Risk factors for migration of retrievable covered expandable metallic stent in patients with persistent benign ureter strictures.

PURPOSE: The purpose of this study is to evaluate the incidence, risk factors, and salvage management of retrievable covered expandable metallic stent (RCEMS) migration in patients with persistent benign ureter strictures. MATERIALS AND METHODS: A retrospective study was performed on 117 consecutive patients who underwent implantation of RCEMS. Univariate and multivariate analyses were used to identify prognostic factors for stent migration, including stricture location and length, hydronephrosis-cortex ratio, ureteral dilation, and the diameter of the narrowest portion of the stricture. RESULTS: Stent migration occurred in 22 (19.5%) of 113 patients who met inclusion criteria. Of the 22 patients, 16 (72.7%) had ordinary ureteral stricture, 3 (13.6%) had stricture in transplanted kidneys, and 3 patients (13.6%) had ureter stricture in orthotopic neobladders. The mean creatinine for the entire cohorts showed significant improvement (p = 0.038). Multivariate analysis identified the following prognostic factors for migration: distal ureteral stricture (p = 0.006), patients who underwent balloon dilation (p = 0.003), hydronephrosis-cortex ratio ≧10 (p = 0.017), larger diameter of wasting of RCEMS (p < 0.001), and patients with a shorter stricture length (p = 0.006). Salvage management was required in 4 of the 22 patients. The strictures in the remaining 18 patients improved with observation. CONCLUSIONS: Stent migration is more likely to occur in patients with the five prognostic factors mentioned above. Our study developed a nomogram to predict stent migration in patients with ureteral strictures treated using RCEMS.

Long-term follow-up study of the malignant transformation potential of the simple renal cysts.

BACKGROUND: We conducted a multi-center study to investigate the prevalence, the malignant transformation potential of the simple renal cysts and the factors that might predict malignancy. METHODS: We defined the simple renal cysts as Bosniak class I & II (including IIF) lesions. In the prevalence study, data from 115,132 ultrasonographies was collected from individuals who participated in a multiphasic health wellness screen. In the natural history and progression study, we retrospectively reviewed 333 participants with simple renal cysts and were followed for at the least 3 years with a mean of 6.3±2.9 years (ranged from 3 to 13 years). RESULTS: About 7.2% (8,303) of the individuals who participated in the study were found to have at the least one simple renal cyst. The incidence increased with age from 0.6% in the first decade to 28.0% in the eighth or later decade of life. The Bosniak class I lesion accounted for 7,559 or 91.0% of the cysts whereas 744 or 9.0% were class II. A slower growth rate was observed in the older age group. Twenty-four patients (7.2%) had their renal cysts upgraded according to the Bosniak classification. Gender, age, initial cyst size, number of cysts and bi-laterality failed to predict the malignancy tendency. CONCLUSIONS: Most of the cysts discovered were the Bosniak class I and II lesions and they rarely progress further. Treatment for the asymptomatic simple renal cyst is not warranted. Treatment decision-making based on older age or larger initial cyst size should not be recommended.

Inadvertent insertion of nephrostomy tube into the renal vein following percutaneous nephrolithotomy: A case report and literature review.

Percutaneous nephrolithotomy (PCNL) is an effective and well accepted procedure for the treatment of large and complex renal calculi. We encountered a patient with a misplaced percutaneous nephrostomy drainage tube (PNDT) into the contralateral renal vein resulting thrombus formation after undergoing right side PCNL. We placed a temporary filter to prevent embolism and started anti-coagulation therapy immediately and finally the PNDT was removed without bleeding.

Use 3D printing technology to enhance stone free rate in single tract percutaneous nephrolithotomy for the treatment of staghorn stones.

This study assesses the feasibility and effectiveness of using a three-dimensional (3D) printing model for preoperative planning in the treatment of full staghorn stones, specifically in the selection of the most optimal calyx for puncture. Twelve patients were enrolled in this trial. A preoperative CT taken in prone position was performed on each of the patients. 3D models were reconstructed using digital imaging and 3D printers. Three identical models were printed for each patient. Three puncture sites from the upper-, middle-, and lower-pole calyces of the kidney models were selected for simulation of percutaneous nephrolithotomy. The stone-free rates were recorded after each of the simulations. The puncture site that yielded the maximum SFR was translated to the patient for the actual procedure. CT was performed postoperatively on both patients and simulation models. The SFR of patients and simulation models was compared. Correlation analysis and consistency analysis suggested that there was a high degree of consistency between patients and 3D-printed models. The Pearson product-moment correlation coefficient r for the postoperative stone volume of the patients (PoSVP) and postoperative stone volume of the models (PoSVM) was 0.972 (P < 0.001, 95% CI = 0.900-0.992). The Bland-Altman plot of PoSVP to PoSVM showed an icon of 95% consistency 205.8(- 725.5 ~ 1137.1), and 100% of the points were within the 95% limits of agreement. 3D-printed models can potentially be used for preoperative planning in the treatment of full staghorn stones, especially in the selection of the most optimal calyx for puncture.

Association of Toll-like 4 receptor gene polymorphism (rs4986790, rs4986791) with the risk of urinary tract infection: A systematic review and meta-analysis.

Recently published studies had shown that there may be a potential link between the Single nucleotide polymorphism (SNP) of Toll-like receptor-4 (TLR4), and the risk of urinary tract infection (UTI); however, no consensus was reached. To further understand the relationship between TLR SNPs and urinary tract infections, we searched for related studies published in PubMed, EMBASE, and Web of Science before October 30, 2018, for further systematic review and meta-analysis. Our study accrued 10 case-control studies, which included 1476 urinary tract infection patients and 1449 healthy controls in TLR4(rs4986790, rs4986791). R3.4.2 and Stata 15.0 software were used for the analysis. In general, there was no statistically significant association between rs4986790 and urinary tract infection in the four genetic models. However, in the subgroup analysis, the Asian population showed significantly difference in the allelic model (G vs A: OR = 1.88 [95% CI:1.42-2.49], P = .03). In addition, there were also significant differences in the dominant model (GG + AG vs AA OR = 1.97 [95% CI:1.46-2.66], P = .01). Due to the small number of available literatures, no meaningful conclusion can be drawn regarding the relationship between TLR4 (rs4986791) and the risk of urinary tract infections in general. Nevertheless, our meta-analysis shows that in Asian populations, TLR4 (rs4986790) may be associated with risk of urinary tract infection.

Safety and efficacy of retrograde intrarenal surgery for the treatment of renal stone in solitary kidney patients.

PURPOSE: We present our experience of retrograde intrarenal surgery (RIRS) for the treatment of renal stones in patients with solitary kidneys and evaluate the safety and efficacy of this treatment modality. MATERIALS AND METHODS: Between March 2011 and July 2015, the clinical records of 60 patients with renal stones in solitary kidneys who underwent RIRS were retrospectively reviewed. Demographic characteristics, preoperative urinary culture, blood biochemistry, stone location, and surface area were documented. The final stone-free rates (SFRs) were assessed one month after the last treatment session by computed tomography (CT). Preoperative, operative, and postoperative parameters were analyzed. Serum creatinine (Scr) and glomerular filtration rate (GFR) were measured preoperatively, one month postoperatively, and at each follow-up visit. RESULTS: The mean stone burden was 628 ± 27.2 mm2 (range 301-1199). The mean operative time was 84.4 ± 21.3 min (range 40-115). The mean drop in postoperative hemoglobin was 0.6 ± 0.21 g/dL (range 0.1-0.7). Twelve patients (20%) required second-stage RIRS for residual stones. The SFRs after the single and second procedures were 80% and 95%, respectively. The mean preoperative Scr level was 111.6 ± 45.59 µmol/L, and the mean postoperative Scr level was 96.7 ± 34.12 µmol/L. The change was statistically significant (p = .008). The same findings were observed for GFR. The mean preoperative GFR was 65.04 ± 25.37 ml/min, and the mean postoperative GFR was 76.89 ± 27.2 ml/min (p = .023). Minor complications occurred in nine patients (15%). One patient experienced septic shock and acute renal failure due to steinstrasse. This patient required hemodialysis and percutaneous nephrostomy drainage. One patient developed perirenal abscess and was treated with percutaneous drainage. CONCLUSION: RIRS is a safe and effective procedure for the treatment of renal stones in patients with solitary kidneys. RIRS did not adversely affect renal function at either the short-term or the long-term follow-up.

Comparison of two cannulation methods for assessment of intracavernosal pressure in a rat model.

Intracavernous pressure (ICP) measurement is a well-established technique for assessing the erectile function, which was performed by cannulating either crus or shaft of the penis. However, there are no studies concerning the experimental performance of the two cannulation sites yet. The aim of this study was to compare the measuring outcomes using two different cannulation sites. To validate the capacity of our study, both normal and the castration-induced erectile dysfunction rat models were conducted. Fifty adult male Sprague-Dawley rats were randomized equally into two groups: an intact group and a castration group. Five rats from each group firstly underwent different stimulation parameters to detect the optimal erectile responses. The residual rats in each group were further assigned into two subgroups (n = 10 per subgroup) according to two different cannulation sites (crus or shaft of the corpus cavernosum). The ICP values were compared between groups after different interventions. The optimal parameters for mean maximum ICP were recorded at 2.5V and a frequency of 15 Hz. The rats under the two different cannulation sites tended to show similar ICP values in both the intact and the castration groups. However, the success rate in monitoring ICP was significantly higher in the groups cannulating into the shaft of the penis compared to the crus (100% vs. 70%; P = 0.02). Our data suggested that the method of cannulation into the penile shaft could serve as a better alternative for the ICP measurement in rats.

A prospective and randomized comparison of rigid ureteroscopic to flexible cystoscopic retrieval of ureteral stents.

BACKGROUND: Flexible cystoscopy has become an accepted alternative for stent retrieval. However, it is associated with higher cost. Some reports have described experiences of using rigid ureteroscope to retrieve ureteral stents. We compared rigid ureteroscopic to flexible cystoscopic retrieval of ureteral stents in a prospective and randomized clinical trial. METHODS: Three hundred patients treated with ureteral stents between July 2012 and July 2013 were accrued in this study. These patients were divided into two groups using the random number table method. Group A, with 162 patients, had stents removed with a flexible cystoscope and Group B, with 138 patients, had stents removed with a rigid ureteroscope. All procedures were performed under topical anesthesia by the same urologist. Patients in each group were compared in terms of preoperative, perioperative, and postoperative data. Postoperative data were collected using telephone interview on the postoperative day two. The postoperative questionnaire used included three items: hematuria, irritable bladder symptoms, and pain scores. RESULTS: All the stents were retrieved successfully. No statistical differences were noted between the two groups in terms of gender, age, laterality and duration of the stents, operative time, postoperative hematuria, irritable bladder symptoms, and pain scores. The per-use cost of instrument was much higher for the flexible cystoscopic group, RMB 723.1 versus 214.3 (USD 107.9 versus 28.2), P < 0.05. CONCLUSION: Ureteral stent retrieval using rigid ureteroscope under topical anesthesia is as safe and effective as flexible cystoscope but with a much lower cost to patients. TRIAL REGISTRATION: This study was registered with Chinese Clinical Trial Registry on March 27, 2017 (retrospective registration) with a trial registration number of ChiCTR-IOR-17010986 .

Predictors for uroseptic shock in patients who undergo minimally invasive percutaneous nephrolithotomy.

To identify risk factors that can predict which patient is likely to progress from systemic inflammatory response syndrome (SIRS) to uroseptic shock after minimally invasive percutaneous nephrolithotomy (MPCNL) for the upper urinary tract stones. We retrospectively reviewed 156 patients who suffered infectious complications after MPCNL from March 2014 to February 2016. Perioperative risk factors that could potentially contribute to uroseptic shock were compared to those of patients with only SIRS. 135 of the 156 patients developed to SIRS only, the remaining 21 patients progressed to uroseptic shock. The rate of positive preoperative urine nitrite was significantly higher (p < 0.001), stone diameter was larger (p = 0.015) and operative time was longer (p < 0.001) in uroseptic shock group. Multivariable logistic analysis showed that preoperative urine nitrite (OR 10.570, p = 0.025), stone size (OR 11.512, p = 0.009) and postoperative blood leukopenia (OR 0.009, p < 0.001) were independently related to uroseptic shock. Moreover, ROC curve analysis showed that white blood count threshold within the first 3 h of uroseptic shock was 2.98 × 109/L. The sensitivity and specificity of leukocyte count in predicting uroseptic shock were 90.5 and 92.6%, respectively. Preoperative urine nitrite, stone size and postoperative leukocyte count are statistically linked to uroseptic shock after MPCNL. Leukopenia of less than 2.98 × 109/L within 3 h after MPCNL can be a predictor for uroseptic shock. For patients who have high risk factors for developing uroseptic shock, the white blood count should be measured within 3 h after MPCNL.

Effect of 5α-Reductase Inhibitors on Sexual Function: A Meta-Analysis and Systematic Review of Randomized Controlled Trials.

INTRODUCTION: 5α-Reductase inhibitors (5ARIs) are widely used for the treatment of benign prostatic hyperplasia (BPH) and androgenetic alopecia (AGA). AIM: To review all the available data on the effect of 5ARIs on sexual function and assess whether 5ARIs increase the risk of sexual dysfunction. METHODS: A systematic search of the literature was conducted using the Medline, Embase, and Cochrane databases. The search was limited to articles published in English and up to October 2015. Article selection proceeded according to the search strategy based on Preferred Reporting Items for Systematic Reviews and Meta-analyses criteria. Data were analyzed using Stata 12.0. A fixed- or a random-effects model was used to calculate the overall combined risk estimates. Publication bias was assessed using Begg and Egger tests. MAIN OUTCOME MEASURES: Sexual dysfunction, erectile dysfunction, and decreased libido. RESULTS: After screening 493 articles, 17 randomized controlled trials with 17,494 patients were included. Nine studies evaluated the efficacy of 5ARIs in men with BPH. The other eight reported using 5ARIs in the treatment of men with AGA. The mean age of participants was 60.10 years across all studies. We included 10 trials (6,779 patients) on the efficacy and safety of finasteride, 4 trials (6,222 patients) on the safety and tolerability of dutasteride, and 3 trials (4,493 patients) using finasteride and dutasteride for AGA. The pooled relative risks for sexual dysfunction were 2.56 (95% CI = 1.48-4.42) in men with BPH and 1.21 (95% CI = 0.85-1.72) in men with AGA; those for erectile dysfunction were 1.55 (95% CI = 1.14-2.12) in men with BPH and 0.66 (95% CI = 0.20-2.25) in men with AGA; and those for decreased libido were 1.69 (95% CI = 1.03-2.79) in men with BPH and 1.16 (95% CI = 0.50-2.72) in men with AGA. Estimates of the total effects were generally consistent with the sensitivity analysis. No evidence of publication bias was observed. CONCLUSION: Evidence from the randomized controlled trials suggested that 5ARIs were associated with increased adverse effects on sexual function in men with BPH compared with placebo. However, the association was not statistically significant in men with AGA. Well-designed randomized controlled trials are indicated to study further the mechanism and effects of 5ARIs on sexual function.

Knockdown of PSCA induces EMT and decreases metastatic potentials of the human prostate cancer DU145 cells.

BACKGROUND: Prostate stem cell antigen (PSCA) expression has been shown to correlate with prostatic carcinogenesis and prostate cancer (PCa) progression. The underlying mechanisms for these processes are currently unknown. Epithelial to mesenchymal transition (EMT) has been associated with the invasiveness and the distant metastasis of PCa. In this study, we investigated the effects of knocking down the PSCA on the cell migration, the invasiveness, and the EMT of the PCa cell line DU145 in vitro and in vivo. METHODS: Four target sequences of the small hairpin RNA for PSCA were designed, and the best effect knockdown sequence shRNA#1 was screened to construct the stable transfected DU145 cell line (DU145 shRNA#1), the scramble sequence was also designed to construct the stable transfected DU145 cell line(DU145 scramble). Cell migration and invasion were studied using Transwell assay. Quantitative RT-PCR, Western blot (WB) were used to quantify PSCA, E-cadherin, ß-catenin, Vimentin, Fibronectin expression in DU145, DU145 scramble, DU145 shRNA#1 in vitro and in vivo. RT-PCR, immunofluorescent staining were used to quantify PSCA, E-cadherin, and Vimentin expression in vitro. EMT-related genes Snail, Slug, and Twist, were quantified by quantitative RT-PCR in vitro. RESULTS: The constructed stable knockdown of the PSCA in the DU145 cell had a silencing effect up to 90.5 %. DU145 shRNA#1 became scattered from the tightly packed colonies. It was associated with decreased cell migration and invasion. There was also an increased Vimentin and Fibronectin expression, an inhibited E-cadherin and ß-catenin expression at both the mRNA and the protein levels when compared to the DU145 and the DU145 scramble in vitro and vivo. Furthermore, with the exception of the Snail, the expression of EMT-related Slug and Twist genes were upregulated. CONCLUSIONS: Our data indicated that knockdown of PSCA induced EMT and reduced metastatic potentials of the DU145 cells, suggesting that PSCA played an important role in prostatic carcinogenesis and progression.

Super-mini percutaneous nephrolithotomy (SMP): a new concept in technique and instrumentation.

OBJECTIVE: To present a novel miniature endoscopic system designed to improve the safety and efficacy of percutaneous nephrolithotomy, named the 'super-mini percutaneous nephrolithotomy' (SMP). PATIENTS AND METHODS: The endoscopic system consists of a 7-F nephroscope with enhanced irrigation and a modified 10-14 F access sheath with a suction-evacuation function. This system was tested in patients with renal stones of <2.5 cm, in a multicentre prospective non-randomised clinical trial. In all, 146 patients were accrued in 14 centres. Nephrostomy tract dilatation was carried out to 10-14 F. The lithotripsy was performed using either a Holmium laser or pneumatic lithotripter. A nephrostomy tube or JJ stent was placed only if clinically indicated. RESULTS: SMP was completed successfully in 141 of 146 patients. Five patients required conversion to larger nephrostomy tracts. The mean (sd) stone size was 2.2 (0.6) cm and the mean operative duration was 45.6 min. The initial stone-free rate (SFR) was 90.1%. The SFR at the 3-month follow-up was 95.8%. Three patients required auxiliary procedures for residual stones. Complications occurred in 12.8% of the patients, all of which were Clavien grade ≤II and no transfusions were needed. In all, 72.3% of the patients did not require any kind of catheter, while 19.8% had JJ stents and 5.7% had nephrostomy tubes placed. The mean hospital stay was 2.1 days. CONCLUSIONS: SMP is a safe and effective treatment for renal stones of <2.5 cm. SMP may be particularly suitable for patients with lower pole stones and stones that ae not amenable to retrograde intrarenal surgery.

Sexual Dysfunction in Patients with Obstructive Sleep Apnea: A Systematic Review and Meta-Analysis.

INTRODUCTION: Sexual dysfunction is an under-recognized problem in men and women with obstructive sleep apnea (OSA). Epidemiologic findings were inconclusive regarding the risk for sexual dysfunction associated with OSA. AIM: The aim of this study was to examine the association between OSA and sexual dysfunction. METHODS: The PubMed, Cochrane Library, and Embase databases were searched for observational studies on the OSA and the risk of sexual dysfunction. The methodologic quality of the case-control and cohort studies was assessed with Newcastle-Ottawa Scale (NOS). The cross-sectional study quality methodology checklist was used for cross-sectional study. Data were pooled for the random-effects model. Sensitivity analyses were conducted to assess potential bias. MAIN OUTCOME MEASURE: The association between OSA and sexual dysfunction was summarized using relative risk (RR) with a 95% confidence interval (CI). RESULTS: This meta-analysis included 1,275 participants from nine studies. Five studies reported the incidence of erectile dysfunction (ED); the remaining four studies reported the incidence of female sexual dysfunction (FSD). Pooled results demonstrated that OSA was associated with increased risk of ED (pooled RR = 1.82, 95% CI: 1.12-2.97) as well as FSD (pooled RR = 2.00, 95% CI: 1.29-3.08). Estimates of the total effects were generally consistent in the sensitivity analysis. No evidence of publication bias was observed. CONCLUSIONS: Evidence from the observational studies suggested that OSA individuals might have an increased incidence of sexual dysfunction despite significant heterogeneity. More researches are warranted to clarify the relationship between OSA and the increased risk of sexual dysfunction.

Urinary stone analysis on 12,846 patients: a report from a single center in China.

We reported a retrospective review of the urinary stone compositions in 12,846 patients. Data on urinary stone compositions analyzed between January 2003 and December 2012 in our center were collected. Infrared spectroscopy was used for stone analysis. Predominant stone component was recorded. Patients were divided into four age groups: 0-18, 19-40, 41-60, and 61-92, and five categories by components. In order to determine the change of stone characteristics with respect to time, data were also divided into two periods, 2003-2007 and 2008-2012. A total of 12,846 stones were included in this study. The age of the patients ranged from 1 to 92 years with 7,736 males and 5,110 females. Stone made of single component was rare, 2.61%. Calcium oxalate stone was the most common component at 82.56%. Calcium oxalate and uric acid stones were more common in male than in female. The incidence of calcium phosphate stones and uric acid stones had increased during the past 5 years, while calcium oxalate stones decreased. We found the highest incidence of stone disease in the 41-60 years old group and the lowest in the 1-18 years old for both genders. Calcium oxalate was the dominant component in every group but was more prevalent in 19-40 years group. The percentage of magnesium ammonium phosphate stone and uric acid stone increased with age.

Minimally invasive percutaneous nephrolithotomy for simple and complex renal caliceal stones: a comparative analysis of more than 10,000 cases.

PURPOSE: To determine whether minimally invasive PCNL (MPCNL) is as safe and effective in the management of complex renal caliceal stones as it is for simple renal stones. PATIENTS AND METHODS: We retrospectively reviewed 5761(41.2%) simple caliceal stones (isolated renal pelvis including isolated calix) and 8223 (58.8%) complex caliceal stones (renal pelvis accompanying two calices at least) that were managed by MPCNL between 1992 nd 2011. The safety, efficacy, and outcome were compared and analyzed. RESULTS: Stone burden was larger in complex caliceal stones (1763.0 vs 1018.6 mm(2), P<0.05). Patients with simple stones had significantly shorter operative time, less frequency of multiple percutaneous accesses, and less hemoglobin drop. They also had a higher initial stone-free rate (SFR) (77.6% vs 66.4%) after a single session of MPCNL (P<0.05). The differences diminished in the final SFR (86.7% vs 86.1%) after relook and/or auxiliary procedures (P>0.05). The complication rate (17.9% vs 19.0%) and blood transfusion rate (grade II) (2.2% vs 3.2%) were similar in both groups (P>0.05). Both groups had a low rate of high Clavien grade complications. Renal vascular embolizations (grade III), however, were significantly higher in patients with complex caliceal stones (P<0.05). CONCLUSIONS: MPCNL is a safe and effective treatment option for patients with complex caliceal stones except there is a slightly higher frequency rate of embolization. There was a higher initial SFR in simple stones, but this difference diminished with secondary procedures.

Comparison of children versus adults undergoing mini-percutaneous nephrolithotomy: large-scale analysis of a single institution.

OBJECTIVE: As almost any version of percutaneous nephrolithotomy (PCNL) was safely and efficiently applied for adults as well as children without age being a limiting risk factor, the aim of the study was to compare the different characteristics as well as the efficacy, outcome, and safety of the pediatric and adult patients who had undergone mini-PCNL (MPCNL) in a single institution. METHODS: We retrospective reviewed 331 renal units in children and 8537 renal units in adults that had undergone MPCNL for upper urinary tract stones between the years of 2000-2012. The safety, efficacy, and outcome were analyzed and compared. RESULTS: The children had a smaller stone size (2.3 vs. 3.1 cm) but had smilar stone distribution (number and locations). The children required fewer percutaneous accesses, smaller nephrostomy tract, shorter operative time and less hemoglobin drop. The children also had higher initial stone free rate (SFR) (80.4% vs. 78.6%) after single session of MPCNL (p<0.05); but no difference was noted in the final SFR (94.7% vs. 93.5%) after auxiliary procedures. The complication rate (15.6% vs. 16.3%) and blood transfusion rate (3.1% vs. 2.9%) were similar in both group (p>0.05). Both groups had low rate of high grade Clavien complications. There was no grade III, IV, V complications and no angiographic embolization required in pediatric group. One important caveat, children who required multiple percutaneous nephrostomy tracts had significant higher transfusion rate than in adults (18.8% vs. 4.5%, p = 0.007). CONCLUSIONS: This contemporary largest-scale analysis confirms that the stone-free rate in pediatric patients is at least as good as in adults without an increase of complication rates. However, multiple percutaneous nephrostomy tracts should be practiced with caution in children.

Failure of initial renal arterial embolization for severe post-percutaneous nephrolithotomy hemorrhage: a multicenter study of risk factors.

PURPOSE: Severe hemorrhage after percutaneous nephrolithotomy is a rare but alarming event. If local tamponade fails to control bleeding, the current treatment of choice is superselective renal arterial embolization. If initial embolization is unsuccessful, repeat embolization or nephrectomy is often required. To our knowledge we report the first study of risk factors for failed initial superselective renal arterial embolization. MATERIALS AND METHODS: We retrospectively reviewed the records of 17,619 patients who underwent a total of 19,185 percutaneous nephrolithotomies from January 2007 to April 2012 at 6 centers. Study inclusion criteria were percutaneous nephrolithotomy and severe postoperative renal hemorrhage requiring superselective renal arterial embolization. Data on patients in whom initial embolization failed were compared to those on patients with successful embolization on univariate and multivariate analysis. RESULTS: Of the 17,619 patients 117 (0.6%), met study inclusion criteria, including 90 males and 27 females. Initial treatment failed in 12 patients (10.3%), 8 underwent repeat superselective renal arterial embolization, 3 required 3 embolizations and 1 underwent nephrectomy. Complete bleeding cessation was achieved in all 11 repeat embolization cases. We identified 3 risk factors for failure of initial superselective renal arterial embolization, including multiple percutaneous access sites, more than 2 bleeding sites identified on renal angiogram and gelatin sponge alone used as the embolic material. CONCLUSIONS: Carefully selecting patients for multitract percutaneous nephrolithotomy, making an extra effort to identify all bleeding vessels during angiography and not using gelatin sponge as the only embolic material could potentially decrease the risk of failure of initial superselective renal arterial embolization after percutaneous nephrolithotomy.