Risk Factors for Postoperative Complications of Percutaneous Nephrolithotomy at a Tertiary Referral Center.

PURPOSE: We sought to describe and evaluate the complications related to percutaneous nephrolithotomy and identify risk factors of morbidity according to the modified Clavien scoring system. We also sought to specify which perioperative factors are associated with minor and major complications. MATERIALS AND METHODS: We retrospectively analyzed data on patients who underwent percutaneous nephrolithotomy from 1990 to 2013. Descriptive statistics were used to analyze patient characteristics, medical comorbidities and perioperative features. Complications were categorized according to the Clavien score for percutaneous nephrolithotomy. The Mann-Whitney and Fisher exact tests were used as appropriate. Logistic regression analysis was performed to look for prognostic factors associated with major complications. RESULTS: A total of 2,318 surgeries were evaluated. Mean age of the population was 53.7 years. The stone-free rate at hospital discharge was 81.6%. The overall complication rate was 18.3%. Two deaths occurred. Patients with any postoperative complications were older, had more comorbidities, were more likely to have staghorn calculi and had longer operative time and hospital stay on univariate analysis (p<0.05). Age 55 years or older and upper pole access were independent predictors of major complications on multivariate analysis. Other factors such as a history of urinary tract infections, body mass index, stone composition, previous percutaneous nephrolithotomy and multiple tracts were not associated with a major complication. CONCLUSIONS: At our center percutaneous nephrolithotomy is an excellent option for complex kidney stone management with a low overall complication rate. Older patient age and upper pole access are significantly associated with an increased risk of a major complication.

Predictive modelling of urinary stone composition using machine learning and clinical data: implications for treatment strategies and pathophysiological insights.

PURPOSE: Preventative strategies and surgical treatment for urolithiasis depend on stone composition. However, stone composition is often unknown until the stone is passed or surgically managed. Given that stone composition likely reflects the physiological parameters during its formation, we used clinical data from stone formers to predict stone composition. MATERIAL AND METHODS: Stone composition, 24-hour urine, serum biochemistry, patient demographic and medical history were prospectively collected from 777 kidney stone patients. Data were used to train gradient boosted machine and logistic regression models to distinguish calcium vs non-calcium, calcium oxalate monohydrate vs dihydrate, and calcium oxalate vs calcium phosphate vs uric acid stone types. Model performance was evaluated using kappa score and the influence of each predictor variable was assessed. RESULTS: The calcium vs non-calcium model successfully differentiated stone types with a kappa of 0.5231. The most influential predictors were 24-hour urine calcium, blood urate and phosphate. The calcium oxalate monohydrate vs dihydrate model is the first of its kind and could discriminate stone types with a kappa of 0.2042. The key predictors were 24-hour urine urea, calcium, and oxalate. The multiclass model had a kappa of 0.3023 and the top predictors were age, and 24-hour urine calcium and creatinine. CONCLUSIONS: Clinical data can be leveraged with machine learning algorithms to predict stone composition, which may help urologists determine stone type and guide their management plan before stone treatment. Investigating the most influential predictors of each classifier may improve the understanding of key clinical features of urolithiasis and shed light on the pathophysiology.

The CROES percutaneous nephrolithotomy global study: the influence of body mass index on outcome.

PURPOSE: In addition to more commonly forming stones, obese patients present a number of challenges when undergoing percutaneous nephrolithotomy. We evaluated percutaneous nephrolithotomy outcomes in 3,709 patients stratified by body mass index. MATERIALS AND METHODS: A prospective database administered by CROES (Clinical Research Office of the Endourological Society) captured data on 5,803 patients treated with percutaneous nephrolithotomy between November 2007 and December 2009. Patients with known solitary kidney, previous percutaneous nephrolithotomy and congenital abnormalities were excluded from analysis. For statistical analysis patients were categorized as normal weight--body mass index 18.5 to 25 kg/m(2), overweight--25 to 30, obese--30 to 40 and super obese--greater than 40. RESULTS: During the study period 5,803 patients underwent percutaneous nephrolithotomy, of whom 3,709 met the inclusion criteria. As expected, obesity was associated with significantly higher rates of comorbid conditions and anticoagulant use (p < 0.001). Operative time was significantly longer in obese patients and use of a balloon device for tract dilation was more common (each p < 0.001). The stone-free rate decreased with obesity (p = 0.009), corresponding to a significantly higher re-treatment rate in this group (p < 0.001). No difference was seen in length of stay or the transfusion rate. No significant difference was seen in the overall complication rate among the 4 groups (p = 0.707). CONCLUSIONS: Percutaneous nephrolithotomy may be done safely in obese patients, although with a longer operative time, an inferior stone-free rate and a higher re-intervention rate.

The use of triclosan eluting stents effectively reduces ureteral stent symptoms: a prospective randomized trial.

UNLABELLED: What's known on the subject? and What does the study add? Infection, encrustation and ureteral-stent-related symptoms (USRS) including pain, urgency and frequency are all major problems associated with stent use. No current ureteral stent or exogenously applied therapy adequately deals with these problems and antibiotic use is ineffective once a bacterial biofilm forms on the device. Triclosan is a broad spectrum antibacterial agent widely used in numerous healthcare products and has been previously shown to reduce inflammation on the skin and in the oral cavity. This study tested a triclosan-impregnated ureteral stent for its ability to reduce infection, encrustation and USRS. This study shows that while a triclosan-impregnated ureteral stent cannot reduce infection rates alone compared with antibiotic use, the stent can reduce several USRS including pain during indwelling. This study suggests that the triclosan eluting stent may have a role in treating patients, perhaps in combination with standard antibiotic therapy. OBJECTIVE: To evaluate the capacity of triclosan-loaded ureteral stents to reduce stent-associated bacterial attachment, biofilm formation and encrustation, thereby potentially reducing infection development and other device-related sequelae. PATIENTS AND METHODS: Twenty subjects requiring short-term stenting (7-15 days) were randomized to receive either a Percuflex Plus(®) non-eluting stent (control) or a Triumph(®) triclosan eluting stent. Control-stented subjects received 3 days of levofloxacin prophylaxis (500 mg once daily) while Triumph(®)-stented subjects did not. All subjects were assessed for positive urine and stent cultures, stent biofilm development and encrustation. Following device removal, each subject completed an analogue-scale symptom assessment questionnaire. RESULTS: Ureteral stenting was performed after nine ureteroscopic and one extracorporeal shock wave lithotripsy procedure in the control group and eight ureteroscopic and two shock wave lithotripsy procedures in the triclosan group. No significant differences were observed for culture, biofilm and encrustation between the two groups. Subjects in the triclosan group reported significant reductions in lower flank pain scores during activity (58.1% reduction, P = 0.017) and urination (42.6%, P = 0.041), abdominal pain during activity (42.1%, P = 0.042) and urethral pain during urination (31.7%, P = 0.049). CONCLUSIONS: In this study, the use of the Triumph(®) triclosan eluting stent had no marked impact on biofilm formation, encrustation or infection development in short-term stented patients. The Triumph(®) device led to significant reductions in several common ureteral-stent-related symptoms, supporting its use in this patient population.

Stone Burden Measurement by 3D Reconstruction on Noncontrast Computed Tomography Is Not a More Accurate Predictor of Stone-Free Rate After Percutaneous Nephrolithotomy Than 2D Stone Burden Measurements.

Purpose: Stone burden has been reported as an independent predictor of stone-free rate after percutaneous nephrolithotomy (PCNL); however no consensus exists on a standardized method for measuring stone burden. Recently, stone volume has been advocated as the most accurate means of measuring stone burden. We aimed to compare different measuring methods of stone burden and to identify the predictive value of each for outcomes after PCNL. Materials and Methods: We performed a retrospective review of a prospective database of patients who underwent PCNL between 2006 and 2013. A preoperative CT and postoperative imaging at discharge were necessary for eligibility. Stone burden was assessed through four different ways on CT images: (1) cumulative stone diameter; (2) estimated SA (surface area) calculated as longest × orthogonal diameter × π/4; (3) manual outline of stone and computer SA calculation; and (4) automated 3D volume calculation using specific software. Primary outcome was stone-free status (SFS) at discharge. Secondary outcomes included operative time and the need for an ancillary procedure. Regression analysis and receiver operating characteristic curve analysis were used to evaluate the predictive value of each method. Results: Of 313 included patients, 69.6% were stone free at discharge. All measures of stone burden were independent predictors of SFS [OR and 95% CI of 1.027 (1.014, 1.040), 1.481 (1.180, 1.858), 1.736 (1.266, 2.380), and 1.311 (1.127, 1.526), respectively] and demonstrated similar predictive accuracy (area under the curve = 0.630, 0.630, 0.627, and 0.638, respectively). Stone burden by any measure was an independent predictor of operative time and secondary procedure. Conclusions: We demonstrated that measuring stone burden by manual outline or automated 3D volume on reformatted CT images had no added value compared with orthogonal measurement for predicting outcomes after PCNL.

The evolution of percutaneous nephrolithotomy: Analysis of a single institution experience over 25 years.

INTRODUCTION: Over time, the incidence of nephrolithiasis has risen significantly, and patient populations have become increasingly complex. Our study aimed to determine the impact of changes in patient demographics on percutaneous nephrolithotomy (PCNL) outcomes. METHODS: A retrospective analysis of a prospectively collected database was carried out from 1990-2015. Patient demographics, comorbidities, stone and procedure characteristics were analyzed. Multivariate logistic regression was used to evaluate differences in operative duration, complications, stone-free rate, and length of stay. RESULTS: A total of 2486 patients with a mean age of 54±15 years, body mass index (BMI) of 31±8, and stone surface area of 895±602 mm2 were analyzed; 47% of patients had comorbidities, including hypertension (22%), diabetes mellitus (14%), and cardiac disease (13%). Complication rate was 19%, including a 2% rate of major complications (Clavien grade III-V). There was a statistically significant increase in patient age, BMI, and comorbidities over time, which was correlated with an increased complication rate (odds ratio [OR] 1.15; p=0.010). The overall transfusion rate was 1.0% and remained stable (p=0.131). With time, both OR duration (mean Δ 16 minutes; p<0.001) and hospital length of stay (mean Δ 2.4 days; p<0.001) decreased significantly. Stone-free rate of 1873 patients with available three-month followup was 87% and decreased significantly over time (OR 1.09; p<0.001), but was correlated with an increased use of computed tomography (CT) scans for followup imaging. CONCLUSIONS: Despite an increasingly complex patient population, PCNL remains a safe and effective procedure with a high stone-free rate and low risk of complications.

Pilot study of ureteral movement in stented patients: first step in understanding dynamic ureteral anatomy to improve stent comfort.

BACKGROUND AND PURPOSE: Ureteral stents may cause significant morbidity, including pain, dysuria, hematuria, and infection. New biomaterials, coatings, and designs have been studied in an attempt to reduce stent-related symptoms, but to date, the ideal comfortable stent has not been developed. In order to facilitate development of a stent that will mold and change with patient movement, we examined stent and ureteral movement with changes in patient body position. PATIENTS AND METHODS: Four women and two men with a median age of 60.5 +/- 7.7 years who underwent shockwave lithotripsy and insertion of a ureteral stent were enrolled. Static radiographs were performed with the patients in four positions: supine, standing, sitting, and bending forward. Differences in stent position were analyzed digitally relative to fixed bony reference points to determine ureteral movement. RESULTS: The renal stent curl was most cephalad when the patient was supine and moved caudally an average of 2.5 +/- 1.5 cm when the patient stood up. The absolute vertical length of the stent was greatest when the patient was supine (31.1 +/- 1.2 cm) and shortened with standing (28.3 +/- 2.3 cm) and sitting (26.6 +/- 1.5 cm). The bladder curl moved an average of 2.3 +/- 1.2 cm vertically with patient movement. CONCLUSIONS: By measuring stent position, we were able to quantify the range of motion of the ureter during changes in body position. Stent movement appears to be a combination of bowing in the proximal ureter and moving within the bladder. Future stent designs may take this into account to decrease stent-related symptoms.

Third prize: contemporary percutaneous nephrolithotripsy: 1585 procedures in 1338 consecutive patients.

BACKGROUND AND PURPOSE: The approach to urinary-stone disease has changed dramatically over the last three decades with a transition from open surgery to minimally invasive procedures. Percutaneous nephrolithotripsy (PCNL) is a cornerstone of the treatment of kidney and selected upper-ureteral stones and continues to evolve with advances in techniques and instrumentation. The purpose of this study was to assess outcomes and trends prospectively in a large contemporary group of patients undergoing PCNL. PATIENTS AND METHODS: Between July 1990 and December 2005, all 1338 patients at a single center scheduled for PCNL (N = 1585 procedures) were enrolled. Their mean age was 53 years (range 4-89 years). Data including comorbidities, stone burden, stone location, surgical time, hospital length of stay, rate of secondary procedures, and adverse events were collected prospectively. The primary outcome measures were stone-free rate and complications. RESULTS: There was a substantial incidence of comorbid medical conditions (48.8%) and anatomic renal abnormalities (25.3%), demonstrating the diverse and challenging patient population in this contemporary series. The overall stone-free rate at 3 to 6 months of follow-up was 94.8%. CONCLUSIONS: Percutaneous nephrolithotripsy is a highly effective procedure and may be performed in a diverse group of patients with comorbid conditions and renal abnormalities. Improved intracorporeal lithotripters, balloon dilation of the tract, use of flexible instruments, and liberal use of secondary nephroscopy result in excellent stone-free rates with low morbidity.

Do urologists follow the golden rule? A global urolithiasis management study by the Clinical Research Office of the Endourological Society.

INTRODUCTION: The primary objective of this study was to compare surgical management options for various urolithiasis scenarios that urologists would choose for themselves vs. the options they would recommend for their patients. The secondary objective was to identify the common recommended treatments for upper urinary tract stones of various sizes and locations. METHODS: Two surveys were sent by the Clinical Research Office of the Endourological Society (CROES) to members of the Endourological Society. Standard demographic information was collected. The first survey asked the urologists to recommend treatment for urolithiasis in 10 different scenarios assuming that they were the patient with stone disease. The second survey, sent eight months later, asked urologists to recommend treatment for the same 10 scenarios for a theoretical patient. Only urologists who responded to the first and the second survey were included. Recommended treatment options were compared between the surveys. Agreement between the two scenarios was measured with Cohen's kappa. Surveys were conducted on the Internet using SurveyMonkey™. All statistical analyses were performed using R statistical program version 2.12.2. RESULTS: The two surveys had response rates of 78% (160/205) and 84% (172/205), respectively with urologists from 38 countries. Median experience of respondents was seven years (range: 2-30). The majority of respondents, 117 (75%), were affiliated with academic hospitals. Recommended treatments for stone disease in different scenarios were not entirely consistent when the urologists considered themselves as the patients compared to the choice they might recommend for their patients. Cohen's kappa ranged from 0.292-0.534 for the different scenarios. Overall, shock wave lithotripsy (SWL) and ureteroscopy (URS) were the most commonly chosen treatment options, with medical expulsive therapy (MET) and laparoscopy being the least recommended by urologists for themselves, as well as for their patients. CONCLUSIONS: Although urologists were not entirely consistent in their recommendations for stone treatment, they generally followed the "golden rule" and treated their patients as they would want to be treated. The most commonly recommended treatments for upper urinary tract stones were SWL and URS.

Long-term results of microwave thermotherapy for symptomatic benign prostatic hyperplasia.

PURPOSE: To study the long-term outcomes of men with moderately severe symptomatic benign prostatic hyperplasia (BPH) who were treated with transurethral microwave thermotherapy (TUMT) with the Dornier Urowave machine. PATIENTS AND METHODS: A total of 220 patients (mean age 66.2 years) with clinical BPH, an American Urological Association (AUA) Symptom Score of >or=13, and a peak urinary flow rate (Qmax) of

Double-blind randomized controlled trial assessing the safety and efficacy of intravesical agents for ureteral stent symptoms after extracorporeal shockwave lithotripsy.

BACKGROUND AND PURPOSE: Ureteral stents are a significant source of pain and discomfort for many urologic patients. A novel approach to addressing this problem is the intravesical instillation of a selected pharmacologic agent after stent insertion. The purpose of this study was to assess the safety and efficacy of intravesical instillation of various agents in reducing ureteral stent-associated discomfort in patients requiring a stent after extracorporeal shockwave lithotripsy (SWL). PATIENTS AND METHODS: In this double-blind prospective trial, 42 patients were randomized to receive intravesical instillation of one of three agents (oxybutynin, alkalinized lidocaine, or ketorolac) or a control solution (0.9% sodium chloride) immediately after stent insertion at time of SWL. The four groups of patients were demographically similar. Preoperative, intraoperative, and postoperative data were collected prospectively and analyzed statistically. The primary outcome measure was reduction in ureteral stent symptoms, and the secondary outcome measure was the safety of intravesical instillation of each agent through assessment of drug-related adverse events. RESULTS: There were no intraoperative or postoperative complications, nor were there any serious side effects attributable to any of the intravesically instilled agents. There was a statistically significant decrease in stent-related discomfort at the 1-hour time point in the group of patients who received intravesical ketorolac compared with the control group. CONCLUSIONS: Intravesical instillation represents a novel approach to the problem of ureteral stent-related discomfort. From our results, ketorolac appears to be the most effective intravesical agent in reducing stent-related patient discomfort, and we have established that intravesical instillation of ketorolac is safe in humans.

A prospective evaluation of the diagnostic and potential prognostic utility of urinary human telomerase reverse transcriptase mRNA in patients with bladder cancer.

Human telomerase reverse transcriptase (hTERT) mRNA expression has been considered a surrogate marker for telomerase activity based on its parallel detection in urological malignancies, including transitional cell carcinoma (TCC) of the bladder. The objective of this study was to prospectively evaluate the diagnostic performance of urine hTERT mRNA marker and urine cytology in the detection of bladder cancer. The multiplex hTERT/GAPDH (glyceraldehyde-3-phosphate dehydrogenase) reverse transcription polymerase chain reaction (RT-PCR) assay was employed to assess hTERT mRNA expression in urine sediments from 43 patients with clinically apparent TCC undergoing transurethral resection. Tumor grade and pathological stage were determined. The results of urine cytology were compared with urine hTERT mRNA expression. The control group consisted of 46 age-matched healthy volunteers without known urinary tract disease. The sensitivity of hTERT mRNA expression marker in the detection of bladder cancer was significantly better than urine cytology (95% versus 65%, p<0.001). The hTERT mRNA was detected with high sensitivity in both low and high grade tumors, and in superficial and invasive phenotypes. No correlation was seen between hTERT mRNA and the histopathological grade and stage. The specificity of urinary hTERT mRNA marker was 93.5%. The detection of hTERT mRNA expression in urine was a highly sensitive marker for the diagnosis of TCC of the bladder in this study. This urine-based marker shows promise as a non-invasive adjunct to cystoscopy in patients undergoing bladder tumor surveillance.

Upper tract imaging after ureteroscopic holmium:YAG laser lithotripsy: when is it necessary?

INTRODUCTION/OBJECTIVE: Advances in ureteroscope design and refinements of ancillary instrumentation have resulted in an expanded role for ureteroscopy in the management of urinary calculi. Technological enhancements coupled with improved endourologic skills have also been associated with a reduction in procedural-related complications. Historically, postoperative imaging with ultrasound (U/S) or intravenous pyelogram (IVP) had been advocated to rule out persistent obstruction due to retained stone fragments or ureteral stricture. The purposes of this study were to evaluate the incidence of postoperative ureteral obstruction in a contemporary series of patients undergoing ureteroscopic holmium:YAG laser lithotripsy without basket extraction of fragments and to identify patient, stone and operative factors predictive of which patients will benefit from postoperative imaging. MATERIALS AND METHODS: The charts and imaging studies of 89 consecutive patients undergoing a total of 94 holmium:YAG ureteroscopic lithotripsy procedures between December 1998 and December 2000 were retrospectively reviewed. Preoperative, intraoperative and postoperative data were collected and analyzed. The primary outcome measure was the incidence of postoperative ureteral obstruction documented on upper tract imaging. Secondary outcome measures included interventions required for postoperative obstruction and other nonobstructive postoperative complications. RESULTS: Twenty-eight females and 61 males were studied, with a mean patient age of 54 (range 13-80) years. Fifty-five percent of patients underwent related procedures prior to referral to our tertiary endourology centre. Complete clinical and radiological follow-up is available for 68 of 89 (76.4%) patients, with a mean follow-up duration of 24.2 weeks. Overall stone-free rate was 97%. Six patients had evidence of urinary tract obstruction on follow-up radiological assessment, two from residual stone fragments and four from ureteral stricture. Each of these four patients had at least one preoperative risk factor for ureteral stricture. CONCLUSIONS: Routine postoperative upper tract imaging is not necessary in all patients undergoing uncomplicated ureteroscopic holmium:YAG laser lithotripsy. Indications for upper tract imaging include chronic stone impaction, significant ureteral trauma, pre-existing renal function impairment, endoscopic evidence of stricture and postoperative flank pain or fever.

The clinical research office of the endourological society percutaneous nephrolithotomy global study: Outcomes in the morbidly obese patient - a case control analysis.

BACKGROUND: Efficacy and safety of percutaneous nephrolithotomy (PCNL) have been demonstrated in obese individuals. Yet, there is a paucity of data on the outcomes of PCNL in morbidly obese patients (body mass index [BMI] >40). METHODS: Perioperative and stone-related outcomes following PCNL in morbidly obese patients was assessed using a prospective database administered by the Clinical Research Office of the Endourological Society (CROES). A multidimensional match of 97 morbidly obese patients with those of normal weight was created using propensity score matching. Student's t-test and Chi-square tests were used to assess for differences between the groups. RESULTS: In total, 97 patients with a BMI >40 kg/m(2) were matched by stone characteristics with 97 patients of normal weight. The morbidly obese population demonstrated higher rates of diabetes mellitus (43% vs. 6%, p < 0.001) and cardiovascular disease (56% vs. 18%, (p < 0.001). Access was achieved more frequently by radiologists in the morbidly obese group (19% vs. 6%, p = 0.016). Mean operative duration was longer in the morbidly obese group (112 ± 56 min vs. 86 ± 43.5 min, p < 0.001). Stone-free rates were lower in the morbidly obese group (66% vs. 77%, p = 0.071). There was no significant difference in length of hospital stay or transfusion rate. Morbidly obese patients were significantly more likely to experience a postoperative complication (22% vs. 6%, p = 0.004). INTERPRETATION: PCNL in morbidly obese patients is associated with longer operative duration, higher rates of re-intervention and an increased risk of perioperative complications. With this knowledge, urologists should seek to develop strategies to optimize the perioperative management of such patients.

Intravesical ropivacaine as a novel means of analgesia post-robot-assisted radical prostatectomy: a randomized, double-blind, placebo-controlled trial.

PURPOSE: This study evaluates the safety and efficacy of intravesical ropivacaine as part of a mulitimodal approach to the provision of analgesia after robot-assisted radical prostatectomy (RARP). PATIENTS AND METHODS: In this double-blind, placebo-controlled trial, 40 patients who were scheduled to undergo RARP for treatment of localized prostate cancer by a single surgeon (SP) were randomized 1:1 to receive either alkalinized intravesical ropivacaine or placebo (0.9% sodium chloride) at the completion of the vesicourethral anastomosis. A standardized general anesthetic was administered in each case. The primary outcome was a reduction in postoperative pain as assessed by a visual analogue scale (VAS). The need for alternate analgesic agents was recorded. Adverse events related to the administration of intravesical ropivacaine were documented prospectively. RESULTS: No serious adverse events related to the administration of intravesical ropivacaine were identified. In the ropivacaine group, there was a significant reduction in the cumulative needed dose of ketoralac relative to placebo at 6 hours postoperatively. There was no statistically significant difference between the groups with regard to pain scores or narcotic use at any time point. CONCLUSIONS: Intravesical administration of ropivacaine may be used safely in the context of RARP and is associated with a significant, albeit modest reduction in the need for supplementary analgesic agents, but did not result in a decrease in postoperative pain scores.

A comparison of the metabolic profiles of diabetic and non-diabetic uric acid stone formers.

INTRODUCTION: The aim of this study was to compare the metabolic profiles of diabetic and non-diabetic patients with uric acid stones to understand whether preventive strategies should be tailored to reflect different causative factors. METHODS: The results of the metabolic evaluation of patients with uric acid stones identified prospectively from the Metabolic Stone Clinic at St. Joseph's Hospital, London, Canada were reviewed. Information included patients' clinical histories, 24 hour urine collections, blood chemistry and stone analysis. RESULTS: Complete data were obtained from 68 patients with uric acid stones. Twenty-two patients had diabetes. There were no statistically significant differences in mean age, body mass index, or history of gout. Among diabetics, pure uric acid stones were identified in 14 patients (63%) and mixed uric acid in 8 (36%). Pure uric acid stones were more common in the diabetic cohort (63% vs. 46%, p = 0.16). Urine pH, serum and urine uric acid levels and 24-hour urine volumes were similar in both groups. The diabetic group had an increased average oxalate excretion (424 µmol/d vs. 324 µmol/d, p = 0.003). CONCLUSION: The exact etiological basis for the higher oxalate excretion in diabetic uric acid stone formers is unclear. Whether this is a metabolic feature of diabetes, due to dietary indiscretion or the iatrogenic consequence of dietary advice requires further investigation.

Urinary expression of novel tissue markers of kidney injury after ureteroscopy, shockwave lithotripsy, and in normal healthy controls.

BACKGROUND AND PURPOSE: Shockwave lithotripsy (SWL) and ureteroscopy (URS) are minimally invasive treatment alternatives for kidney stones. Although less invasive, SWL subjects the renal parenchyma to a high level of energy and the potential to cause renal injury. The ability to detect renal injury post-SWL in a reliable and noninvasive way would be clinically beneficial. Kidney injury molecule 1 (KIM-1) and N-acetyl-ß-D-glucosaminidase (NAG) are two proteins secreted by the kidney into the urine and have been found to be sensitive markers of acute kidney injury in transplant patients. The aim of this work was to measure urinary levels of KIM-1 and NAG in patients with kidney stone who were treated by SWL or URS and in nonstone volunteers. PATIENTS AND METHODS: Patients with kidney stones who were treated by SWL (n = 50) or URS (n = 10) were recruited. Voided urine samples were collected before and 2 to 3 hours after URS and SWL. In addition, further urinary specimens were collected 2 days and 2 weeks post-SWL treatment. Voided urine samples from healthy volunteers were also collected. RESULTS: Mean KIM-1 values were increased in patients with kidney stones when compared with volunteers. KIM-1 and NAG levels significantly increased post-SWL and returned to baseline within 2 weeks post-SWL. Poor kidney function was significantly associated with increased biomarker activity both in baseline and post-SWL measurements. There was no significant change in urinary KIM-1 and NAG concentrations before and after URS. CONCLUSIONS: Kim-1 and NAG levels significantly increased post-SWL treatment suggesting a potential role for these urinary markers in identifying patients at higher risk of tissue injury.

Risk factors for perinephric hematoma formation after shockwave lithotripsy: a matched case-control analysis.

PURPOSE: To determine the incidence of and evaluate the potential risk of a symptomatic perinephric hematoma (PNH) after shockwave lithotripsy (SWL) with the Storz Modulith SLX-F2 device. PATIENTS AND METHODS: Patient and treatment-related data from 6172 SWL treatments for proximal ureteral and kidney stones were collected prospectively from April 2006 to August 2010. Patients in whom signs or symptoms of a PNH developed after SWL were investigated with imaging studies. Each patient identified with a PNH was matched with four controls using sex, age (±5 years), shockwave rate, energy and number, and no SWL within the previous 6 months as the matching variables. The baseline characteristics of the 21 cases and 84 controls were compared using the Student t test. The independent variables of hypertension (intraoperative value >140/90 mm Hg), anticoagulant/antiplatelet drugs, obesity (body mass index ≥30), and diabetes were compared using a conditional logistic regression analysis. The dependent variable was hematoma. RESULTS: A PNH developed after SWL with the Storz Modulith SLX-F2 device in 21 (0.34%) adult patients (19 men, 2 women) with a mean age of 55.2 years. Significant risk factors identified included intraoperative hypertension (hazard ratio [HR] 3.302, 1.066-10.230, P=0.0384) and anticoagulant/antiplatelet medications (HR 4.198, 1.103-15.984, P=0.0355). Diabetes (P=0.1043) and obesity (P=0.1021) were not associated with PNH. CONCLUSIONS: A clinical PNH occurred in less than 1% of our population. This is consistent with reports from earlier generation devices. Risk factors identified for hematoma formation were intraoperative hypertension and the use of anticoagulant/antiplatelet drugs.

Percutaneous nephrolithotripsy in patients with urinary diversions: a case-control comparison of perioperative outcomes.

PURPOSE: To compare the operative techniques and perioperative outcomes of patients with urinary intestinal diversions undergoing percutaneous nephrolithotripsy (PCNL), to a control cohort of patients without diversions. PATIENTS AND METHODS: The medical records of all patients who were treated with PCNL from 1990 to 2009 were retrospectively reviewed. Each urinary diversion patient's first PCNL was age-matched with four controls who were undergoing PCNL. The perioperative outcomes were compared between the diversion and control cohorts. RESULTS: Twenty-five patients with a urinary diversion who had undergone 33 PCNLs were identified. The mean age was 49.3 (8-85) years for the diversion group and 48.9 (4-84) for the control group. Urinary tract infection (64% vs 15% patients, P<0.0001), neurologic disease (64% vs 2%, P<0.0001), previous procedure for the same calculus (24% vs 4%, P=0.0004), urinary tract abnormalities (56% vs 14%, P<0.0001), solitary kidney (20% vs 3%, P=0.0081), and struvite stones (80% vs 12.5%, P=0.0006) were more commonly observed in the diversion group. Percutaneous access gained by a radiologist (40% vs 0%, P<0.0001), second-look nephroscopy (36% vs 16%, P=0.0466), and an increase in the frequency of fever or sepsis (8% vs 0%, P=0.0387) were identified more frequently in the diversion group. CONCLUSIONS: Patients with upper tract calculi and urinary diversions are challenging to the endourologist because of anatomic factors that can make percutaneous access more difficult; ultrasonography-guided access can be helpful in this setting. Patients with urinary diversions can be treated as safely and effectively by PCNL as nondiverted patients.

A multicentre single-blind randomized controlled trial comparing bipolar and monopolar transurethral resection of the prostate.

INTRODUCTION: Monopolar transurethral resection of the prostate (TURP) is the gold standard surgical therapy for men with lower urinary tract symptoms due to benign prostatic hyperplasia. Although generally considered safer, TURP experience is limited in Canada. METHODS: Forty-three patients from 5 Canadian centres were randomized to TURP with either bipolar or monopolar platforms. Patients underwent baseline determinations of American Urological Association (AUA) symptom score, peak urinary flow rate, post-void residual bladder volume and transrectal ultrasound prostate volume. Primary outcome measures were improvement in AUA symptom score, quality of life assessment and bother assessment. Secondary outcomes included procedural times, duration of catheterization, length of hospitalization, complications and the degree of thermal artifact in tissue specimens. Patients were followed for 6 months. RESULTS: Twenty-two patients were treated with bipolar and 21 with monopolar TURP. Preoperative demographics were not statistically different between groups. Postoperative data collection times were equivalent in AUA symptom, quality of life, bother and sexual function assessments. No differences were observed in the procedure time (60.7 min, bipolar vs. 47.4, monopolar) or the duration of urethral catheterization (1.5 days, bipolar vs. 1.1, monopolar). More patients in the bipolar group were discharged on the same day of surgery. There were no differences in the degree of tissue thermal artifact or complication rate. CONCLUSION: This trial suggests equivalent short-term outcomes for men undergoing monopolar or bipolar TURP.