The Yield of Genetic Testing in Management of Nephrolithiasis.

OBJECTIVE: To describe the yield and indications for performing genetic testing in patients with nephrolithiasis. Genetic testing for nephrolithiasis is becoming more accessible and rapid due to technologic advances. This study aimed to determine the diagnostic yield of genetic testing in a cohort of high-risk stone formers and to identify 24-hour urine characteristics to prompt genetic screening. MATERIALS AND METHODS: We retrospectively identified patients who underwent genetic testing for nephrolithiasis from 2020 to 22 at a single institution using a custom PerkinElmer genomics panel for nephrolithiasis. We compared characteristics of patients with and without genetic abnormalities. We used receiver operator characteristic (ROC) analysis to identify candidate thresholds for genetic testing. RESULTS: Fourteen of 36 patients (39%) who underwent genetic testing had identifiable mutations. Five patients (14%) had known pathogenic mutations, including genes for primary hyperoxaluria (PH2 and PH3), cystinuria, and enamel-renal syndrome. The remaining mutations were variants of uncertain significance. Of the 14 patients with identified mutations, only 6 had concordant 24-hour urine abnormalities, including 3/5 with known pathogenic mutations. In patients with urine oxalate ≥ 40 mg/day, 3/29 (10.3%) had PH2 or PH3. ROC analysis showed that an oxalate threshold of ≥ 80 mg/day may have promising screening characteristics. CONCLUSION: Genetic testing for nephrolithiasis remains controversial due to unknown yield and the time and energy required to discuss results with patients. This preliminary report describes the yield and identifies clinical factors and a potential cut-off that may assist clinicians in deciding when genetic profiling should be pursued.

Renal Autotransplantation: Association Between Preoperative Disease Duration and Surgical Outcomes.

OBJECTIVE: To determine whether early versus delayed autotransplantation are associated with adverse outcomes in patients undergoing renal autotransplantation. METHODS: Patients who underwent renal autotransplantation from June 2012 to September 2022 were divided into 2 groups based on timing of autotransplant in relation to initial intervention or diagnosis (early cohort: ≤1-year; delayed cohort: >1-year). Primary outcomes were perioperative complications, aborted surgery, renal function (glomerular filtration rate [GFR]), and postoperative complications at most recent follow-up. RESULTS: Autotransplantation patients (N = 72) were predominantly female (68%) and White (54%), with a median age of 49 years. Ninety percentage of patients had undergone previous interventions, including stenting (40%) and nephrostomy tubes (49%), primarily for obstruction (64%). Early versus delayed cohorts had median preoperative disease durations of 143 (IQR 83-222) versus 673 days (IQR 529-1703, P <.001), with similar median follow-up times (879 vs 818 days, P = .8). Groups were similar in demographics and comorbidities. There were no significant differences in rates of aborted surgery (15% vs 4.2%, P = .3), perioperative complications (15% vs 17%, P > .9), long-term complications (49% vs 48%, P > .9), or changes in GFR (median change +3 vs +4, P = .7). Outcomes were comparable across preoperative disease durations ranging from 6 to 24 months. These findings were confirmed following adjustments for sex, body mass index, American Society of Anesthesiologists classification, race, preoperative creatinine levels, laterality, gastroesophageal reflux disease, diabetes, hypertension, nephrolithiasis, hyperlipidemia, history of colon surgery, urologic surgery, abdominal surgery, and prior interventions in separate logistic models. CONCLUSION: Disease duration before autotransplantation does not influence outcomes, offering reassurance for clinical decision-making in complex cases.

Comparison of Minimally Invasive Procedures for Benign Prostatic Hyperplasia: A Cost-effectiveness Analysis.

Background Benign prostatic hyperplasia (BPH) is a disease that affects millions of U.S. men and is costly to treat. Purpose To compare the cost-effectiveness of four minimally invasive therapies (MITs) and medical management for the treatment of BPH. Materials and Methods A cost-effectiveness analysis from a payer's perspective with Markov modeling was performed, comparing prostatic artery embolization (PAE), prostatic urethral lift, aquablation, water vapor thermal therapy, and medical management for BPH spanning a time horizon of 5 years. The model incorporated the probability of procedural complications and recurrent symptoms necessitating retreatment, which were extracted from published studies with long-term follow-up. Costs were based on Medicare reimbursements using CPT codes for ambulatory surgery centers. Outcomes were measured using the quality-adjusted life year (QALY), incorporating both life quality and expectancy. Statistical analyses included a base case calculation (using the most probable value of each parameter) and probabilistic and deterministic sensitivity analyses. Results In the base case calculation, outcomes for the strategies were comparable, with a difference of 0.030 QALY (11 days of life in perfect health) between the most (PAE) and least (medical management) effective strategies. PAE was the most cost-effective strategy relative to medical management, with an incremental cost-effectiveness ratio of $64 842 per QALY. Probabilistic sensitivity analysis showed PAE was more cost-effective compared with prostatic urethral lift, aquablation, water vapor therapy, and medical management in pairwise comparisons. In sensitivity analysis of retreatment risk, PAE remained the most cost-effective strategy until its repeat treatment rates exceeded 2.30% per 6 months, at which point water vapor therapy became the optimal choice. PAE was the most cost-effective procedure when its procedural cost was lower than $4755. Aquablation and prostatic urethral lift became more cost-effective when their procedural costs were lower than $3015 and $1097, respectively. Conclusion This modeling-based study showed that PAE appears to be a cost-effective modality among medical management and MITs for patients with BPH, with comparable outcomes to prostatic urethral lift, water vapor therapy, and aquablation at a lower expected cost. © RSNA, 2023 Supplemental material is available for this article. See also the editorial by Gemmete in this issue.

Voided volume may not impact stone outcomes: Review of a large institutional nephrolithiasis cohort.

Background: Urologic guidelines universally recommend increasing fluid intake for kidney stone prevention. Increased voided volume is thought to help reduce stone recurrence and severity, but supporting evidence is limited. Patients and Methods: Nephrolithiasis outcomes and 24-h urine data for patients from the Registry for Stones of the Kidney and Ureter (ReSKU), a registry of nephrolithiasis patients collected between 2015 and 2020, were retrospectively analysed. Outcome was stone events, either an office visit where a patient reports symptomatic passage of stones or surgery for stone removal. Results: We identified 450 stone patients with 24-h urine and kidney stone outcome data. There was no significant difference in 24-h voided volume between patients with one stone event and patients with two or more stone events. On multivariable logistic regression, after controlling for age, gender, BMI, and 24-h sodium and creatinine per kilogram, no significant associations were found between voided volume and stone events. There was a statistically significant negative correlation noted between voided volume and stone events in calcium oxalate dihydrate stone formers (Spearman R = -0.42, p = 0.04), but not others. Conclusions: Twenty-four-hour voided volume was not associated with stone events in a large institutional cohort, and subset analysis reveals that some stone formers may benefit more from increased voided volume than others; identifying such patients represents a novel precision medicine opportunity.

Clinical and postoperative characteristics of stentless ureteroscopy patients: a prospective analysis from ReSKU.

INTRODUCTION: To evaluate the clinical characteristics as well as the postoperative course of urolithiasis patients undergoing a ureteroscopy (URS) without stent placement. MATERIALS AND METHODS: This was a prospective case cohort study utilizing data collected in the Registry for Stones of the Kidney and Ureter (ReSKU) from a single institution between October 2015 and December 2020. We identified all consecutive patients undergoing URS for stone disease and analyzed data encompassing demographics, medical history, intra and postoperative characteristics, including complications and postoperative symptoms. Univariate and multivariate logistic regression analyses were performed based on the presence or absence of an indwelling ureteral stent. RESULTS: A total of 470 patients were included for analysis, 92 patients in the stentless group (19.5%). Factors associated with stentless ureteroscopy were a lower stone burden (p < 0.001), the pre-existence of a ureteral stent (37.4% vs. 27.9% p = 0.011), absence of an access sheath (14.6% vs. 69.5% p < 0.001), and a shorter operative time (31 vs. 58 min p < 0.001). Postoperative gross hematuria and lower urinary tract symptoms (LUTS) were reported less frequently in stentless patients (p = 0.02, p = 0.01, respectively). There was no difference in postoperative complications between both groups (15.2% vs. 12.0%, p = 0.385). On multivariate analysis, the risk of postoperative complications was associated with obesity, stone burden ≥ 1 cm, and positive preoperative urine culture. There was no patient who required emergent stent placement in the stentless group. CONCLUSION: Our data show that, in well selected patients, omitting ureteral stent placement after URS can decrease postoperative gross hematuria and LUTS without increasing postoperative complications.

Effects of Delayed Surgical Intervention Following Emergency Department Presentation on Stone Surgery Complexity.

Introduction and Objective: Prior literature had demonstrated increased stone burden and higher rates of staged surgery in individuals of lower socioeconomic status (SES). Low SES individuals are more likely to experience delays in definitive stone surgery after initial presentation to the emergency department (ED) for kidney stones. This study aims to investigate the relationship between delays in definitive kidney stone surgery and the subsequent need for percutaneous nephrolithotomy (PNL) and/or staged surgical procedures using a statewide data set. Methods: This retrospective cohort study gathered longitudinal data from 2009 to 2018 using the California Department of Health Care Access and Information data set. Patient demographic characteristics, comorbidities, diagnosis/procedure codes, and distance were analyzed. Complex stone surgery was defined as initial PNL and/or undergoing more than one procedure within 365 days of initial intervention. Results: A total of 1,816,093 billing encounters from 947,798 patients were screened, resulting in 44,835 patients with ED visits for kidney stones followed by a urologic stone procedure. Multivariable analysis revealed that relative to patients who underwent surgery within 1 month of initial ED visit for stone disease, patients were at increased odds of undergoing complex surgery if waiting ≥6 months (odds ratio [OR] 1.18, p = 0.022), ≥1 year (OR 1.29, p < 0.001), and ≥3 years (OR 1.43, p < 0.001). Conclusions: Delays in definitive stone surgery after initial ED encounter for stone disease were associated with increased likelihood of undergoing a complex stone treatment.

Ultrasound-Only Percutaneous Nephrolithotomy Is Safe and Effective Compared to Fluoroscopy-Directed Percutaneous Nephrolithotomy.

Introduction: Outcomes after ultrasound-only percutaneous nephrolithotomy (PCNL), in which no fluoroscopy is used, are not well known. The goal of this study was to compare outcomes of ultrasound-only and fluoroscopy-directed PCNL. Materials and Methods: Prospectively collected data from the Registry for Stones of the Kidney and Ureter database were reviewed for all patients who underwent PCNL at one academic center from 2015 to 2021. Primary outcomes were complications and stone-free rates (no residual fragments ≥3 mm). Results: Of the 141 patients who underwent ultrasound-only PCNL and 147 who underwent fluoroscopy-directed PCNL, there was no difference in complication rates (15% vs 16%, p = 0.87) or stone-free status (71% vs 65%, p = 0.72), respectively. After adjusting for body mass index, American Society of Anesthesiologists (ASA), stone size, and stone complexity by Guy score, ultrasound-only PCNL was not associated with any increased odds of complications (odds ratio [OR] 0.7, 95% confidence interval [CI] 0.3-1.6, p = 0.41) or residual stone fragments ≥3 mm (OR 1.0, 95% CI 0.5-1.9, p = 0.972) compared with fluoroscopy-directed PCNL. Ultrasound-only PCNL was associated with shorter operative time (median 99.5 vs 126 minutes, p < 0.001), and the use of ultrasound remained a significant predictor of short operative time (<100 minutes) after controlling for supine positioning, stone size, and stone complexity by Guy score (OR 2.31, 95% CI 1.01-5.29, p = 0.048). Patients in the ultrasound-only group were spared a mean radiation exposure dose of 10 mGy per procedure. Conclusions: Ultrasound-only PCNL is safe and achieves similar stone-free rates compared with fluoroscopy-directed PCNL with the added benefit of avoidance of radiation.

Single-Use Ureteroscopes Are Associated with Decreased Risk of Urinary Tract Infection After Ureteroscopy for Urolithiasis Compared to Reusable Ureteroscopes.

Objective: Urinary tract infection (UTI) is a common complication after ureteroscopy. Despite sterilization, there is evidence that reusable ureteroscopes can still harbor bacteria. Whether this property is associated with increased risk of UTI is unknown. The objective of this study was to compare rates of postoperative UTI after ureteroscopy for urolithiasis performed with single-use ureteroscopes vs reusable ureteroscopes. Materials and Methods: This was a single-center, retrospective cohort study of all patients who underwent ureteroscopy for urolithiasis between June 2012 and March 2021. Outcomes were compared between those who underwent stone removal with single-use and reusable ureteroscopes. The primary endpoint was postoperative UTI. The secondary endpoints were intra-operative and postoperative outcomes, and health service utilization after surgery. Results: Of 991 patients identified, 500 (50.4%) underwent ureteroscopy with a single-use ureteroscope. Rates of postoperative UTI were lower in those undergoing ureteroscopic stone removal with a single-use ureteroscope compared to a reusable ureteroscope (6.5% vs 11.9%, p = 0.018). In multivariable analysis, use of a single-use ureteroscope was associated with lower odds of postoperative UTI compared to a reusable ureteroscope when adjusting for risk (odds ratio 0.37, p = 0.015). Use of a single-use ureteroscope was associated with a higher stone clearance rate compared to a reusable ureteroscope (90.0% vs 83.9%, p = 0.005). There was no difference in operative time, overall complication rate, readmission, or emergency department visits between two groups. Conclusion: Single-use ureteroscopes are associated with a twofold decreased risk of UTI and increased stone clearance rate after ureteroscopy for urolithiasis compared to reusable ureteroscopes.

Underinsurance And Multiple Surgical Treatments for Kidney Stones.

OBJECTIVE: To further elucidate the relationship between low socioeconomic status (SES) and larger, more complex stones requiring staged surgical interventions. Specifically, we aimed to determine if underinsurance (Medicaid, Medicare, and self-pay insurance types) is associated with multiple surgeries within 1 year. METHODS: We performed a retrospective longitudinal analysis of prospectively collected data from the California statewide Department of Health Care Access and Information (HCAI) dataset. We included adult patients who had their first recorded kidney stone encounter between 2009 and 2018 and underwent at least 1 urologic stone procedure. We followed these patients within the dataset for one year after their initial surgery to assess for factors predicting multiple surgical treatments for stones. RESULTS: A total of 156,319 adults were included in the study. The proportions of individuals in private insurance, Medicaid, Medicare and self-pay/indigent groups differed by the presence or absence of additional surgeries (64.0%, 13.5%, 19.4%, and 0.1%, vs 70.3%, 10.1%, 16.6%, and 0.1%, respectively). Compared to private insurance, Medicaid (1.46 [1.40-1.53] P < .001) and Medicare (1.15 [1.10-1.20] P < .001) insurance types were associated with significantly greater odds of multiple surgeries, whereas no significant association was seen in the self-pay/indigent insurance type (1.35 [0.83-2.19], P = 1.0). CONCLUSION: In a statewide, California database from 2009 to 2018, underinsured adults had higher odds of undergoing a second procedure for kidney stones within 1 year of initial surgical treatment. This study adds to the expanding body of literature linking suboptimal healthcare access and disparate outcomes for kidney stone patients.

The Duration of Stone Disease and the Impact of a Stone Event on Patients' Quality of Life.

Introduction: With a 5-year stone recurrence rate of 30% to 50%, kidney stone formers are subject to significant morbidity that negatively impacts their health-related quality of life (HRQOL). We sought to determine the impact of age at kidney stone onset, duration of stone disease, and kidney stone event (surgery or stone passage) on HRQOL of individual patients by querying the validated and prospectively collected Wisconsin Stone Quality of Life (WISQOL) database. Patients and Methods: Cross-sectional data were obtained from a total of 2438 kidney stone formers from 14 institutions in North America who completed the WISQOL questionnaire during the period from 2014 to 2019. The 28-question survey has a 1- to 5-point scale for each item (total score range 0-140). Multivariable linear regression models assessed the impact of age at kidney stone onset, duration of stone disease, and time since most recent surgery or stone passage on HRQOL. Results: Of 2438 patients, older age at kidney stone onset and longer duration of disease were both independent predictors of better WISQOL scores (ß = 0.33 points/year; confidence interval [CI] 0.17-0.49; p < 0.001; and ß = 0.50 points/year; CI 0.32-0.68; p < 0.001, respectively). Of 1376 patients who underwent surgery between 2010 and 2019, longer time since most recent surgery was an independent predictor of better WISQOL scores (ß = 2.28 points/year; CI: 1.47-3.10; p = <0.001). Of 1027 patients with spontaneous stone passage occurring between 2010 and 2019, longer time since most recent stone passage was an independent predictor of better WISQOL scores (ß = 1.59 points/year; CI: 0.59-2.59; p = <0.05). Conclusions: Our study demonstrates that older age at onset, longer duration of disease, and longer time since most recent surgery or stone passage were independent predictors of better HRQOL in kidney stone formers. Results of future studies that focus on optimizing stone-related modifiable risk factors to decrease the number of recurrent stone episodes and thus the need for recurrent surgeries will be essential.

Therapeutic Living Donor Nephrectomy for Proximal Ureteral Pathology: A Longitudinal Case Series.

OBJECTIVE: To raise awareness that patients with proximal ureteral stricture who elect for nephrectomy can consider donating the kidney. We present a series of patients undergoing therapeutic living donor nephrectomy (TLDN), a scenario in which a patient undergoing nephrectomy for an underlying medical problem donates the kidney to a person with end-stage renal disease. This practice is underutilized, and only a single TLDN with proximal ureteral stricture has been previously described. We aim to help define the indications, risks, and benefits for patients. METHODS: This is a retrospective case series of seven therapeutic donors with proximal ureteral pathology and stone disease. Patient characteristics, donor work up, operative details, and donor and recipient outcome were collected. RESULTS: All seven donors had proximal ureteral pathology, and six of the seven had nephrolithiasis or ureterolithiasis. After electing for nephrectomy, the mean time to TLDN was 57.9 days. No recipients experienced delayed graft function . Mean follow up was 40.1 months (range 8-131), and the most recent follow-up mean creatinine was 1.08 (mg/dL). Graft and recipient survival is 100%. No recipients developed recurrence of ureteral stricture or stones. CONCLUSION: This is the first series demonstrating patients with proximal ureteral stricture, even with concomitant stone disease, may donate kidneys for transplantation. Recipient outcomes suggest this practice is safe, and appropriately selected patients that have already elected for nephrectomy should receive counseling about this opportunity. Importantly, patients who donate a kidney receive waiting list priority if they ever need a kidney transplant in the future.

Community Income, Healthy Food Access, and Repeat Surgery for Kidney Stones.

OBJECTIVE: To determine if limited food access census tracts and food swamp census tracts are associated with increased risk for repeat kidney stone surgery. And to elucidate the relationship between community-level food retail environment relative to community-level income on repeat stone surgery over time. METHODS: Data were abstracted from the University of California, San Francisco Information Commons. Adult patients were included if they underwent at least one urologic stone procedure. Census tracts from available geographical data were mapped using Food Access Research Atlas data from the United States Department of Agriculture Economic Research Service. Kaplan-Meier curves were employed to illustrate time to a second surgical procedure over 5 years, and log-rank tests were used to test for statistically significant differences. A multivariate Cox regression model was used to generate hazard ratios for undergoing second surgery by group. RESULTS: A total of 1496 patients were included in this analysis. Repeat stone surgery occurred in 324 patients. Kaplan-Meier curves demonstrated a statistically significant difference in curves depicting patients living in low income census tracts (LICTs) vs those not living in LICTs (P <.001). On Cox regression models, patients in LICTs had significantly higher risk of undergoing repeat surgery (P = .011). Patients from limited food access census tracts and food swamp census tracts did not have a significantly higher adjusted risk of undergoing second surgery (P = .11 and P = .88, respectively). CONCLUSION: Income more so than food access associates with increased risk of repeat kidney stone surgery. Further research is needed to explore the interaction between low socioeconomic status and kidney stone outcomes.

Low Urologist Density Predicts High-Cost Surgical Treatment of Stone Disease.

Introduction and Objectives: Lack of access to urologic specialists is approaching crisis levels as the number of urologists is decreasing, while the demand for urologic care is increasing. The financial implications of this have not been explored. The objective of this study is to examine the impact of access and other patient factors on cost to treat urolithiasis. We hypothesized that markers of poor access would associate with higher costs of surgical encounters for patients presenting with urolithiasis. Methods: A retrospective review of prospectively collected data from the Registry for Stones of the Kidney and Ureter (ReSKU) from September 2015 to July 2018 was conducted to investigate characteristics of surgical patients treated for urinary stone disease. Univariate analysis was performed using the Welch two-sample t-test. Multivariate analysis was performed using logistic regression. Statistical analysis was performed in R version 3.5. Results: When taking into account age, delayed presentation, procedure type, stone size >20 mm, American Society of Anesthesiologists (ASA) code, gender, race, income, distance, urologist density, body mass index, diabetes, infection, education, language, insurance, and stone complexity, patients undergoing percutaneous nephrolithotomy procedure (p < 0.001; odds ratio [OR] 12.9, confidence interval [CI] 4.05-48.5), urologist density in the bottom quartile (p = 0.014; OR 4.66, CI 1.40-16.9), diabetes (p = 0.018; OR 4.38, CI 1.32-15.6), and infection (p = 0.007; OR 4.51, CI 1.55-14.0) were the only variables statistically significant for association with top quartile of total cost. Conclusions: Surgical encounter costs are largely dictated by patient clinical factors, but low regional urologist density appears to independently predicted for high-cost stone surgery. Increasing patients' access to a urologist may prove to be financially beneficial in the longitudinal reduction in health care costs for stone disease.

Long-Term Antibiotic Treatment Prior to Laparoscopic Nephrectomy for Xanthogranulomatous Pyelonephritis Improves Postoperative Outcomes: Results from a Multicenter Study.

PURPOSE: Xanthogranulomatous pyelonephritis is a destructive bacterial infection typically necessitating nephrectomy. We hypothesized that long-term preoperative antibiotics would facilitate laparoscopic nephrectomy by reducing the renal inflammation. MATERIALS AND METHODS: We reviewed the records of all patients with histologically confirmed xanthogranulomatous pyelonephritis at 3 University of California institutions between 2005 and 2018. Patients were stratified by antibiotic treatment duration and surgical approach. Patients treated with long-term preoperative antibiotics (28 days or more of continuous treatment until surgery) were compared to patients treated with short-term antibiotics (less than 28 days) and those who only received single-dose prophylactic antibiotics before surgery. Patient demographics and operative outcomes were analyzed. Complications were assigned by Clavien-Dindo classification. RESULTS: Among the 61 patients, 51 (84%) were female and mean age was 50 years. There were 21 (34%) open procedures and 40 (66%) laparoscopic procedures. Median duration of antibiotic treatment was 5 days in those who received a short-term treatment and 87 days in those who received long-term treatment. Eleven patients received only prophylactic single-dose antibiotics. Using multivariate analysis among patients undergoing laparoscopic nephrectomy, controlling for preoperative drainage, long-term antibiotics resulted in a 6.5-day shorter length of stay (p=0.023) and less overall as well as milder postoperative complications (p <0.001). CONCLUSIONS: Greater than or equal to 4 weeks of preoperative antibiotics before laparoscopic nephrectomy for xanthogranulomatous pyelonephritis was associated with shorter length of stay and fewer, less severe postoperative complications.

Live Renal Ultrasonography Facilitates Double-J Ureteral Stent Insertion at the Bedside: A Pilot Study for the COVID-19 Era.

Objectives: To investigate the feasibility and efficacy of live renal ultrasonography to guide Double-J ureteral stent placement at the bedside. Patients and Methods: Between April 12 and June 5, 2020, patients presenting with acute ureteral obstruction requiring decompression were prospectively selected for ultrasound-guided bedside ureteral stent placement. During stent placement, upper tract access confirmed using ultrasound with or without retrograde injection of ultrasound contrast before Double-J stent insertion. A postprocedural abdominal X-ray was obtained for stent position confirmation. Results: Eight patients (four men and four women) were offered bedside ultrasound-guided ureteral stent placement, and all eight consented to proceed. Stents were placed in seven of eight patients. One patient had an impacted ureterovesical junction stone and stricture requiring ureteroscopy and laser lithotripsy in the operating room. All patients tolerated procedures without immediate complications. Conclusion: Live renal ultrasonography can facilitate a high success rate for bedside ureteral stent placement outside the operating room. This approach is an attractive alternative to fluoroscopy-guided stent placement in the operating room and is of particular value in the COVID-19 era when judicious use of these resources is salient.

Ectopic biomineralization in kidney stone formers compared to non-stone formers.

BACKGROUND: Kidney stone formers (SFs) are at increased risk of stroke, myocardial infarction, and atherosclerosis of the carotid and coronary arteries. These cardiovascular and urologic pathologies can result from ectopic biomineral deposition. The objectives of this study are: (I) to evaluate risk factors for ectopic biomineralization, and (II) to characterize the overall burden of ectopic minerals in known SFs compared to non-stone formers (NSFs) matched for these risk factors. METHODS: Presence and quantity of biominerals at eight anatomic locations (abdominal aorta, common iliac arteries, pelvic veins, prostate or uterus, mesentery, pancreas, and spleen) were determined in a case control study by retrospective analysis of clinical non-contrast computed tomography scans obtained from 190 SFs and 190 gender- and age-matched NSFs (renal transplant donors). Predictors of biomineralization were determined using negative binomial regression. A subgroup of 140 SFs and 140 NSFs were matched for risk factors for systemic biomineralization, and mineralization was compared between these matched SFs and NSFs using ordinal logistic regression. RESULTS: Hypertension, hyperlipidemia, diabetes mellitus, and smoking were more common amongst SFs. Risk factors for increased systemic biomineralization included history of nephrolithiasis, male gender, older age, and history of hyperlipidemia. When controlling for these comorbidities, SFs had significantly increased biomineralization systemically and at the abdominal aorta, iliac arteries, prostate, mesentery, pancreas, and spleen compared to NSFs. CONCLUSIONS: The current study provides evidence that SFs are at increased risk of biomineralization systemically, independent of common risk factors of atherosclerosis.

Stone formation in patients less than 20 years of age is associated with higher rates of stone recurrence: Results from the Registry for Stones of the Kidney and Ureter (ReSKU).

INTRODUCTION: Nephrolithiasis is a major source of morbidity in the United States. In recent decades, there has been a notable increase in stone incidence in the pediatric population. We investigate whether recurrent stone formers who had their initial stone episode earlier in life are at risk for more frequent stone recurrences, compared to those with initial episodes later in life. We also examine possible risk factors that might change our approach to treatment of these patients. METHODS: A review of prospectively collected data from the Registry for Stones of the Kidney and Ureter (ReSKU) from September 2015 to July 2018 was conducted to compare stone recurrence and other patient factors in patients who reported an initial stone episode prior to 20 years of age versus patients who reported an initial stone episode after age 20. Data on patient age, gender, BMI, family history, race, income, infectious symptoms, and number of prior stone episodes was analyzed. We excluded patients with a history of cystinuria stones. Univariate analysis was performed using Fisher's exact test and student's T test. Multivariate analysis was performed using logistic regression. RESULTS: Of the 1140 patients enrolled during this study period, 472 patients were recurrent stone formers, and of these, 66 had their first stone episode prior to the age of 20. On univariate analysis, early stone formers were more likely to be female, present at a younger age, and have more prior stone episodes on enrollment. Using multivariate modelling to control for age, gender, race, BMI, family history, and number of stone episodes, early stone formers were more likely to be female (CI 1.17 - 3.54) and have more than one prior stone episode (CI 1.13 - 3.78). Late stone formers were more likely to have BMI > 30 (CI 0.26 - 0.94). CONCLUSION: Recurrent stone formers who have their first episodes prior to age 20 are more likely to present to stone clinics with multiple prior recurrences and hence more aggressive stone disease. Female gender seems to be a risk factor. Earlier stone formers should be encouraged to have close follow up and surveillance due to the increased rate of recurrence. Adult stone databases focusing on early presentations can improve understanding of pediatric stone disease.

Thiel-embalmed cadavers as a novel training model for ultrasound-guided supine endoscopic combined intrarenal surgery.

OBJECTIVE: To evaluate Thiel-embalmed cadavers (TEC) as a training model for percutaneous nephrolithotomy (PCNL), more specifically for ultrasound (US)-guided supine endoscopic combined intrarenal surgery (ECIRS). SUBJECTS AND METHODS: Thirteen urologists (nine experienced endourologists, four fellows/residents) performed an US-guided supine ECIRS procedure on a TEC. The model was evaluated by way of a questionnaire (5-point Likert scale). Descriptive statistical analysis was performed and results were graphically presented using divergent bar graphs. RESULTS: US images were appreciated as lifelike in all aspects. Although distention of the collecting system was not ideal in one out of three TEC, US visualisation of the distended calyces during puncture was good. Skin penetration was more difficult and less realistic in TEC, while kidney puncture and dilatation were deemed very realistic. Ureteric and collecting system anatomy and consistency were similar to real life, although the mucosa appeared paler. US needle guidance was perceived as excellent. Overall, needle puncture assessment was realistic and useful as a training tool. Overall quality and satisfaction of TEC in US-guided supine ECIRS was good to excellent and comparable to a real-life procedure. Overall appropriateness of the TEC model was considered excellent for both initial and advanced supine PCNL training. CONCLUSION: Despite the minor drawbacks of tough skin and non-ideal collecting system dilatation during ureteroscopy, the TEC model was considered good to excellent as a training model for US-guided PCNL, in particular, US-guided needle puncture of the kidney during supine ECIRS.

Ultrasound guidance can be used safely for renal tract dilatation during percutaneous nephrolithotomy.

OBJECTIVES: To compare clinical outcomes in patients who underwent percutaneous nephrolithotomy (PCNL) with renal tract dilatation performed under fluoroscopic guidance vs renal tract dilatation with ultrasound guidance. PATIENTS AND METHODS: We conducted a prospective observational cohort study, enrolling successive patients undergoing PCNL between July 2015 and March 2018. Included in this retrospective analysis were cases where the renal puncture was successfully obtained with ultrasound guidance. Cases were then grouped according to whether fluoroscopy was used to guide renal tract dilatation or not. All statistical analyses were performed using Stata version 15.1 including univariate (Fisher's exact test, Welch's t-test) and multivariate analyses (binomial logistic regression, ordinal logistic regression, and linear regression). RESULTS: A total of 176 patients underwent PCNL with successful ultrasonography-guided renal puncture, of whom 38 and 138 underwent renal tract dilatation with fluoroscopic vs ultrasound guidance, respectively. There were no statistically significant differences in patient age, gender, body mass index (BMI), preoperative hydronephrosis, stone burden, procedure laterality, number of dilated tracts, and calyceal puncture location between the two groups. Among ultrasound tract dilatations, a higher proportion of patients were placed in the modified dorsal lithotomy position as opposed to prone, and a significantly shorter operating time was observed. Only modified dorsal lithotomy position remained statistically significant after multivariate regression. There were no statistically significant differences in postoperative stone clearance, complication rate, or intra-operative estimated blood loss. A 5-unit increase in a patient's BMI was associated with 30% greater odds of increasingly severe Clavien-Dindo complications. A 5-mm decrease in the preoperative stone burden was associated with 20% greater odds of stone-free status. No variables predicted estimated blood loss with statistical significance. CONCLUSIONS: Renal tract dilatation can be safely performed in the absence of fluoroscopic guidance. Compared to using fluoroscopy, the present study demonstrated that ultrasonography-guided dilatations can be safely performed without higher complication or bleeding rates. This can be done using a variety of surgical positions, and future studies centred on improving dilatation techniques could be of impactful clinical value.