Alkaline Water: Help or Hype for Uric Acid and Cystine Urolithiasis?

PURPOSE: The consumption of alkaline water, water with an average pH of 8 to 10, has been steadily increasing globally as proponents claim it to be a healthier alternative to regular water. Urinary alkalinization therapy is frequently prescribed in patients with uric acid and cystine urolithiasis, and as such we analyzed commercially available alkaline waters to assess their potential to increase urinary pH. MATERIALS AND METHODS: Five commercially available alkaline water brands (Essentia, Smart Water Alkaline, Great Value Hydrate Alkaline Water, Body Armor SportWater, and Perfect Hydration) underwent anion chromatography and direct chemical measurements to determine the mineral contents of each product. The alkaline content of each bottle of water was then compared to that of potassium citrate (the gold standard for urinary alkalinization) as well as to other beverages and supplements used to augment urinary citrate and/or the urine pH. RESULTS: The pH levels of the bottled alkaline water ranged from 9.69 to 10.15. Electrolyte content was minimal, and the physiologic alkali content was below 1 mEq/L for all brands of alkaline water. The alkali content of alkaline water is minimal when compared to common stone treatment alternatives such as potassium citrate. In addition, several organic beverages, synthetic beverages, and other supplements contain more alkali content than alkaline water, and can achieve the AUA and European Association of Urology alkali recommendation of 30 to 60 mEq per day with ≤ 3 servings/d. CONCLUSIONS: Commercially available alkaline water has negligible alkali content and thus provides no added benefit over tap water for patients with uric acid and cystine urolithiasis.

Real-World Effectiveness of Preventive Pharmacological Therapy in Patients With Urolithiasis: A Retrospective Cohort Study.

RATIONALE & OBJECTIVE: Data supporting the efficacy of preventive pharmacological therapy (PPT) to reduce urolithiasis recurrence are based on clinical trials with composite outcomes that incorporate imaging findings and have uncertain clinical significance. This study evaluated whether the use of PPT leads to fewer symptomatic stone events. STUDY DESIGN: Retrospective cohort study. SETTING & PARTICIPANTS: Medicare enrollees with urolithiasis who completed 24-hour urine collections that revealed hypercalciuria, hypocitraturia, low urine pH, or hyperuricosuria. EXPOSURE: PPT (thiazide diuretics for hypercalciuria, alkali for hypocitraturia or low urine pH, or uric acid lowering drugs for hyperuricosuria) categorized as (1) adherent to guideline-concordant PPT, (2) nonadherent to guideline-concordant PPT, or (3) untreated. OUTCOME: Symptomatic stone event occurrence (emergency department [ED] visit or hospitalization for urolithiasis or stone-directed surgery). ANALYTICAL APPROACH: Cox proportional hazards regression. RESULTS: Among 13,942 patients, 31.0% were prescribed PPT. Compared with no treatment, concordant/adherent PPT use was associated with a significantly lower hazard of symptomatic stone events for patients with hypercalciuria (HR, 0.736 [95% CI, 0.593-0.915]) and low urine pH (HR, 0.804 [95% CI, 0.650-0.996]) but not for patients with hypocitraturia or hyperuricosuria. These associations were largely driven by significantly lower rates of ED visits after initiating PPT among the concordant/adherent group versus untreated patients. Patients with hypercalciuria had adjusted 2-year predicted probabilities of a visit of 3.8% [95% CI, 2.5%-5.2%%] and 6.9% [95% CI, 6.0%-7.7%] for the concordant/adherent PPT and no-treatment groups, respectively. Among patients with low urine pH, these probabilities were 4.3% (95% CI, 2.9%-5.7%) and 7.3% (95% CI, 6.5%-8.0%) for the concordant/adherent PPT and no-treatment groups, respectively. LIMITATIONS: Potential bias from the possibility that patients prescribed PPT had more severe disease than untreated patients. CONCLUSIONS: Patients with urolithiasis and hypercalciuria who were adherent to treatment with thiazide diuretics as well as those with low urine pH adherent to prescribed alkali therapy had fewer symptomatic stone events than untreated patients. PLAIN-LANGUAGE SUMMARY: Despite multiple clinical trials demonstrating the efficacy of thiazide diuretics and alkali for secondary prevention of kidney stones, they are infrequently prescribed due in part to a lack of data about their effectiveness in real-world settings. We analyzed medical claims from older adults with kidney stones for whom urine chemistry data were available. We found that patients who took prescribed thiazide diuretics for elevated urine calcium levels or alkali for low urinary pH were less likely to experience symptomatic stone recurrences than untreated patients. This benefit was expressed as lower rates of emergency department visits after initiating therapy. Our findings should inform the prescription of and adherence to treatment with thiazide diuretics and alkali for the prevention of recurrent kidney stones.

Risk of urolithiasis associated with allopurinol versus benzbromarone among patients with gout: a population-based cohort study.

OBJECTIVES: To compare the risk of urolithiasis in gout patients initiating allopurinol, a xanthine oxidase inhibitor, vs benzbromarone, a uricosuric. METHODS: Using the 2011-2020 Korea National Health Insurance Service database, we conducted a cohort study on gout patients initiating allopurinol vs benzbromarone as the 1st-line urate-lowering treatment (ULT). The primary outcome was a new onset urinary stone. The secondary outcome was a stone requiring intervention. We estimated hazard ratios (HRs) and 95% confidence intervals (CIs) using Cox proportional hazard models with a 5:1 ratio propensity-score matching on > 80 variables. Subgroup analyses were done by age, sex, thiazide use, and cardiovascular (CV) risk. RESULTS: 61 300 allopurinol initiators PS-matched on 12 260 benzbromarone initiators were included (mean age 59 years, 79% male). During a mean follow-up of 322 days, 619 urolithiasis cases occurred with an incidence rate of 0.87 per 100 person-years in allopurinol and 1.39 in benzbromarone initiators, showing a HR of 0.64 (95% CI, 0.51-0.80). ∼44% of urinary stones required intervention with a HR of 0.61 (95% CI 0.43-0.88). The lower risk associated with allopurinol compared with benzbromarone persisted across subgroups but was greater in the high than non-high CV risk subgroup (p for interaction = 0.02). CONCLUSION: This population-based cohort study found that allopurinol compared with benzbromarone was associated with a substantially lower risk of urolithiasis particularly in the presence of the high CV risk. This finding provides important safety information for clinicians' decision-making on ULTs of different mechanisms of action.

Holmium:yttrium-aluminium-garnet laser with MOSES technology is more efficient than thulium fibre laser in supine mini-percutaneous nephrolithotomy.

OBJECTIVES: To address the paucity of literature comparing outcomes achieved with utilisation of the high-power holmium:yttrium-aluminium-garnet (Ho:YAG) laser with MOSES technology vs those achieved with the thulium fibre laser (TFL) in mini-percutaneous nephrolithotomy (PCNL). METHODS: A retrospective review was performed of patients undergoing supine mini-PCNL between August 2021 and May 2023. Exclusion criteria were urinary diversion, simultaneous utilisation of >1 laser platform, use of any other form of fragmentation, and ureteric stones. The Ho:YAG platform (Lumenis Pulse P120H™ with MOSES technology, 120W; Boston Scientific®) and the TFL (Soltive SuperPulsed Thulium Fibre [SPTF], 60W; Olympus®) were compared. Data on stone-free rate (SFR) were determined by computed tomography performed on the first postoperative day and presented as absence of stone fragments, no fragments larger than 2 mm, or no fragments larger than 4 mm. RESULTS: A total of 100 patients met the inclusion criteria, 51 mini-PCNLs with the Ho:YAG laser and 49 with the SPTF laser. No significant differences in demographics or stone characteristics were detected between the two groups. The Ho:YAG laser utilised less energy and time, resulting in higher ablation efficiency (P < 0.05) and less total operating time (P < 0.05). Overall, there was no difference in SFR in any category between the Ho:YAG group and the SPTF group (no fragments: relative risk [RR] 0.81, 95% confidence interval [CI] 0.59-1.12, P = 0.21; fragments <2 mm: RR 0.86, 95% CI 0.67-1.10, P = 0.23; fragments <4 mm: RR 0.96, 95% CI 0.80-1.15, P = 0.67). CONCLUSIONS: Although we observed an equivalent postoperative SFR, this study supports a shorter operating time and greater intra-operative laser efficiency with the Ho:YAG laser over the SPTF laser in mini-PCNL.

Genetic susceptibility of urolithiasis: comprehensive results from genome-wide analysis.

BACKGROUND: The pathogenesis of urolithiasis is multi-factorial and genetic factors have been shown to play a significant role in the development of urolithiasis. We tried to apply genome-wide Mendelian randomization (MR) analysis and figure out reliable gene susceptibility of urolithiasis from the largest samples to date in two independent genome-wide association studies (GWAS) database of European ancestry. METHODS: We extracted summary statistics of expression quantitative trait locus (eQTL) from eQTLGen consortium. Urolithiasis phenotype information was obtained from both FinnGen Biobank and UK Biobank. Multiple two-sample MR analysis with a Bonferroni-corrected P threshold (P < 2.5e-06) was conducted. The primary endpoint was the causal effect calculated by random-effect inverse variance weighted (IVW) method. Sensitivity analysis, volcano plots, scatter plots, and regional plots were also performed and visualized. RESULTS: After multiple MR tests between 19942 eQTLs and urolithiasis phenotype from both cohorts, 30 common eQTLs with consistent effect size direction were found to be causally associated with urolithiasis risk. Finally only one gene (LMAN2) was simultaneously identified among all top significant eQTLs from both FinnGen Biobank (beta = 0.6758, se = 0.0327, P = 6.775e-95) and UK Biobank (beta = 0.0044, se = 0.0009, P = 2.417e-06). We also found that LMAN2 was with the largest beta effect size on urolithiasis phenotype from the two cohorts. CONCLUSION: We for the first time implemented genome-wide MR analysis to investigate the genetic susceptibility of urolithiasis in general population of European ancestry. Our results provided novel insights into common genetic variants of urinary stone disease, which was of great help to subsequent researches.

Basal metabolic rate and the risk of urolithiasis: a two-sample Mendelian randomization study.

OBJECTIVE: Few studies have investigated the impact of basal metabolic rate (BMR) on the development of urolithiasis, and the causal relationship is yet to be established. In this study, a two-sample Mendelian randomization (MR) analysis was utilized to identify the causal relationship between BMR and risk of urolithiasis. METHOD: Genetic instruments for BMR were drawn from a public genome-wide association study (GWAS). Summary dates on BMR and urolithiasis were obtained from a GWAS meta-analysis with sample sizes of 454,874 and 212,453, respectively. The inverse-variance weighted (IVW) method was provided as the main approach to estimate the causal relationship. The weighted-median method and the MR-Egger method were used as supplements to the IVW method. In addition, we conducted sensitivity analyses, including heterogeneity tests, pleiotropy tests and leave-one-out analysis, to assess the robustness of the outcomes. Furthermore, the funnel plot asymmetry was visually inspected to evaluate possible bias. RESULTS: The inverse-variance weighted data revealed that genetically predicted BMR significantly decreased the risk of urolithiasis [beta coefficient (beta): - 0.2366, odds ratio (OR): 0.7893, 95% confidence interval (CI) 0.6504-0.9579, p = 0.0166]. CONCLUSIONS: BMR has causal effects on urolithiasis in an MR study, and the risk of urolithiasis in patients with lower levels of BMR is higher.

International Alliance of Urolithiasis (IAU) guideline on staghorn calculi management.

BACKGROUND: The stone burden based management strategy reported in the guidelines published by different associations is well known for a long time. Staghorn calculi, representing the largest burden and most complex stones, is one of the most challenging cases to practicing urologists in clinical practice. The International Alliance of Urolithiasis (IAU) has released a series of guidelines on the management of urolithiasis. PURPOSE: To develop a series of recommendations for the contemporary management management of staghorn calculi and to provide a clinical framework for urologists treating patients with these complex stones. METHODS: A comprehensive literature search for articles published in English between 01/01/1976 and 31/12/2022 in the PubMed, OVID, Embase and Medline database is performed. A series of recommendations are developed and individually graded following the review of literature and panel discussion. RESULTS: The definition, pathogenesis, pathophysiology, preoperative evaluation, intraoperative treatment strategies and procedural advice, early postoperative management, follow up and prevention of stone recurrence are summarized in the present document. CONCLUSION: A series of recommendations regarding the management of staghorn calculi, along with related commentary and supporting documentation offered in the present guideline is intended to provide a clinical framework for the practicing urologists in the management of staghorn calculi.

Development of the self-management scale for urolithiasis patients with indwelling double-J tube.

PURPOSE: To develop a specific self-management scale applicable to patients with indwelling double-J tube in urolithiasis, and to test its reliability and validity. METHODS: The construction and validation of our scale involved three stages. First, an initial version of the questionnaire was formed through literature analysis, group discussions, semi-structured interviews, and the Delphi method. Second, a pre-survey was conducted with 20 urolithiasis patients with indwelling double-J stent placement to test their understanding of the initial questionnaire items and its acceptability. Finally, a formal survey of 234 patients with indwelling double-J tube for urolithiasis was conducted, and the scale was tested for reliability and validity. RESULTS: After the three stages, a specific self-management scale for urolithiasis patients with indwelling double-J tube was developed, consisting of 30 items across five dimensions with a cumulative contribution rate of 52.541%. The content validity index for item level ranged from 0.8 to 1, and the content validity index for the questionnaire level was 0.93. The correlation between each item and its dimension was > 0.4. The Cronbach's alpha coefficient for the overall questionnaire was 0.910, and the Cronbach's alpha coefficients for each dimension ranged from 0.672 to 0.865. The split-half reliability of the overall questionnaire was 0.864, and the split-half reliabilities for each dimension ranged from 0.659 to 0.827. The test-retest reliability of the overall questionnaire was 0.840, and the test-retest reliabilities for each dimension ranged from 0.674 to 0.818. CONCLUSION: The specific self-management scale for urolithiasis patients with indwelling double-J tube has good reliability and validity, and it is a reliable and effective tool for evaluating and assessing the self-management level of patients with indwelling double-J tube in urolithiasis.

Accurate prediction of pure uric acid urinary stones in clinical context via a combination of radiomics and machine learning.

PURPOSE: Oral chemolysis is an effective and non-invasive treatment for uric acid urinary stones. This study aimed to classify urinary stones into either pure uric acid (pUA) or other composition (Others) using non-contrast-enhanced computed tomography scans (NCCTs). METHODS: Instances managed at our institution from 2019 to 2021 were screened. They were labeled as either pUA or Others based upon composition analyses, and randomly split into training or testing data set. Several instances contained multiple NCCTs which were all collected. In each of NCCTs, individual urinary stone was treated as individual sample. From manually drawn volumes of interest, we extracted original and wavelet radiomics features for each sample. The most important features were then selected via the Least Absolute Shrinkage and Selection Operator for building the final model on a Support Vector Machine. Performance on the testing set was evaluated via accuracy, sensitivity, specificity, and area under the precision-recall curve (AUPRC). RESULTS: There were 302 instances, of which 118 had pUA urinary stones, generating 576 samples in total. From 851 original and wavelet radiomics features extracted for each sample, 10 most important features were ultimately selected. On the testing data set, accuracy, sensitivity, specificity, and AUPRC were 93.9%, 97.9%, 92.2%, and 0.958, respectively, for per-sample prediction, and 90.8%, 100%, 87.5%, and 0.902, respectively, for per-instance prediction. CONCLUSION: The machine learning algorithm trained with radiomics features from NCCTs can accurately predict pUA urinary stones. Our work suggests a potential assisting tool for stone disease treatment selection.

Cumulative sum analysis of the learning curve for retrograde intrarenal stone surgery in newbie surgeons.

INTRODUCTION: This study investigated the learning curve of retrograde intrarenal surgery (RIRS) in patients with medium-sized stones using cumulative sum analysis (CUSUM) to evaluate the competence and proficiency of three new surgeons during their first RIRS procedures. MATERIALS AND METHODS: We conducted a retrospective review of 227 patients from 2019 to 2022 at a single institution. The patients were divided into four groups based on the operating surgeon: tutor surgeon (85 patients), newbie surgeon A (21 patients), newbie surgeon B (85 patients), and newbie surgeon C (36 patients). Patients had one or multiple stones with the largest stone diameter fell within the range of 10-30 mm. Fragmentation efficacy was calculated as "removed stone volume (mm3) divided by operative time (minutes)." CUSUM analysis monitored changes in fragmentation efficacy and validated surgical outcomes. RESULTS: No statistically significant differences were observed in the total stone volume, maximum stone size, or total operation time between the three newbie surgeons and the tutor surgeon. The mean fragmentation efficacy value was comparable among the newbie surgeons, but significantly different from that of the tutor surgeon. The minimum acceptable fragmentation efficacy level was set at 25.12 mL/min, based on the tutor's average value. The CUSUM curves for the three surgeons initially remained relatively flat until Cases 12-15, after which they increased and eventually plateaued. Stone-free rates and postoperative complications did not differ significantly among the surgeons. CONCLUSION: Learning curve analysis for the three newbie surgeons indicated that approximately 12-15 cases were required to reach a plateau.

Effect of climate on emergency department admissions for renal colic: a comparative analysis of sedentary and non-sedentary lifestyles.

OBJECTIVE: To investigate the impact of climate and seasonal variations on emergency department (ED) admissions for renal colic, while specifically comparing the differences between individuals with sedentary and non-sedentary lifestyles. PATIENTS AND METHODS: A retrospective, single center study was conducted. Between the years 2017- 2020, medical records of patients admitted to the ED with renal colic, found to harbor ureteric stones on CT scans, were examined. Data on patients' occupational activities was collected through telephone questionnaires. Patients were categorized into two groups: sedentary and active. Precise weather data was obtained from the Israeli Meteorological Service website. The monthly average daily maximum temperatures were calculated. RESULTS: In the final sample of 560 participants, 285 were in the sedentary group, and 275 were in the active group. The study population consisted of 78.1% males and 21.9% females, with consistent gender ratios in both occupational groups. Prevalence of uric acid stones was higher in the sedentary group (p < 0.05). While there was a slight increase in admissions during the summer, seasonal distribution did not significantly differ among occupational groups. The study found no significant differences in admissions across different temperature ranges. Both groups exhibited a pattern of increased referrals during the summer and reduced referrals in the colder winter months. The baseline data revealed notable differences between the sedentary and active groups, particularly in the prevalence of uric acid stones. CONCLUSIONS: Climate factors, including temperature and seasonal variations, had limited impact on ED admissions for renal colic in patients with kidney stones, irrespective of their sedentary or active lifestyles. Both groups exhibited similar admission patterns, with a higher rate of admissions during the summer and a lower rate of admissions during the winter.

Risk factors of early infectious complications after ureterorenoscopy for stone disease: a prospective study.

PURPOSE: To prospectively evaluate the rate and associated risk factors of early infectious complications after ureterorenoscopy for urolithiasis. METHODS: After ethical committee approval, 400 therapeutic retrograde ureterorenoscopy procedures between August 3, 2020 and November 24, 2021 were included for analysis in a single-center study. Postoperative infection was defined as an afebrile urinary tract infection, fever (≥ 38 °C) with pyuria (≥ 300 WBC/µL) or proven urinary pathogen, and urosepsis. The primary outcome was the rate of infectious complications after ureterorenoscopy. Secondary outcomes were the perioperative factors that increased the risk of infectious complications within 30 days of surgery using univariate and multivariate logistic regression analysis. RESULTS: Twenty-nine of four hundred (7.3%) patients developed an infectious complication within 30 days after ureterorenoscopy. Ten (2.5%) patients developed an afebrile urinary tract infection, eight (2.0%) developed fever with pyuria, five (1.3%) febrile urinary tract infection, and six (1.5%) urosepsis. On univariate analysis, preoperative stent-type JFil® pigtail suture stent was significantly associated with the dependent variable (p < 0.001). On multivariate logistic regression analysis, older age (OR 1.035; 95% CI 1.006-1.070; p = 0.02) was found to be significantly associated with developing a postoperative infectious complication. CONCLUSIONS: A 7.3% rate of postoperative infectious complications and 1.5% urosepsis rate were observed after therapeutic ureterorenoscopy, without the need of intensive care admission. The only significant risk factors were preoperative stent type (JFil® pigtail suture stent) on univariate analysis, and older age on multivariate logistic regression analysis. Further multicentric prospective observational data are needed in this field.

A nomogram clinical prediction model for predicting urinary infection stones: development and validation in a retrospective study.

PURPOSE: This study aimed to develop a nomogram prediction model to predict the exact probability of urinary infection stones before surgery in order to better deal with the clinical problems caused by infection stones and take effective treatment measures. METHODS: We retrospectively collected the clinical data of 390 patients who were diagnosed with urinary calculi by imaging examination and underwent postoperative stone analysis between August 2018 and August 2023. The patients were randomly divided into training group (n = 312) and validation group (n = 78) using the "caret" R package. The clinical data of the patients were evaluated. Univariate and multivariate logistic regression analysis were used to screen out the independent influencing factors and construct a nomogram prediction model. The receiver operating characteristic curve (ROC), calibration curves, and decision curve analysis (DCA) and clinical impact curves were used to evaluate the discrimination, accuracy, and clinical application efficacy of the prediction model. RESULTS: Gender, recurrence stones, blood uric acid value, urine pH, and urine bacterial culture (P < 0.05) were independent predictors of infection stones, and a nomogram prediction model ( https://zhaoyshenjh.shinyapps.io/DynNomInfectionStone/ ) was constructed using these five parameters. The area under the ROC curve of the training group was 0.901, 95% confidence interval (CI) (0.865-0.936), and the area under the ROC curve of the validation group was 0.960, 95% CI (0.921-0.998). The results of the calibration curve for the training group showed a mean absolute error of 0.015 and the Hosmer-Lemeshow test P > 0.05. DCA and clinical impact curves showed that when the threshold probability value of the model was between 0.01 and 0.85, it had the maximum net clinical benefit. CONCLUSIONS: The nomogram developed in this study has good clinical predictive value and clinical application efficiency can help with risk assessment and decision-making for infection stones in diagnosing and treating urolithiasis.

Play it safe: renal function after bilateral flexible ureteroscopy for kidney stones.

PURPOSE: We searched for perioperative renal function deterioration risk factors in patients that underwent bilateral flexible ureteroscopy (fURS) for kidney stones. METHODS: From August 2016 to February 2020, symptomatic patients > 18 years old with bilateral kidney stones up to 20 mm in each side were prospectively studied. Serum creatinine samples were collected on admission to surgery, immediate postoperative (IPO), on POD 3, 10, and 30. Estimated glomerular filtration rate (eGFR) was calculated using Chronic Kidney Disease Epidemiology Collaboration equation (CKD-EPI) without a race coefficient. RESULTS: Thirty patients underwent bilateral fURS. Comparing to preoperative eGFR, median IPO and POD3 eGFR (p < 0.001) were significantly lower, and POD10 (p = 0.092) and POD30 (p = 0.648) were similar to preoperative eGFR. During follow-up, 22/30 (73.3%), 14/30 (46.7%), and 7/30 (23.3%) of the patients presented a decrease > 10% eGFR, > 20% eGFR, and > 30% eGFR, respectively. Multivariate analysis demonstrated that lower preoperative eGFR is a risk factor for eGFR < 60 mL/min/1.73 m2, p = 0.019 [1.021-1.263; 1.136]; ASA > 1 is a risk factor for decrease of eGFR > 10%, p = 0.028 [1.25-51.13; 8.00]; longer operative time is a risk factor for decrease of eGFR > 20%, p = 0.042 [1.00-1.05; 1.028]; and operative time ≥ 120 min is a risk factor for decrease of eGFR > 30%, p = 0.026 [0.016-0.773; 0.113]. CONCLUSIONS: Renal function suffers a reversible decrease after bilateral fURS. Our study suggests that adequate selection of patients and maintaining operative time < 120 min are relevant factors in preventing acute renal function deterioration following bilateral fURS.

Advancements in stone classification: unveiling the beauty of urolithiasis.

PURPOSE: Urolithiasis has become increasingly prevalent, leading to higher disability-adjusted life years and deaths. Various stone classification systems have been developed to enhance the understanding of lithogenesis, aid urologists in treatment decisions, and predict recurrence risk. The aim of this manuscript is to provide an overview of different stone classification criteria. METHODS: Two authors conducted a review of literature on studies relating to the classification of urolithiasis. A narrative synthesis for analysis of the studies was used. RESULTS: Stones can be categorized based on anatomical position, size, medical imaging features, risk of recurrence, etiology, composition, and morphoconstitutional analysis. The first three mentioned offer a straightforward approach to stone classification, directly influencing treatment recommendations. With the routine use of CT imaging before treatment, precise details like anatomical location, stone dimensions, and Hounsfield Units can be easily determined, aiding treatment planning. In contrast, classifying stones based on risk of recurrence and etiology is more complex due to dependencies on multiple variables, including stone composition and morphology. A classification system based on morphoconstitutional analysis, which combines morphological stone appearance and chemical composition, has demonstrated its value. It allows for the rapid identification of crystalline phase principles, the detection of crystalline conversion processes, the determination of etiopathogenesis, the recognition of lithogenic processes, the assessment of crystal formation speed, related recurrence rates, and guidance for selecting appropriate treatment modalities. CONCLUSIONS: Recognizing that no single classification system can comprehensively cover all aspects, the integration of all classification approaches is essential for tailoring urolithiasis patient-specific management.

Intrarenal pressure and flow rate profile using LithoVue™ elite: impact of different irrigation systems and working channel instruments.

PURPOSE: To report real-time IRP and FR while performing flexible ureteroscopy in porcine kidney model utilizing LithoVue™ Elite (Boston Scientific®) with different irrigation systems, including automated pumps. METHODS: Using an ex-vivo model of porcine kidney, IRPs were measured with LithoVue Elite. Ureteroscopic settings (US) were tested with all permutations of irrigation methods (IM), working channel occupant (WCO), and ureteral access sheaths (UAS). IMs included: Single Action Pumping System (SAPS™, Boston Scientific), Thermedx FluidSmart™ (Stryker®), and ENDOMAT™ (Karl Storz®). Pumps were tested at 50, 100, and 150 mmHg. WCOs included a 1.9Fr zero-tip basket, 200 µm, and 365 µm laser fibers. UASs utilized 11/13Fr and 12/14Fr 36 cm. RESULTS: 84 different US were tested (252 experiments). ENDOMAT had higher IRP but the same FR as Thermedx at the same US for 50 and 100 mmHg (p < 0.01). SAPS had higher IRP and FR than pumps in all US studies (p < 0.01). There was positive correlation between pressure set by the pump and both IRP and FR (rho > 0.9). As the diameter of the WCO increased, lower IRP and FR were observed with the pumps (p < 0.01). With SAPS, IRP was similar regardless of WCO, but FR was decreased with the increased diameter of WCO (p = 0.81 and p < 0.01, respectively). There was significantly higher IRP when using 11/13Fr UAS than 12/14Fr (p < 0.01). CONCLUSION: IRP was higher with SAPS than automated pumps. ENDOMAT showed higher IRP than Thermedx when under 150 mmHg. IRP and FR increase with higher pump pressure and decrease with larger diameter WCO. Likewise, a larger UAS significantly reduced IRP.

Consensus statement addressing controversies and guidelines on pediatric urolithiasis.

PURPOSE: We aimed to investigate controversial pediatric urolithiasis issues systematically, integrating expert consensus and comprehensive guidelines reviews. METHODS: Two semi-structured online focus group meetings were conducted to discuss the study's need and content, review current literature, and prepare the initial survey. Data were collected through surveys and focus group discussions. Existing guidelines were reviewed, and a second survey was conducted using the Delphi method to validate findings and facilitate consensus. The primary outcome measures investigated controversial issues, integrating expert consensus and guideline reviews. RESULTS: Experts from 15 countries participated, including 20 with 16+ years of experience, 2 with 11-15 years, and 4 with 6-10 years. The initial survey identified nine main themes, emphasizing the need for standardized diagnostic and treatment protocols and tailored treatments. Inter-rater reliability was high, with controversies in treatment approaches (score 4.6, 92% agreement), follow-up protocols (score 4.8, 100% agreement), and diagnostic criteria (score 4.6, 92% agreement). The second survey underscored the critical need for consensus on identification, diagnostic criteria (score 4.6, 92% agreement), and standardized follow-up protocols (score 4.8, 100% agreement). CONCLUSION: The importance of personalized treatment in pediatric urolithiasis is clear. Prioritizing low-radiation diagnostic tools, effectively managing residual stone fragments, and standardized follow-up protocols are crucial for improving patient outcomes. Integrating new technologies while ensuring safety and reliability is also essential. Harmonizing guidelines across regions can provide consistent and effective management. Future efforts should focus on collaborative research, specialized training, and the integration of new technologies in treatment protocols.

Ureteroscopy for urolithiasis in bedridden patients: it is feasible and acceptable.

PURPOSE: To investigate the safety of transurethral ureteroscopy (URS) for urolithiasis in bedridden patients and to identify bedridden patient-specific risk factors for postoperative complications. METHODS: The patients who underwent URS for urolithiasis were divided into bedridden patients and good performance status (PS) patients, and the groups were compared regarding their clinical characteristics and postoperative complications. A multivariable logistic regression analysis was performed to evaluate independent predictors of postoperative febrile urinary tract infection (fUTI). RESULTS: A total of 1626 patients were included, 276 in the bedridden patient group, and 1350 in the good PS patient group. The bedridden patient group had a significantly higher age and higher proportion of females and had multiple comorbidities. In 77 patients (27.9%), 88 postoperative complications developed for the bedridden patient group. Clavien-Dindo grade III or IV complications were observed in only 8 patients. No grade V complications were observed. The most common complication was fUTI. The frequency of fUTI with grade III or IV for the bedridden patient group (2.2%) was higher compared with the good PS patient group (0.5%), but the difference was not statistically significant (p = 0.13). Bedridden patient-specific risk factors for fUTI included female sex, diabetes mellitus, cerebrovascular comorbidities, lower extremity contracture, and prolonged operative time. CONCLUSION: URS for urolithiasis is a feasible and acceptable procedure in bedridden patients, despite the moderate rate of postoperative complications. The identified risk factors provide a framework for risk stratification and individualized care in this unique patient population.

Impact of previously failed extracorporeal shock wave lithotripsy on ureterorenoscopy outcomes in upper urinary tract stones: a prospective comparative study.

OBJECTIVE: We sought to prospectively evaluate the impact of previously failed SWL on subsequent URS outcomes in the treatment of upper urinary tract stones. MATERIALS AND METHODS: Between May 2021 and May 2023, one hundred thirty-six patients with proximal ureteral stones < 1.5 cm and renal stones < 2.5 cm who were candidates for URS were prospectively assigned to a non-SWL group, which included patients without a history of failed SWL before URS, and a post-SWL group, which included patients with a history of failed SWL before URS. The success rate was the primary outcome. The perioperative data of the two groups were compared. RESULTS: The stone-free rate was 83.3% in the post-SWL group versus 81.3% in the non-SWL group, and 8.3% in the post-SWL group versus 9.4% in the non-SWL group had clinically insignificant residual fragments. There was no significant difference in the stone-free rate or success rate between the groups. No significant differences in intraoperative fluoroscopy time, operative time, intraoperative stone appearance, perioperative complications, or the presence of embedded fragments in the ureteral mucosa were detected between the two groups. CONCLUSION: Compared with patients who underwent primary URS, patients who underwent salvage URS for upper urinary tract stones had similar stone-free rates, success rates, operative times, fluoroscopy times, and complication rates without any significant differences.

Radiation exposure of patients during endourological procedures.

PURPOSE: Considering the existing gaps in the literature regarding patient radiation dose (RD) and its associated risks, a systematic review of the literature on RD was conducted, focusing on percutaneous nephrolithotomy (PCNL), extracorporeal shock wave lithotripsy (SWL), and ureteroscopy (URS). METHODS: Two authors conducted a literature search on PubMed, Web of Science, and Google Scholar to identify studies on RD during endourological procedures. Two thousand two hundred sixty-six articles were screened. Sixty-five publications met the inclusion criteria using the PRISMA standards. RESULTS: RD was generally highest for PCNL, reaching levels up to 33 mSv, 28,700 mGycm2, and 430.8 mGy. This was followed by SWL, with RD reaching up to 7.32 mSv, 13,082 mGycm2, and 142 mGy. URS demonstrated lower RD, reaching up to 6.07 mSv, 8920 mGycm2, and 46.99 mGy. Surgeon experience and case load were inversely associated with RD. Strategies such as optimizing fluoroscopy settings, implementing ultrasound (US), and following the ALARA (As Low As Reasonably Achievable) principle minimized RD. CONCLUSIONS: This is the first systematic review analyzing RD, which was generally highest during PCNL, followed by SWL and URS. There is no specific RD limit for these procedures. Implementation of strategies such as optimizing fluoroscopy settings, utilizing US, and adhering to the ALARA principle proved effective in reducing RD. However, further research is needed to explore the factors influencing RD, assess their impact on patient outcomes, and establish procedure-specific reference levels for RD.