Endourological Society Research Articles

Antibiotic Utilization Before Endourological Surgery for Urolithiasis: Endourological Society Survey Results.

Ureteroscopy (URS) and percutaneous nephrolithotomy (PCNL) are common procedures performed to treat kidney stones. Despite advances in technology/technique, serious infectious complications can occur. To better understand the preoperative antibiotic administration patterns and adherence to guidelines from the American Urological Association (AUA) and the European Association of Urology (EAU), members of the Endourological Society were sent a clinical vignette-based survey to assess the antibiotic use in a variety of pre-URS and pre-PCNL scenarios. Endourological Society members were e-mailed a survey that queried antibiotic therapy duration before uncomplicated URS and PCNL with negative and asymptomatic positive preoperative urine cultures (PUCs). For negative PUC questions, selecting more perioperative antibiotics was considered a "prolonged" course as it extends past the maximum of 24-hour perioperative prophylaxis recommended by both the AUA and EAU. The response rate was 16.3% for a total of 326 responders. Twenty-one percent to 39% of respondents reported giving prolonged courses of preoperative antibiotics before a URS or PCNL with a negative PUC (p < 0.0001). When presented with a negative PUC, more prolonged antibiotic courses were reported with the following hierarchy: PCNL for 2 cm intrarenal stones (39%) > URS for 12 mm renal pelvis stone (28%) > URS for 7 mm distal ureteral stones (21%) (p < 0.0001). In both negative and positive PUC questions, differences were noted in preoperative antibiotic prescribing patterns among site of practice (United States, Canada, Europe, Asia, South America, and Others), type of practice (academic vs all others), years in practice (<10 or ≥10 years), and surgical volume (URS and PCNL >100 or ≤100 annual cases). Adherence to guidelines on antibiotic administration before PCNL and URS with a negative PUC varies by scenario and provider. In 21% to 39% of negative PUC cases, reported antibiotic use before a URS or PCNL is not consistent with recommendations from the AUA and EAU. Before a positive PUC URS or PCNL, nearly all surveyed provide preoperative antibiotics; however, the regimen length is variable.

Editorial introductions

Editorial introductions

Current use of medical expulsive therapy among endourologists.

We aimed to characterize current practice patterns among endourologists on medical expulsive therapy (MET) for treatment of ureteral calculi. An online survey was administered to Endourological Society members. Respondents' MET usage, index case management, and awareness of recent guidelines and literature were compared based on international status, practice setting, interval since training, and endourological fellowship training. Of the 237 complete responses, 65% were international, 61% were academic, 66% had &gt;10 years in practice, and 71% were endourology fellowship-trained. MET was used by 88%, with no differences between international, academic, practice length, and fellowship-trained groups. MET was used more frequently for &lt;8 mm and distal stones and more U.S.-based respondents reported use for proximal/midureteral stones (68% vs 43%; p&lt;0.001). For the index patient, 70% preferred MET as the initial approach and respondents &lt;10 years from training were more likely to choose MET (82% vs. 64%; p=0.006). While 82% of respondents were aware of the SUSPEND trial, 70% reported that it had not altered their use of MET. Current American Urological Association (AUA) guideline awareness was 90%. Mean MET prescription length was 19.9±10.3 days, and was statistically significantly longer for respondents who were U.S.-based, academic and &lt;10 years from training. MET is the preferred approach for patients with ureteral calculi &lt;10 mm among endourologists despite conflicting data in the literature. While current AUA practice guidelines are followed by the majority of respondents, our survey suggests MET is being used more liberally than the guideline criteria, specifically in proximal and midureteral stones.

Editorial Comment on: Worldwide Use of Antiretropulsive Techniques: Observations from the Clinical Research Office of the Endourological Society Ureteroscopy Global Study by Saussine et al.

Editorial Comment on: Worldwide Use of Antiretropulsive Techniques: Observations from the Clinical Research Office of the Endourological Society Ureteroscopy Global Study by Saussine <i>et al.</i>

Differences in the percutaneous nephrolithotomy practice patterns among Latin American urologists with and without endourology training.

ABSTRACTPurpose:Although the worldwide percutaneous nephrolithotomy (PCNL) practice pat- terns determined via a survey sent to members of the Endourological Society have been published, differences in PCNL practice patterns among Latin American urologists based on endourological or lithiasis training have not been published.To determine the PCNL practice patterns among Latin American urologists with and without training in endourology.Materials and Methods:The SurveyMonkey® web platform was used to develop a 27-item survey on PCNL for the treatment of renal stones, and the survey was sent via e- -mail and other electronic media to 2000 urologists from 15 Latin American countries. Endourology-trained (group 1) and nontrained urologists (group 2) were analyzed. The group results were compared using the chi-squared and Fisher's exact tests. SPSS version 20 for Windows was used for all analyses.Results:A total of 331 urologists responded to the survey (rate of 16.55%): 221 (66.7%) in group 1 and 110 (33.2%) in group 2). In groups 1 and 2, 91.9% and 63.2% performed PCNL, respectively: 85.1% and 58.5% used preoperative tomography, respectively; 12.7% and 4.7% used preoperative nephrolitometry nomograms, respectively: 45.2% and 32.1% used endoscopic combined intrarenal surgery, respectively: 68.3% and 38.7% used mul- tiple percutaneous tract realization, respectively: and 19.9% and 5.7% used minimally invasive PCNL, respectively (all p=0.0005).Conclusions:Statistically significant differences were observed in PCNL practice patterns of Latin American urologists with and without training in endourology. Specific training in endourology significantly influence the practice patterns of Latin American urologists.

Worldwide Use of Antiretropulsive Techniques: Observations from the Clinical Research Office of the Endourological Society Ureteroscopy Global Study.

Retropulsion, defined as unintended migration of a stone under the influence of the fragmentation device in ureteroscopy (URS) procedures, occurs in 2% to 60% of the cases. Antiretropulsive devices (ARDs) have been studied in experimental and small clinical studies. The current study aims at describing the worldwide usage of ARD and the outcomes related to their usage. The Clinical Research Office of the Endourological Society URS Global Study enrolled 11,885 patients who underwent URS and stone fragmentation for ureteral and/or renal stones. Of the 11,885 treated patients, 9877 were treated for ureteral stones, and data were available on stone migration and ARD use. Of all procedures, 14.5% were performed with the use of an ARD. Less stone migration (-2.0%; p = 0.050), higher stone-free rates (SFRs) (2.8%; p < 0.001), and shorter length of stay (-4.7%; p = 0.001) were observed in the antiretropulsive group. When an ARD is used during URS, less migration, higher SFRs, and shorter length of hospital stay are observed. This effect is independent from baseline differences and corrected for other treatment characteristics.

Evaluation of Guidelines for Surgical Management of Urolithiasis

Many urological societies have provided evidence-based guidelines to help the urologist make therapeutic choices. However, the recommendations in these guidelines may be heterogeneous because they were developed using various methods. The objective of this study was to review key guidelines on the surgical management of urinary stones to provide practical guidance for clinical application. Guidelines on urolithiasis from all international urological societies were searched through the society websites. A search on PubMed® and Medline® restricted to publications in English was also performed for guidelines published between January 1, 2010 and July 1, 2017. Only the latest versions of guidelines containing an evaluation of the level of evidence and the grade of recommendation were included in the final analysis. All recommendations on surgical stone management and recommended techniques for each surgical modality were included. The AGREE II (Appraisal of Guidelines for Research and Evaluation II) instrument was used to assess the quality of the included guidelines. Three international guidelines were included in analysis, including those of AUA (American Urological Association)/ES (Endourological Society), EAU (European Association of Urology) and SIU (Société Internationale d'Urologie)/ICUD (International Consultation on Urological Diseases). We highlighted the heterogeneity in the level of evidence and the grade of recommendation which arose due to the different methods of evaluations that had been adopted. Despite this our review highlighted the considerable similarities among the guidelines. In certain specific situations for which no good evidence was available the recommendations could only be based on expert opinion. An option to provide clear guidance to the urologist might be to combine these international guidelines into one to reduce confusion about the surgical management of urolithiasis.

Urological laparoendoscopic single-site and reduced port surgery: A nationwide survey in Japan.

To evaluate the current status of urological laparoendoscopic single-site and reduced port surgery in Japan. Of the 152 institutions to which councilors of the Japanese Society of Endourology belong, 42 (28%) have carried out laparoendoscopic single-site and reduced port surgery. A total of 32 of these institutions agreed to participate in this survey. Patients who had undergone surgery between January 2008 and March 2014 were included in the present study. Overall, 1145 cases of laparoendoscopic single-site and reduced port surgery were recorded during the study period. The most frequent procedures were adrenalectomy and radical nephrectomy. Laparoendoscopic single-site and reduced port surgery represented 12% (872/7311) of all laparoscopic procedures carried out at participating institutions. The number of patients who underwent pyeloplasty, donor nephrectomy and simple nephrectomy tended to increase, whereas those who underwent adrenalectomy, radical nephrectomy and nephroureterectomy peaked in 2012, and then tended to decrease in 2013. The rates of conversion, perioperative and postoperative complications, were 2.7%, 2.2% and 4.5%, respectively. The number of laparoendoscopic single-site and reduced port urological surgeries in Japan has increased for benign indications, such as pyeloplasty, donor nephrectomy and simple nephrectomy. In contrast, procedures such as adrenalectomy and radical nephrectomy are trending down after reaching a peak in 2012. Overall, laparoendoscopic single-site and reduced port urological surgery in Japan is being safely carried out when compared with other reported series of laparoendoscopic single-site surgery and conventional laparoscopic surgery.

Stone free rate assessment after percutaneous nephrolithotomy using nephrolitometric nomogram

Abstract Background Percutaneous nephrolithotomy remains the standard of care for kidney stones larger than 2 cm. Therefore, setting a prognosis for complete stone resolution through this method is essential. The prognostic tools available have limited prediction. Objectives To evaluate the stone-free rate in patients undergoing percutaneous nephrolithotomy with the Clinical Research Office of the Endourological Society nomogram and suggest modifications to improve the classification. Material and methods We analyzed a retrospective cohort of patients undergoing percutaneous nephrolithotomy applying the nephrolithometric nomogram specified. We modified the scale dividing the patients into 3 groups: I from 80 to 110 points, II from 111 to 170 points, and III more than 170 points, respectively assessing the stone-free rate (Kruskal–Wallis test was performed, p Results A total of 126 patients were included. According to the nehrolithometric nomogram the stone-free rate was 12.5% for patients with fewer than 111 points and 70.9% for those with 111 points or more. In the modification proposed for groups I, II and III the stone-free rate was 12.5%, 50% and 80% respectively (p = 0.000). Conclusions Evaluation using the nephrolithometric nomogram demonstrated accurate stone-free rate prediction for complex and simple stones, with a lack of discrimination for patients with intermediate scores. Our modification enabled better differentiation of the intermediate groups from the high and low stone-free rate groups.

Predictability and Practicality of Image-Based Scoring Systems for Patient Assessment and Outcome Stratification During Percutaneous Nephrolithotomy: a Contemporary Update.

Preoperative nomograms offer systematic and quantitative methods to assess patient- and stone-related characteristics and their impact on successful treatment and potential risk of complication. Discrepancies in the correlation of perioperative variables to patient outcomes have led to the individual development, validation, and application of four independent scoring systems for the percutaneous nephrolithotomy: Guy's stone score, S.T.O.N.E. nephrolithometry, Clinical Research Office of the Endourology Society nomogram, and Seoul National University Renal Stone Complexity. The optimal nomogram should have high predictive ability, be practically integrated into clinical use, and be widely applicable to urinary stone disease. Herein, we seek to provide a contemporary evaluation of the advantages, disadvantages, and commonalities of each scoring system. While the current data is insufficient to conclude which scoring system is destined to become the gold standard, it is crucial that a nephrolithometric scoring system be incorporated into common practice to improve surgical planning, patient counseling, and outcome assessment.

A Survey of Morcellator Preference and Cost Comparison of the Lumenis VersaCut and Wolf Piranha Morcellators

To evaluate operating room (OR) costs associated with the 2 available morcellators in the United States in a matched cohort and to determine benign prostatic hyperplasia surgeon's morcellator preference. Patients from 2013, the last year our institution exclusively used the VersaCut device, were matched 1:1 with the most recent patient cohort, utilizing the Wolf Piranha morcellator. Cost of morcellation including the expense of OR time and disposable instrument costs were calculated. A survey to the Endourological Society e-mail listserv was sent to determine morcellator preference. We identified 142 patients who underwent holmium laser enucleation of the prostate in 2013. When compared with the VersaCut group, morcellation efficiency (4.4 vs 7.0 g/min, P <.01) and expense of OR time ($1420.80 vs $992.21, P <.005) both favored the Piranha morcellator system even when the costs of disposable instruments were factored into the analysis ($1338.81 vs $1637.50, P <.05). A total of 126 urologists responded to the survey. Of these, 56 (44.5%) perform transurethral prostate enucleations, which included 48 (86%) holmium. More endourologists use the VersaCut (n = 33, 59%) than the Piranha (n = 24, 43%) morcellator. Qualities that impacted the preference of morcellator included the preferred device is safer, faster, easier to use, reusable, and less expensive. We identified a significant improved efficiency and improved cost savings utilizing the Piranha morcellator even when controlling for disposable costs. Of the endourologists who responded to the survey, less than half perform transurethral enucleation. Morcellator preference is largely based on safety, efficiency, and ease of use, whereas cost and reusablility were of lesser importance.

A Survey Regarding Preference in the Management of Bilateral Stone Disease and a Comparison of Clavien Complication Rates in Bilateral vs Unilateral Percutaneous Nephrolithotomy

To discuss complications of simultaneous bilateral percutaneous nephrolithotomy (SB-PCNL) when compared with unilateral percutaneous nephrolithotomy and survey surgeon preference in bilateral stone disease management. A database of all participating percutaneous nephrolithotomy (PCNL) patients who underwent treatment at Indiana University Health Methodist Hospital within a 10-year period from 2006 to 2015 by a single surgeon (JL) was utilized. Perioperative data, as well as complications, defined according to the Clavien grading system, were recorded. A survey of members of the Endourological Society was performed regarding surgical management in the setting of bilateral stone disease. A total of 563 patients were identified over the study period with 129 undergoing SB-PCNL. Overall, SB-PCNL patients had a longer procedure (176.9 vs 115.6 minutes, P <.0001), were more likely to undergo a secondary procedure (73% vs 44, P <.001), and had a longer hospital stay (3.2 vs 2.3 days, P <.001). Notably, there were no differences in the number or the severity of complications between the 2 groups. A total of 153 endourologists completed the survey. Of these endourologists, 58 (38%) performed bilateral PCNL under anesthesia. The top reasons for electing not to perform bilateral PCNLs included the duration of bilateral procedures (53%), bilateral renal injury (48%), and rare performance of bilateral surgery (35%). Although the procedure length was longer in the SB-PCNL group, there were similar rates of complications and severity between unilateral PCNL and SB-PCNL. A majority of endourologists surveyed do not perform bilateral PCNL but would perform bilateral ureteroscopy with the duration of the procedure and concern for bilateral renal injury representing the most common reasons.

Outcomes of Ureterorenoscopic Stone Treatment in 301 Patients with a Solitary Kidney.

Objectives: To determine the stone-free rates and intra- and postoperative complication rates and grades of ureterorenoscopic stone treatment in patients with a solitary kidney. Methods: This study is a subanalysis of the Clinical Research Office of the Endourological Society (CROES) ureterorenoscopy (URS) study, which is a prospective international multicenter observational study. Over a 1-year period, consecutive patients treated with ureterorenoscopy for urinary stones were included. Patients entered in this analysis were those with a solitary functioning kidney. Descriptive data on patient characteristics, stone-free rates, complication rates, and grades were evaluated for three separate groups: patients treated with ureteroscopy for ureteral stones, for renal stones, and a combination of renal and ureteral stones. Results: A total of 301 patients were treated for stones in a solitary kidney; 219 were treated for ureteral stones. In this group, the stone-free rate was 88.6%, with an intraoperative complication rate of 7.4% and postoperative complication rate of 4.1%. Totally, 57 patients were treated for renal stones. In this group, the stone-free rate was 56.4%, with an intraoperative complication rate of 7.0% and postoperative complication rate of 10.5%. There were 25 patients who were treated for renal stones in combination with ureter stones. In this group, the stone-free rate was 60.0%, with an intraoperative complication rate of 12.0% and postoperative complication rate of 10.5%. Within the three groups, 72% of the postoperative complications were classified as Clavien I and II. Conclusions: Ureteroscopy is an effective and safe treatment modality for the removal of ureteral and renal stones in patients with a solitary kidney. Stone location as well as total stone burden seems to be important factors influencing the ability to render patients stone free. Moreover, single session ureteroscopic stone removal was less effective for the treatment of larger renal stones or renal stones in combination with ureteral stones.

External validation and comparison of the scoring systems (S.T.O.N.E, GUY, CROES, S-ReSC) for predicting percutaneous nephrolithotomy outcomes for staghorn stones: A single center experience with 160 cases

The aim of this study was validation and comparison of stone scoring systems (S.T.O.N.E, GUY, CROES, S-ReSC) used to predict postoperative stone-free status and complications after percutaneous nephrolithotomy (PCNL) for staghorn stones. A total of 160 patients who had staghorn renal stones and underwent PCNL between January 2012 and August 2015 were included in the current retrospective study. Guy, S.T.O.N.E., S-ReSC (Seoul National University Renal Stone Complexity) and CROES (Clinical Research Office of the Endourological Society) nephrolithometry scores were calculated for each patient, and their potential association with stone-free status, operative and fluoroscopy time, and length of hospital stay (LOS) were evaluated. Postoperative complications were graded according to the modified Clavien classification, and the correlation of scoring systems with postoperative complications was also investigated. The mean CROES, S.T.O.N.E, Guy and S-ReSC scores were 143.5 ± 33.6, 9.7 ± 1.6, 3.5 ± 0.5 and 6.2 ± 2.0 respectively. The overall stone-free rate was 59%. All scoring systems were significantly correlated with stone-free status in univariate analysis. However, Guy and S-ReSC scores were the only significant independent predictor in multivariate analysis. And all four nomograms failed to predict complication rates. Current study demonstrated that Guy and S-ReSC scoring systems could effectively predict postoperative stone-free status for staghorn stones. However all four scoring systems failed to predict complication rates.

Ureteroscopic Urinary Stone Treatment Among Patients With Renal Anomalies: Patient Characteristics and Treatment Outcomes

To evaluate patients' characteristics, surgical procedure data, and outcomes of ureterorenoscopy (URS) stone treatment in patients with a horseshoe kidney (HSK), ectopic kidney (EK), and malrotated kidney (MK). This study is a subanalysis of the Clinical Research Office of the Endourological Society URS Global Study, which was a prospective multicenter observational study, collecting data on URS stone treatment from consecutive patients over a 1-year period. A total of 114 centers in 32 countries participated. This analysis acuminated on URS stone treatment in the specified renal anomalies: HSK, EK, and MK. For each group, patient characteristics, operation data, and treatment outcomes were evaluated. Of the 11,885 patients included in the Clinical Research Office of the Endourological Society URS study, 43 patients had HSK, 27 EK, and 16 MK. The stone-free rate (SFR) in the HSK group was 77% for renal stones and 85% for ureteral stones. In the HSK group, the intraoperative complication rate was 11.6% and the postoperative complication rate was 7%, including 1 Clavien grade IIIa and 1 IIIb complication. In the EK group, the SFR was 20% for renal stones and 94% for ureteral stones, with an intraoperative complication rate of 14.8% and a postoperative complication rate of 7.4%. One Clavien IVa complication was reported. In the MK group, the SFR was 71% for renal stones and 88% for ureteral stones, with an intraoperative complication rate of 6.3%. No postoperative complications occurred in this group. URS is an effective and safe treatment modality to remove ureteral and renal stones in patients with HSK and MK. The effectiveness of URS for renal stones in EK was low.

The Decline of Laparoendoscopic Single-Site Surgery: A Survey of the Endourological Society to Identify Shortcomings and Guidance for Future Directions.

To analyze the most recent temporal trends in the adoption of urologic laparoendoscopic single-site (LESS), to identify the perceived limitations associated with its decline, and to determine factors that might revive the role of LESS in the field of minimally invasive urologic surgery. A 15 question survey was created and sent to members of the Endourological Society in September 2016. Only members who performed LESS procedures in practice were asked to respond. In total, 106 urologists responded to the survey. Most of the respondents were from the United States (35%) and worked in an academic hospital (84.9%). Standard LESS was the most popular approach (78.1%), while 14.3% used robotics, and 7.6% used both. 2009 marked the most popular year to perform the initial (27.6%) and the majority (20%) of LESS procedures. The most common LESS procedure was a radical/simple nephrectomy (51%) followed by pyeloplasty (17.3%). In the past 12 months, 60% of respondents had performed no LESS procedures. Compared to conventional laparoscopy, respondents only believed cosmesis to be better, however, this enthusiasm waned over time. Worsening shifts in enthusiasm for LESS also occurred with patient desire, marketability, cost, safety, and robotic adaptability. The highest rated factor to help LESS regain popularity was a new robotic platform. The decline of LESS is apparent, with few urologists continuing to perform procedures attributed to multiple factors. The availability of a purpose-built robotic platform and better instrumentation might translate into a renewed future interest of LESS.

Current trends in percutaneous nephrolithotomy: an internet-based survey.

The aim of this study was to report current practices of percutaneous nephrolithotomy (PCNL) among endourologists. An internet survey was administered to Endourological Society members. Responders were distributed into three groups according to the number of PCNL cases per year (<50, 50-100, >100). PCNL technical details as well as opinions regarding specific clinical case scenarios were evaluated and compared between groups. We received 300 responses from 47 different countries. Prone position was used in 77% of cases, while 16% used supine position and only 7% used modified lateral decubitus. Most endourologists performed their own access. There were no significant differences between the three groups regarding patient position (p = 0.1), puncture acquisition by urologist or radiologist (p = 0.2) and fluoroscopic puncture technique (p = 0.2). Endourologists with high annual PCNL practice (>100) had least probability to utilize nephrostomy tube (p = 0.0005) or use balloon dilator (p = 0.0001). They also had the highest probability of performing mini-PERC (p = 0.0001). The majority of endourologists performing PCNL obtain their own access. Prone positioning is predominant, while totally tubeless PCNL are uncommon. Mini-PERC is gaining more popularity among endourologists. Most endourologists follow the guidelines for their choice of treatment modality in different sizes and locations of upper tract calculi.

Trends in the Management of Small Renal Masses: A Survey of Members of the Endourological Society.

Treatment modalities for small renal masses (SRMs) include open or minimally invasive radical or partial nephrectomy, and laparoscopic or percutaneous ablations. Members of the Endourological Society were surveyed to evaluate how practitioner and clinical practice characteristics may be associated with the management of SRMs over time. The survey assessed characteristics of urologists (recency of residency and fellowship training, clinical practice type and location, and treatment modalities available) and their management of SRMs over the past year and over the course of the year 5 years prior. Of the 1495 surveys e-mailed, there were 129 respondents (8.6%). Comparing the past year to 5 years prior, there was increasing utilization of robotic partial nephrectomy (p < 0.001) and robotic radial nephrectomy (p = 0.031). In contrast, there was decreasing utilization of open partial nephrectomy (p < 0.001), open radical nephrectomy (p = 0.039), laparoscopic partial nephrectomy (p = 0.002), and laparoscopic radical nephrectomy (p = 0.041). Employment of laparoscopic ablation decreased (p = 0.001), but that of percutaneous ablation did not change significantly. For masses treated with image-guided therapy, there was increasing utilization of microwave ablation (p = 0.008) and decreasing usage of radiofrequency ablation (p = 0.002). Future studies should focus on the most effective treatment modalities based on provider, patient, and tumor characteristics.

Prediction of Pediatric Percutaneous Nephrolithotomy Outcomes Using Contemporary Scoring Systems.

We evaluate the applicability of contemporary percutaneous nephrolithotomy scoring systems in pediatric patients and compare their predictive power regarding postoperative outcomes. We retrospectively analyzed the records of 125 children who were diagnosed with renal calculi and underwent percutaneous nephrolithotomy between March 2011 and April 2016. Predictive scores, which consisted of Guy's Stone Score, S.T.O.N.E. (stone size, tract length, obstruction, number of involved calyces and essence/stone density) nephrolithometry and CROES (Clinical Research Office of the Endourological Society) nomogram, were calculated for all patients included in the study. Patient demographics, stone-free rate and complications were all analyzed and are reported. Median Guy's Stone Score was 2 (IQR 2 to 3) in patients with residual stones (group 1) and 2 (1 to 2) in those who were stone-free (group 2). Median respective CROES nomogram scores were 215 (IQR 210 to 235) and 257 (240 to264), and S.T.O.N.E. nephrolithometry scores were 8 (7 to 9) and 5 (5 to 6, all p<0.0001). S.T.O.N.E. score demonstrated the greatest accuracy in predicting stone-free rate. Guy's Stone Score was significantly correlated with complications but the CROES and S.T.O.N.E. scores were not significantly correlated with complications. The scoring systems analyzed could be used to predict success of percutaneous nephrolithotomy in the pediatric setting. However, further studies are needed to formulate modifications for use in children. The main variables in the scoring systems, ie stone burden, tract length and case volume, were measured using records from adult patients. Besides these variables, the relatively small pelvicalyceal system and higher incidence of anatomical malformations in children could potentially affect percutaneous nephrolithotomy outcomes.

Evaluación de la tasa libre de litos posterior a la nefrolitotomía percutánea mediante el nomograma nefrolitométrico

BackgroundPercutaneous nephrolithotomy remains the standard of care for kidney stones larger than 2cm. Therefore, setting a prognosis for complete stone resolution through this method is essential. The prognostic tools available have limited prediction. ObjectivesTo evaluate the stone-free rate in patients undergoing percutaneous nephrolithotomy with the Clinical Research Office of the Endourological Society nomogram and suggest modifications to improve the classification. Material and methodsWe analyzed a retrospective cohort of patients undergoing percutaneous nephrolithotomy applying the nephrolithometric nomogram specified. We modified the scale dividing the patients into 3groups: i from 80 to 110 points, II from 111 to 170 points, and III more than 170 points, respectively assessing the stone-free rate (Kruskall-Wallis test was performed, p<0.05). ResultsA total of 126 patients were included. According to the nehrolithometric nomogram the stone-free rate was 12.5% for patients with fewer than 111 points and 70.9% for those with 111 points or more. In the modification proposed for groups I, IIand III the stone-free rate was 12.5%, 50% and 80% respectively (p=0.000). ConclusionsEvaluation using the nephrolithometric nomogram demonstrated accurate stone-free rate prediction for complex and simple stones, with a lack of discrimination for patients with intermediate scores. Our modification enabled better differentiation of the intermediate groups from the high and low stone-free rate groups.