Percutaneous Nephrolithotomy Access: A Meta-Analysis Comparing Access by Urologist vs Radiologist.

Introduction: Percutaneous nephrolithotomy is a minimally invasive procedure indicated for the management of staghorn calculi or renal calculi >2.0 cm. Percutaneous renal access is a critical step in this procedure and can be performed by either urologists or interventional radiologists. The purpose of this study is to perform a meta-analysis to compare outcomes between urologist and interventional radiologist-mediated access. Methods: An electronic literature search was conducted to identify studies comparing urologist- and interventional radiologist-acquired access. Studies must have included both urologist- and intervention radiologist-acquired access data but were excluded if (1) not in English; (2) abstract without full text; (3) unable to determine who acquired access; and (4) only included either urologist or interventional radiologist data. Meta-analysis comparison was generated with the Review Manager 5.4 software. Results: After screening the abstracts and title, 55 relevant studies were identified. Nine articles were utilized in the meta-analysis. Urologist-acquired access was associated with a greater stone-free rate (risk ratio [RR] = 1.10; 95% confidence interval [CI], 1.01-1.20), a reduction in major complications (RR = 0.69; 95% CI, 0.53-0.92), and a shorter hospital stay (mean difference -0.40; 95% CI, -0.64 to -0.16) in comparison with radiologist-acquired access. Urologist-acquired access was associated with greater blood loss (mean difference 0.46; 95% CI, 0.32-0.60) when compared with interventional radiology-acquired access. No significant differences were found with regard to unusable access, multiple tracts, supracostal access, ancillary procedure requirement, operative time, minor complications, and transfusions. Conclusions: Urologist-acquired access may be associated with a higher stone-free rate and a reduction in major complications, whereas interventional radiologist-mediated access may be associated with a reduction in blood loss, despite similar transfusion rates.

Heterogeneity in stone culture protocols and endourologist practice patterns: a multi-institutional survey.

Kidney stone cultures can be beneficial in identifying bacteria not detected in urine, yet how stone cultures are performed among endourologists, under what conditions, and by what laboratory methods remain largely unknown. Stone cultures are not addressed by current clinical guidelines. A comprehensive REDCap electronic survey sought responses from directed (n = 20) and listserv elicited (n = 108) endourologists specializing in kidney stone disease. Questions included which clinical scenarios prompt a stone culture order, how results influence post-operative antibiotics, and what microbiology lab protocols exist at each institution with respect to processing and resulting stone cultures. Logistic regression statistical analysis determined what factors were associated with performing stone cultures. Of 128 unique responses, 11% identified as female and the mean years of practicing was 16 (range 1-46). A specific 'stone culture' order was available to only 50% (64/128) of those surveyed, while 32% (41/128) reported culturing stone by placing a urine culture order. The duration of antibiotics given for a positive stone culture varied, with 4-7 days (46%) and 8-14 days (21%) the most reported. More years in practice was associated with fewer stone cultures ordered, while higher annual volume of percutaneous nephrolithotomy was associated with ordering more stone cultures (p < 0.01). Endourologists have differing practice patterns with respect to ordering stone cultures and utilizing the results to guide post-operative antibiotics. With inconsistent microbiology lab stone culture protocols across multiple institutions, more uniform processing is needed for future studies to assess the clinical benefit of stone cultures and direct future guidelines.

Comparison of Management and Outcomes of Symptomatic Urolithiasis During the COVID-19 Pandemic to a Comparative Cohort.

OBJECTIVE: To analyze the clinical presentation and outcomes for patients who presented with symptomatic urolithiasis during the initial months of the COVID-19 pandemic. METHODS: We retrospectively reviewed Emergency Department (ED) presentations from a Philadelphia healthcare system for symptomatic urolithiasis between March and June 2020 and compared these with presentations for the same time period from the year prior. Patient demographics, stone characteristics, management, and clinical outcomes were compared between the 2 years. RESULTS: One hundred and thirty-nine patients presented during 2020 compared to 269 in 2019. There were fewer patients who presented during the initial COVID-19 pandemic surge who had obesity (37.41% vs 49.44%, P = .024), hyperlipidemia (18.71% vs 31.60, P = .006), and asthma (5.76% vs 16.73%, P = .002). Although overall stone characteristics did not differ between the 2 groups, a larger proportion of patients in 2020 presented with an obstructing stone (81.16% vs 64.1%, P = .001). Patients who presented during the COVID-19 pandemic did not have higher rates of infection, acute kidney injury, or complications. Rates of surgical modalities, emergent procedures, and discharges from the ED were similar between the 2 years. CONCLUSION: The COVID-19 pandemic initial surge resulted in fewer ED presentations for symptomatic urolithiasis; however, patients who did present were more likely to have obstructing stones, perhaps due to delaying presentation to avoid COVID-19 exposure in the ED. Despite higher rates of obstruction, clinical outcomes and morbidity were similar.

Improving Compliance with 24-H Urine Collections: Understanding Inadequacies in the Collection Process and Risk Factors for Poor Compliance.

PURPOSE OF REVIEW: The purpose of this review paper is to describe the 24-h urine collection in terms of its utility, collection process, and common problems with its acquisition. RECENT FINDINGS: Although 24-h urine collections are standard of care for high-risk stone formers, several nuances in test acquisition including inaccurate urine collections 50% of the time and poor patient compliance limit its potential utility. Compliance in obtaining 24-h urine collections has been shown to be improved in patients who have not undergone surgical treatment of urinary calculi, patients with metabolic stone disease or family history of stone disease, Caucasian ethnicity, and in those with more sedentary occupations. Studies show conflicting data of compliance regarding patient age and gender. Physicians must understand the difficulties regarding 24-h urine collections including patient compliance, variability between collections, and complexities with interpretation to best utilize this tool in guiding clinical management for the treatment of nephrolithiasis.

Investigating Fluid Intake in an Underserved Community: What Factors Are Associated with Low Urine Volume on 24-Hour Urine Collection?

Background: Stone prevention is dependent on high fluid intake, with evidence that low urine volume (LUV) can promote nephrolithiasis in the absence of other metabolic abnormalities. Herein, we investigate patient-related factors associated with LUV on initial 24-hour urine collection in an underserved population. Materials and Methods: A retrospective chart review was performed of patients treated by a single surgeon for nephrolithiasis from August 2014 to January 2019. Patients who submitted 24-hour urine samples were divided into two groups based on whether their initial collection was >2 L or not. Factors associated with 24-hour urine volume were analyzed using bivariate and multivariate analyses. As a secondary outcome, we investigated factors associated with corrected 24-hour urine volume on repeat 24-hour urine collection. Results: Two hundred eight patients (45.1%) submitted 24-hour urine collections, 63.9% (133/208) of which demonstrated a urine volume of <2 L. LUV was more common in female patients (77.1% vs 49.5%; p = 0.001) and patients with no insurance and Medicaid (no insurance [100%] vs Medicaid [74.1%] vs Medicare/private [58.6%]; p = 0.02). Female gender and insurance status were independent predictors of LUV in the multivariable analysis. Seventeen of 43 patients (39.5%) with LUV who provided a subsequent collection were able to correct their urine volume. Patients who improved their LUV were older (58.5 vs 45.9 years, p = 0.0149) and more likely to have surgical intervention for their kidney stones (94.1% vs 53.8%, p = 0.006). In our multivariable analysis, surgical intervention was associated with correcting urine volume. Conclusions: Female patients and those with no insurance or Medicaid were more likely to have LUV on an initial 24-hour urine collection. Further research into barriers to fluid intake is important for these two groups, along with directed patient education on strategies for increasing fluid intake.

Prescribing Trends in Post-operative Pain Management After Urologic Surgery: A Quality Care Investigation for Healthcare Providers.

OBJECTIVE: To assess prescribing and refilling trends of narcotics in postoperative urology patients at our institution. Although the opioid epidemic remains a public health threat, no series has assessed prescribing patterns across urologic surgery disciplines following discharge. METHODS: All urologic surgeries were retrospectively reviewed from May 2017-April 2018. Demographics, comorbidities, and postoperative pain management strategies were analyzed. Narcotics usage following surgery were reported in total morphine equivalents (TME). Opioid refill rate was characterized by medical specialty and stratified by urologic discipline. RESULTS: 817 cases were reviewed. Mean age and TME at discharge was 57±15.6 years and 35.43±19.5 mg, respectively. 13.6% (mean age 55±15.9) received a narcotic refill following discharge (mean TME/refill 37.7±28.9 mg). A higher proportion of patients with a pre-operative opioid prescription received a refill compared to opioid naïve patients (38.2% vs 21.6%, P < .01). Refill rate did not differ between urologic subspecialties (P = .3). Urologists were only responsible for 20.4% of all refills filled, despite all patients continuing follow-up with their surgeon. Procedures with the highest rates of post-operative refills were in oncology, male reconstruction/trauma and endourology. Patients with a history of chronic pain (OR 1.9, CI 1.1-3.3) preoperative narcotic prescription (OR 1.6, CI 1.0-2.6), and higher ASA score (OR 1.8, CI 1.6-2.8) were more likely to obtain a postoperative opioid prescription refill. CONCLUSION: Approximately 1 in 7 postoperative urology patients receive a postoperative narcotics refill; however, nearly two-thirds receive refills exclusively from non-urologic providers. Attempts to avoid overprescribing of postoperative narcotics need to account for both surgeon and nonsurgeon sources of opioid refills.

Dual-Energy CT for Urinary Stone Evaluation.

PURPOSE OF REVIEW: Conventional CT imaging is an excellent tool for the diagnosis of nephrolithiasis however is limited in its ability to detect stone composition. Dual-energy CT (DECT) scans have demonstrated promise in overcoming this limitation. We review the current utility of DECT in nephrolithiasis. RECENT FINDINGS: DECT is superior to conventional CT in differentiating uric acid stones from non-uric acid stones, with numerous studies reporting sensitivities and specificities approaching > 95%. Dose reduction protocols incorporating low-dose CT scans are commonly used, providing significantly lower effective radiation doses compared to conventional CT. DECT remains an effective diagnostic tool in patients with large body habitus. DECT can accurately detect uric acid stones, which can help guide which stones may be suitable to medical dissolution. Further studies evaluating the effectiveness of DECT in guiding management of patients with nephrolithiasis can help to promote its widespread use.

Nonalcoholic Fatty Liver Disease Is an Independent Risk Factor for Nephrolithiasis in Women: Findings from NHANES III.

Objective: To determine if radiologically diagnosed nonalcoholic fatty liver disease (NAFLD) is an independent risk factor for nephrolithiasis using data from National Health and Nutrition Examination Survey III (NHANES III). Patients and Methods: NHANES III participants aged 20-74 years who underwent hepatobiliary ultrasound were classified as with NAFLD (moderate or severe hepatic steatosis in absence of other known causes of liver disease; n = 2498) or without NAFLD (controls; n = 9361). Risk of nephrolithiasis caused by NAFLD was estimated using logistic regression with propensity score adjustment. Secondary outcomes included medical stone management, lithotripsy, and surgical stone removal. Results: Participants with NAFLD were older (48.7 ± 0.4 vs 43.3 ± 0.3 years, p < 0.001) and exhibited greater prevalence of all components of metabolic syndrome: obesity (48% vs 21%), impaired glucose tolerance (17% vs 11%), diabetes mellitus (15% vs 6%), hypertension (36% vs 24%), and gout (4% vs 2%) (all p < 0.001). After adjusting for demographic, lifestyle, and metabolic factors, NAFLD was associated with increased risk nephrolithiasis (odds ratio [OR] = 1.29, 95% confidence interval [CI] [1.02-1.61], p = 0.03). The association persisted in women (OR = 1.65, 95% CI [1.17-2.32], p = 0.004) but not in men (OR = 1.04, 95% CI [0.77-1.40], p = 0.80). NAFLD was not associated with increased occurrence of medical management (OR = 1.31, 95% CI [0.84-2.05], p = 0.24), lithotripsy (OR = 1.61, 95% CI [0.83-3.33], p = 0.20), or surgical stone removal (OR = 0.83, 95% CI [0.48-1.44], p = 0.52). Conclusions: In a large U.S. population-based cross-sectional analysis, NAFLD was found to be associated with increased risk of nephrolithiasis in women after adjusting for demographic, clinical, and metabolic factors.

Factors Associated With Compliance With 24-Hour Urine Collection.

OBJECTIVE: To identify how demographic factors, stone-associated medical comorbidities, and treatment predict compliance with 24-hour urine collection. MATERIALS AND METHODS: A retrospective medical record review of patients treated for urolithiasis between August 2014 and March 2017 was performed. Patient demographics, medical characteristics, stone factors, type of treatment, and compliance data were included for patients requested to submit a collection. Variables that were statistically significant on bivariate analysis were then used to formulate a model predicting submission of a 24-hour urine sample. RESULTS: Of the 303 patients who met inclusion criteria, 183 (60.4%) submitted an initial 24-hour urine collection. On bivariate analysis, patients older than 50 were more likely to submit a 24-hour urine collection (71.4% vs 51.5%; P <.001), patients with a metabolic predisposition for stones were more likely to submit a 24-hour urine collection (70.6% vs 53.1%; P <.003), and patients who did not have surgery were more likely to submit a 24-hour urine collection (97.9% vs 53.5%; P <.001). Our 3-variable prediction model found that not undergoing surgery was a strong predictor of 24-hour urine collection. CONCLUSIONS: We suspect that patients perceive surgery as a more definitive treatment for kidney stones than conservative management. Patient education on the natural history and role of metabolic management in the prevention of nephrolithiasis is essential in improving compliance with 24-hour urine collection.

Use of Google Trends to Track Online Behavior and Interest in Kidney Stone Surgery.

OBJECTIVE: To explore internet search trends data as a unique resource for monitoring online health information-seeking behavior. We utilized Google trends to sample population interest and search inquiries into surgical treatment options of kidney stones, and we examined the relative frequency of searches across the United States. METHODS: Google trends was queried via the Google Insights for Search (http://google.com/trends) using terms related to kidney stone surgeries from 2011 to 2017. "Kidney stone surgery" was identified to be the most common term. The search volume index graph for the U.S. was recorded as well as regional distribution and related queries. For specific surgical treatment modalities, the following medical terminology was used: percutaneous nephrolithotomy, extracorporeal shockwave lithotripsy, ureteroscopy, and laser lithotripsy. Each query was then compared and analyzed to assess changes in the interest in these search terms over time. RESULTS: The research trends for the search "kidney stone surgery" as well as specific surgical modalities remained constant over time. extracorporeal shockwave lithotripsy had the highest search volume index and laser lithotripsy had the lowest. The top 5 US states with greatest search volume was Tennessee, Indiana, Ohio, Michigan, and North Carolina, whereas the top 5 metropolitan regions were Atlanta, Tampa, Detroit, Philadelphia, and Boston. CONCLUSION: Google trends data is a useful tool to analyze online health information-seeking behavior. Despite an increase in stone prevalence over the past decade, search rates have remained relatively constant. High relative search volume was seen from states within and outside the traditional stone belt, suggesting a possible changing trend.

Endoscopic Management of Ureteral Strictures: an Update.

PURPOSE OF REVIEW: This review focuses on the role of endoscopic treatment of ureteral stricture disease (USD) in the era of minimally invasive surgery. RECENT FINDINGS: There is a relative paucity of recent literature regarding the endoscopic treatment of USD. Laser endopyelotomy and balloon dilation are associated with good outcomes in treatment-naïve patients with short (< 2 cm), non-ischemic, benign ureteral strictures with a functional renal unit. If stricture recurs, repetitive dilation and laser endopyleotomy is not recommended, as success rates are low in this scenario. Patients with low-complexity ureteroenteric strictures and transplant strictures may benefit from endoscopic treatment options, although formal reconstruction offers higher rates of success. Formal ureteral reconstruction remains the gold-standard treatment for ureteral stricture disease as it is associated with higher rates of complete resolution. However, in carefully selected patients, endoscopic treatment modalities provide a low-cost, low-morbidity alternative.

Do Urinary Cystine Parameters Predict Clinical Stone Activity?

PURPOSE: An accurate urinary predictor of stone recurrence would be clinically advantageous for patients with cystinuria. A proprietary assay (Litholink, Chicago, Illinois) measures cystine capacity as a potentially more reliable estimate of stone forming propensity. The recommended capacity level to prevent stone formation, which is greater than 150 mg/l, has not been directly correlated with clinical stone activity. We investigated the relationship between urinary cystine parameters and clinical stone activity. MATERIALS AND METHODS: We prospectively followed 48 patients with cystinuria using 24-hour urine collections and serial imaging, and recorded stone activity. We compared cystine urinary parameters at times of stone activity with those obtained during periods of stone quiescence. We then performed correlation and ROC analysis to evaluate the performance of cystine parameters to predict stone activity. RESULTS: During a median followup of 70.6 months (range 2.2 to 274.6) 85 stone events occurred which could be linked to a recent urine collection. Cystine capacity was significantly greater for quiescent urine than for stone event urine (mean ± SD 48 ± 107 vs -38 ± 163 mg/l, p <0.001). Cystine capacity significantly correlated inversely with stone activity (r = -0.29, p <0.001). Capacity also correlated highly negatively with supersaturation (r = -0.88, p <0.001) and concentration (r = -0.87, p <0.001). Using the suggested cutoff of greater than 150 mg/l had only 8.0% sensitivity to predict stone quiescence. Decreasing the cutoff to 90 mg/l or greater improved sensitivity to 25.2% while maintaining specificity at 90.9%. CONCLUSIONS: Our results suggest that the target for capacity should be lower than previously advised.

Extracorporeal Shock Wave Therapy: Current Perspectives and Future Directions.

PURPOSE OF REVIEW: Since its introduction, extracorporeal shock wave lithotripsy (ESWL) has undergone a variety of changes; however, it remains one of the most utilized treatment modalities for urolithiasis. The goal of this review is to provide the practicing urologist an update on contemporary trends, new technologies, and related controversies in utilizing ESWL for stone treatment. RECENT FINDINGS: ESWL use has come under scrutiny with a shift in focus to cost-effectiveness and healthcare outcomes. Fortunately, advances in lithotripter technology have spawned several generations of devices that strive to improve stone-free rates and decrease complications. Most of all, a focus on patient selection criteria has helped improve procedural success. Years of experience utilizing ESWL for stone treatment have helped urologists better optimize its use and minimize complications. Improvements in technique along with more stringent patient and stone selection have helped ESWL remain a mainstay in the treatment of stone disease.

Factors Associated with Compliance in Submitting 24-Hour Urine Collections in an Underserved Community.

PURPOSE: Patients living in underserved areas do regularly express an interest in stone prevention; however, factors limiting participation, aside from obvious cost considerations, are largely unknown. To better understand factors associated with compliance with submitting 24-hour urine collections, we reviewed our patient experience at the kidney stone clinic at a hospital that provides care for an underserved urban community. MATERIALS AND METHODS: A retrospective chart review of patients treated for kidney and/or ureteral stones between August 2014 and May 2016 was performed. Patient demographics, medical characteristics, stone factors, and compliance data were compiled into our data set. Patients were divided into two groups: those who did and did not submit the requested initial 24-hour urine collection. Analysis of factors related to compliance was performed using univariate analysis and multivariate logistic regression. RESULTS: A total of 193 patients met inclusion criteria for our study, 42.5% (82/193) of whom submitted 24-hour urine samples. Of the 82 collections submitted, 34.1% (28/82) were considered inadequate by creatinine level. A second urine collection within 6 months was obtained in 14.0% (27/193) of patients. Univariate analysis demonstrated that African American (AA) patients were less likely to submit an initial 24-hour urine collection than Caucasian patients (collected: 30.9% vs 51.8%; p < 0.05, respectively). Patients with a family history of kidney stones were more likely to submit an initial 24-hour urine collection than patients without a family history of kidney stones (61.1% vs 38.2%, p < 0.02, respectively). On multivariate analysis, both factors remained significant predictors of compliance with submitting a 24-hour urine collection. CONCLUSIONS: In our underserved patient population, AA patients were half as likely to submit a 24-hour urine collection than Caucasian patients, whereas patients with a positive family history of stones were more than twice as likely to submit than patients with no family history.

Comparative Effects of Irreversible Electroporation, Radiofrequency Ablation, and Partial Nephrectomy on Renal Function Preservation in a Porcine Solitary Kidney Model.

OBJECTIVE: To evaluate kidney function preservation or regeneration and pathological changes post-irreversible electroporation (IRE) in comparison with partial nephrectomy and radiofrequency ablation (RFA) in a solitary kidney porcine model. Tissue ablation using IRE has been reported to spare critical anatomic structures within or near the ablation zone with associated regeneration of adjacent parenchyma, possibly offering functional preservation. METHODS: Fifteen pigs initially underwent laparoscopic nephrectomy. The lower third of the remaining kidney was then ablated or removed with either IRE, RFA, or partial nephrectomy. Serum creatinine (SCr) was measured at baseline, 24 hours, 3, 7, 14, and 28 days postoperatively. The impact of the type of procedure on SCr over time was evaluated. Acute and chronic histological changes were analyzed and cellular viability was assessed using nicotinamide adenine dinucleotide staining in the IRE ablations. RESULTS: Ten ablations (5 IRE, 5 RFA) and 5 partial nephrectomies of the entire lower third of a solitary kidney were performed. The type of procedure did not affect SCr significantly at baseline (P = .14) or change in SCr over time (P = .48). Histologically, IRE and RFA lesions showed similar findings including coagulative necrosis that progressively was replaced by reparative stromal changes and fibrous tissue. Nicotinamide adenine dinucleotide staining of the IRE lesions at 14 and 28 days showed no viability in the necrotic areas with viable tissue at the margins demonstrating reparative changes. CONCLUSION: Large volume IRE ablation of normal renal parenchyma in the porcine model does not provide a functional advantage as compared with conventional renal tumor treatments.

An Assessment of Patient Comfort and Morbidity After Robot-Assisted Radical Prostatectomy with Suprapubic Tube Versus Urethral Catheter Drainage.

OBJECTIVE: Robot-assisted laparoscopic prostatectomy (RALP) with suprapubic tube (SPT), compared to urethral catheter (UC) drainage, has been proposed to improve patient comfort and recovery. We sought to compare short-term outcomes for pain and morbidity after RALP with SPT vs UC drainage. METHODS: Between August 2012 and 2014, 159 men underwent a RALP and prospectively completed a questionnaire addressing postoperative pain and satisfaction. Group 1 (n = 94) underwent a RALP by one surgeon who placed a UC and removed it between postoperative day (POD) 7 and 10. Group 2 (n = 65) underwent a RALP by a different surgeon who placed an SPT and UC. On POD 1, the UC was removed. On POD 9, the SPT was capped and removed on POD 11 if the patient was voiding adequately. Preoperative and intraoperative data, complications, questionnaires, and patient-reported morbidity, including unplanned telephone calls and emergency department (ED) visits, were compared between groups. RESULTS: Patient characteristics were similar between groups. One week after surgery, the penile pain score was statistically significantly lower in Group 2 compared to Group 1 (56.9% and 79.8%, respectively, reported minimal-to-moderate pain, p = 0.003). Bladder spasms and overall pain were not significantly higher for Group 1 compared to Group 2 (p > 0.05). When asked "How big a problem has your urine storage device been?," 20.2% of patients in Group 1 reported it as a "moderate-to-big" problem compared to 10.8% in Group 2 (p > 0.05). The number of catheter-related unplanned telephone encounters did not differ between the two groups (p = 0.7), however, although not statistically significant, 4.6% of patients in Group 2 presented to the ED with catheter-related issues (p = 0.07). CONCLUSION: SPT after RALP was associated with less penile pain compared to UC drainage, and modestly better patient satisfaction. There were no significant differences in bladder spasms, overall pain, and patient-reported morbidity between groups.

Association of estimated glomerular filtration rate with 24-h urinalysis and stone composition.

The aim of this study is to determine the association of estimated glomerular filtration rate (eGFR) with 24-h urine analysis and stone composition. We performed a retrospective review of 1060 stone formers with 24-h urinalysis, of which 499 had stone composition analysis available. Comparisons of baseline patient characteristics and urinary abnormalities across eGFR groups (<60, 60-89.9, ≥90 mL/min/1.73 m(2)) were performed using Fisher's exact test for categorical data and analysis of variance for continuous variables. Analyses of 24-h urinalysis and stone composition across eGFR groups were performed using linear regression with eGFR groups as a continuous variable to evaluate trends. Of the 1060 patients in the study, 595 (56 %) were males. The mean age was 53.8 years. A total of 38 (4 %), 77 (7 %), and 945 (89 %) patients had eGFR <60, 60-89.9, and ≥90 mL/min/1.73 m(2), respectively. Lower eGFR was associated with older age, lower body-mass index, and female gender (all P < 0.05). Lower eGFR was also associated with lower urinary volume, calcium, citrate, uric acid, sodium, magnesium, phosphorus, sulfate, and creatinine on both univariable and multivariable analyses, adjusted for demographics, comorbidities and medication use (all P < 0.05). The prevalence of hypocitraturia and hypomagnesuria was associated with decreased eGFR, while hypercalciuria, hyperoxaluria, hyperuricosuria and hyperphosphaturia were associated with higher eGFR (all P < 0.05). Stone composition was similar across eGFR groups (all P > 0.05). In conclusion, lower eGFR was associated with lower excretion of urinary elements in a routine 24-h urinalysis, but similar stone composition.

Stenting for malignant ureteral obstruction: Tandem, metal or metal-mesh stents.

Extrinsic malignant compression of the ureter is not uncommon, often refractory to decompression with conventional polymeric ureteral stents, and frequently associated with limited survival. Alternative options for decompression include tandem ureteral stents, metallic stents and metal-mesh stents, though the preferred method remains controversial. We reviewed and updated our outcomes with tandem ureteral stents for malignant ureteral obstruction, and carried out a PubMed search using the terms "malignant ureteral obstruction," "tandem ureteral stents," "ipsilateral ureteral stents," "metal ureteral stent," "resonance stent," "silhouette stent" and "metal mesh stent." A comprehensive review of the literature and summary of outcomes is provided. The majority of studies encountered were retrospective with small sample sizes. The evidence is most robust for metal stents, whereas only limited data exists for tandem or metal-mesh stents. Metal and metal-mesh stents are considerably more expensive than tandem stenting, but the potential for less frequent stent exchanges makes them possibly cost-effective over time. Urinary tract infections have been associated with all stent types. A wide range of failure rates has been published for all types of stents, limiting direct comparison. Metal and metal-mesh stents show a high incidence of stent colic, migration and encrustation, whereas tandem stents appear to produce symptoms equivalent to single stents. Comparison is difficult given the limited evidence and heterogeneity of patients with malignant ureteral obstruction. It is clear that prospective, randomized studies are necessary to effectively scrutinize conventional, tandem, metallic ureteral and metal-mesh stents for their use in malignant ureteral obstruction.

Does hypertension impact 24-hour urine parameters in patients with nephrolithiasis?

OBJECTIVE: To examine the differences in 24-hour urine parameters and stone composition between patients with and without systemic hypertension (HTN) in a large cohort of stone formers. MATERIALS AND METHODS: We performed a retrospective review over a 10-year period of patients with stone, who had completed a 24-hour urinalysis (Litholink) and for whom demographic information was available, including the presence of HTN. Univariate and multivariate analyses were performed, comparing the 24-hour urinalysis profiles of patients with HTN with that of normotensive patients. RESULTS: Of the 1115 patients eligible for inclusion, 442 patients (40%) had HTN and 673 (60%) did not. Patients with HTN were significantly older, had a higher body mass index, and had a greater number of comorbid conditions than normotensive patients. Univariate analysis revealed significantly lower urine pH, calcium, supersaturation (SS) of calcium oxalate (CaOx) and SS calcium phosphate (all P <.05) in patients with HTN. Multivariate analysis showed significantly lower calcium, citrate, and SS CaOx in patients with HTN (all P <.05). CONCLUSION: Our results demonstrate lower levels of calcium and SS CaOx on univariate and multivariate analysis, as well as lower levels of citrate on multivariate analysis in patients with HTN. These results suggest that lower levels of citrate may contribute to stone formation to a greater degree in patients with HTN than abnormalities in calcium metabolism.

Equivocal ureteropelvic junction obstruction on diuretic renogram--should minimally invasive pyeloplasty be offered to symptomatic patients?

PURPOSE: Equivocal ureteropelvic junction obstruction refers to clinical symptoms and/or other radiological suggestions of possible ureteropelvic junction obstruction but with inconclusive results of obstruction on diuretic renogram. We evaluated long-term outcomes in patients with equivocal ureteropelvic junction obstruction treated with minimally invasive pyeloplasty. MATERIALS AND METHODS: We retrospectively analyzed the records of 125 consecutive patients who underwent minimally invasive pyeloplasty as performed by a single surgeon from May 2004 to July 2013. Of 98 patients with followup those with more than 6-month followup were included in analysis. Equivocal ureteropelvic junction obstruction, defined as half-life less than 20 minutes on diuretic renogram, was identified in 23 patients. All patients underwent transperitoneal minimally invasive pyeloplasty. We evaluated patient demographics, preoperative and postoperative symptoms and renal function. RESULTS: The 16 female and 7 male patients with equivocal ureteropelvic junction obstruction had flank pain and associated hydronephrosis on imaging. At a median followup of 20.2 months (range 7 to 75) 95.7% of patients with equivocal obstruction achieved complete symptom resolution. Mean ± SD preoperative and postoperative half-life was 14.1 ± 3.7 and 7.4 ± 4.2 minutes, respectively, for an improvement of 6.7 minutes (p < 0.001). In 1 patient (4.3%) with equivocal obstruction of a complicated iatrogenic etiology treatment ultimately failed postoperatively and endopyelotomy was required. There was no statistically significant difference in clinical or radiological success between the equivocal obstruction group and the 75 patients treated with minimally invasive pyeloplasty for definitive ureteropelvic junction obstruction (p = 0.44 and 0.07, respectively). CONCLUSIONS: In patients with radiographic equivocal ureteropelvic junction obstruction and flank pain minimally invasive pyeloplasty efficaciously provides symptomatic relief and functional preservation. Results are comparable to those in patients with high grade obstruction.