Prediction of clinically significant prostate cancer by [68 Ga]Ga-PSMA-11 PET/CT: a potential tool for selecting patients for active surveillance.

PURPOSE: In our study, our aim was to investigate the role of [68 Ga]Ga-PSMA-11 PET /CT imaging in the diagnosis of clinically significant prostate cancer (csPCa) (ISUP GG 2 and higher) in patients initially diagnosed with ISUP GG 1 and 2 after prostate biopsy. MATERIALS AND METHODS: We retrospectively reviewed 147 patient records in whom [68 Ga]Ga-PSMA-11 PET/CT imaging was performed preoperatively. All patients were initially diagnosed with ISUP GG 1 and 2 PCa by biopsy. Final pathology reports were obtained after radical prostatectomy. The [68 Ga]Ga-PSMA-11 PET/CT images were evaluated to determine the PRIMARY score. Patients' mpMRI-PIRADS scores were also recorded when available and analyzed in correlation with the pathology results. RESULTS: For the 114 patients scored using PRIMARY, 19 out of 37 patients with scores of 1 and 2 (51%) were diagnosed with csPCa. Of the 77 patients with PRIMARY scores between 3 and 5, 64 (83%) had csPCa. Notably, every patient with a PRIMARY score of 5 had csPCa. PRIMARY scoring had a sensitivity of 77% and specificity of 58%, with a positive predictive value of 83%. A moderate correlation was observed between PRIMARY scores and ISUP GG (Rho = 0.54, p < 0.001). In contrast, the PIRADS score displayed a sensitivity and specificity of 86% and 25% respectively, with a positive predictive value of 68%. No substantial correlation was found between PIRADS and ISUP GG. Statistical analysis revealed a significant correlation between PRIMARY and ISUP GG (p < 0.001), but not between PIRADS and ISUP GG (p = 0.281). Comparatively, PRIMARY scoring was significantly more reliable than PIRADS scoring in identifying csPCa. CONCLUSION: [68 Ga]Ga-PSMA-11 PET/CT imaging is promising for distinguishing high-risk prostate cancer patients from those apt for active surveillance, potentially aiding in the identification of csPCa.

The Efficacy and Safety of Retrograde Intrarenal Surgery in Elderly Patients: A Propensity Score Matching Study by the RIRSearch Group.

INTRODUCTION: To evaluate the efficacy and safety of retrograde intrarenal surgery (RIRS) in elderly patients by comparing them with propensity score-matched age groups. METHODS: Patients who underwent RIRS to treat upper urinary tract stone disease at seven centers were included in the study and were divided into four groups. The age intervals of the patients in Group 1, Group 2, Group 3, and Group 4 were 18-29 years old, 30-49 years old, 50-64 years old, and over 65 years old, respectively. Propensity score matching analysis was used to homogenize the groups in terms of demographic and clinical properties. Operative results, preoperative complications, peroperative complications, postoperative complications, duration of hospitalization time, and stone-free status were compared between groups. RESULTS: A total of 1,017 patients were included in the study. There were 69 (9.9%) patients in Group 1, 324 (46.5%) in Group 2, 217 (31.1%) in Group 3, and 87 (12.5%) in Group 4 after propensity score matching. The operation time and postoperative complication rates were significantly different among groups, whereas the hospitalization time, peroperative complication rates, and stone-free status were similar. The operation time was significantly higher in patients over 65 years old (p=0.001). The postoperative complication rates were significantly higher in Group 1 with Clavien I-II complication predominance (p=0.003). CONCLUSION: The efficacy and safety of RIRS did not change with aging, and RIRS was an effective option for the treatment of upper urinary system stones in elderly patients.

Voiding dynamics of pelvic organ prolapse: Large scale comparative study.

PURPOSE: To determine the voiding dynamics of the patients with pelvic organ prolapse (POP). MATERIALS AND METHODS: A retrospective patient file review was performed of 877 female patients with lower urinary tract symptoms. After exclusion criteria 373 female patients were eligible for the study. Two patient groups w/wo prolapse were identified. The symptoms, patient characteristics, patterns of free urine flow, and detrusor voiding pressure curves were compared between two groups. A comparison of the urodynamic findings between the subgroups (mild/moderate, severe, and w/o prolapse) was made and shown on a scatter plot graphics of Pdet Qmax versus Qmax as well. RESULTS: A total of 373 patients with median age 54 (18-92), 189 (51%) had varying degrees and forms of POP while 184 (49%) did not have any prolapse (p < 0.003). Logistic regression analysis results showed that older age [p = 0.023, odds ratio (OR) = 1.01, confidence interval (CI): (1.00-1.03)], weaker pelvic floor muscle strength [p = 0.032, OR = 1.67, CI: (1.04-2.69)], more frequent symptom of hesitancy [p = 0.003 OR = 2.15 CI: (1.29-3.58)], prolonged-tailed shaped curve pattern of free urine flow [p = 0.027 OR = 1.97 CI: (1.08-3.58)], and higher Pdet Qmax (22 cmH2 O) values [p = 0.002, OR = 1.02, CI: (1.00-1.03)] were the independent different features of the patients with prolapse. Subgroup urodynamic analysis showed significantly lower free flowmetry Qmax and higher Pdet Qmax values in patients with severe prolapse. Prolonged/tailed-shaped curve pattern of free urine flow was significantly more frequent in patients with prolapse. CONCLUSIONS: Voiding dynamics of the patients with prolapse were significantly different from the patients' w/o prolapse. They had higher Pdet Qmax values, more frequent symptom of hesitancy, and prolonged shaped free flow curve pattern. Free flow Qmax values were lower in patients with severe prolapse.

Retrograde Intrarenal Surgery Learning Curves of Urology Residents Supervised by an Experienced Endourologist: An RIRSearch Study.

INTRODUCTION: Although retrograde intrarenal surgery (RIRS) is being performed with increasing frequency, there are only a limited number of studies about the learning curve (LC). This study aimed to analyze the LC of RIRS for five surgeons who underwent the same training. MATERIALS AND METHODS: The data of the 410 patients who underwent RIRS between April 2017 and 2022 in a single institution, which were performed consecutively by five surgeons, were analyzed. All 50 cases performed by each surgeon were included and numbered consecutively and separately, according to the date of the operation. The combined stone-free rate (SFR) was calculated for each surgeon's cases in the same row, and the LCs were created using moving average and cumulative sum (CUSUM) analyses. Separate multivariable analyses identified each period's (LC vs. beyond) characteristics. RESULTS: The LCs from the combined SFRs reached a plateau after approximately 50 cases for both the CUSUM and the moving average. The effect of stone burden on SFR was more evident in the first 50 cases compared to subsequent cases in the multivariable analyses (p = 0.001 and p = 0.047, respectively). Case order and stone density were independent factors in the first 50 cases (OR: 1.02 [95% CI 1.00-1.04], p = 0.04 and OR: 0.99 [95% CI 0.99-1.00], p = 0.04) but not significant in subsequent cases (OR: 0.97 [95% CI 0.94-1.00], p = 0.1 and OR: 1.00 [95% CI 0.99-1.00], p = 0.7, respectively). Compared to single locations except the lower calyx, the unfavorable effect of the multiple-stone localization on SFR grew in strength after the 50th case (OR: 0.42 [95% CI 0.23-0.78], p = 0.01 and OR: 0.20 [95% CI 0.09-0.46], p < 0.001, respectively). CONCLUSIONS: This is the first study reporting on the RIRS LCs of urology residents. While stone burden, density, and multiple-stone localization were the factors determining SFR in the learning period, after completing the LC, the effect of stone burden weakened and multiple-stone localization became stronger.

External validation of Modified Seoul National University Renal Stone Complexity Score to predict outcome and complications of retrograde intrarenal surgery: a RIRSearch Group study.

INTRODUCTION: The Modified Seoul National University Renal Stone Complexity Score (S-ReSC) is a simple model based solely on stone location regardless of stone burden. The aims of this study were to validate S-ReSC for outcomes and complications of retrograde intrarenal surgery (RIRS) and to evaluate its predictive power against the stone burden. MATERIAL AND METHODS: Data of 1007 patients with kidney stones who had undergone RIRS were collected from our RIRSearch database. Linear-by-linear association, logistic regression, ANOVA/post hoc analysis and ROC curve (with Hanley and McNeil's test) were used for evaluation. The main outcomes were stone-free status and complications of RIRS. RESULTS: The overall stone-free rate was 76.8% (773/1007). Higher S-ReSC scores were related to lower stone-free rates and higher total, perioperative and postoperative complication rates (p<.001, p<.001, p=.008 and p<.001, respectively). S-ReSC score (p=.02) and stone burden (p<.001) were independent predictors of stone-free status. But stone burden (AUC = 0.718) had a more powerful discriminating ability than the S-ReSC score (AUC = 0.618). CONCLUSIONS: The S-ReSC score is able to predict not only stone-free status but also complications of RIRS. Although this location-only based scoring system has a fair discriminative ability, stone burden is a more powerful predictor of stone-free status after RIRS. An ideal scoring system aiming to predict outcomes of RIRS must include stone burden as a parameter.

Risk factors predicting upper urinary tract deterioration in children with spinal cord injury.

AIM: The aim of this study is to determine the risk factors predicting upper urinary tract (UUT) deterioration in children with spinal cord injury (SCI). METHODS: The medical records of 108 children with SCI who were referred to our unit between 1996 and 2018 were retrospectively reviewed. The data included general patient demographics, SCI characteristics, bladder management methods, presence of urinary tract infection, radiological evaluation of the UUT and lower urinary tract (LUT), and videourodynamic findings. The receiver operating characteristic (ROC) curve analysis was performed to determine the cutoff values of the maximum detrusor pressure during filling and the bladder volume ratio (BVR) for predicting UUT deterioration. Multivariate analyses were used to determine the risk factors predicting UUT deterioration. RESULTS: Complete data were available for 76 children. The median patient age was 15 years (2-17). The leading causes of SCI were motor vehicle accidents (44%) and fall (33%). UUT deterioration was identified in 33 patients (43%). Iatrogenic SCI etiology, abnormal radiological LUT findings, and detrusor pressures greater than 70 cmH2 O were found to be independent risk factors for UUT deterioration using regression analysis. In addition, ROC analysis revealed that a BVR less than 0.7 was the cutoff value for UUT deterioration in children with SCI. CONCLUSION: Abnormal radiological LUT findings, iatrogenic SCI etiology, detrusor pressure greater than 70 cmH2 O, and a BVR less than 0.7 were independent risk factors for UUT deterioration in children with SCI.

Relationship between the types of urinary incontinence, handgrip strength, and pelvic floor muscle strength in adult women.

AIM: To investigate the relationship between handgrip strength with types of urinary incontinence (UI) and pelvic floor muscle strength (PFMS) in women. METHODS: Ninety-two women, who presented to the geriatric and urology outpatient clinics complaining of UI between July 2019 and February 2020 and had indicated to undergo urodynamic assessment after basic neurourological evaluation, were included in this cross-sectional study. The presence and types of UI were identified by clinical examination and urodynamic studies. Demographic parameters, anthropometric data, comorbidities and medications were recorded. The International Consultation on Incontinence Questionnaire-Short Form was applied. Handgrip strength (HGS) was measured by a hand dynamometer. The PFMS was subjectively assessed via vaginal digital palpation and measured quantitatively by the vaginal probe of the perineometer. RESULTS: Thirty-eight urodynamic stress, 28 detrusor overactivity, 26 urodynamic mixed UI patients were reported. Perineometer measurements were significantly lower in the urodynamic stress UI group compared to the other two groups (p = 0.020). There was no relationship between the types of urinary incontinence and HGS. However, a positive correlation was found between PFMS and HGS (p = 0.045, r = 0.298). CONCLUSION: The positive correlation between HGS and PFMS indicates that low HGS may be a marker for PFMS weakness. Furthermore, the association between sarcopenia and UI may be explained by this condition.

Natural history of patients with infantile nephrolithiasis: what are the predictors of surgical intervention?

BACKGROUND: We evaluated the risk factors for the requirement of surgical intervention in infants with nephrolithiasis. METHODS: The medical records of 122 (156 kidney units (KU)) infants were reviewed. The clinical features, stone characteristics, changes in stone status, and treatment protocols were noted. The stone status of the KU was categorized into 3 groups according to the change in size between the first and last ultrasound: resolution, unchanged, and growth. RESULTS: The median age was 8 months (r: 2-12). The median length of follow-up was 16 months (r: 10-36). Resolution was detected in 94 KUs (60%). Stone growth was detected in 39 KUs (25%), and stone size was unchanged in 23 KUs (15%). Surgical intervention was required in 26 patients (17%). A history of intensive care unit (ICU) follow-up and a stone size > 5 mm at time of diagnosis were defined as independent risk factors for stone growth (p = 0.005, < 0.001, respectively). The surgical intervention rate was higher in stones > 5 mm and stones with pelvic localization (p = 0.018, 0.021, respectively). Stone resolution was higher in patients with stone size ≤ 5 mm (p = 0.018). CONCLUSION: A stone size > 5 mm at the time of diagnosis and a history of ICU follow-up are independent risk factors for stone growth. Pelvic localization of stones and stones > 5 mm are associated with an increased risk of surgical intervention.

Clinical outcomes of radical surgery in patients with renal carcinoma and associated venous thrombosis: Single-centre experience in a tertiary care institution.

BACKGROUND: Renal carcinoma and associated venous thrombosis cause specific perioperative and postoperative challenges. We aimed to evaluate the factors affecting clinical outcomes in patients undergoing radical surgery because of renal carcinoma and associated venous thrombosis. MATERIALS AND METHODS: Hospital records were retrospectively reviewed to identify patients with renal carcinoma and associated venous thrombosis treated with radical surgery between 2006 and 2019. Preoperative, perioperative, and postoperative findings were analysed to determine the associations between clinical and survival outcomes. Overall and disease-free survival were analysed by the Kaplan-Meier method. Other associated prognostic variables were assessed using univariate and multivariate Cox regression analyses. RESULTS: Thirty-three patients with renal carcinoma and associated venous thrombosis were enrolled for this study. There were 15 (45.4%) patients with level I, five (15.2%) with level II, eight (24.2%) with level III, and five (15.2%) with level IV venous thrombosis according to the Mayo Clinic classification system. The median follow-up was 35.6 months. In the univariate analysis, increased tumour size was associated with poor overall and disease-free survival. Preoperative clinic M1 disease was associated with poor overall survival. A high Mayo Clinic thrombus level was associated with poor disease-free survival. In the multivariate analysis, only tumour size and clinic M1 disease were independently correlated with poor overall survival. No independent statistically significant association was detected between thrombus level and survival outcomes. CONCLUSIONS: Although the thrombus level was not associated with overall and disease-free survival, tumour size and clinic M1 disease were found to have an independent prognostic impact on overall survival.

Do urinary mast cell mediators predict immune response to BCG in patients with primary high-grade non-muscle invasive bladder cancer?

BACKGROUND: Mast cells play a critical role in cancer-associated immunity. We aimed to determine the predictive value of urinary mast cell mediators in patients with non-muscle invasive bladder cancer (NMIBC) treated with Bacillus Calmette-Guérin (BCG) immunotherapy. METHODS: In this prospective study, 19 patients who received immunotherapy because of NMIBC (Group 1) and 19 healthy participants (Group 2) were enrolled. Urine samples were collected to assay N-methylhistamine, histamine, and tryptase levels immediately before the first BCG instillation, immediately after the third and sixth instillations, and 4 weeks after the sixth instillation in Group 1 and at a single visit in Group 2. The changes in urinary markers because of BCC response, BCG instillation, and the presence of NMIBC were assessed. RESULTS: The average age was 56.1 ± 10.5 years in Group 1 and 52.6 ± 9.7 years in Group 2. Fourteen patients had high-grade Ta tumours and five had T1 tumours. While 12 patients had responded to the BCG, seven patients did not respond to the BCG. There was no correlation between mast cell mediators and BCG response. The N-methylhistamine and histamine levels significantly increased with the onset of immunotherapy, and N-methylhistamine levels significantly decreased when immunotherapy was terminated (P < .05). The pre-BCG estimated marginal mean values of N-methylhistamine were significantly higher in Group 1 than in Group 2 (P < .05). CONCLUSIONS: Our study is the first to identify the changes in mast cell mediators with the onset of immunotherapy and in presence of bladder cancer. However, these mediators cannot predict patients' response to immunotherapy.

Ureteral wall thickness is an independent parameter affecting the success of extracorporeal shock wave lithotripsy treatment in ureteral stones above the iliac crest.

BACKGROUND: To investigate the relationship between ureteral wall thickness (UWT) and other variables of patients who underwent extracorporeal shock wave lithotripsy (SWL) in the primary treatment of the ureteral stone above the iliac crest level. MATERIAL AND METHODS: A total of 147 patients aged 18 years and older, who underwent SWL in our clinic between December 2016 and December 2019 for the treatment of ureteral stones above the iliac crest level and had non-contrast enhanced abdominal computed tomography scans before the procedure were included in the clinical study. The results were evaluated at 3 months after SWL. The absence of residual fragments was considered as stone-free status, and the existence of any size residual fragment was considered as treatment failure. RESULTS: In our study, the mean age of the patients was 42.4 ± 12.8 years, and the stone-free rate was 92.5%. The median transverse stone size was 7.5 mm (min 2.8-max 15), and the median UWT was 4.2 mm (1-8.7). In the multivariate analysis, UWT (P = .002) and multiple stone presence (P = .027) were found to be independent factors affecting stone-free status. In the receiver operating characteristic curve analysis, the optimal threshold value for UWT was determined as 5.25 mm. CONCLUSIONS: We found that UWT was the most important independent variable associated with increased failure in SWL treatment. The presence of multiple stones was another independent factor that increased the failure rates. Using SWL technology through experience accumulated with the mechanical hardware of the machine, we can select patients who are more suitable for this treatment and improve treatment outcomes.

Does extracorporeal shock wave lithotripsy before retrograde intrarenal surgery complicates the surgery for upper ureter stone? The results of the RIRSearch group.

AIMS: To evaluate the effect of pre-RIRS ESWL on the efficiency and safety of RIRS in the treatment of proximal ureter stones. METHODS: The patients in the study population were divided into two groups. Group-1 was composed of patients who had undergone ESWL for proximal ureter stones before RIRS and Group-2 was composed of patients who directly underwent RIRS without any prior ESWL. The clinical and demographic properties of the patients were analysed in the RIRSearch database. The operative outcomes, peroperative complications, postoperative complications, hospitalisation time and stone-free rates were compared between the groups. RESULTS: There were 56 patients in Group 1 and 95 patients in Group 2. The demographic and clinical properties were similar between the groups. The stone-free rates, peroperative complications and postoperative complications were also similar between the groups; however, the fluoroscopy time was significantly higher in Group 1 (P = .043). The cut-off duration of 10 weeks between ESWL and RIRS had reasonable/favourable discriminating ability, with a 51% sensitivity and 88% specificity rate for stone-free status. CONCLUSION: Performing ESWL on the proximal ureter stones before RIRS did not change the efficacy and safety of RIRS. The time between the patient's last ESWL session and RIRS had a predictive value for stone-free status, but did not have any effect on complications.

Clinical practice in vesicoureteral reflux with respect to EAU guidelines: A multicenter study.

PURPOSE: We designed a multicenter, retrospective study to investigate the current trends in initial management of reflux with respect to European Association of Urology (EAU) Guidelines in Urology clinics of our country. MATERIALS AND METHODS: The study group consisted of 1988 renal units (RU) of 1345 patients treated surgically due to vesicoureteral reflux (VUR) (between years 2003 and 2017) in nine different institutions. Patients were divided into two groups according to time of initial treatment and also grouped according to risk factors by "EAU guidelines on VUR." RESULTS: In this series, 1426 RUs were treated initially conservatively and 562 RUs were initially treated with surgery. In initially surgically treated group, success rates of surgery decreased significantly in low and moderate risk groups after 2013 (P = .046, P = .0001, respectively), while success rates were not significantly different in high risk group (P = .46). While 26.6% of patients in low risk group were initially surgically treated before 2013, this rate has increased to 34.6% after 2013, but the difference was not statistically significant (P = .096). However, performing surgery as the initial treatment approach increased significantly in both moderate and high risk groups (P = .000 and P = .0001, respectively) after 2013. Overall success rates of endoscopic treatments and ureteroneocystostomy (UNC) operations were 65% and 92.9% before 2013 and 60% and 78.5% after 2013, respectively. Thus, the overall success rate for surgery was 72.6%. There was significant difference between success rates of UNC operations before and after 2013 (P = .000), while the difference was not significant in the injection group (P = .076). CONCLUSION: Current trends in management of reflux in our country do not yet follow the EAU guidelines on VUR in low and moderate risk groups despite these reliable and accepted guidelines were expected to influence our daily approach.

Nation-wide analysis of the impact of Covid-19 pandemic on daily urology practice in Turkey.

OBJECTIVE: To present a nation-wide analysis of the workload of urology departments in Turkey week-by-week during Covid-19 pandemic. METHODOLOGY: The centres participating in the study were divided into three groups as tertiary referral centres, state hospitals and private practice hospitals. The number of outpatients, inpatients, daily interventions and urological surgeries were recorded prospectively between 9-March-2020 and 31-May-2020. All these variables were recorded for the same time interval of 2019 as well. The weekly change of the workload of urology during pandemic period was evaluated, also the workload of urology and the distributions of certain urological surgeries were compared between the pandemic period and the same time interval of the year 2019. RESULTS: A total of 51 centres participated in the study. The number of outpatients, inpatients, urological surgeries and daily interventions were found to be dramatically decreased by the 3rd week of pandemics in state hospitals and tertiary referral centres; however, the daily urological practice were similar in private practice hospitals throughout the pandemic period. When the workload of urology in pandemic period and the same time interval of the year 2019 were compared, a huge decrease was observed in all variables during pandemic period. However, temporary measures like ureteral stenting, nephrostomy placement and percutaneous cystostomy have been found to increase during Covid-19 pandemic compared with normal life. CONCLUSIONS: Covid-19 pandemic significantly affected the routine daily urological practice likewise other subspecialties and priority was given to emergent and non-deferrable surgeries by urologists in concordance with published clinical guidelines.

Does Previous Open Stone Surgery Affect the Outcome of Shock Wave Lithotripsy Treatment in Children?

INTRODUCTION: The aim of the study was to evaluate the efficiency of shock wave lithotripsy (SWL) in children who previously underwent ipsilateral open renal stone surgery (ORSS). METHODS: A total of 315 renal units (RUs) with renal stones underwent SWL treatment in our department over a period of 18 years. A total of 274 RUs (87%) with no history of ORSS were categorized as group 1 and 41 RUs (13%) with a history of ORSS were categorized as group 2. The characteristics of the patients and renal stones, as well as the treatment modalities, were reviewed retrospectively, and the results were compared in terms of the rates of stone-free patients and complications. RESULTS: The stone-free rates were statistically lower in patients with an existing history of ORSS (p = 0.002), especially for stones located at the lower calyx (p = 0.006). However, there were no differences between groups in the rate of complications (p = 0.75). History of ipsilateral ORSS, age, and stone burden were independent risk factors that predicted a stone-free status in the regression analysis (p = 0.016, p = 0.045, and p = 0.001, respectively). CONCLUSION: The overall stone-free rate after SWL was found to be significantly lower in children with a history of ORSS than in those without, and this finding was significantly prominent for lower calyx stones. In spite of the possible difficulties in achieving surgical access due to anatomical changes in retrograde intrarenal surgery or mini-/micro-percutaneous nephrolithotomy, we believe that these techniques might be good alternatives for SWL in future cases.

Comparison of a Modified Antegrade and Retrograde Ureteral Double-J Stenting Techniques during Laparoscopic and Robotic Pyeloplasty.

INTRODUCTION: To compare the effect of a modified antegrade and retrograde double-J stenting techniques on stenting and operation time in patients who underwent laparoscopic or robotic pyeloplasty. METHODS: A total of 74 patients undergoing transperitoneal laparoscopic or robotic pyeloplasty were enrolled into this study. The antegrade (Group 1) and retrograde (Group 2) techniques were compared for operation time, stenting time, complication, and reoperation rates. RESULTS: There were 41 and 33 patients in Groups 1 and 2, respectively. Both groups were similar in terms of age, side, and gender distribution. The mean operation times were 122.4 and 139.7 min in Groups 1 and 2, respectively (p < 0.001). The stenting times were 2.39 and 14.15 min in Groups 1 and 2, respectively (p < 0.001). The reoperation and complication rates were 7.3 and 6%, respectively, and similar for both groups (p = 1). CONCLUSIONS: Our new technique significantly shortens the duration of laparoscopic and robotic pyeloplasty without compromising success and complication rates.

Renal stone composition does not affect the outcome of percutaneous nephrolithotomy in children.

PURPOSE: We sought to investigate the association between renal stone composition and percutaneous nephrolithotomy outcomes in pediatric patients and define the characterization of the stone composition. METHODS: The data of 1157 children who underwent percutaneous nephrolithotomy between 1991 and 2012 were retrieved from the multicenter database of the Turkish Pediatric Urology Society. The study population comprised 359 children (160 girls, 199 boys) with stone analyses. Patients were divided into five groups according to the stone composition [group 1: calcium oxalate; group 2: calcium phosphate; group 3: infection stones (magnesium ammonium phosphate, ammonium urate); group 4: cystine; group 5: uric acid, xanthine stones]. RESULTS: Patient characteristics, perioperative, postoperative, and stone characteristics were compared considering the stone composition. There were no significant differences between the groups concerning age, sex, side involved, preoperative hematocrit levels, and solitary renal unit. Patients with cystine stones were more likely to have a history of stone treatment. Groups 2 and 5 had mostly solitary stones. However, group 3 had staghorn stone more often, and group 4 frequently had multiple stones. Overall stone-free rate (79.4%) was similar among the groups. Although stone composition was related to blood transfusion and prolonged operative and fluoroscopy screening times on univariate analysis, it was not a significant predictor of them on multivariate analysis. CONCLUSIONS: Stone composition was not a predictor of outcomes of pediatric percutaneous nephrolithotomy. However, cystine and infection stones, which are larger and filled multiple calyxes due to the nature of stone forming, were more challenging cases that need multiple tracts.