International Alliance of Urolithiasis guideline on retrograde intrarenal surgery.

OBJECTIVES: To set out the second in a series of guidelines on the treatment of urolithiasis by the International Alliance of Urolithiasis that concerns retrograde intrarenal surgery (RIRS), with the aim of providing a clinical framework for urologists performing RIRS. MATERIALS AND METHODS: After a comprehensive search of RIRS-related literature published between 1 January 1964 and 1 October 2021 from the PubMed database, systematic review and assessment were performed to inform a series of recommendations, which were graded using modified GRADE methodology. Additionally, quality of evidence was classified using a modification of the Oxford Centre for Evidence-Based Medicine Levels of Evidence system. Finally, related comments were provided. RESULTS: A total of 36 recommendations were developed and graded that covered the following topics: indications and contraindications; preoperative imaging; preoperative ureteric stenting; preoperative medications; peri-operative antibiotics; management of antithrombotic therapy; anaesthesia; patient positioning; equipment; lithotripsy; exit strategy; and complications. CONCLUSION: The series of recommendations regarding RIRS, along with the related commentary and supporting documentation, offered here should help provide safe and effective performance of RIRS.

Alkali Citrate Content of Common Over-the-Counter and Medical Food Supplements.

Objective: Potassium citrate effectively decreases kidney stone recurrence, but it is costly and associated with side effects. While several over-the-counter supplements and medical foods purport to provide sufficient citrate to prevent recurrent stones, corroborating data on their actual citrate content is limited. Materials and Methods: Nine common nonprescription products were purchased online. Reported citrate content was obtained from packaging, promotional materials, or ingredient labels. Using a single serving of each product, actual citrate, sodium, potassium, calcium, magnesium, and oxalate content was measured using spectrophotometry and chromatography. Total alkali citrate, cost, and amounts of each component per 10 mEq of alkali citrate were also calculated. Results: Nearly all products contained more citrate than advertised, except for Litholyte® powder, Litholyte® Coffee, and Horbäach® potassium citrate. Per serving, Moonstone® powder, LithoBalance™, and KSP tabs™ contained the most citrate (means of 63.9, 33.5, and 26.9 mEq, respectively). Moonstone and LithoBalance had the greatest discrepancy between total citrate and alkali citrate (15.7 and 11.8 mEq per serving, respectively). NOW® potassium citrate was least expensive ($0.04/10 mEq alkali citrate). KSP tabs delivered the most daily sodium (mean 158 mg/10 mEq alkali citrate, Litholyte Coffee provided the most potassium (mean of 13 mEq/10 mEq alkali citrate), and Kidney COP® provided the most calcium (mean 147 mg/10 mEq alkali citrate). Conclusion: Some common over-the-counter products contain sufficient alkali to potentially promote a citraturic response; Moonstone provides the most alkali citrate, but at a higher cost than other products. Sodium, potassium, and calcium from these products must also be considered in daily consumption.

International Alliance of Urolithiasis (IAU) guidelines on the metabolic evaluation and medical management of urolithiasis.

The aim of this study was to construct the fourth in a series of guidelines on the treatment of urolithiasis by the International Alliance of Urolithiasis (IAU) that by providing a clinical framework for the metabolic evaluation, prevention, and follow-up of patients with urolithiasis based on the best available published literature. All recommendations were summarized following a systematic review and assessment of the literature in the PubMed database from January 1976 to June 2022. Each generated recommendation was graded using a modified GRADE methodology. Guideline recommendations were developed that addressed the following topics: initial evaluation, metabolic testing, dietary measures, medical management, and follow-up of recurrent stone formers. It was emphasized by the Panel that prevention of new stone formation is as important as the surgical removal of the stones. Although general preventive measures may be effective in reducing stone recurrence rates in some patients, specific medical and dietary management should be well considered and eventually applied in an individualized manner based on the outcomes of metabolic work-up, stone analysis and some certain patient related factors. A detailed follow-up of each case is essential depending on the metabolic activity of each individual patient.

Diet and Stone Disease in 2022.

Diet plays a central role in the development and prevention of nephrolithiasis. Although pharmacologic treatment may be required for some patients who are resistant to dietary measures alone, dietary modification may be sufficient to modulate stone risk for many patients. While there is no single specialized diet for stone prevention, several dietary principles and recommendations for stone prevention are supported by practice guidelines, including adequate fluid intake, modest calcium intake, low dietary sodium, and limited animal protein. In this review, we summarized the evidence supporting these dietary recommendations and reviewed the current literature regarding specific dietary components and comprehensive diets for stone prevention.

Impact of an Enhanced Recovery After Surgery Protocol on Unplanned Patient Encounters in the Early Postoperative Period After Ureteroscopy.

Introduction: Ureteroscopy (URS) is associated with substantial patient-perceived morbidity. To improve the patient experience, we developed an enhanced recovery after surgery (ERAS) protocol for URS. We sought to determine if an ERAS protocol could reduce unplanned patient-initiated encounters. Materials and Methods: The ERAS protocol involves the preoperative administration of four medications to patients undergoing URS. We reviewed data on 100 consecutive patients undergoing URS with ureteral stent placement between April 2018 and August 2018. All unplanned postoperative encounters, including phone calls and electronic medical record messages, unplanned urology outpatient visits, emergency department (ED) visits, and re-admissions within 30 days of surgery, were recorded. A control group of patients undergoing URS between July 2013 and November 2014 served as a comparison group. Propensity score matching was performed. Statistical analysis included Mann-Whitney U test, Student's t-test, and Fischer's exact test. Univariable and multivariable (MVA) analyses were performed. Results: Using propensity score matching, 71 pre-ERAS (median age 57 years, interquartile range [IQR] 44-65) and 71 post-ERAS (median age 56 years, IQR 47-68) patients were compared. Although ED visits and postoperative readmissions were comparable between the two groups, significantly more unplanned phone calls/messages occurred in the pre-ERAS group than in the post-ERAS group (71 vs 27, respectively, p < 0.001). MVA regression analysis identified the ERAS protocol as a significant independent predictor of fewer patient calls (odds ratio 0.24, 95% confidence interval 0.12-0.50, p < 0.001). Conclusions: Analysis of an ERAS protocol for patients undergoing URS showed a reduction in unplanned patient-initiated communication, with implementation of the protocol. ClinicalTrials.gov: NCT04112160.

Clinical and radiographic outcomes following salvage intervention for ureteropelvic junction obstruction

ABSTRACT Purpose: We aimed to assess failure rates of salvage interventions and changes in split kidney function (SKF) following failed primary repair of ureteropelvic junction obstruction (UPJO). Materials and Methods: A retrospective review of adult patients at an academic medical center who underwent salvage intervention following primary treatment for UPJO was performed. Symptomatic failure was defined as significant flank pain. Radiographic failure was defined as no improvement in drainage or a decrease in SKF by ≥7%. Overall failure, the primary outcome, was defined as symptomatic failure, radiographic failure, or both. Results: Between 2008-2017, 34 patients (median age 38 years, 50% men) met study criteria. UPJO management was primary pyeloplasty/secondary endopyelotomy for 21/34 (62%), primary pyeloplasty/secondary pyeloplasty for 6/34 (18%), and primary endopyelotomy/secondary pyeloplasty for 7/34 (21%). Median follow-up was 3.3 years following secondary intervention. Patients undergoing primary pyeloplasty/secondary endopyelotomy had significantly higher overall failure than those undergoing primary pyeloplasty/secondary pyeloplasty (16/21 [76%] vs. 1/6 [17%], p=0.015). Among patients undergoing secondary endopyelotomy, presence of a stricture on retrograde pyelogram, stricture length, and SKF were not associated with symptomatic, radiographic, or overall failure. Serial renography was performed for 28/34 (82%) patients and 2/28 (7%) had a significant decline in SKF. Conclusions: Following failed primary pyeloplasty, secondary endopyelotomy had a greater overall failure rate than secondary pyeloplasty. No radiographic features assessed were associated with secondary endopyelotomy failure. Secondary intervention overall failure rates were higher than reported in the literature. Unique to this study, serial renography demonstrated that significant functional loss was overall infrequent.

Clinical and radiographic outcomes following salvage intervention for ureteropelvic junction obstruction.

PURPOSE: We aimed to assess failure rates of salvage interventions and changes in split kidney function (SKF) following failed primary repair of ureteropelvic junction obstruction (UPJO). MATERIALS AND METHODS: A retrospective review of adult patients at an academic medical center who underwent salvage intervention following primary treatment for UPJO was performed. Symptomatic failure was defined as significant flank pain. Radiographic failure was defined as no improvement in drainage or a decrease in SKF by ≥7%. Overall failure, the primary outcome, was defined as symptomatic failure, radiographic failure, or both. RESULTS: Between 2008-2017, 34 patients (median age 38 years, 50% men) met study criteria. UPJO management was primary pyeloplasty/secondary endopyelotomy for 21/34 (62%), primary pyeloplasty/secondary pyeloplasty for 6/34 (18%), and primary endopyelotomy/secondary pyeloplasty for 7/34 (21%). Median follow-up was 3.3 years following secondary intervention. Patients undergoing primary pyeloplasty/secondary endopyelotomy had significantly higher overall failure than those undergoing primary pyeloplasty/secondary pyeloplasty (16/21 [76%] vs. 1/6 [17%], p=0.015). Among patients undergoing secondary endopyelotomy, presence of a stricture on retrograde pyelogram, stricture length, and SKF were not associated with symptomatic, radiographic, or overall failure. Serial renography was performed for 28/34 (82%) patients and 2/28 (7%) had a significant decline in SKF. CONCLUSIONS: Following failed primary pyeloplasty, secondary endopyelotomy had a greater overall failure rate than secondary pyeloplasty. No radiographic features assessed were associated with secondary endopyelotomy failure. Secondary intervention overall failure rates were higher than reported in the literature. Unique to this study, serial renography demonstrated that significant functional loss was overall infrequent.

Causes and prevention of kidney stones: separating myth from fact.

Despite high-level evidence supporting the use of pharmacotherapy therapy for the prevention of kidney stones, adherence to medications is often poor because of side-effects, inconvenience and cost. Furthermore, with a desire for more 'natural' products, patients seek dietary and herbal remedies over pharmacotherapy. However, patients are often unaware of the potential side-effects, lack of evidence and cost of these remedies. Therefore, in the present review we examine the evidence for a few of the commonly espoused non-prescription agents or dietary recommendations that are thought to prevent stone formation, including lemonade, fish oil (omega fatty acids), Phyllanthus niruri and the Dietary Approaches to Stop Hypertension (DASH) diet. While the present review includes only a few of the stone-modulating recommendations available to the lay community, we focussed on these four due to their prevalent use. Our goal is not to only dispel commonly held notions about stone disease, but also to highlight the lack of high-level evidence for many commonly utilised treatments.

Artificial intelligence in stone disease.

PURPOSE OF REVIEW: Artificial intelligence (AI) is the ability of a machine, or computer, to simulate intelligent behavior. In medicine, the use of large datasets enables a computer to learn how to perform cognitive tasks, thereby facilitating medical decision-making. This review aims to describe advancements in AI in stone disease to improve diagnostic accuracy in determining stone composition, to predict outcomes of surgical procedures or watchful waiting and ultimately to optimize treatment choices for patients. RECENT FINDINGS: AI algorithms show high accuracy in different realms including stone detection and in the prediction of surgical outcomes. There are machine learning algorithms for outcomes after percutaneous nephrolithotomy, extracorporeal shockwave lithotripsy, and for ureteral stone passage. Some of these algorithms show better predictive capabilities compared to existing scoring systems and nomograms. SUMMARY: The use of AI can facilitate the development of diagnostic and treatment algorithms in patients with stone disease. Although the generalizability and external validity of these algorithms remain uncertain, the development of highly accurate AI-based tools may enable the urologist to provide more customized patient care and superior outcomes.

Urolithiasis in the COVID Era: An Opportunity to Reassess Management Strategies.

Delayed evaluation and/or treatment for urolithiasis during the COVID-19 pandemic provide a unique opportunity to organically reassess many well-established stone management strategies. Nonopioid analgesia for renal colic and spontaneous passage trials appear to be two avenues worthy of investigation.

Initial Results from the M-STONE Group: A Multi-Center Collaboration to Study Treatment Outcomes in Nephrolithiasis Evaluation.

Introduction: Despite proven effectiveness of medications in preventing stone recurrence, compliance with pharmacotherapy (PT) is often poor because of cost, side effects, and impact on lifestyle. We sought to compare the risk of stone recurrence between patients managed with conservative therapy (CT) vs PT controlling for aggressiveness of stone disease. Materials and Methods: The Multi-center collaboration to Study Treatment Outcomes in Nephrolithiasis Evaluation (MSTONE) database contains patient data and outcomes from July 2001 to April 2015 across four centers. The database was queried for patients whose stone disease was managed with CT alone (fluid and dietary recommendations) vs PT. Patients were risk stratified according to number of previous passed stones. Within each risk group, we compared CT vs PT with respect to 2-year stone event rate and stone event-free survival (SEFS) using the Kaplan-Meier method. Results: A total of 245 patients, with a median follow-up of 29 months (interquartile range = 16-44), were identified, including 93 on CT and 152 on PT. The overall 2-year stone event rate was 38% for all patients. Stone events at 2 years occurred less frequently in the PT group compared with the CT group (31% vs 44%, p = 0.043), with the difference most pronounced in the high-risk group (71% vs 32% for CT and PT, respectively, p = 0.058). The 30-month SEFS was significantly higher for PT (58%) than CT (46%) overall. When stratified by risk group, 30-month SEFS was statistically significantly higher for PT than CT in the intermediate risk group (65% vs 45% for PT and CT, respectively). Conclusion: Controlling for aggressiveness of stone disease, PT was more effective than CT in reducing and delaying stone-related events. However, CT appeared to be as effective as PT in low-risk patients. PT is best reserved for recurrent stone formers, regardless of metabolic background.

Medical therapy for nephrolithiasis: State of the art.

The prevalence of nephrolithiasis is increasing worldwide. Understanding and implementing medical therapies for kidney stone prevention are critical to prevent recurrences and decrease the economic burden of this condition. Dietary and pharmacologic therapies require understanding on the part of the patient and the prescribing practitioner in order to promote compliance. Insights into occupational exposures and antibiotic use may help uncover individual risk factors. Follow-up is essential to assess response to treatment and to modify treatment plans to maximize therapeutic benefit.

Impact of Potassium Citrate vs Citric Acid on Urinary Stone Risk in Calcium Phosphate Stone Formers.

PURPOSE: To our knowledge no medication has been shown to be effective for preventing recurrent calcium phosphate urinary stones. Potassium citrate may protect against calcium phosphate stones by enhancing urine citrate excretion and lowering urine calcium but it raises urine pH, which increases calcium phosphate saturation and may negate the beneficial effects. Citric acid can potentially raise urine citrate but not pH and, thus, it may be a useful countermeasure against calcium phosphate stones. We assessed whether these 2 agents could significantly alter urine composition and reduce calcium phosphate saturation. MATERIALS AND METHODS: In a crossover metabolic study 13 recurrent calcium phosphate stone formers without hypercalciuria were evaluated at the end of 3, 1-week study phases during which they consumed a fixed metabolic diet and received assigned study medications, including citric acid 30 mEq twice daily, potassium citrate 20 mEq twice daily or matching placebo. We collected 24-hour urine specimens to perform urine chemistry studies and calculate calcium phosphate saturation indexes. RESULTS: Urine parameters did not significantly differ between the citric acid and placebo phases. Potassium citrate significantly increased urine pH, potassium and citrate compared to citric acid and placebo (p <0.01) with a trend toward lower urine calcium (p = 0.062). Brushite saturation was increased by potassium citrate when calculated by the relative supersaturation ratio but not by the saturation index. CONCLUSIONS: Citric acid at a dose of 60 mEq per day did not significantly alter urine composition in calcium phosphate stone formers. The long-term impact of potassium citrate on calcium phosphate stone recurrence needs to be studied further.

Dual-layer spectral detector CT: non-inferiority assessment compared to dual-source dual-energy CT in discriminating uric acid from non-uric acid renal stones ex vivo.

PURPOSE: To assess the non-inferiority of dual-layer spectral detector CT (SDCT) compared to dual-source dual-energy CT (dsDECT) in discriminating uric acid (UA) from non-UA stones. METHODS: Fifty-seven extracted urinary calculi were placed in a cylindrical phantom in a water bath and scanned on a SDCT scanner (IQon, Philips Healthcare) and second- and third-generation dsDECT scanners (Somatom Flash and Force, Siemens Healthcare) under matched scan parameters. For SDCT data, conventional images and virtual monoenergetic reconstructions were created. A customized 3D growing region segmentation tool was used to segment each stone on a pixel-by-pixel basis for statistical analysis. Median virtual monoenergetic ratios (VMRs) of 40/200, 62/92, and 62/100 for each stone were recorded. For dsDECT data, dual-energy ratio (DER) for each stone was recorded from vendor-specific postprocessing software (Syngo Via) using the Kidney Stones Application. The clinical reference standard of X-ray diffraction analysis was used to assess non-inferiority. Area under the receiver-operating characteristic curve (AUC) was used to assess diagnostic performance of detecting UA stones. RESULTS: Six pure UA, 47 pure calcium-based, 1 pure cystine, and 3 mixed struvite stones were scanned. All pure UA stones were correctly separated from non-UA stones using SDCT and dsDECT (AUC = 1). For UA stones, median VMR was 0.95-0.99 and DER 1.00-1.02. For non-UA stones, median VMR was 1.4-4.1 and DER 1.39-1.69. CONCLUSION: SDCT spectral reconstructions demonstrate similar performance to those of dsDECT in discriminating UA from non-UA stones in a phantom model.

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.

Update of the ICUD-SIU consultation on stone technology behind ureteroscopy.

INTRODUCTION: Ureteroscopy is now the most frequent treatment used around the world for stone disease. Technological advancement, efficiency, safety, and minimally invasiveness of this procedure are some of the reasons for this change of trend. MATERIALS AND METHODS: In this review of the literature, a search of the PubMed database was conducted to identify articles related to ureteroscopy and accessories. The committee assigned by the International Consultation on Urological Disease reviewed all the data and produced a consensus statement relating to the ureteroscopy and all the particularities around this procedure. CONCLUSION: This manuscript provides literatures and recommendations for endourologists to keep them informed in regard to the preoperative, intraoperative, and postoperative consideration in regard of a ureteroscopy.

Use of Nonprostate Ultrasound in Urology Practice.

INTRODUCTION: Ultrasound imaging is necessary for the care of urology patients, and urology residents are encouraged to learn ultrasound technique and interpretation. However, there is limited mandated education in this field. Currently the only ultrasound procedure considered an index case is transrectal ultrasound for prostate biopsy. We investigated the current use of nonprostate ultrasound in urological practice. METHODS: We reviewed ABU (American Board of Urology) certification and recertification logs of practicing urologists from 2012 to 2014. We obtained data for the codes 76700-76776 (kidney), 76870 (scrotal), 76999 (unlisted) and 93975-93981 (Doppler including penile). Codes 51798 (post-void residual) and 76950 (ultrasound for interstitial radiotherapy) were excluded from the study. We analyzed the results based on self-identified demographic information provided by the urologists. RESULTS: The practices of 2,427 urologists were reviewed and of these, 43% billed for at least 1 renal, scrotal or penile ultrasound. General and subspecialist urologists perform similar percentages of ultrasound studies, except for pediatrics (0% penile) and andrology (40% penile). Of those who reported on practice type (2,067) 82% self-identify as in private practice and performed more ultrasound studies than academic urologists, including renal 42% vs 23%, scrotal 33% vs 15% and penile 8% vs 6%, respectively. Men performed more nonprostate ultrasounds than women (44% vs 36%, p <0.001). CONCLUSIONS: In addition to prostate ultrasound, renal and scrotal ultrasound is relevant to all urologists regardless of practice model or subspecialty. Graduating residents can expect to perform ultrasound examinations in their practices and, therefore, in addition to prostate ultrasound we should train residents in renal and scrotal ultrasound.