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Background: Higher temperatures have been associated with increased stone formation and subsequent utilization of hospital resources, including inpatient admission. However, these observations have been derived from the adult population. We sought to examine if this purported association extends to the pediatric population. Methods: We used the 2016 Kids' Inpatient Database to identify nationwide pediatric inpatient admissions related to nephrolithiasis. Temperature data from the National Oceanic and Atmospheric Administration was linked to each admission. Comparative statistics analyzed patient and admission characteristics. Multivariable logistic regression analyzed associations between stone-related admissions and temperature. As a frame of reference, this analysis was replicated using the National Inpatient Sample from 2016 to evaluate associations in the adult population. Results: Of the 2,496,257 pediatric admissions, 8453 (0.33%) were related to nephrolithiasis. Temperatures at the time of stone admission were higher than those during nonstone admission (55.9°F vs 54.8°F, p  < 0.001). The stone admission group had a higher proportion of females than the nonstone admission group (64.8% vs 55.4%, p  < 0.001). Stone admission was significantly associated with temperature (odds ratio [OR] 1.025 per 10°F, confidence interval [95% CI] 1.003-1.049, p  = 0.03) and female gender (OR 1.097, 95% CI 1.027-1.171, p  = 0.006). In the adult population, 380,520 out of 30,000,941 patients (1.3%) were admitted with a stone. The effect of temperature on stone admissions was similar to that in the pediatric population (OR 1.020, 95% CI 1.014-1.026, p  < 0.001), but women were >20% less likely to be admitted for stones than men (OR 0.770, 95% CI 0.757-0.784, p  < 0.001). Conclusions: Increased temperatures were associated with an increased risk of stone-related admission in both the pediatric and adult populations. Females were at increased risk for stone-related admissions during childhood, but this trend reverses in adulthood.

Background: Retrograde intrarenal surgery (RIRS) has become the preferred treatment modality for nephrolithiasis. However, because of ongoing uncertainties regarding the optimal perioperative management, operative technique, and postoperative follow-up, as well as a lack of standardization for outcome reporting, consensus is needed to achieve more uniform clinical practice worldwide., Objective: To develop recommendations for RIRS on the basis of existing data and expert consensus., Design, Setting, and Participants: A protocol-driven, three-phase study was conducted by the European Association of Urology Section of Urolithiasis (EULIS) and the International Alliance of Urolithiasis (IAU). The process included: (1) a nonsystematic review of the literature to define domains for discussion; (2) a two-round modified Delphi survey involving experts in this field; and (3) an additional group meeting and third-round survey involving 64 senior representative members to formulate the final conclusions., Outcome Measurements and Statistical Analysis: The results from each previous round were returned to the participants for re-evaluation of their decisions during the next round. The agreement threshold was set at 70%., Results and Limitations: The panel included 209 participants who developed 29 consensus statements on the following topics of interest: (1) perioperative infection management; (2) perioperative antithrombotic therapy; (3) fundamentals of the operative technique; and (4) standardized outcome reporting. Although this consensus can be considered as a useful reference for more clinically oriented daily practice, we also acknowledge that a higher level of evidence from further clinical trials is needed., Conclusions: The consensus statements aim to guide and standardize clinical practice and research on RIRS and to recommend standardized outcome reporting., Patient Summary: An international consensus on the best practice for minimally invasive surgery for kidney stones was organized and developed by two international societies. It is anticipated that this consensus will provide further guidance to urologists and may help to improve clinical outcomes for patients., (Copyright © 2021 European Association of Urology. All rights reserved.)

The presence of lower pole stones poses a unique challenge due to the anatomical considerations involved in their management and treatment. Considerable research has been performed to determine the optimal strategy when faced with this highly relevant clinical scenario. Standard options for management include observation, shock wave lithotripsy, retrograde intrarenal surgery, or percutaneous nephrolithotomy. Indeed, each approach confers a distinct set of risks and benefits, which must be placed into the context of patient preference and expected outcomes. The current state of practice reflects a combination of lessons learned from managing calculi not only in the lower pole, but also from other locations within the kidney as well., Competing Interests: None declared., (Copyright® by the International Brazilian Journal of Urology.)

Objective: The aim of this study was to comprehensively evaluate the quality of patient-oriented, mobile health applications (apps) available for medical management of kidney stone disease (KSD). Materials and Methods: A systematic search was performed to identify apps from the Apple and Google Play app stores. Eligible apps were divided into two categories: (1) fluid apps and (2) dietary apps. Descriptive characteristics were summarized and app quality was independently evaluated on the basis of technical quality, usability, clinical value, and privacy/security. The validated Mobile App Rating Scale (MARS) was the backbone for the evaluation framework. Results: In total, 31 apps (18 fluid apps and 13 dietary apps) were included. Fluid apps outscore dietary apps in all dimensions of MARS quality. All but one fluid app exceeded the minimum acceptable MARS score of 3.0 vs 46% of dietary management apps. Dietary apps feature less functionality and most are limited to noninteractive informational content. While most data-capturing apps provide a privacy policy and ensure that security measures are taken to protect user identity, only 36% offer users choice or consent for secondary use of their data after data have already been collected. Overall, only one app has undergone any form of real-world clinical investigation. Conclusions: Fluid management apps outperform dietary apps in technical quality, usability, and clinical value at the cost of greater privacy/security risks. Despite not being targeted to patients with KSD, they are higher in most quality measures and offer greater functionality to support long-term disease management compared with dietary apps.

Objective: To assess the quality and accuracy of online videos about the medical management of nephrolithiasis., Materials and Methods: To evaluate trends in online interest, we first examined the frequency of worldwide YouTube searches for 'kidney stones' from 2015 to 2020. We then queried YouTube with terms related to symptoms and treatment of kidney stones and analysed English-language videos with >5000 views. Quality was assessed using the validated DISCERN instrument. Evidence-based content analysis of video content and viewer comments was performed., Results: Online searches for videos about kidney stones doubled between 2015 and 2019 (P < 0.001). We analysed 102 videos with a median (range) number of views of 46 539 (5024-3 631 322). The mean (sd) DISCERN score was 3.0 (1.4) out of 5, indicating 'moderate' quality; scores were significantly higher for the 21 videos (21%) authored by academic hospitals (mean 3.7 vs 2.8, P = 0.02). Inaccurate or non-evidence-based claims were identified in 23 videos (23%); none of the videos authored by academic institutions contained inaccurate claims. Videos with inaccurate statements had more than double the viewer engagement (viewer-generated comments, 'thumbs up' and 'thumbs down' ratings) compared to videos without inaccuracies (P < 0.001). Among viewer comments, 43 videos (43%) included comments with inaccurate or non-evidence-based claims, and a large majority (82 videos, 80%) had 'chatbot' recommendations., Conclusions: Interest in YouTube videos about nephrolithiasis has doubled since 2015. While highly viewed videos vary widely in quality and accuracy, videos produced by academic hospitals have significantly fewer inaccurate claims. Given the high prevalence of stone disease and poor-quality videos, patients should be directed to evidence-based content online., (© 2020 The Authors BJU International © 2020 BJU International Published by John Wiley & Sons Ltd.)

Introduction: Accurate estimation of stone fragment size during ureteroscopic lithotripsy procedures facilitates operative efficiency and predicts the safety of fragment extraction or spontaneous passage. Using a novel stone measurement software application, this study assesses the feasibility of performing integrated real-time digital stone measurement during ureteroscopy. Methods: This workflow feasibility study was conducted in two phases. First, in the ex vivo simulation, mock stone fragments were placed in a renal collecting system training model. A basket extraction task was performed using a digital ureteroscope, with and without digital stone measurement. The time required to perform the tasks was recorded and compared. Second, in the in vivo workflow trial, adult patients undergoing ureteroscopic stone procedures were prospectively enrolled. Intraoperative measurements of stone fragments were performed to determine the time required to complete the measurements. Technical failures and perioperative complications were recorded. Results: In the ex vivo simulation, 20 mock stones mimicking varied fragmentation conditions were tested in the training model. The mean completion time of the basketing task without vs with digital stone measurement was 16.5 seconds (range 10.2-33.7) vs 38.9 seconds (range 27.2-60.0). Mean additional time required to measure stones was 22.3 seconds (range 8.4-42.7). In the in vivo workflow trial, nine patients undergoing ureteroscopy were enrolled. A median of five fragments (range 3-10) were measured in each patient. Mean completion time for each measurement was 10.1 seconds (range 8.2-12.8). Mean total time required to perform digital measurement per procedure was 50.8 seconds (range 25.9-99.0). No technical failures or clinical complications were observed. Conclusions: Integrating real-time digital stone measurement during ureteroscopy is safe and feasible. The findings support clinical trials of digital stone measurement to enhance intraoperative decision-making during ureteroscopy.

Introduction: Numerous dietary supplements claiming to treat or prevent kidney stones have recently been brought to the market. However, the evidence for these claims is not clear. This study assesses the scientific evidence supporting dietary supplements for the treatment and prevention of urinary stone disease. Materials and Methods: Two online marketplaces (Amazon and Google) were queried for dietary supplements available without a prescription to treat, alleviate, or prevent stone disease. Product labels were reviewed to compile stone-related claims and active ingredients. The 30-day cost of treatment and consumer star rating were assessed. MEDLINE, Web of Science, and Google Scholar were queried with labeled ingredients to assess the scientific evidence from published and lay sources. Results: A total of 27 dietary supplements containing 56 ingredients were analyzed. Supplements made a variety of claims, including dissolving stones (12 products, 44%), preventing stone formation (7 products, 26%), and reducing stone symptoms (6 products, 22%). Mean 30-day cost was $32 (range $4-$189). All products were rated highly by consumers (mean 4.2 of 5 stars). Of the 56 ingredients, 9 (16%) had any published studies for use in stone disease, and 5 (9%) had exclusively studies supporting their use. Eighteen scientific publications about the ingredients were identified, of which six showed mixed or no benefit in stone disease. Overall, 18 (67%) supplements contained ingredients with conflicting or absent evidence of benefit. No association was found between product cost or rating and products containing ingredients supported by human or animal studies ( p  > 0.05). Conclusions: Two-thirds of dietary supplements claiming to treat or prevent kidney stones contain ingredients with conflicting or no scientific evidence to support their claims. Clinicians should counsel stone formers that the effects of most supplements are unknown or unstudied in humans, and that the absence of evidence does not imply absence of potential harm.

Objective: In recent years, there has been increasing interest in the use of ultrasound guidance for endoscopic and percutaneous procedures. Kidney mockups could be used for training, however, available mockups are normally incompatible with ultrasound imaging. We developed a reproducible method to manufacture an ultrasound-compatible collecting system mockup that can be made at urology laboratories. Methods: Positive and negative molding methods were used. A three-dimensional (3D) digital model of a urinary collecting system and the overlying skin surface were segmented from computed tomography. A containment mold (negative) was made following the shape of the skin surface using 3D printing. A collecting system mold (positive) was also 3D printed, but made of a dissolvable material. The containment mold was filled with a gelatin formula with the collecting system mold submersed in situ within. After the gelatin solidified, a solution was used to dissolve the collecting system mold, but not the gelatin, leaving a cavity with the shape of the collecting system. The gelatin was extracted from the container mockup and the collecting system cavity was filled with water. The mockup was imaged with ultrasound to assess echogenicity and suitability for simulating ultrasound-guided procedures. Results: A clear shape corresponding to the collecting system was observed inside the gel structure. Structural integrity was maintained with no observable manufacturing marks or separation seams. Ultrasound images of the mockup demonstrated clear differentiation at the gelatin/water interface. A mock stone was placed in the collecting system and needle targeted to simulate percutaneous needle access. Conclusion: We developed a simple method to manufacture a personalized mockup of the renal collecting system of a patient that can be used for ultrasound-guided percutaneous needle access. Generic collecting system mockups can be used for training, and patient-specific models can be used to simulate and decide the best access path before a clinical case.

Introduction: CT is the gold standard for visualizing renal and ureteral calculi. CT three-dimensional reformatting allows for automatic, accurate, and reliable measurement of stone size, volume, density, and location. In this study, we aimed to develop and test a software platform capable of calculating a battery of clinically important urinary stone parameters at the point-of-care (POC)., Methods: The syngo Calcium Scoring (Siemens Corporation) algorithm was modified to identify calcium-based stones using an attenuation threshold (250 HU) within a region of interest. Information automatically obtained after reconstruction included voxel sum and calculated volume, maximum diameter, largest diameter in the x, y, and z planes, cumulative diameter, distribution of attenuation in HU, and position relative to the skin for calculation of the skin-to-stone distance (SSD). This algorithm was packaged into a stand-alone application (MATLAB 9.1). From April 2017 to May 2017, all patients undergoing a noncontrast CT of the abdomen or the abdomen and pelvis at the Johns Hopkins Hospital were eligible for inclusion in this validation cohort., Results: A total of 55 index renal stones were included. The mean volume calculated by voxel sum was 216.53 mm 3 (standard deviation [SD] ±616.19, range 1.50-4060.13). The mean volume calculated using the Ackermann's formula and for a sphere was 232.96 mm 3 (SD ± 702.65, range 1.24-4074.04) and 1214.63 mm 3 (SD ± 4233.41, range 1.77-25,246.40), respectively. The mean largest diameter in any one direction was 6.95 mm (SD ± 7.31, range 1.50-36.40). The maximum density of the stones ranged from 164 to 1725 HU. The mean SSD at the shortest possible point was 14.19 cm (SD ± 6.13, range 6.67-31.28)., Conclusions: We developed a stand-alone platform with a simple easy-to-use interface, which will allow any user the ability to calculate a battery of clinically important urinary stone parameters from CT imaging at the POC. This program is now freely available online.

Introduction: Urolithiasis is a globally-distributed disease; however, its prevalence varies across countries and regions. Countries in the Middle East have been reported to have particularly high nephrolithiasis prevalence rates. To date, however, we have an incomplete understanding of the composition of stones seen in this region. Therefore, we performed a study to characterize stone composition over a 14-year period in the Eastern Province of the Kingdom of Saudi Arabia (KSA)., Materials and Methods: A retrospective review of all adult patients who had the composition of their upper urinary tract calculi analyzed at Johns Hopkins Aramco Healthcare (JHAH) between 1999 and 2013 was performed. Patient demographics and pathology results were obtained from the electronic medical record., Results: A total of 1,747 stones were analyzed in the study period. The results are presented in the Table. Male patients predominated (79%). For both men and women, the majority of stones were calcium oxalate: 85.2% male, 85.9% female. Uric acid stones were the next most common: 10.1% male; 9.0% female. Overall, there were no significant differences between gender with regards to the distribution of stone types., Conclusion: This study represents one of the largest characterizations of stone composition in the Middle East. There remains a significant gender disparity in stone prevalence in the Eastern Province of KSA, with males affected to a significantly greater extent. Calcium oxalate is the most common type of stone, and this is true for both men and women. Future investigations of dietary and environmental factors can build on these initial epidemiologic findings.
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Purpose: There is scant evidence in the literature to support dusting vs active basket extraction during ureteroscopy for kidney stones. We prospectively evaluated and followed patients to determine which modality produced a higher stone-free rate with the fewest complications., Materials and Methods: Members of the Endourologic Disease Group for Excellence research consortium prospectively enrolled patients with a renal stone burden ranging from 5 to 20 mm in this study. A holmium laser was used and all patients were stented postoperatively. Ureteral access sheaths were used in 100% of basketing cases while sheaths were optional when dusting. The primary study outcome was the stone-free rate at 6 weeks as determined by x-ray and ultrasound., Results: A total of 84 and 75 patients were enrolled in the basketing and dusting arms, respectively. Stones in the dusting group were significantly larger (mean ± SD stone area 96.1 ± 65.3 vs 63.3 ± 46.0 mm 2 , p <0.001). The stone-free rate was significantly higher in the basketing group on univariate analysis (74.3% vs 58.2%, p = 0.04) but not on multivariate analysis (1.9 OR, 95% CI 0.9-4.3, p = 0.11). In patients who underwent a basketing procedure operative time was 37.7 minutes longer than in those treated with a dusting procedure (95% CI 23.8-51.7, p <0.001). There was no statistically significant difference in complication rates, hospital readmissions or additional procedures between the groups., Conclusions: The stone-free rate was higher for active basket retrieval of fragments at short-term followup on univariate analysis but not on multivariate analysis. There was no difference in postoperative complications or procedures. The 2 techniques should be in the armamentarium of the urologist., (Copyright © 2018 American Urological Association Education and Research, Inc. Published by Elsevier Inc. All rights reserved.)

A 40-year-old woman presents to the emergency department after a motor vehicle accident, and a CT scan revealed no injuries but incidentally notes three non-obstructing stones in the left kidney of 3, 4, and 5 mm in size. She is completely asymptomatic and has no history of urolithiasis.

Purpose: This Guideline is intended to provide a clinical framework for the surgical management of patients with kidney and/or ureteral stones. The summary presented herein represents Part I of the two-part series dedicated to Surgical Management of Stones: American Urological Association/Endourological Society Guideline. Please refer to Part II for an in-depth discussion of patients presenting with ureteral or renal stones., Materials and Methods: A systematic review of the literature (search dates 1/1/1985 to 5/31/2015) was conducted to identify peer-reviewed studies relevant to the surgical management of stones. The review yielded an evidence base of 1,911 articles after application of inclusion/exclusion criteria. These publications were used to create the Guideline statements. Evidence-based statements of Strong, Moderate, or Conditional Recommendation were developed based on benefits and risks/burdens to patients. Additional directives are provided as Clinical Principles and Expert Opinions when insufficient evidence existed., Results: The Panel identified 12 adult Index Patients to represent the most common cases seen in clinical practice. Three additional Index Patients were also created to describe pediatric and pregnant patients with such stones. With these patients in mind, Guideline statements were developed to aid the clinician in identifying optimal management., Conclusions: Proper treatment selection, which is directed by patient- and stone-specific factors, remains the greatest predictor of successful treatment outcomes. This Guideline is intended for use in conjunction with the individual patient's treatment goals. In all cases, patient preferences and personal goals should be considered when choosing a management strategy., (Copyright © 2016 American Urological Association Education and Research, Inc. Published by Elsevier Inc. All rights reserved.)

Several professional organizations have developed evidence-based guidelines for the initial evaluation, diagnostic imaging selection, symptomatic management, surgical treatment, medical therapy, and prevention of recurrence for both ureteric and renal stones. The purpose of this article is to summarize these guidelines with reference to the strength of evidence. All guidelines endorse an initial evaluation to exclude concomitant infection, imaging with a non-contrast computed tomography scan, and consideration of medical expulsive therapy or surgical intervention depending on stone size and location. Recommends for metabolic evaluation vary by guideline, but all endorse increasing fluid intake to reduce the risk of recurrence., (© 2015 The Authors BJU International © 2015 BJU International Published by John Wiley & Sons Ltd.)

Background and Purpose: Percutaneous nephrolithotomy (PCNL) is the treatment of choice for patients with complex stone burdens. We performed a study to assess the effect of urologist-specific parameters on the use of PCNL-both the access component of the procedure as well as the stone removal. We also examined trends in PCNL utilization over time., Methods: We analyzed self-reported 6-month case logs submitted to The American Board of Urology (ABU) for urologists who certified or recertified between 2004 and 2013. Surgeons performing PCNL were identified by Current Procedural Terminology coding. Urologist-specific data, including fellowship training, practice type, and practice population, were used to further stratify this cohort. Trends were examined over the study period., Results: A total of 7278 urologists submitted case logs to the ABU between 2004 and 2013. The median ages of the initial certification group, first recertification group, and second recertification group were 36.0, 43.7, and 53 years, respectively. A greater proportion of newly certified urologists performed PCNL (53%) compared with urologists in the first (41%) and second (29%) recertification groups; initially certified urologists were also more likely to be high volume (>10) PCNL surgeons. Urologists with fellowship training were more likely to use PCNL (66%) and be high-volume surgeons (26.4%). PCNL utilization increased significantly during the study period, with 1330 procedures performed in 2004 and 2888 procedures performed in 2012 (117% increase)., Conclusions: Younger and fellowship-trained urologists are the primary users of PCNL; the majority of senior urologists do not perform this operation. Overall, the use of PCNL and urologist-directed access has increased in the previous decade.

Purpose: The purpose of this guideline is to provide a clinical framework for the diagnosis, prevention and follow-up of adult patients with kidney stones based on the best available published literature., Materials and Methods: The primary source of evidence for this guideline was the systematic review conducted by the Agency for Healthcare Research and Quality on recurrent nephrolithiasis in adults. To augment and broaden the body of evidence in the AHRQ report, the AUA conducted supplementary searches for articles published from 2007 through 2012 that were systematically reviewed using a methodology developed a priori. In total, these sources yielded 46 studies that were used to form evidence-based guideline statements. In the absence of sufficient evidence, additional statements were developed as Clinical Principles and Expert Opinions., Results: Guideline statements were created to inform clinicians regarding the use of a screening evaluation for first-time and recurrent stone formers, the appropriate initiation of a metabolic evaluation in select patients and recommendations for the initiation and follow-up of medication and/or dietary measures in specific patients., Conclusions: A variety of medications and dietary measures have been evaluated with greater or less rigor for their efficacy in reducing recurrence rates in stone formers. The guideline statements offered in this document provide a simple, evidence-based approach to identify high-risk or interested stone-forming patients for whom medical and dietary therapy based on metabolic testing and close follow-up is likely to be effective in reducing stone recurrence., (Copyright © 2014 American Urological Association Education and Research, Inc. Published by Elsevier Inc. All rights reserved.)

Purpose: We conducted this study to identify differences in the re-treatment rates and ancillary procedures for the two most commonly utilized stone treatment procedures in the Medicare population: ureteroscopy (URS) and shock wave lithotripsy (SWL)., Materials and Methods: A retrospective claims analysis of the Medicare standard analytical file 5% sample was conducted to identify patients with a new diagnosis of urolithiasis undergoing treatment with URS or SWL from 2009-2010. Outcomes evaluated: (1) repeat stone removal procedures within 120 days post index procedure, (2) stent placement procedures on the index date, 30 days prior to and 120 days post index date, and (3) use of general anesthesia., Results: We identified 3885 eligible patients, of which 2165 (56%) underwent SWL and 1720 (44%) underwent URS. Overall, SWL patients were 1.73 times more likely to undergo at least one repeat procedure than URS patients, and twice as likely to require multiple re-treatments compared to URS. Among those with ureteral stones, SWL patients were 2.27 times more likely to undergo repeat procedures. The difference was not statistically significant in renal stone patients. Overall, SWL patients were 1.41 times more likely than URS patients to have a stent placed prior to index procedure, and 1.33 times more likely to have a stent placed subsequent to the index procedure. The majority of URS patients (77.8%) had a stent placed at the time of index procedure. There was no significant difference in anesthetic approaches between SWL and URS., Conclusions: Patients undergoing SWL are significantly more likely to require re-treatments than URS patients. SWL patients are also significantly more likely to require ureteral stent placement as a separate event. SWL and URS patients have similar rates of general anesthesia.

Kidney stones affect 10% of people at some point in their lives and, for some unfortunate women, this happens during pregnancy. Pregnancy is a complex state and both physiological and mechanical changes alter risk factors for kidney stone formation. When a pregnant woman develops acute nephrolithiasis, the situation is more complicated than in nonpregnant women. Imaging limitations and treatment restrictions mean that special diagnostic and management algorithms are needed upon presentation. Ultrasonography remains the gold-standard first-line diagnostic imaging modality for kidney stones during pregnancy but several second-line alternatives exist. Acute renal colic during pregnancy is associated with risks to both mother and fetus. As such, these patients need to be handled with special attention. First-line management is generally conservative (trial of passage and pain management) and is associated with a high rate of stone passage. Presentation of obstructive nephrolithiasis with associated infection represents a unique and serious clinical situation requiring immediate drainage. If infection is not present and conservative management fails, ureteroscopy can be offered if clinically appropriate, but, in some circumstances, temporary drainage with ureteral stent or nephrostomy tube might be indicated. Shockwave lithotripsy and percutaneous nephrolithotomy are contraindicated during pregnancy.

Objective: Surgical treatment of kidney stones in an obese patient (body mass index [BMI] >30 kg/m(2)) remains challenging as shockwave lithotripsy may not be an option due to weight limitations. We sought to determine the effectiveness of ureteroscopic laser lithotripsy in obese patients compared to nonobese controls., Materials and Methods: Patients from 2004 to 2007 were retrospectively analyzed providing a group of 292 patients (163 obese, 76 overweight, 53 normal) who underwent ureteroscopic procedures for urolithiasis at four centers in the United States and Canada., Results: The percentage of obese patients requiring flexible ureteroscopy (URS) (79%) was higher than in the other groups (P<0.0001). Flexible URS was associated with a lower stone-free rate (SFR) on multivariate analysis (P=0.034). There was no difference in SFRs of patients who required a ureteral access sheath, basket extraction, or received a postoperative stent. Complication rates did not differ between groups., Conclusion: SFRs using ureteroscopic lithotripsy in obese and overweight populations are the same as in the normal weight patients. A flexible ureteroscope was associated with a decreased SFR, but this likely due to a more proximal stone location in these patients. Ureteroscopic laser lithotripsy is an effective and safe technique to treat urolithiasis in the overweight/obese patient.

Kidney stones are common and do not spare the pregnant population. Although a simple stone event is usually straightforward in the general population, it is complex during pregnancy. Acute nephrolithiasis is associated with a unique set of complications during pregnancy and, because of imaging limitations, diagnosis is challenging. Multidisciplinary care is the key in proper management decisions. The pathophysiology of kidney stone formation in the pregnant state is also unique. Herein, we discuss the complexity of kidney stones and pregnancy., (Copyright © 2013 National Kidney Foundation, Inc. Published by Elsevier Inc. All rights reserved.)

Purpose: Underuse of partial vs radical nephrectomy for renal tumors was noted in recent population based analyses. An explanation is the learning curve associated with laparoscopic partial nephrectomy. We analyzed state trends in renal surgery and their relationship to the introduction of robotic technology., Materials and Methods: We used the Maryland HSCRC (Health Services Cost Review Commission) database to identify patients who underwent radical or partial nephrectomy, or renal ablation from 2000 to 2011. Utilization trends, and associated patient and hospital factors were analyzed using multivariate logistic regression. ICD-9 robotic modifier codes were established in October 2008., Results: Of the 14,260 patients included in analysis 11,271 (79.0%), 2,622 (18.4%) and 367 (2.6%) underwent radical and partial nephrectomy, and renal ablation, respectively. Partial nephrectomy increased from 8.6% in 2000 to 27% in 2011. Open radical nephrectomy decreased by 33%, while minimally invasive radical nephrectomy increased by 15%. Robot-assisted laparoscopic partial nephrectomy increased from 2008 to 2011, attaining a 14% rate at university and 10% at nonuniversity hospitals (p = 0.03). It was associated with increased partial nephrectomy (OR 9.67, p <0.001). Younger age, male gender and low patient complexity predicted partial nephrectomy on overall analysis, while higher hospital volume and university status were predictors only in earlier years., Conclusions: Partial nephrectomy use increased in Maryland from 2001 to 2011, which was facilitated by robotic technology. Associations with hospital factors decreased with time. These data suggest that robotic technology may enable surgeons across practice settings to more frequently perform nephron sparing surgery., (Copyright © 2013 American Urological Association Education and Research, Inc. Published by Elsevier Inc. All rights reserved.)

Purpose: We evaluated the cost-effectiveness of ureteral/renal stone treatment by comparing ureteroscopy, extracorporeal shock wave lithotripsy and percutaneous nephrolithotomy., Materials and Methods: We performed a systematic literature search to identify studies of treatment for adults with ureteral and renal stones that were published between 1995 and 2010. For inclusion in analysis studies had to provide the stone-free rate and the cost of at least 2 therapies., Results: Ten studies were identified, including 8 with an observational design and 2 that synthesized data using decision modeling techniques. Five of 6 studies, including 1 of 2 from the United States, compared ureteroscopy vs shock wave lithotripsy for proximal stones and showed a higher stone-free rate and lower cost for ureteroscopy. Four of the 5 studies, including the only American study, compared ureteroscopy vs shock wave lithotripsy for distal ureteral stones and also showed such an economically dominant result. Studies of shock wave lithotripsy vs percutaneous nephrolithotomy and ureteroscopy vs percutaneous nephrolithotomy for renal stones demonstrated higher cost and a higher stone-free rate for percutaneous nephrolithotomy., Conclusions: Despite the great heterogeneity and limited quality of available cost-effectiveness evaluations most studies demonstrated that ureteroscopy was more favorable than shock wave lithotripsy for ureteral stones in stone-free rate and cost., (Copyright © 2012 American Urological Association Education and Research, Inc. Published by Elsevier Inc. All rights reserved.)

Introduction: The emergency department (ED) is a common setting for evaluation of patients with urolithiasis based on acute symptoms and a propensity for recurrent disease. We sought to characterize practice patterns in the emergency treatment of stone disease, and to identify potential disparities in care based on non-medical factors., Materials and Methods: We performed a cross-sectional analysis of ED visits using the National Hospital Ambulatory Medical Care Survey from 2005-2009. Visits with a diagnosis of urolithiasis were identified. The associations between patient, provider and institutional characteristics were analyzed with regard to timing of clinical assessment, use of diagnostic imaging, and use of medical expulsive therapy (MET)., Results: The likelihood of a delay in clinical assessment ranged from 30.8%-37.9%. Neither patient nor provider characteristics were associated with a delay in assessment, although urban location (p = 0.004) was more likely, and proprietary ownership was less likely (p = 0.002) to be associated with delay. Factors associated with use of CT included ambulance arrival (p = 0.043), initial ED visit (p = 0.000), and Northeast region (p = 0.030). Patients seen by a resident/intern were more likely to receive MET (p = 0.028). Overall, 10.8% of patients were presenting for follow up treatment, and 7.1% had been seen in the same ED within the last 72 hours., Conclusions: Kidney stones are associated with a high rate of repeated presentations to the ED. Certain non-medical factors did impact details of management. Future efforts should focus on optimizing clinical pathways to improve the efficiency of acute care for kidney stone patients.

Purpose: We compared the clinical outcomes of patients with ureteral or renal stones treated with ureteroscopy, shock wave lithotripsy using HM3 (Dornier®) and nonHM3 lithotripters, and percutaneous nephrolithotomy., Materials and Methods: A systematic literature search identified 6, 4 and 3 randomized, controlled trials of treatment of distal and proximal ureteral stones, and renal stones, respectively, published between 1995 and 2010. Overall stone-free, re-treatment and complication rates were calculated by meta-analytical techniques., Results: Based on the randomized, controlled trials evaluated the treatment of distal ureteral stones with semirigid ureteroscopy showed a 55% greater probability (pooled RR 1.55, 95% CI 1.13-2.56) of stone-free status at the initial assessment than treatment with shock wave lithotripsy. Patients treated with semirigid ureteroscopy were also less likely to require re-treatment than those treated with shock wave lithotripsy (nonHM3) (RR 0.14, 95% CI 0.08-0.23). The risk of complications was no different between the 2 modalities. Only 2 of the 4 randomized, controlled trials identified for proximal ureteral stones evaluated flexible ureteroscopy and each focused specifically on the treatment of stones 1.5 cm or greater, limiting their clinical relevance. The degree of heterogeneity among the studies evaluating renal stones was so great that it precluded any meaningful comparison., Conclusions: Semirigid ureteroscopy is more efficacious than shock wave lithotripsy for distal ureteral stones. To our knowledge there are no relevant randomized, controlled trials of flexible ureteroscopy treatment of proximal ureteral calculi of a size commonly noted in the clinical setting. Collectively the comparative effectiveness of ureteroscopy and shock wave lithotripsy for proximal ureteral and renal calculi is poorly characterized with no meaningful published studies., (Copyright © 2012 American Urological Association Education and Research, Inc. Published by Elsevier Inc. All rights reserved.)

Background and Purpose: The optimal management of renal and ureteral calculi in transplanted kidneys is not well defined. Although larger (>1.5 cm) stone burdens are generally treated with percutaneous nephrolithotomy (PCNL), smaller stones may be reasonably approached with retrograde or antegrade ureteroscopy (URS). We report our multicenter experience with URS for transplant lithiasis., Patients and Methods: URS performed for stone disease within a transplanted kidney were retrospectively identified at three stone-referral centers between 2006 and 2011. Demographic and disease parameters were recorded, as were perioperative and postoperative details., Results: Twelve patients underwent URS for a calculus in a transplant renal unit and/or ureter. For retrograde procedures (7), access to the ureteral orifice was facilitated by the use of a Kumpe catheter; a two-wire (safety and working guidewire) technique was used. For antegrade procedures (5), the ureteroscope was passed into the kidney using a two-wire technique without tract dilation. All stones but one necessitated holmium:yttrium-aluminum-garnet laser lithotripsy with extraction of stone fragments. All patients were stone free on postoperative imaging except for one patient with a 2-mm fragment that was observed. Stone analysis included calcium oxalate (6), calcium phosphate (4), and struvite (1)., Conclusion: Antegrade and retrograde URS are safe and effective treatments for patients with simple stone burdens in a transplanted kidney. Although retrograde access to the ureter can be challenging, specialized techniques and modern endoscope technology facilitate this process. Antegrade URS for small stone burdens can be performed safely and effectively without tract dilation.

Objective: The aim of this in vitro study was to examine the capability of three protocols of dual-energy CT imaging in distinguishing calcium oxalate, calcium phosphate, and uric acid kidney stones., Materials and Methods: A total of 48 calcium oxalate, calcium phosphate, and uric acid human kidney stone samples were placed in individual containers inside a cylindric water phantom and imaged with a dual-energy CT scanner using the following three scanning protocols of different combinations of tube voltage, with and without a tin filter: 80 and 140 kVp without a tin filter, 100 and 140 kVp with a tin filter, and 80 and 140 kVp with a tin filter. The mean attenuation value (in Hounsfield units) of each stone was recorded in both low- and high-energy CT images in each protocol. The dual-energy ratio of the mean attenuation values of each stone was computed for each protocol., Results: For all three protocols, the uric acid stones were significantly different (p < 0.001) from the calciferous stones according to their dual-energy ratio values. For differentiating calcium oxalate and calcium phosphate stones, the difference between their dual-energy ratio values was statistically significant, with different degrees of significance (range, p < 0.001 to p = 0.03) for all three protocols. On the basis of the values of the area under receiver operating characteristic curve (AUC) of calcified stone differentiation, the three protocols were ranked in the following order: the 80- and 140-kVp tin filter protocol (AUC, 0.996), the 100- and 140-kVp tin filter protocol (AUC, 0.918), and the 80- and 140-kVp protocol (AUC, 0.871)., Conclusion: The tin filter added to the high-energy tube and the use of a wider dual-energy difference are important for improving the stone differentiation capability of dual-energy CT imaging.

Purpose: A kidney stone event in a commercial aviation pilot has significant vocational implications since the Federal Aviation Administration specifically prohibits medical certification in the setting of recent or recurrent stone disease. Given these serious concerns, an understanding of the burden of stone disease on the commercial aviation community is important. Thus, we performed a study in partnership with the Federal Aviation Administration to better characterize the epidemiology of this condition., Materials and Methods: We reviewed the Federal Aviation Administration Aerospace Medical Certification database for 2000 through 2007. Pilots with a class I certificate (scheduled commercial aviation) were selected for further review. All medical certificates submitted with a pathology code of 573 (urolithiasis) were identified for analysis., Results: From 2000 through 2007 between 3.7% and 4.6% of scheduled commercial aviation pilots were diagnosed with urolithiasis. However, during the study period there was a significant decrease in the proportion of pilots diagnosed with urolithiasis., Conclusions: A meaningful number of commercial aviation pilots are affected by urolithiasis each year. Our analysis detected a significant decrease in the proportion of affected pilots, although the reason for this trend is not well understood. It may be that changes in the occupational environment that could affect risk factors for stone formation are responsible. Further efforts to characterize stone risk in this unique population are welcome, given the larger vocational and societal consequences of a stone event in the setting of airline transport., (Copyright © 2011 American Urological Association Education and Research, Inc. Published by Elsevier Inc. All rights reserved.)

Objectives: • To compare the Cyberwand (Gyrus/ACMI, Southborough, MA, USA), a dual-probe ultrasonic lithotrite, with a single-probe ultrasonic lithotrite. • The Cyberwand incorporates coaxial high- and low-frequency ultrasonic probes that work synergistically., Patients and Methods: • An institutional review board-approved, multicentre, randomized controlled trial to compare the Cyberwand to the Olympus LUS-II (Olympus America, Inc., Melville, NY, USA) single-probe lithotrite was performed. • Patients undergoing a percutaneous nephrolithotomy (PCNL) with a target stone > 2 cm in diameter were eligible for the study. • The primary outcome was the time to removal of the targeted stone., Results: • A total of 57 PCNLs were performed after randomization: 25 Cyberwand and 32 LUS-II. • There was no difference (P > 0.05) observed between the two devices for target stone surface area (Cyberwand 526.6 cm³ vs LUS-II 540.1 cm³), time to clearance of target stone (Cyberwand 15.8 min vs LUS-II 14.2 min) and target stone clearance rate (Cyberwand 61.9 mm²/min vs LUS-II 75.8 mm²/min). • Of the patients with stone analysis, hard stones (calcium oxalate monohydrate, brushite and cystine) were noted in 14 (56.0%) of the 25 Cyberwand and 18 (62.1%) of the 29 LUS-II patients. • Fifteen of the 25 (60.0%) Cyberwand and 20 of the 32 (62.5%) LUS-II patients were stone-free after the initial PCNL. • Those patients not rendered stone-free went on to receive a secondary PCNL. • Device malfunction occurred in eight of 25(32.0%) Cyberwand and five of 32 (15.6%) LUS II patients. • Complications were similar in both treatment groups., Conclusion: • No appreciable difference between the dual-probe Cyberwand and the standard ultrasonic Olympus LUS-II lithotrites can be identified., (© 2010 THE AUTHORS. BJU INTERNATIONAL © 2010 BJU INTERNATIONAL.)

Objectives: To characterize the relationship between pediatric kidney stone disease and the presence of hypertension (HTN), diabetes mellitus (DM), and obesity. In adults, kidney stone disease has been associated with medical comorbidities such as HTN, DM, and obesity. Similar analyses have never been performed for the pediatric population., Methods: The 2003 and 2006 Kids' Inpatient Databases were queried to identify subjects treated for kidney stone disease ("International Classification of Diseases" codes 9592.0 and 592.1). The comorbidities of HTN, DM, and obesity were identified using the provided comorbidity software. The risk of kidney stone disease associated with age, sex, and comorbidity status was evaluated using multivariate logistic regression., Results: A total of 6,115,443 subjects were evaluated. Of these, 14,245 (0.2%) had a diagnosis of upper tract calculus (4092 boys and 10,045 girls, sex unavailable for 108). Age was the strongest independent predictor of stone risk (P < .0001). HTN was associated with a significantly increased risk of stone diagnosis in children ≤10 years old and DM for children ≤5 years old. Stone risk was not affected by obesity in any age group., Conclusions: The results of our study have shown that kidney stone disease is significantly associated with age among all children and both HTN and DM for young children. Although exploratory, these findings are novel and suggest that kidney stone disease among young children might be associated with nonrenal, systemic disease states., (Copyright © 2011 Elsevier Inc. All rights reserved.)

The epidemiology of pediatric kidney stone has not yet been as rigorously defined as that of adult kidney stone disease. Herein, we review our recent epidemiologic works characterizing pediatric stone disease using the Kids' Inpatient Database (KID). Specifically we investigated the age and gender distribution of pediatric kidney stone disease, changes in disease prevalence over time, and medical comorbidities associated with this disorder. We identified patients by International Classification of Disease 9th Edition (ICD-9) codes for renal and ureteral calculi as the primary diagnosis. Medical comorbidities were identified using specific comorbidity software. Statistical comparisons between children with and without stone disease were performed. In the first decade of life, stone disease was more prevalent among males than females; however, in the second decade of life females were more commonly affected. Of note, there was a significant increase in treated stone disease across both genders between 1997 and 2003. We also found that the risk of kidney stone diagnosis in children younger than 6 years of age was significantly associated with hypertension and diabetes mellitus. The gender distribution among pediatric stone formers varies significantly by age, although overall females have a greater prevalence than males. There is also a strong association of stone disease and both diabetes and hypertension, although this was only observed in children less than 6 years of age. Taken all together, these findings suggest that urolithiasis in the young child is a complex systemic disease process.

Purpose of Review: Nephrolithiasis is a not infrequent complication of pregnancy. The occurrence of a stone event in a pregnant woman is a complex situation. Therefore, a clear understanding of the management options available and their relative advantages and disadvantages for this unique population is important., Recent Findings: When initial, conservative measures have failed in the treatment of a pregnant woman suffering from an acute stone event, management options have historically been of a temporizing nature: generally, either ureteral stent placement or nephrostomy drainage. However, with recent advances in surgical technology and surgeon technique, a more definitive approach to these patients has become more widely adopted. Indeed, several recent case series have reported the complication rate for ureteroscopy during pregnancy to be low. Furthermore, a meta-analysis of case series of ureteroscopy during pregnancy suggests definitive endoscopic treatment is well tolerated in this patient population., Summary: In a pregnant patient without contraindications to ureteroscopy, the definitive endoscopic treatment of an acute stone event is a reasonable management strategy, should conservative measures fail. Although further investigation with randomized control trials is ideally needed to confirm these results, at present, the published case series and meta-analysis confirm the safety of ureteroscopy in pregnant patients in the appropriate setting. A multidisciplinary approach is key to the successful management of this complex patient population.

Purpose: Previous epidemiological works have reported that obesity is a risk factor for kidney stone disease. However, the effect of increasing degrees of obesity on stone formation has yet to be defined. To address this question we examined how an increasing body mass index affects the risk of kidney stone disease., Materials and Methods: We evaluated claims from a 5-year period (2002 to 2006) in a national private insurance database to identify subjects diagnosed with or treated for kidney stones. From a data set of 95,598 patients, subjects were identified by ICD-9 or CPT codes specific to kidney stone disease. Descriptive analyses were performed and odds ratios were calculated., Results: Gender distribution of the 3,257 stone formers was 42.9% male and 57.1% female. Obesity (body mass index greater than 30 kg/m(2)) was associated with a significantly greater likelihood of being diagnosed with a kidney stone. However, when obese patients were stratified by body mass index there were no significant differences in the likelihood of a kidney stone diagnosis, suggesting a stabilization of risk once body mass index increased above 30 kg/m(2). The association of body mass index and a stone removal procedure was significant only for men and women with a body mass index between 30 and 45 kg/m(2) relative to a body mass index less than 25 kg/m(2) (p <0.001)., Conclusions: An obese body mass index is associated with an increased risk of kidney stone disease. However, the magnitude of this risk appears to be stable in the morbidly obese population. Once body mass index is greater than 30 kg/m(2), further increases do not appear to significantly increase the risk of stone disease., (Copyright 2010 American Urological Association. Published by Elsevier Inc. All rights reserved.)

Objectives: To evaluate the likelihood of being diagnosed with, or treated for, an upper urinary tract calculus after gastric banding. Bariatric surgical procedures are being increasingly utilized in the treatment of patients with morbid obesity. Certain malabsorptive bariatric procedures have been associated with an increased risk for kidney stone formation. However, the kidney stone risk of gastric banding, a restrictive bariatric procedure, is unknown., Methods: We identified 201 patients who underwent gastric banding and a control group of 201 obese patients who did not have bariatric surgery in a national private insurance claims database within a 5-year period from 2002-2006. All patients had at least 2 years of continuous claims data follow-up. Our 2 primary outcomes were the diagnosis and the surgical treatment of a urinary calculus., Results: After gastric banding, the diagnosis of an upper urinary tract calculus occurred in 3 subjects (1.49%), as compared with 12 subjects (5.97%) in the comparison cohort (P = .0179). One subject in each cohort (0.50%) underwent a surgical procedure for the treatment of an upper urinary tract (P = 1.0000)., Conclusions: Gastric banding is not associated with an increased risk for kidney stone disease or kidney stone surgery in the postoperative period. Additional long-term studies are required to confirm these findings.

Objectives: To define the sex prevalence of inpatient hospital discharges for pediatric patients diagnosed with upper urinary tract stone disease., Methods: The study examined inpatient admissions for pediatric urolithiasis in 2003, using the Healthcare Cost and Utilization Project Kids' Inpatient Database. We used the International Classification of Disease, 9th edition, Clinical Modification codes, to identify patients with a principal diagnosis of renal (592.0) or ureteral (592.1) calculi. Sex prevalence was assessed, and the results were stratified by age group., Results: In the 2003 Kids' Inpatient Database, the sex distribution among pediatric patients with stone formation varied significantly by age. In the first decade of age, a male predominance was found that had shifted to a female predominance in the second decade. Overall, however, girls in the pediatric population were more commonly affected by stones than were boys., Conclusions: In this nationally representative sample, the sex distribution of pediatric urolithiasis varied with age, with boys more commonly affected in the first decade of age and girls in the second decade. Although the reason for this unique epidemiologic finding is not readily apparent, additional studies can build on this hypothesis-generating work.

Purpose: Recent studies have demonstrated that mineral and electrolyte abnormalities develop in patients who undergo bariatric surgery. While it is known that these abnormalities are a risk factor for urolithiasis, the prevalence of stone disease after bariatric surgery is unknown. We evaluated the likelihood of being diagnosed with or treated for an upper urinary tract calculus following Roux-en-Y gastric bypass surgery., Materials and Methods: We identified 4,639 patients who underwent Roux-en-Y gastric bypass surgery and a control group of 4,639 obese patients who did not have surgery in a national private insurance claims database in a 5-year period (2002 to 2006). All patients had at least 3 years of continuous claims data. Our 2 primary outcomes were the diagnosis and the surgical treatment of a urinary calculus., Results: After Roux-en-Y gastric bypass surgery 7.65% (355 of 4,639) of patients were diagnosed with urolithiasis compared to 4.63% (215 of 4,639) of obese patients in the control group (p <0.0001). Subjects in the treatment cohort more commonly underwent shock wave lithotripsy (81 [1.75%] vs 19 [0.41%], p <0.0001) and ureteroscopy (98 [2.11%] vs 27 [0.58%], p <0.0001). Logistic regression demonstrated that Roux-en-Y gastric bypass surgery was a significant predictor of being diagnosed with a urinary calculus (OR 1.71, CI 1.44-2.04) as well as undergoing a surgical procedure (OR 3.65, CI 2.60-5.14)., Conclusions: Roux-en-Y gastric bypass surgery is associated with an increased risk of kidney stone disease and kidney stone surgery in the postoperative period. Clinicians should be aware of this hazard and inform patients of this potential complication. Future studies are needed to evaluate preventive measures in the high risk population.

Objective: To confirm that more than half of all idiopathic calcium oxalate (CaOx) stones grow on interstitial plaque, as CaOx stones can grow attached to interstitial apatite plaque but whether this is the usual mechanism of stone formation is uncertain., Patients and Methods: In nine idiopathic CaOx stone formers (ICSF) undergoing percutaneous nephrolithotomy or ureteroscopy all accessible renal papillae were endoscopically imaged using a digital endoscope. All stones were removed intact, and recorded by the operating surgeon as being attached or unattached; for all attached stones the surgeon determined if the site of attachment was to plaque. This determination was further verified by reviewing the intraoperative video record, and only instances where plaque was reliably seen on video were used for analysis. Surgical observations were further validated by a combination of microcomputed tomographic analysis and papillary biopsy. The results were analysed statistically using fixed-sample testing and group sequential sampling., Results: The nine patients had a total of 115 stones, primarily CaOx; 90 stones were attached. Of these, 81 were attached to plaque; surgeons could not visualize the site of attachment with sufficient clarity to judge in the other nine cases. Based on these data, the final point estimate for the number of stones attached to plaque was 0.754 (95% confidence interval 0.575-0.933; P = 0.013)., Conclusions: In ICSF most stones grow attached to papillae, on plaque, so growth on plaque is the main mechanism for stone formation in this very common group of patients.

Purpose: We performed a literature review and analysis to compare the safety of ureteroscopic stone removal during pregnancy with findings from a set of contemporary studies of that procedure in nonpregnant patients., Materials and Methods: A systematic review of MEDLINE(R) and EMBASE(R) was done to identify all reports of ureteroscopic stone removal in pregnant women. Complications were stratified according to modified Clavien criteria. We then reviewed a contemporary, multi-national meta-analysis of ureteroscopic stone removal (American Urological Association/European Association of Urology 2007 Guideline for the Management of Ureteral Calculi) to define the complication rate in a series of nonpregnant patients. Complication rates in the 2 reviews were compared using Fisher's exact test., Results: A total of 14 reports of ureteroscopic stone removal in pregnant women were identified, representing 108 patients. Nine complications were noted. By Clavien criteria 2 complications were level 1, 6 were level 2 and 1 was level 3. When compared to the multinational meta-analysis of ureteroscopy in nonpregnant women, there was no significant difference in the ureteral injury and urinary tract infection complication rates (p = 0.191 and 0.597, respectively)., Conclusions: Our analysis shows that the safety of ureteroscopic stone removal in pregnant patients is not significantly different from the safety of that procedure in nonpregnant patients and in each cohort the complication rate is low. Therefore, ureteroscopic stone removal may reasonably be considered appropriate first line therapy in pregnant patients with stone disease.

Introduction: Dual source computed tomography (CT), a novel technology that employs two different x-ray sources, may provide an image resolution that has not been possible with conventional single source CT. We tested the ability of dual source CT imaging to distinguish calcium oxalate (CaOx) stones from calcium phosphate (CaP) stones, and both types of calciferous stones from uric acid (UA) stones., Methods: CaOx, CaP, and UA stones were placed in a tissue phantom and imaged with dual source multidetector CT at both 80kV and 140 kV. Hounsfield units (HU) of each stone were recorded for the 140 kV and the 80 kV datasets by drawing regions of interest by circle, hand-drawing, and using a volume calculation method. The differences between, and the ratios of, the HU obtained by the two energy sources were compared among the stone groups., Results: Between CaOx and CaP stones, HU differences (80kV-140kV difference, hand-drawing technique: CaOx = 270.7; CaP = 369.5; UA = 11.45; P = 0.020 for CaOx vs. CaP; P < 0.001 for CaOx and CaP vs. UA) as well as ratios (140kV:80kV ratio, hand-drawing technique: CaOx = 1.44; CaP = 1.51; UA = 1.04; P = 0.001 for CaOx vs. CaP; P < 0.001 for CaOx and CaP vs. UA) were significantly different. There were no significant differences in stone size among the groups., Conclusions: Dual source CT has the ability to distinguish not only between calciferous stones and uric acid stones, but also among stones composed of different calcium salts. Further studies are warranted to confirm these findings in a clinical setting.