Randomized Controlled Trial Comparing Three Different Modalities of Lithotrites for Intracorporeal Lithotripsy in Percutaneous Nephrolithotomy

PURPOSE

To compare the efficiency (stone fragmentation and removal time) and complications of three models of intracorporeal lithotripters in percutaneous nephrolithotomy (PCNL).

MATERIALS AND METHODS

Prospective, randomized controlled trial at nine centers in North America from 2009 to 2016. Patients were randomized to one of three lithotripter devices: the Cyberwand, a dual-probe ultrasonic device; the Swiss Lithoclast Select, a combination pneumatic and ultrasonic device; and the StoneBreaker, a portable pneumatic device powered by CO₂ cartridges. Since the StoneBreaker lacks an ultrasonic component, it was used with the LUS-II ultrasonic lithotripter to allow fair comparison with combination devices.

RESULTS

Two hundred seventy patients were enrolled, 69 were excluded after randomization. Two hundred one patients completed the study: 71 in the Cyberwand group, 66 in the Lithoclast Select group, and 64 in the StoneBreaker group. The baseline patient characteristics of the three groups were similar. Mean stone surface area was smaller in the StoneBreaker group at 407.8 mm² vs 577.5 mm² (Lithoclast Select) and 627.9 mm² (Cyberwand). The stone clearance rate was slowest in the StoneBreaker group at 24.0 mm²/min vs 28.9 mm²/min and 32.3 mm²/min in the Lithoclast Select and Cyberwand groups, respectively. After statistically adjusting for the smaller mean stone in the StoneBreaker group, there was no difference in the stone clearance rate among the three groups (p = 0.249). Secondary outcomes, including complications and stone-free rates, were similar between the groups.

CONCLUSIONS

The Cyberwand, Lithoclast Select, and the StoneBreaker lithotripters have similar adjusted stone clearance rates in PCNL for stones >2 cm. The safety and efficacy of these devices are comparable.

Retained Digital Flexible Ureteroscopes

This report documents two instances of retained flexible ureteroscopes at the time of ureteroscopy and laser lithotripsy in a healthy 37-year-old male and a 53-year-old male with a pelvic kidney. We describe maneuvers to remove the ureteroscope endoscopically in the first case, while the second case required conversion to open surgery for ureteroscope extrication.

Questions and challenges associated with studying the microbiome of the urinary tract

Urologists are typically faced with clinical situations for which the microbiome may have been a contributing factor. Clinicians have a good understanding regarding the role of bacteria related to issues such as antibiotic resistance; however, they generally have a limited grasp of how the microbiome may relate to urological issues. The largest part of the human microbiome is situated in the gastrointestinal tract, and though this is mostly separated from the urinary system, bacterial dissemination and metabolic output by this community is thought to have a significant influence on urological conditions. Sites within the urogenital system that were once considered "sterile" may regularly have bacterial populations present. The health implications potentially extend all the way to the kidneys. This could affect urinary tract infections, bladder cancer, urinary incontinence and related conditions including the formation of kidney stones. Given the sensitivity of the methodologies employed, and the large potential for contamination when working with low abundance microbiomes, meticulous care in the analyses of urological samples at various sites is required. This review highlights the opportunities for urinary microbiome investigations and our experience in working with these low abundance samples in the urinary tract.

KIM-1 Is a Potential Urinary Biomarker of Obstruction: Results from a Prospective Cohort Study

INTRODUCTION

Partial or complete obstruction of the urinary tract is a common and challenging urological condition that may occur in patients of any age. Serum creatinine is the most commonly used method to evaluate global renal function, although it has low sensitivity for early changes in the glomerular filtration rate or unilateral renal pathology. Hence, finding another measurable parameter that reflects the adaptation of the renal physiology to these circumstances is important. Several recent studies have assessed the use of new biomarkers of acute kidney injury (AKI), but the information among patients with stone disease and those with obstructive uropathy is limited.

MATERIAL AND METHODS

A prospective cohort study was conducted to determine the urinary levels of kidney injury molecule-1 (KIM-1), Total and Monomeric neutrophil gelatinase-associated lipocalin (NGAL) in patients with hydronephrosis secondary to renal stone disease, congenital ureteropelvic junction obstruction or ureteral stricture. Comparison between patients with hydronephrosis and no hydronephrosis was carried out along with correlation analysis to detect factors associated with biomarker expression.

RESULTS

Urinary levels of KIM-1 significantly decreased after hydronephrosis treatment in patients with unilateral obstruction (1.19 ng/mL vs 0.76 ng/mL creatinine, p = 0.002), additionally KIM-1 was significantly higher in patients with hydronephrosis compared to stone disease patients without radiological evidence of obstruction (1.19 vs 0.64, p = 0.006). Total and Monomeric NGAL showed a moderate correlation with the presence of leukocyturia. We found that a KIM-1 value of 0.735 ng/mg creatinine had a sensitivity of 75% and specificity of 67% to predict the presence of hydronephrosis in preoperative studies (95% CI 0.58-0.87, p = 0.006).

CONCLUSION

Our results show that KIM-1 is a promising biomarker of subclinical AKI associated with hydronephrosis in urological patients. NGAL values were influenced by the presence of leukocyturia, limiting its usefulness in this population.

Surgical Management of Stones: American Urological Association/Endourological Society Guideline, PART II

PURPOSE

This Guideline is intended to provide a clinical framework for the surgical management of patients with kidney and/or ureteral stones. The summary presented herein represents Part II of the two-part series dedicated to Surgical Management of Stones: American Urological Association/Endourological Society Guideline. Please refer to Part I for introductory information and a discussion of pre-operative imaging and special cases.

MATERIALS AND METHODS

A systematic review of the literature (search dates 1/1/1985 to 5/31/2015) was conducted to identify peer-reviewed studies relevant to the surgical management of stones. The review yielded an evidence base of 1,911 articles after application of inclusion/exclusion criteria. These publications were used to create the Guideline statements. Evidence-based statements of Strong, Moderate, or Conditional Recommendation were developed based on benefits and risks/burdens to patients. Additional directives are provided as Clinical Principles and Expert Opinions when insufficient evidence existed.

RESULTS

The Panel identified 12 adult Index Patients to represent the most common cases seen in clinical practice. Three additional Index Patients were also created to describe the more commonly encountered special cases, including pediatric and pregnant patients. With these patients in mind, Guideline statements were developed to aid the clinician in identifying optimal management.

CONCLUSIONS

Proper treatment selection, which is directed by patient- and stone-specific factors, remains the greatest predictor of successful treatment outcomes. This Guideline is intended for use in conjunction with the individual patient's treatment goals. In all cases, patient preferences and personal goals should be considered when choosing a management strategy.

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.

Multicenter External Validation and Comparison of Stone Scoring Systems in Predicting Outcomes After Percutaneous Nephrolithotomy

BACKGROUND AND PURPOSE

Several scoring systems have recently emerged to predict stone-free rate (SFR) and complications after percutaneous nephrolithotomy (PCNL). We aimed to compare the most commonly used scoring systems (Guy's stone score, S.T.O.N.E. nephrolithometry, and CROES nomogram), assess their predictive accuracy for SFR and other postoperative variables, and develop a risk group stratification based on these scoring systems.

MATERIALS AND METHODS

We performed a retrospective review of patients who have had a PCNL at four academic institutions between 2006 and 2013. Primary outcome was SFR within 3 weeks of the surgery and secondary outcomes were operative time (OT), complications, and length of stay (LOS). We performed chi-squared, t-test, logistic, linear, and Poisson regressions, as well as receiver operating characteristics curve with area under the curve (AUC) calculation.

RESULTS

We identified 586 patients eligible for analysis. Of these, 67.4% were stone free. Guy's, S.T.O.N.E., and CROES score were predictive of SFR on multivariable logistic regression (odds ratio [OR]: 1.398, 95% confidence interval [CI]: 1.056, 1.852, p = 0.019; OR: 1.417, 85% CI: 1.231, 1.631, p < 0.001; OR: 0.993, 95% CI: 0.988, 0.998, p = 0.004) and have similar predictive accuracy with AUCs of 0.629, 0.671, and 0.646, respectively. On multivariable linear regression, only S.T.O.N.E. was an independent predictor of longer OT (β = 14.556, 95% CI: 12.453, 16.660, p < 0.001). None of the scores were independent predictors of postoperative complications or a longer LOS. Poisson regression allowed for risk group stratification and showed the S.T.O.N.E. score and CROES nomogram to have the most distinct risk groups.

CONCLUSIONS

The three evaluated scoring systems have similar predictive accuracy of SFR. S.T.O.N.E. has additional value in predicting OT. Risk group stratification can be used for patient counseling. Further research is needed to identify whether or not any is superior to the others with regard to clinical usefulness and predictive accuracy.

Combining Mean and Standard Deviation of Hounsfield Unit Measurements from Preoperative CT Allows More Accurate Prediction of Urinary Stone Composition Than Mean Hounsfield Units Alone

INTRODUCTION AND OBJECTIVES

The mineral composition of a urinary stone may influence its surgical and medical treatment. Previous attempts at identifying stone composition based on mean Hounsfield Units (HUm) have had varied success. We aimed to evaluate the additional use of standard deviation of HU (HUsd) to more accurately predict stone composition.

METHODS

We identified patients from two centers who had undergone urinary stone treatment between 2006 and 2013 and had mineral stone analysis and a computed tomography (CT) available. HUm and HUsd of the stones were compared with ANOVA. Receiver operative characteristic analysis with area under the curve (AUC), Youden index, and likelihood ratio calculations were performed.

RESULTS

Data were available for 466 patients. The major components were calcium oxalate monohydrate (COM), uric acid, hydroxyapatite, struvite, brushite, cystine, and CO dihydrate (COD) in 41.4%, 19.3%, 12.4%, 7.5%, 5.8%, 5.4%, and 4.7% of patients, respectively. The HUm of UA and Br was significantly lower and higher than the HUm of any other stone type, respectively. HUm and HUsd were most accurate in predicting uric acid with an AUC of 0.969 and 0.851, respectively. The combined use of HUm and HUsd resulted in increased positive predictive value and higher likelihood ratios for identifying a stone's mineral composition for all stone types but COM.

CONCLUSIONS

To the best of our knowledge, this is the first report of CT data aiding in the prediction of brushite stone composition. Both HUm and HUsd can help predict stone composition and their combined use results in higher likelihood ratios influencing probability.

Novel Methods of Determining Urinary Calculi Composition: Petrographic Thin Sectioning of Calculi and Nanoscale Flow Cytometry Urinalysis

Accurate determination of urinary stone composition has significant bearing on understanding pathophysiology, choosing treatment modalities and preventing recurrence. A need exists for improved methods to determine stone composition. Urine of 31 patients with known renal calculi was examined with nanoscale flow cytometry and the calculi collected during surgery subsequently underwent petrographic thin sectioning with polarized and fluorescent microscopy. Fluorescently labeled bisphosphonate probes (Alendronate-fluorescein/Alendronate-Cy5) were developed for nanoscale flow cytometry to enumerate nanocrystals that bound the fluorescent probes. Petrographic sections of stones were also imaged by fluorescent and polarized light microscopy with composition analysis correlated to alendronate +ve nanocrystal counts in corresponding urine samples. Urine samples from patients with Ca²⁺ and Mg²⁺ based calculi exhibited the highest alendronate +ve nanocrystal counts, ranging from 100–1000 nm in diameter. This novel urine based assay was in agreement with composition determined by petrographic thin sections with Alendronate probes. In some cases, high alendronate +ve nanocrystal counts indicated a Ca²⁺ or Mg²⁺ composition, as confirmed by petrographic analysis, overturning initial spectrophotometric diagnosis of stone composition. The combination of nanoscale flow cytometry and petrographic thin sections offer an alternative means for determining stone composition. Nanoscale flow cytometry of alendronate +ve nanocrystals alone may provide a high-throughput means of evaluating stone burden.

Assessing the Magnitude of Effect of Bone Structures on Shockwave Lithotripsy Fragmentation: Results from an In Vitro Study

INTRODUCTION

Several anatomic and clinical factors have been implicated in the failure rates of shock wave lithotripsy (SWL), including the attenuating effects of bony structures. We designed an in vitro model that incorporates the lumbar spine, including vertebral bodies and transverse processes along the pathway of shockwaves, to mimic the clinical scenario during SWL of upper ureteral stones. We hypothesized that the presence of bone structures in the SWL pathway significantly affects the fragmentation rate.

MATERIALS AND METHODS

An ordnance gelatin (OG) model was conceptualized and created to allow a pig's lumbar spine to be embedded within it. Artificial urinary calculi weighing 2 ± 0.1 g (1.2-cm diameter) were prepared using BegoStone plaster. The trial was divided into two arms: group 1 models had OG only and served as the control and group 2 models had the bone embedded in the gelatin with stone wells placed above the transverse processes. Twenty-four stones per group were subjected to SWL using the STORZ MODULITH SLX-F2 lithotripter, using the same treatment parameters. Fragments were sieved through 2- and 4-mm filters, and the fragmentation coefficients (FC) were calculated. The Mann-Whitney test was used to compare FC between the two groups.

RESULTS

The mean fragmentation rate of group 1 was statistically significantly higher compared with group 2 using a 4-mm sieve (43% vs 0.62%, p < 0.001) and the 2-mm filter (18% vs 0.52%, p < 0.001).

CONCLUSIONS

The presence of bone structures dramatically reduces the fragmentation rate of phantom stones using an OG in vitro model. The OG model is inexpensive and simple to use to simulate clinical situations during SWL.

A comparison of outcomes after percutaneous nephrolithotomy in children and adults: a matched cohort study

INTRODUCTION

Percutaneous nephrolithotomy (PCNL) has surpassed open stone surgery as the operation of choice for large and complex stone burdens (figure). Although the procedure was developed in adults, its principles have been extrapolated to children. There is a paucity of literature comparing outcomes of PCNL in adults and children for similar stone burdens.

OBJECTIVE

The purpose of this study was to evaluate outcomes following PCNL among children and adults with similar stone burdens.

PATIENTS AND METHODS

Data on patient characteristics and outcomes for 2196 consecutive patients undergoing PCNL at a single institution were collected prospectively from January 1992 to July 2013. Thirty-one pediatric patients undergoing 39 PCNLs were identified. Each pediatric PCNL was matched in a ratio of 1:4 to adult PCNLs by year of surgery and stone burden characteristics (staghorn, partial staghorn, number of stones). All PCNLs were performed by two fellowship-trained endourologists who operate on both adult and pediatric patients. Ultrasonic lithotripsy was used primarily. The primary outcome measure was stone-free rate (SFR) at hospital discharge. Secondary outcomes included the need for second-look nephroscopy, length of hospital stay, complication rate, and blood transfusion rate. The Student t test was used for continuous variables and the Fisher exact for categorical variables.

RESULTS

The median age for the pediatric group was 13.9 ± 4.30 years and for the adult group was 55.4 ± 15.1 years. Pediatric patients tended to present with metabolic stones, with no difference in rates of infection stones. No difference was found in SFR at time of hospital discharge (86.1% vs. 86.4%, p = 0.2). More pediatric patients required a second access tract than adult patients (15.4% vs. 4.52%, p = 0.02). There was no significant difference in the need for second-look nephroscopy, length of stay, or complication rates (overall and by Clavien classification subgroup) between both groups. The rates of blood transfusion were low in both groups (0% vs. 0.6%, p = 0.80).

DISCUSSION

There was no difference in primary and secondary outcomes among children compared with adults undergoing PCNL in our study. The outcomes reported in this study were similar to published literature. A limitation of this study is the low number of pediatric patients. However, it is unique to have a single-center study that compares PCNL outcomes in both adult and pediatric patient and accounts for stone burden characteristics.

CONCLUSIONS

Although principles of PCNL were developed in adults, this study affirms the safety and efficacy of PCNL in both pediatric and adult patients.

Robotic Proximal Ureteropyelostomy After Unsuccessful Endourologic Management of Complicated Proximal Ureteral Stone Disease

We present a clinical case of a 66-year-old female with a left ureteropelvic junction impacted renal calculi associated with a tortuous ureter. After a failed combined retrograde and antegrade endoscopic procedure, a robot-assisted laparoscopic ureteropyelostomy was successful.

The Effect of Renal Cysts on the Fragmentation of Renal Stones During Shockwave Lithotripsy: A Comparative In Vitro Study

PURPOSE

To assess the potential effect of simple renal cysts (SRC) on stone fragmentation during shockwave lithotripsy (SWL) in an in vitro model.

MATERIALS AND METHODS

The in vitro model was constructed using 10% ordnance gelatin (OG). Models were created to mimic four scenarios: Model A-with an air-filled cavity (suboptimal for stone fragmentation); model B-without a cavity (normal anatomy); model C-with a 3-cm serum filled cavity (to represent a small SRC); model D-with a 4-cm serum filled cavity (to represent a larger SRC). SWL was applied to 24 standardized phantom stones (weight of 2±0.1 g) in each model using a standardized protocol. Stone fragments were retrieved, then dried overnight at room air temperature. Fragmentation coefficient (FC) was calculated for each stone, for fragments<4 mm and <2 mm.

RESULTS

The OG in vitro model was robust enough for the proposed research. There was no fragmentation evident in model A as expected. The mean FC was 29.7 (±20.5) and 39.7 (±23.7) for <4 mm fragments (P=0.069) and 7.6 (±4.1) and 10.6 (±6.7) for <2 mm fragments (P=0.047), for noncystic and cystic models, respectively. The mean FC was 29.7 (±20.5), 38.8 (±26.2) and 40.7 (±21.3) for <4 mm fragments (P=0.213) and 7.6 (±4.1), 11.1 (±8) and 10.2 (±5.3) for <2 mm fragments (P=0.138), for models B, C, and D, respectively.

CONCLUSION

Our in vitro experiment confirms better stone fragmentation associated with SWL in the presence of adjacent SRC.

The microbiome of the urinary tract--a role beyond infection

Urologists rarely need to consider bacteria beyond their role in infectious disease. However, emerging evidence shows that the microorganisms inhabiting many sites of the body, including the urinary tract--which has long been assumed sterile in healthy individuals--might have a role in maintaining urinary health. Studies of the urinary microbiota have identified remarkable differences between healthy populations and those with urologic diseases. Microorganisms at sites distal to the kidney, bladder and urethra are likely to have a profound effect on urologic health, both positive and negative, owing to their metabolic output and other contributions. Connections between the gut microbiota and renal stone formation have already been discovered. In addition, bacteria are also used in the prevention of bladder cancer recurrence. In the future, urologists will need to consider possible influences of the microbiome in diagnosis and treatment of certain urological conditions. New insights might provide an opportunity to predict the risk of developing certain urological diseases and could enable the development of innovative therapeutic strategies.

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.

Differences in ureteroscopic stone treatment and outcomes for distal, mid-, proximal, or multiple ureteral locations: the Clinical Research Office of the Endourological Society ureteroscopy global study

BACKGROUND

Ureteroscopy has traditionally been the preferred approach for treatment of distal and midureteral stones, with shock wave lithotripsy used for proximal ureteral stones.

OBJECTIVE

To describe the differences in the treatment and outcomes of ureteroscopic stones in different locations.

DESIGN, SETTING, AND PARTICIPANTS

Prospective data were collected by the Clinical Research Office of the Endourological Society on consecutive patients treated with ureteroscopy at centres around the world over a 1-yr period.

INTERVENTION

Ureteroscopy was performed according to study protocol and local clinical practice guidelines.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Stone location, treatment details, postoperative outcomes, and complications were recorded. Pearson's chi-square analysis and analysis of variance were used to compare outcomes among the different stone locations.

RESULTS AND LIMITATIONS

Between January 2010 and October 2012, 9681 patients received ureteroscopy treatment for stones located in the proximal ureter (n=2656), midureter (n=1980), distal ureter (n=4479), or multiple locations (n=440); location in 126 patients was not specified. Semirigid ureteroscopy was predominantly used for all stone locations. Laser and pneumatic lithotripsy were used in the majority of cases. Stone-free rates were 94.2% for distal ureter locations, 89.4% for midureter locations, 84.5% for proximal ureter locations, and 76.6% for multiple locations. For the proximal ureter, failure and retreatment rates were significantly higher for semirigid ureteroscopy than for flexible ureteroscopy. A low incidence of intraoperative complications was reported (3.8-7.7%). Postoperative complications occurred in 2.5-4.6% of patients and varied according to location, with the highest incidence reported for multiple stone locations. Limitations include short-term follow-up and a nonuniform treatment approach.

CONCLUSIONS

Ureteroscopy for ureteral stones resulted in good stone-free rates with low morbidity.

PATIENT SUMMARY

This study shows that patients who have ureteral stones can be treated successfully with ureteroscopy with a low rate of complications for the patient.

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-β-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.

Evaluation and medical management of the kidney stone patient

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2010 Update: Guidelines for the management of benign prostatic hyperplasia

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Metabolic testing of the first-time calcium oxalate stone former: Is it indicated? No

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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.

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 urinarytract symptoms due to benign prostatic hyperplasia. Althoughgenerally considered safer, TURP experience is limited in Canada.Methods: Forty-three patients from 5 Canadian centres were randomizedto TURP with either bipolar or monopolar platforms.Patients underwent baseline determinations of American UrologicalAssociation (AUA) symptom score, peak urinary flow rate, postvoidresidual bladder volume and transrectal ultrasound prostatevolume. Primary outcome measures were improvement in AUAsymptom score, quality of life assessment and bother assessment.Secondary outcomes included procedural times, duration of catheterization,length of hospitalization, complications and the degreeof thermal artifact in tissue specimens. Patients were followed for6 months.Results: Twenty-two patients were treated with bipolar and 21 withmonopolar TURP. Preoperative demographics were not statisticallydifferent between groups. Postoperative data collection times wereequivalent in AUA symptom, quality of life, bother and sexualfunction assessments. No differences were observed in the proceduretime (60.7 min, bipolar vs. 47.4, monopolar) or the durationof urethral catheterization (1.5 days, bipolar vs. 1.1, monopolar).More patients in the bipolar group were discharged on the sameday of surgery. There were no differences in the degree of tissuethermal artifact or complication rate.Conclusion: This trial suggests equivalent short-term outcomes formen undergoing monopolar or bipolar TURP.

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.

Renal stone disease in spinal-cord-injured patients

Renal stone disease is common among patients with spinal cord injury (SCI). They frequently have recurrent stones, staghorn calculi, and bilateral stone disease. The potential risk factors for stones in the SCI population are lesion level, bladder management strategy, specific metabolic changes, and frequent urinary tract infections. There has been a reduction in struvite stones among these patients, likely as a result of advances in their urologic care. The clinical presentation of stone disease in patients with SCI may involve frequent urinary infections or urosepsis, and at the time of presentation patients may need emergency renal drainage. The proportion of patients who have their stones treated with different modalities is largely unknown. Shockwave lithotripsy (SWL) is commonly used to manage stones in patients with SCI, and there have been reports of stone-free rates of 50% to 70%. The literature suggests that the morbidity associated with percutaneous nephrolithotomy in these patients is considerable. Ureteroscopy is a common modality used in the general population to treat patients with upper tract stone disease. Traditional limitations of this procedure in patients with SCI have likely been overcome with new flexible scopes; however, the medical literature has not specifically reported on its use among patients with SCI.

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.

Effects of subinhibitory concentrations of ciprofloxacin on Staphylococcus saprophyticus adherence and virulence in urinary tract infections

BACKGROUND AND PURPOSE

Staphylococcus saprophyticus is a frequent cause of both uncomplicated and complicated urinary tract infections (UTI) in young females and has recently been established as the most prominent gram-positive uropathogen. Although the effects of subinhibitory concentrations of antimicrobials on numerous other pathogenic bacteria have been studied, little is known regarding how S saprophyticus responds under such conditions.

MATERIALS AND METHODS

In this study, we investigated the effects of subminimum inhibitory concentrations (MIC) of ciprofloxacin (CIP) on S saprophyticus attachment to glass microscope slides, ureteral stent material, and T24 bladder cells, as well as its effects on S saprophyticus-induced proinflammatory cytokine expression in bladder cells.

RESULTS

Adherence to glass microscope slides, ureteral stent material, and bladder cell monolayers were all significantly increased in the presence of sub-MIC levels of CIP. While the S saprophyticus challenge of T24 bladder cell monolayers significantly upregulated both interleukin (IL)-6 and IL-8 expression, sub-MIC CIP abrogated these effects, returning their secretion to control levels.

CONCLUSIONS

Our results demonstrate that exposure to sub-MIC CIP increases S saprophyticus adherence to both abiotic and biotic surfaces including urinary device material and cultured bladder cells. In addition, low levels of this antimicrobial downregulate S saprophyticus-stimulated proinflammatory cytokine secretion in the bladder. These changes may make S saprophyticus more effective at colonizing the urinary tract and highlights the need for clinicians to consider the impact of subinhibitory concentrations of antimicrobials on bacteria when designing treatment strategies to manage UTI.

Percutaneous nephrolithotomy of caliceal diverticular calculi: a single center experience

BACKGROUND AND PURPOSE

Caliceal diverticula are rare renal anomalies present in approximately 0.6% of the population. They are associated with calculi in 50% of cases. Therapeutic options include several minimally invasive techniques. We report a retrospective review of outcomes and complications from our series of patients who were treated with a percutaneous approach.

PATIENTS AND METHODS

A database of outcomes related to percutaneous nephrolithotomy (PCNL) has been maintained at our institution since 1992. Data on all patients with caliceal diverticular stones who underwent PCNL during a 17-year period from 1992 to 2009 were reviewed retrospectively. Our preferred approach to PCNL in these patients is to puncture directly into the diverticulum and to try to advance a guidewire through the infundibular neck. In cases where the caliceal neck could not be intubated, we performed a transdiverticular approach with creation of a neoinfundibulum as a salvage procedure. We evaluated the two techniques with regard to stone-free rates and early postoperative complications.

RESULTS

Seventy-six procedures were performed. The mean age was 43 years (range 17-72 y). The mean stone area was 583 mm(2). The surgical approach was direct puncture in 47, transdiverticular in 20, retrograde in 8, and unknown in 1 patient. Eight patients underwent lining fulguration. The average duration of surgery was 75 minutes (23-169 min) with an average hospital stay of 4.7 days. There were a total of 23 complications, of which 11 necessitated additional intervention. The overall stone-free rates were 77% and 89% for direct puncture and transdiverticular approaches, respectively.

CONCLUSIONS

The percutaneous management of caliceal diverticular calculi is highly effective and can be accomplished with low morbidity.

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.