiliated to Acibadem University Maslak Hospital.

^fDr. Erkan is currently affiliated to Istanbul Egitim ve Arastirma Hastanesi.

^gDr. Wong is currently affiliated to University Hospitals Ahuja Medical Center Beachwood; Southwest Urology.

^hDr. Assimos is currently affiliated to UAB School of Medicine.

Abbreviations Used

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