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Background: The objective of this study was to explore the frequency of occurrence of extra-renal manifestations associated with monogenic nephrolithiasis. Methods: A literature review was conducted to identify genes that are monogenic causes of nephrolithiasis. The Online Mendelian Inheritance in Man (OMIM) database was used to identify associated diseases and their properties. Disease phenotypes were ascertained using OMIM clinical synopses and sorted into 24 different phenotype categories as classified in OMIM. Disease phenotypes caused by the same gene were merged into a phenotypic profile of a gene (PPG) such that one PPG encompasses all related disease phenotypes for a specific gene. The total number of PPGs involving each phenotype category was measured, and the median phenotype category was determined. Phenotype categories were classified as overrepresented or underrepresented if the number of PPGs involving them was higher or lower than the median, respectively. Chi-square test was conducted to determine whether the number of PPGs affecting a given category significantly deviated from the median. Results: Fifty-five genes were identified as monogenic causes of nephrolithiasis. A total of six significantly overrepresented and three significantly underrepresented phenotype categories were identified (p < 0.05). Four phenotypic categories (growth, neurological, skeletal, and abdomen/gastrointestinal) are significantly overrepresented after Bonferroni correction for multiple comparisons (p < 0.002). Among all phenotypes, impaired growth is the most common manifestation. Conclusion: Recognizing the extra-renal manifestations associated with monogenic causes of kidney stones is critical for earlier diagnosis and optimal care in patients. [ABSTRACT FROM AUTHOR]

The purpose of this study was to measure and compare renal pelvic pressure (RPP) between prone and supine percutaneous nephrolithotomy (PCNL) in a benchtop model. Six identical silicone kidney models were placed into anatomically correct prone or supine torsos constructed from patient CT scans in the corresponding positions. A 30-Fr renal access sheath was placed in either the upper, middle, or lower pole calyx for both prone and supine positions. Two 9-mm BegoStones were placed in the respective calyx and RPPs were measured at baseline, irrigating with a rigid nephroscope, and irrigating with a flexible nephroscope. Five trials were conducted for each access in both prone and supine positions. The average baseline RPP in the prone position was significantly higher than the supine position (9.1 vs 2.7 mmHg; p < 0.001). Similarly, the average RPP in prone was significantly higher than supine when using both the rigid and flexible nephroscopes. When comparing RPPs for upper, middle, and lower pole access sites, there was no significant difference in pressures in either prone or supine positions (p > 0.05 for all). Overall, when combining all pressures at baseline and with irrigation, with all access sites and types of scopes, the mean RPP was significantly higher in the prone position compared to the supine position (14.0 vs 3.2 mmHg; p < 0.001). RPPs were significantly higher in the prone position compared to the supine position in all conditions tested. These differences in RPPs between prone and supine PCNL could in part explain the different clinical outcomes, including postoperative fever and stone-free rates. [ABSTRACT FROM AUTHOR]

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Purpose: To compare different treatment approaches in patients with failed ureteral access sheath placement during first flexible ureterorenoscopy (f-URS) session. Methods: Patients with kidney stones measuring 1–2 cm, presented to our urology clinic between September 2020 and September 2021, were included in the study for evaluation. The study was designed prospectively (Clinical-Trials number NCT05911945). Patients were randomized into two groups, in case of a failed ureteral access sheath placement during the first f-URS session. In group 1, JJ stent was placed for dilation and second session of f-URS was planned. In group 2, mini percutaneous nephrolithotomy (mPNL) was performed in the same session. Results: Twenty-four patients were included in each group. Pre-operative demographic data and stone characteristics of the patients in each group were comparable. Operation time, fluoroscopy time, and hospital stay were significantly higher in the mini-PNL group. When SF-36 values were compared, physical function, pain, role limitation, and general health value scores were improved in both groups after treatment. The improvement in physical function and pain parameters was statistically significant in the mPNL group. In patients with failed ureteral access sheath placement, placing a JJ stent for dilation and postponing f-URS for 4–6 weeks provides the advantages of low hospitalization time for each admission, shorter fluoroscopy and operation time. Conclusions: Performing mPNL in the same session, results in better improvements in SF-36 parameters such as pain and physical function compared to f-URS. The success and complication rates of the two procedures were comparable. [ABSTRACT FROM AUTHOR]

Purpose: Technological advancements in laser lithotripsy are expanding into numerous fields of urology, like ureteroscopy (URS), percutaneous nephrolithotomy (PCNL), and benign and malignant soft-tissue treatments. Since the amount of research regarding lasers in urology has grown exponentially, we present a systematic review of the most recent and relevant advances encompassing all lasers used in urological endoscopic treatment. Methods: We performed a literature search using PubMed (May 2023) to obtain information about lasers for urological purposes. We included only recent data from published articles between 2021 and 2023 or articles ahead of print. Results: Lasers are widely used in lithotripsy for ureteric, renal, and bladder stones, benign prostate surgery, and bladder and upper tract tumor ablation. While the holmium (Ho:YAG) laser is still predominant, there seems to be more emphasis on pulse modulation and newer lasers such as thulium fiber laser (TFL) and pulsed Tm:YAG laser. Conclusion: The use of lasers and related technological innovations have shown increasing versatility, and over time have proven to be invaluable in the management of stone lithotripsy, treatment of benign and malignant prostate diseases, and urothelial tumors. Laser endoscopic treatment is heavily based on technological nuances, and it is essential to know at least the basics of these technologies. Ultimately the choice of laser used depends on its availability, cost, surgeon experience and expertise. [ABSTRACT FROM AUTHOR]

Nedosiran is an N-acetyl-D-galactosamine (GalNAc)–conjugated RNA interference agent targeting hepatic lactate dehydrogenase (encoded by the LDHA gene), the putative enzyme mediating the final step of oxalate production in all three genetic subtypes of primary hyperoxaluria (PH). This phase I study assessed the safety, pharmacokinetics (PK), and pharmacodynamics (PD) of subcutaneous nedosiran in patients with PH subtype 3 (PH3) and an estimated glomerular filtration rate ≥ 30 mL/min/1.73 m2. Single-dose nedosiran 3 mg/kg or placebo was administered in a randomized (2:1), double-blinded manner. Safety/tolerability, 24-h urinary oxalate (Uox) concentrations, and plasma nedosiran concentrations were assessed. The main PD endpoint was the proportion of participants achieving a > 30% decrease from baseline in 24-h Uox at two consecutive visits. Six participants enrolled in and completed the study (nedosiran, n = 4; placebo, n = 2). Nedosiran was well-tolerated and lacked safety concerns. Although the PD response was not met, 24-h Uox excretion declined 24.5% in the nedosiran group and increased 10.5% in the placebo group at Day 85. Three of four nedosiran recipients had a > 30% reduction in 24-h Uox excretion during at least one visit, and one attained near‐normal (i.e., ≥ 0.46 to < 0.60 mmol/24 h; ≥ 1.0 to < 1.3 × upper limit of the normal reference range) 24-h Uox excretion from Day 29 to Day 85. Nedosiran displayed predictable plasma PK. The acceptable safety and trend toward Uox-lowering after single-dose nedosiran treatment enables further clinical development of nedosiran in patients with PH3 who currently have no viable therapeutic options. A plain language summary is available in the supplementary information. [ABSTRACT FROM AUTHOR]

The effect of obstructive sleep apnea (OSA) on 24-h urine parameters and resultant kidney stone risk is unknown. We sought to compare urinary lithogenic risk factors among patients with kidney stone disease with and without OSA. We performed a retrospective cohort study of adult patients with nephrolithiasis undergoing both polysomnography and 24-h urine analysis. Measures of acid load including gastrointestinal alkali absorption, urinary titratable acid, and net acid excretion were calculated from 24-h urine. We performed univariable comparisons of 24-h urine parameters between those with and without OSA and fit a multivariable linear regression model adjusting for age, sex, and BMI. Overall, there were 127 patients who underwent both polysomnography and a 24-h urine analysis from 2006 to 2018. There were 109 (86%) patients with OSA and 18 (14%) without. Patients with OSA were more commonly male, had greater BMI and had higher rates of hypertension. Patients with OSA had significantly higher levels of 24-h urinary oxalate, uric acid, sodium, potassium, phosphorous, chloride, and sulfate; higher supersaturation of uric acid; higher titratable acid, and net acid excretion; and lower urinary pH and supersaturation of calcium phosphate (p < 0.05). The difference in urinary pH and titratable acid, but not net acid excretion, remained significant when adjusting for BMI, age, and gender (both p = 0.02). OSA is associated with changes in urinary analytes that promote kidney stone formation, similar to those observed with obesity. After accounting for BMI, OSA is independently associated with lower urine pH and increased urinary titratable acid. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate outcomes of flexible ureteroscopy for renal stones by comparing hard versus soft stones based on their attenuation on computed tomography (Hounsfield Units—HU). Methods: Patients were divided into two groups according to the type of laser employed [Holmium:YAG (HL) or Thulium fiber laser (TFL)]. Residual fragments (RF) were defined as > 2 mm. Multivariable logistic regression analysis was performed to evaluate factors associated with RF and RF needing further intervention. Results: 4208 patients from 20 centers were included. In whole series, age, recurrent stones, stone size, lower pole stones (LPS), and multiple stones were predictors of RF at multivariable analysis and LPS and stone size with RF requiring further treatment. HU and TFL were associated with lesser RF and RF requiring an additional treatment. In HU < 1000 stones, recurrent stones, stone size, and LPS were predictors of RF at multivariable analysis, whereas TFL was less likely associated with RF. Recurrent stones, stone size, and multiple stones were predictors of RF requiring further treatment, while LPS and TFL were associated with lesser RF requiring further treatment. In HU ≥ 1000 stones, age, stone size, multiple stones, and LPS were predictors of RF at multivariable analysis, while TFL was less likely associated with RF. Stone size and LPS were predictors of RF requiring further treatment, whereas TFL was associated with RF requiring further treatment. Conclusion: Stone size, LPS, and use of HL are predictors of RF after RIRS for intrarenal stones regardless of stone density. HU should be considered an important parameter in predicting SFR. [ABSTRACT FROM AUTHOR]

Objectives: To assess the accuracy of low-dose dual-energy computed tomography (DECT) to differentiate uric acid from non-uric acid kidney stones in two generations of dual-source DECT with stone composition analysis as the reference standard. Methods: Patients who received a low-dose unenhanced DECT for the detection or follow-up of urolithiasis and stone extraction with stone composition analysis between January 2020 and January 2022 were retrospectively included. Collected stones were characterized using X-ray diffraction. Size, volume, CT attenuation, and stone characterization were assessed using DECT post-processing software. Characterization as uric acid or non-uric acid stones was compared to stone composition analysis as the reference standard. Sensitivity, specificity, and accuracy of stone classification were computed. Dose length product (DLP) and effective dose served as radiation dose estimates. Results: A total of 227 stones in 203 patients were analyzed. Stone composition analysis identified 15 uric acid and 212 non-uric acid stones. Mean size and volume were 4.7 mm × 2.8 mm and 114 mm3, respectively. CT attenuation of uric acid stones was significantly lower as compared to non-uric acid stones (p < 0.001). Two hundred twenty-five of 227 kidney stones were correctly classified by DECT. Pooled sensitivity, specificity, and accuracy were 1.0 (95%CI: 0.97, 1.00), 0.93 (95%CI: 0.68, 1.00), and 0.99 (95%CI: 0.97, 1.00), respectively. Eighty-two of 84 stones with a diameter of ≤ 3 mm were correctly classified. Mean DLP was 162 ± 57 mGy*cm and effective dose was 2.43 ± 0.86 mSv. Conclusions: Low-dose dual-source DECT demonstrated high accuracy to discriminate uric acid from non-uric acid stones even at small stone sizes. Key Points: • Two hundred twenty-five of 227 stones were correctly classified as uric acid vs. non-uric acid stones by low-dose dual-energy CT with stone composition analysis as the reference standard. • Pooled sensitivity, specificity, and accuracy for stone characterization were 1.0, 0.93, and 0.99, respectively. • Low-dose dual-energy CT for stone characterization was feasible in the majority of small stones < 3 mm. [ABSTRACT FROM AUTHOR]

A well-accepted strategy to prevent kidney stones is to increase urine volume by increasing oral intake of fluids, especially water, to lower supersaturation of the relevant, relatively insoluble salts, and thereby lower the risk of precipitation. Randomized controlled trials have shown that this strategy works. It is inexpensive, safe, and intuitively attractive to patients. However, although any beverage can increase urine volume, and citrus juices can increase urine citrate content and pH, no beverage other than water has been clearly shown by randomized controlled trial to prevent kidney stones. We designed an innovative, palatable, low-calorie, high alkali citrate beverage to prevent kidney stones, called Moonstone. One packet of Moonstone powder, mixed in 500 ml of water, contains 24.5 meq of alkali citrate. We administered one packet twice a day to ten calcium stone formers. Moonstone resulted in an increase in mean 24-h urine citrate and urine pH, and a decrease in supersaturation of calcium oxalate in calcium stone formers compared to an equal volume of water. These changes, comparable to those seen in a prior study of a similar amount of (potassium–magnesium) citrate, will likely be associated with a clinically meaningful reduction in kidney stone burden in patients with calcium stones. The effect to increase urine pH would also be expected to benefit patients with uric acid and cystine stones, groups that we hope to study in a subsequent study. The study preparation was well tolerated and was selected as a preferred preventative strategy by about half the participants. Moonstone is an alternative, over-the-counter therapy for kidney stone prevention. [ABSTRACT FROM AUTHOR]

Introduction: Renal colic is one of the most common urological emergencies, and is usually caused by ureteral colic spasms. Pain management in renal colic remains the central focus of emergency treatment. The purpose of this meta-analysis is to identify the efficacy and safety of ketamine versus opioids in the treatment of patients with renal colic. Methods: We searched PubMed, EMBASE, Cochrane Library, and Web of Science databases for published randomized controlled trials (RCTs) that referred to the use of ketamine and opioids for patients with renal colic. The methodology was based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The mean difference (MD) or odds ratio (OR) with a 95% confidence interval (CI) was used to analyze the data. The results were pooled using a fixed-effects model or random-effects model. The primary outcome measure was patient-reported pain scores 5, 15, 30, and 60 min after drug administration. The secondary outcome measure was side effects. Results: The data analysis revealed that ketamine was similar to opioids in pain intensity at the time of 5 min post-dose (MD = − 0.40, 95% CI − 1.82 to 1.01, P = 0.57), 15 min post-dose (MD = − 0.15, 95% CI − 0.82 to 0.52, P = 0.67), 30 min post-dose (MD = 0.38, 95% CI − 0.25 to 1.01, P = 0.24). Also, the pain score of ketamine was better than that of opioids at 60 min after administration (MD = − 0.12, 95% CI − 0.22 to − 0.02, P = 0.02). As for safety, the ketamine group was linked to a significant decrease in the incidence of hypotensive (OR = 0.08, 95% CI 0.01–0.65, P = 0.02). The two groups did not statistically differ in the incidence of nausea, vomiting, and dizziness. Conclusions: Compared with opioids, ketamine showed a longer duration of analgesia in renal colic, with satisfactory safety. Trial Registration: The PROSPERO registration number is CRD42022355246. [ABSTRACT FROM AUTHOR]

Purpose of Review: Robotic surgery in urology has already been widely employed in robotic-assisted laparoscopic surgery for minimally invasive procedures (MIS). We wanted to analyse rapidly developing robotic ureteroscopy (RoboURS) for the treatment of renal stone disease. Recent Findings: A comprehensive literature review was performed for technical aspects and clinical outcomes of RoboURS. RoboURS has made significant breakthroughs with each model proving that this technology improves ergonomics and supports surgeon and instrument longevity while minimising musculoskeletal issues in retrograde intra-renal surgery (RIRS). Further randomised controlled trials are required to compare the efficacy of RoboURS vs manual flexible ureteroscopy (FURS). The cost-effectiveness will also need to be assessed prior to widespread acceptance into urological infrastructure and mainstream practice. Summary: RoboURS continues to evolve despite the limitations of infrastructure and cost-effectiveness. It holds the promise of a better future for surgeon longevity, reduced peri-operative morbidity and better workplace environment. [ABSTRACT FROM AUTHOR]

Purpose of Review: The prevalence of uric acid (UA) urolithiasis contributes significantly to global disease burden, due to high rates of recurrence and diagnostic challenges. Dissolution therapy plays a valuable role in the conservative management of UA calculi, reducing the requirement for surgical intervention. This review summarises the existing evidence for the efficacy of medical dissolution of uric acid urolithiasis. Recent Findings: A systematic search was conducted of worldwide literature according to PRISMA methodology and Cochrane standards for systematic review. Studies were included if they reported outcome data for the administration of medical therapy for the dissolution of UA calculi. A total of 1075 patients were included in the systematic review. Complete or partial dissolution of UA calculi was observed in 80.5% of patients (865/1075 patients), with 61.7% (647/1048 patients) achieving complete dissolution and 19.8% (207/1048 patients) achieving partial dissolution. A discontinuation rate of 10.2% (110/1075 patients) was noted, and 15.7% (169/1075 patients) required surgical intervention. Summary: Dissolution therapy is a safe and effective method of conservatively managing uric acid stones in the short term. Despite the significant disease burden of UA calculi, current guidelines are limited by deficiencies in the existing body of research. Further research should be undertaken to develop evidence-based clinical guidelines for diagnosis, treatment, and prevention of UA urolithiasis. [ABSTRACT FROM AUTHOR]

Purpose of Review: Urinary pH is an important factor related to renal stone disease, and it plays an essential role in stone prevention. Monitoring of urinary pH by patients at home provides information that can help to assess the treatment needed by each patient. We conducted a systematic review is to assess the available evidence concerning urinary pH monitoring methods along with their accuracy, cost, and usefulness by patients with urolithiasis. Recent Findings: A total of 9 articles were included (1886 urinary pH measurements). They reported information about urinary dipsticks, portable electronic pH meters and electronic strip readers, amongst other methods. Accuracy was compared with a laboratory pH meter (gold standard). Urinary dipsticks were found to be not accurate enough to guide clinical decision making and portable electronic pH meters showed promising results. Summary: Urinary dipsticks are neither precise nor accurate enough. Portable electronic pH meters seem to be more accurate, easy to use, and cost-effective. They are a reliable source for patients to use at home in order to prevent future episodes of nephrolithiasis. [ABSTRACT FROM AUTHOR]

Purpose of Review: We wanted to analyse the outcomes of surgical (SWL, URS, PCNL) and medical management of cystine stones in the paediatric population in terms of stone-free status and complication rates, based on all the available literature evidence. Recent Findings: A systematic review of literature was performed for all studies with paediatric cystine stone management. Twelve studies met the eligibility criteria, of which 4 analysed outcomes of SWL, 2 of URS and 3 of PCNL and 3 focused on the effect of either alkalising agents (potassium citrate, citric acid) or cysteine-binding thiol (CBT) agents (tiopronin, penicillamine). The reported SFR in studies ranged from 50 to 83%, 59 to 100% and 63 to 80.6%, with a complication rate of 2.8–51%, 14–27% and 12.9–15.4% with SWL, URS and PCNL, respectively. Summary: Paediatric cystine stones treatment should aim at complete stone clearance, preservation of renal function and prevention of further recurrences. SWL achieves inferior results in case of cystine stones. URS and PCNL are safe and effective procedures in the paediatric population, with a low rate of major complications. Adherence to medical prevention therapies may prolong recurrence-free periods. [ABSTRACT FROM AUTHOR]

Introduction: To decrease complication rate, we developed a novel MG needle for kidney puncture consisting of a pointed cannula, an atraumatic mandrin-bulb and a spring mechanism pushing the mandrin-bulb forward. Aim of the study: To assess efficacy and safety of kidney puncture during percutaneous nephrolithotomy (PCNL) using a novel less-traumatic MG needle within a clinical trial. Materials and methods: We conducted a prospective randomized single-center study. In the experimental group, kidney puncture was performed with a novel MG needle while in the control group, standard Trocar or Chiba puncture needles were used. Primary endpoint: hemoglobin drop. Results: A total of 67 patients were enrolled. Patients who underwent standard puncture (n = 33) had higher hemoglobin drop in the early postoperative period (p = 0.024). Although there was no statistical difference in overall complication rate between the two groups (p = 0.351), two severe Clavien-Dindo IIIa complications with urinoma occurred in patients from the control group. Conclusion: Less-traumatic needle for kidney puncture may reduce hemoglobin drop and prevent the development of severe complications. At the same time, in terms of stone-free rate (SFR), the efficacy of PCNL remains the same regardless of the needle used for renal access. [ABSTRACT FROM AUTHOR]

Introduction: Ureteroscopy and stone lasertripsy (URSL) is a recognized technique for treatment of urinary tract stones. Holmium:Yag laser has been successfully used for this purpose for the last two decades. More lately, pulse modulation with Moses technology and high power lasers have been introduced with the result of faster and more efficient stone lasertripsy. Pop dusting is a two-stage combined treatment using a long pulse Ho:YAG laser, initially in contact mode with the stone 'dusting' (0.2–0.5 J/40–50 Hz) followed by non-contact mode 'pop-dusting' (0.5–0.7 J/20–50 Hz). We wanted to look at the outcomes of lasertripsy for renal and ureteric stones using a high-power laser machine. Methods: Over a period of 6.5 years (January 2016–May 2022), we prospectively collected data for patients undergoing URSL for stones larger than 15 mm treated using high power Ho:YAG laser (60W Moses or 100W laser). Patient parameters, stone demographics and outcomes of URSL were analyzed. Results: A total of 201 patients, underwent URSL for large urinary stones. In 136 patients (61.6%) stones were multiple and the mean single and cumulative stone size was 18 mm and 22.4 mm respectively. A pre- and post-operative stent was placed in 92 (41.4%) and 169 (76%) respectively. The initial and final stone free rate (SFR) were 84.5% and 94% respectively and 10% patients underwent additional procedure to achieve stone free status. 7 (3.9%) complications were recorded, all related to UTI/sepsis, with 6 Clavien II and 1 Clavien IVa complication. Conclusion: Dusting and pop-dusting has shown to be successful and safe with the ability to treat large, bilateral or multiple stones with low retreatment and complication rates. [ABSTRACT FROM AUTHOR]

Purpose of Review: While urologists are traditionally taught to perform percutaneous nephrolithotomy (PCNL) utilizing exclusively fluoroscopy, ultrasound has emerged as a safe alternative. This article showcases the major reasons why ultrasound-guided access should be considered the first-line approach for performing access for PCNL. Recent Findings: There continues to be a need to further reduce radiation exposure in the management of kidney stone patients. This review showcases how performing ultrasound-guided PCNL has been associated with a shorter learning curve, increased patient safety, and the ability to perform x-ray free PCNL. Summary: Ultrasound-guided PCNL is not only an achievable skill for urologists to learn but provides multiple advantages over traditional fluoroscopic access. As every effort should be given to help reduce radiation exposure for kidney stone patients as well as performing surgeons and operating theater personnel, endourologists should strive to add this technique to their armamentarium. [ABSTRACT FROM AUTHOR]

Purpose of Review: Kidney puncture is a key step in percutaneous nephrolithotomy (PCNL). Ultrasound/fluoroscopic-guided access to the collecting systems is commonly used in PCNL. Performing a puncture is often challenging in kidneys with congenital malformations or complex staghorn stones. We aim to perform a systematic review to examine data on in vivo applications, outcomes, and limitations of using artificial intelligence and robotics for access in PCNL. Recent Findings: The literature search was performed on November 2, 2022, using Embase, PubMed, and Google Scholar. Twelve studies were included. 3D in PCNL is useful for image reconstruction but also in 3D printing with definite benefits seen in improving anatomical spatial understanding for preoperative and intraoperative planning. 3D model printing and virtual and mixed reality allow for an enhanced training experience and easier access which seems to translate into a shorter learning curve and better stone-free rate compared to standard puncture. Robotic access improves the accuracy of the puncture for ultrasound- and fluoroscopic-guided access in both supine and prone positions. The potential advantage robotics are using artificial intelligence to do remote access, reduced number of needle punctures, and less radiation exposure during renal access. Summary: Artificial intelligence, virtual and mixed reality, and robotics may play a key role in improving PCNL surgery by enhancing all aspects of a successful intervention from entry to exit. There is a gradual adoption of this newer technology into clinical practice but is yet limited to centers with access and the ability to afford this. [ABSTRACT FROM AUTHOR]

Purpose of Review: Ureteroscopy is a well-established treatment modality for kidney and ureteric calculi in addition to playing a key role in upper tract cancer diagnostics. Traditional reusable flexible ureteroscopes are technologically advanced and expensive pieces of equipment that require repeat sterilisation and periodical repair. These issues have led to the development of single-use flexible ureteroscopes that are disposed of after each case. Whilst this may be advantageous in many respects, the environmental impact of such technology is yet to be fully determined. The aim of this review is to therefore identify and summarise the available literature concerning the environmental footprint of single-use ureteroscopy. Recent Findings: To identify the latest research on this topic, a systematic search of world literature was conducted using the Medline, Embase, and PsycINFO databases. PRISMA guidelines were followed and articles were assessed by all authors and relevant study results were included in a narrative format. Only one relevant article was identified and included. This study found that a single-use flexible ureteroscope (LithoVueTM by Boston Scientific) generated an equivalent amount of carbon dioxide per case to a contemporary reusable flexible ureteroscope. Summary: Literature concerning the environmental footprint of single-use ureteroscopy is worryingly lacking. No conclusions can be definitively drawn from a single study and further research is imperative given the global climate crisis and the significant contribution that healthcare services have to the environmental problem. [ABSTRACT FROM AUTHOR]

Objectives: To systematically investigate the usability of virtual non-contrast reconstructions (VNC) derived from dual-layer CT (DLCT) for detection and size measurements of kidney stones with regards to different degrees of surrounding iodine-induced attenuation and radiation dose. Methods: Ninety-two kidney stones of varying size (3–14 mm) and composition were placed in a phantom filled with different contrast media/water mixtures exhibiting specific iodine-induced attenuation (0–1500 HU). DLCT-scans were acquired using CTDIvol of 2 mGy and 10 mGy. Conventional images (CI) and VNC0H-1500HU were reconstructed. Reference stone size was determined using a digital caliper (Man-M). Visibility and stone size were assessed. Statistical analysis was performed using the McNemar test, Wilcoxon test, and the coefficient of determination. Results: All stones were visible on CI0HU and VNC200HU. Starting at VNC400 HU, the detection rate decreased with increasing HU and was significantly lower as compared to CI0HU on VNC≥ 600HU (100.0 vs. 94.0%, p < 0.05). The overall detection rate was higher using 10 mGy as compared to 2 mGy protocol (87.9 vs. 81.8%; p < 0.001). Stone size was significantly overestimated on all VNC compared to Man-M (7.0 ± 3.5 vs. 6.6 ± 2.8 mm, p < 0.001). Again, the 10 mGy protocol tended to show a better correlation with Man-M as compared to 2 mGy protocol (R2 = 0.39–0.68 vs. R2 = 0.31–0.57). Conclusions: Detection and size measurements of kidney stones surrounded by contrast media on VNC are feasible. The detection rate of kidney stones decreases with increasing iodine-induced attenuation and with decreasing radiation dose as well as stone size, while remaining comparable to CI0HU on VNC ≤ 400 HU. Key Points: • The detection rate of kidney stones on VNC depends on the surrounding iodine-induced attenuation, the used radiation dose, and the stone size. • The detection rate of kidney stones on VNC decreases with greater iodine-induced attenuation and with lower radiation dose, particularly in small stones. • The visibility of kidney stones on VNC≤ 400 HUremains comparable to true-non-contrast scans even when using a low-dose technique. [ABSTRACT FROM AUTHOR]

Purpose of Review: Extracorporeal shock wave lithotripsy success rates depend on several stone and patient-related factors, one of which is stone density which is calculated on computed tomography scan in Hounsfield Units. Studies have shown inverse correlation between SWL success and HU; however, there remains considerable variation between studies. We performed a systematic review regarding the use of HU in SWL for renal calculi to consolidate the current evidence and address current knowledge gaps. Recent Findings: Database including MEDLINE, EMBASE, and Scopus were searched from inception through August 2022. Studies in English language analysing stone density/attenuation in adult patients undergoing SWL for renal calculi were included for assessment of Shockwave lithotripsy outcomes, use of stone attenuation to predict success, use of mean and peak stone density and Hounsfield unit density, determination of optimum cut-off values, nomograms/scoring systems, and assessment of stone heterogeneity. 28 studies with a total of 4,206 patients were included in this systematic review with sample size ranging from 30 to 385 patients. Male to female ratio was 1.8, with an average age of 46.3 years. Mean overall ESWL success was 66.5%. Stone size ranged from 4 to 30 mm in diameter. Mean stone density was used by two-third of the studies to predict the appropriate cut-off for SWL success, ranging from 750 to 1000 HU. Additional factors such as peak HU and stone heterogeneity index were also evaluated with variable results. Stone heterogeneity index was considered a better indicator for success in larger stones (cut-off value of 213) and predicting SWL stone clearance in one session. Prediction scores had been attempted, with researchers looking into combining stone density with other factors such as skin to stone distance, stone volume, and differing heterogeneity indices with variable results. Summary: Numerous studies demonstrate a link between shockwave lithotripsy outcomes and stone density. Hounsfield unit < 750 has been found to be associated with shockwave lithotripsy success, with likelihood of failure strongly associated with values over 1000. Prospective standardisation of Hounsfield unit measurement and predictive algorithm for shockwave lithotripsy outcome should be considered to strengthen future evidence and help clinicians in the decision making. Trial Registration: International Prospective Register of Systematic Reviews (PROSPERO) database: CRD42020224647 [ABSTRACT FROM AUTHOR]

Purpose: To collect a multicentric database on behalf of TOWER research group to assess practice patterns and outcomes of retrograde intrarenal surgery (RIRS) for kidney stones. Methods: Inclusion criteria: age ≥ 18 years, normal renal/calyceal system anatomy, calculi of any size, number, and position. Study period: January 2018 and August 2021. Stone-free status: absence of fragments > 2 mm, assessed post procedure according to the local protocol (KUB X-Ray and/or ultrasound or non-contrast CT scan). Results: Twenty centers from fifteen countries enrolled 6669 patients. There were 4407 (66.2%) men. Mean age was 49.3 ± 15.59 years. Pain was the most frequent symptom indication for intervention (62.6%). 679 (10.2%) patients underwent RIRS for an incidental finding of stones. 2732 (41.0%) patients had multiple stones. Mean stone size was 10.04 ± 6.84 mm. A reusable flexible ureteroscope was used in 4803 (72.0%) procedures. A sheath-less RIRS was performed in 454 (6.8%) cases. Holmium:YAG laser was used in 4878 (73.1%) cases. A combination of dusting and fragmentation was the most common lithotripsy mode performed (64.3%). Mean operation time was 62.40 ± 17.76 min. 119 (1.8%) patients had an intraoperative injury of the ureter due to UAS insertion. Mean postoperative stay was 3.62 ± 3.47 days. At least one postoperative complication occurred in 535 (8.0%) patients. Sepsis requiring intensive care admission occurred in 84 (1.3%) patients. Residual fragments were detected in 1445 (21.7%) patients. Among the latter, 744 (51.5%) patients required a further intervention. Conclusion: Our database contributes real-world data to support to a better understanding of modern RIRS practice and outcomes. [ABSTRACT FROM AUTHOR]

Despite its critical nature, the role of matrix in calcium oxalate stone formation is poorly understood. The wide diversity of proteins comprising matrix has contributed to the ambiguity. This study compares the protein distributions measured by mass spectrometry in human calcium oxalate stone matrix to that observed in cat stone matrix, because cats share many clinical characteristics of their stone disease with humans. The observed protein distributions were analyzed in the context of a recent model based on the aggregation of strongly anionic and strongly cationic proteins which includes selective adsorption of other proteins based on total charge. Matrix protein distributions shared many common features between species, including enrichment of both strongly anionic and strongly cationic proteins, increased total charge in matrix proteins compared to urine proteins, and a high degree of similarity of prominent strongly anionic proteins in the matrix of both species. However, there was weaker overlap of the specific dominant proteins in other regions of the net charge distribution. Collectively, these observations support the conceptual model where the strongly anionic proteins associate most strongly with the calcium oxalate crystal surfaces, while the other proteins associate with the strongly anionic proteins through non-specific, charge interactions with each other to create stones. Also, cats appear to be the best animal model of human stone disease identified to date based on these similarities. [ABSTRACT FROM AUTHOR]

Purpose of Review: The association of kidney stone disease (KSD) and gastrointestinal (GI) surgery has been well established. With a rising obesity crisis, we wanted to see the correlation of urinary composition in patients undergoing bariatric surgery and their risk of KSD. The objective of this paper is to perform a systematic review and meta-analysis of literature to evaluate the changes in urinary composition and risk of KSD following bariatric surgery. Recent Findings: A total of seven studies (2498 patients) underwent bariatric surgery with a mean age of 46.7 years and a male:female ratio of 1:3. The most popular bariatric surgery was the Roux-en-Y procedure. Meta-analysis of the studies showed that significant decrease in urinary calcium, citrate, and urate, and increase in urinary oxalate. There was also a nonsignificant volume reduction in the post-operative cohort. The decrease in urinary citrate and increase in urinary oxalate are both predisposing factors of stone formation. Summary: There is strong evidence that bariatric surgery results in significant changes in urine composition in keeping with the increased risk of developing KSD. This identifies useful therapeutic targets in the prophylactic management of patients who have undergone bariatric surgery. [ABSTRACT FROM AUTHOR]

Purpose: This study evaluated possible predictors of long-term opioid usage among patients with ureteric stones who received ureteroscopy (URS) or shockwave lithotripsy (SWL). We also assessed opioid usage characteristics of URS and SWL recipients. Materials and methods: This retrospective study used IQVIA PharMetrics® Plus for Academics administrative claims database from years 2006–2020 to identify patients with a diagnosis of kidney or ureteral stones who were treated with either SWL or URS. We performed unadjusted bivariate analyses to compare opioid use characteristics of URS and SWL recipients, and performed logistic regression to determine demographic and clinical factors associated with becoming a long-term opioid user. Results: The study population consisted of opioid naive individuals having a diagnosis of a kidney stone who underwent URS (N = 9407) or SWL (N = 4894). About 6.7% (N = 964) of study subjects were long-term opioid users. Unadjusted bivariate associations showed that compared to non-long-term opioid users, long-term opioid users had significantly greater total days' supply, total morphine milliequivalents (MME) supplied, and claims per month. A similar trend was observed for URS (vs. SWL) recipients. However, compared to SWL recipients, URS recipients had 14.3% (1.2–25.6%; p = 0.034) lower odds of becoming long-term users. Total days' supply (OR: 1.041 (95% CI 1.030–1.052; p < 0.001) and total MME supplied (OR 1.001 (95% CI 1.000–1.001; p < 0.001) were significantly associated with long-term usage. Conclusion: Higher total days' supply and total MME supplied as well as SWL were identified as risk factors for becoming long-term opioid users. [ABSTRACT FROM AUTHOR]

Purpose of the Review: The global burden of kidney stone disease (KSD) and its management relies on ionising radiation. This includes the diagnosis, treatment and follow-up of KSD patients. The concept 'As Low As Reasonably Achievable' (ALARA) developed in response to the radiation risks and the key principles include optimisation, justification and limitation of radiation. This article provides an overview of the topic including background to the risks and steps that can be taken during all stages of endourological management. Recent Findings: Our review suggests that ionising radiation is an invaluable tool in delineating the anatomy, localising disease, guiding manoeuvres and monitoring treatment in patients with KSD. It therefore plays an integral role in many stages of patient care; preoperatively, intraoperatively and postoperatively. The reduction of radiation pre- and post-surgical intervention relies on the use of low-radiation CT scan and ultrasound scan. It can also be achieved through various intraoperative techniques or fluoroless techniques in selected patients/procedures, customised to the patients and procedural complexity. Summary: There are many parts of the patient journey where exposure to radiation can take place. Urologists must be diligent to minimise and mitigate this wherever possible as they too face exposure risks. Implementation of strategies such as teaching programmes, fluoroscopy checklists and judicious use of CT imaging among other things is a step towards improving practice in this area. [ABSTRACT FROM AUTHOR]

Introduction: Since the construction of the first laser, many companies around the world have contributed to the development of new lasers technologies. To be user-friendly, some companies have developed a pre-setting mode in their laser devices. We aimed to review and compare all laser companies' pre-settings (PS) already established in the market. Materials and methods: An online search of holmium:YAG (Ho:YAG) and thulium fiber laser (TFL) devices was carried out. Manual and PS mode, pulse width and pulse modulation technology data were collected. The PS parameters were collected directly from the brochure devices or by asking the companies consulting agents. Results: Thirty-nine laser devices were analyzed (33 Ho:YAG and 6 TFL). The power range varies from 15 to 152 W and 35 W to 60 W for Ho:YAG and TFL, respectively. PS are present in 66% of Ho:YAG lasers and the 33% of TFL. Long-pulse modes can be modified in 12 Ho:YAG and 1 TFL lasers. The median (IQR) PS for dusting stones with Ho:YAG laser is 0.4 J (0.2–1), 21.5 Hz (5–120), and 10 W (1.5–28) for energy, frequency and power, respectively; for Ho:YAG fragmentation is 0.8 J (0.3–5), 10 (3–15) Hz and 5 (1.5–50) W for energy, frequency, and power, respectively; and for popcorn is 0.8 J (0.4–1.2), 10 Hz (6–15) and 5 W (4–18) for energy, frequency, and power, respectively. Dusting and fragmentation mode of Rocamed MH01 and EMS LaserClast 35 are programmed according to the stone type. Most of these settings do not depend on the size of the fiber being used nor the location and type of stone. For TFL, the pre-sets are divided in bladder stone, dusting, fine dusting, fragmentation, and ureteral stone. Conclusion: There is a huge variability regarding pre-sets offered by companies because there is no consensus. Pre-sets should provide a range to work efficacy and safety. [ABSTRACT FROM AUTHOR]

Purpose of Review: Kidney stone disease (KSD) and recurrent urinary tract infections (rUTI) are frequently concomitant conditions. We conducted a systematic review to determine the association of UTI in patients with KSD and to assess the outcomes of kidney stone treatment in the resolution of rUTI. Recent Findings: Our systematic review included 17 papers and a strong association between KSD and rUTI was demonstrated by numerous studies. Surgical clearance of kidney stones usually resulted in the resolution of UTI, but discordant data persist regarding recurrence rates after surgery. In vitro studies might unveil the causative role of bacteria in the formation of "metabolic" stones. Summary: Our SR clearly shows that UTI and KSD are mutually coexisting, and reciprocally causal and such patients should be counselled for proactive intervention by stone removal especially when UTIs are recurrent or additional risk factors are present irrespective of stone composition. To prevent further UTI episodes, if possible, a stone culture must be obtained for an effectively targeted antibiotic treatment regime tailored to bacterial prevalence. [ABSTRACT FROM AUTHOR]

Purpose: Studies on howmetabolic syndrome affects renal stone progression in untreated asymptomatic patients are lacking. Therefore, we investigated the effect of metabolic syndrome on changes in renal stone size. Materials and methods: We retrospectively analyzed 820 patients with renal stones incidentally detected on CT during regular health examinations and who underwent follow-up CT evaluations for > 1 year. The patients were divided into two groups according to the presence of metabolic syndrome. Changes in stone size during the follow-up were assessed, and differences were compared according to various factors. Predictors of stone size change on CT were assessed using linear regression analysis. Results: Overall, 820 asymptomatic patients without a history of stone treatments and with a mean follow-up of 52.4 months were included. Of these, 104 (12.7%) had metabolic syndrome and 335 (40.9%) showed stone size increase during the follow-up. The stone size at diagnosis was not significantly different between patients with and without metabolic syndrome (225.3 ± 332.6 vs. 183.9 ± 310.2 mm3, p = 0.159); however, a significant difference was observed in the change in stone size at follow-up (148.5 ± 352.0 vs. 81.5 ± 222.4 mm3, p = 0.001). Multivariable analysis showed that age (β = − 0.11; − 5.92 to −0.69; p = 0.013), fasting glucose level ≥ 100 mg/dl (β = 0.11; 9.78–99.73; p = 0.017), and metabolic syndrome (β = 0.10; 9.78–99.73; p = 0.017) were factors predictive of stone size changes. Conclusion: Metabolic syndrome, fasting glucose level ≥ 100 mg/dl and young age are positively related to renal stone size changes. Therefore, periodic follow-up and metabolic syndrome management are required in asymptomatic patients with renal stones, especially in young age. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the outcomes of pre-stented (PS) versus non-pre-stented (NPS) patients who have undergone retrograde intrarenal surgery (RIRS) for renal calculi with subgroup analysis of Asian and non-Asian cohorts. Methods: Protocol is registered in PROSPERO, CRD42021261123. Eligible studies identified from four electronic databases. Meta-analysis was done to enumerate the outcomes of RIRS in between PS and NPS. Secondary sub-analysis was done to look for differences in outcomes in Asian and non-Asian cohorts. Results: Fourteen studies involving 3831 patients (4 prospective, 10 retrospective studies) were included. PS patients experienced higher success rates of ureteral access sheath (UAS) insertion than NPS (RR 1.09, 95% CI 1.05–1.13, p < 0.00001). PS patients had lower risk of ureteral injuries from UAS placement (RR 0.69, 95% CI 0.50–0.96, p = 0.03). No significant differences in intra- and postoperative complications between two groups were found. Stone-free rate (SFR) outcomes for residual fragment (RF) cut-off of < 1 mm and < 4 mm favoured the PS patients (RR 1.10, 95% CI 1.04–1.17, p = 0.002 for < 4 mm, RR1.10, 95% CI 1.02–1.19, p = 0.02 for < 1 mm). In the subgroup analysis, PS Asian patients had similar SFR as NPS patients for SFR(< 4 mm) but non-Asian population showed better outcomes in the PS patients for SFR(< 4 mm) (RR 1.31, 95% CI 1.13–1.52, p = 0.0005). Conclusions: This meta-analysis suggests that pre-stenting results in a higher success for UAS placement, minimising intraoperative ureteric injury, with higher overall SFR for any RF cut-off in PS cohorts. In non-Asian cohort, significant differences occurred at SFR < 4 mm but not for SFR < 1 mm. No difference was seen in our Asian cohort for any SFR cut-off in both PS and NPS patients. [ABSTRACT FROM AUTHOR]

Purpose: Shock wave lithotripsy (SWL) is the first option in the treatment of pediatric kidney stones; however, optimal frequency is still uncertain. The aim of this study was to compare low frequency [60 shocks per minute (SWs/min)] and intermediate frequency [90 SWs/min] in terms of lithotripsy success, complications, cardiac arrhythmia, anesthesia time, secondary procedures, and efficiency quotient (EQ) in children. Methods: Seventy-eight consecutive children who received SWL for radiopaque renal stones between July 2016 and January 2020 were randomly divided into two groups: Group 60 (SWL frequency: 60 SWs/min) and Group 90 (SWL frequency: 90 SWs/min). After exclusion (remaining 71 children), Group 60 (n = 38) and Group 90 (n = 33) were compared using univariate analysis. Results: The median age of children (37 girls, 34 boys) was 5 (1–16) years. Patient demographics and stone features were similar between the groups. Success rate after the last SWL session was 81.6% (n = 31) for Group 60 and 87.9% (n = 29) for Group 90 (p = 0.527). Stone-free rate after the first, second, and third sessions was 42.1%, 18.4%, and 21.1% for Group 60 and 48.5%, 27.3%, and 12.1% for Group 90, respectively. Additional treatment rate was similar between the groups. In Group 60, the EQ was 57.83, and it was 64.07 in Group 90. Median total anesthesia time was significantly longer in Group 60 (74.5 min) than in Group 90 (32 min; p < 0.001). Conclusion: Intermediate frequency and low-frequency pediatric SWL have similar success rates; however, intermediate-frequency SWL has a shorter anesthesia time. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the associations of DECT parameters with extracorporeal shock wave lithotripsy (ESWL) outcomes in pediatric patients. Methods: A retrospective study of consecutive patients with calculi who underwent ESWL and DECT in our hospital was performed in 2011–2019. The primary outcome was DECT imaging's correlation with ESWL outcomes. The secondary outcome was to determine DECT parameters independently predicting ESWL outcomes, including stone-free (SF) and residual stone (RS) statuses. Results: The study included 207 patients. The mean CT attenuations at 140 kVp, 80 kVp, and 120 kVp and effective atomic number (Zeff) were significantly correlated with stone free (SF) and residual stone (RS) (P < 0.05). Areas under the curves (AUCs) of CT attenuations at 120 kVp, 80 kVp, 140 kVp, and dual-energy index (DEI) were 0.784 (95% CI 0.672–0.897), 0.780 (95% CI 0.677–0.884), 0.766 (95% CI 0.658–0.885), and 0.709 (95% CI 0.578–0.840) (all P < 0.05). With cutoffs of 882.5, 1330.5, 1042.5, and 0.103 for CT attenuations at 140 kVp, 80 kVp, 120 kVp, and DEI, respectively, sensitivities and specificities were 75.0% and 31.1%, 83.3% and 31.8%, 80.3% and 31.1%, and 58.3% and 44.7%, respectively. Conclusion: Our results demonstrated that the parameters of DECT could be used to predict ESWL outcomes (especially the SF status) in children with urolithiasis. ESWL success can be accurately predicted by DECT, and it is hard to predict ESWL failure. [ABSTRACT FROM AUTHOR]

Our objective was to identify the rate of revisit to either emergency department (ED) or inpatient (IP) following surgical stone removal in the ambulatory setting, and to identify factors predictive of such revisits. To this end, the AHRQ HCUP ambulatory, IP, and ED databases for NY and FL from 2010 to 2014 were linked. Cases were selected by primary CPT for shock-wave lithotripsy (SWL), ureteroscopy (URS), and percutaneous nephrolithotomy (PNL) with accompanying ICD-9 for nephrolithiasis. Cystoscopy (CYS) was selected as a comparison group. The risk of revisit was explored using multivariate models. The overall unplanned revisit rate following stone removal was 6.4% (4.2% ED and 2.2% IP). The unadjusted revisit rates for SWL, URS, and PNL are 5.9%, 6.8%, and 9.0%, respectively. The adjusted odds of revisit following SWL, URS, and PNL are 1.93, 2.25, and 2.70 times higher, respectively, than cystoscopy. The majority of revisits occurred within the first two weeks of the index procedure, and the most common reasons for revisit were due to pain or infection. Younger age, female sex, lower income, Medicare or Medicaid insurance, a higher number of chronic medical conditions, and hospital-owned surgery centers were all associated with an increased odds of any revisit. The most important conclusions were that ambulatory stone removal has a low rate of post-operative revisits to either the ED or IP, there is a higher risk of revisit following stone removal as compared to urological procedures that involve only the lower urinary tract, and demographic factors appear to have a moderate influence on the odds of revisit. [ABSTRACT FROM AUTHOR]

Purpose of Review: To review the latest evidence about intrarenal pressures (IRPs) generated during flexible ureteroscopy (fURS) and mini percutaneous nephrolithotomy (mPCNL) and present tools and techniques to maintain decreased values. Recent Finding: fURS and PCNL constitute the primary means of stone treatment. New flexible ureterorenoscopes with small diameter and miniaturized PCNL instruments achieve optimal stone-free rates (SFRs) while decreasing invasiveness and morbidity. Nevertheless, endourologists must remain cognizant regarding the dangers of increased IRPs to avoid complications. Current research presents essential information for urologists regarding this topic. Summary: During fURS, using a ureteral access sheath (UAS), we avoid extremely high IRPs with all irrigation types. During mPCNL, pressure remains low, mainly using the purging effect or a vacuum-assisted sheath. Devices of intraoperative IRP measurement and intelligent pressure control have proven their feasibility, accuracy and efficacy. These will have an increasing role to play in the future management of stone disease. [ABSTRACT FROM AUTHOR]

Purpose of Review: The prevalence of kidney stones is rising and historically carries a preponderance for males. However, recent evidence has questioned whether this gender gap is closing. The aim of this systematic review was to examine this further as well as evaluate possible underlying causes. Recent Findings: Recent evidence confirms the disparity in kidney stone disease between genders is closing. In the modern era, the rise in prevalence among females has been greater, especially in adolescence. Quality of life is also more adversely affected by kidney stone events among females who are also more likely to develop sepsis after endourological surgery. Males, however, are more likely to present with stone events during periods of high ambient temperatures Summary: Recent literature demonstrates a temporal change in the disease burden of KSD among men and women. The latter, especially adolescent females, are more likely to develop KSD in their lifetime compared to previous eras. Determining causation is complex and continued research is warranted. [ABSTRACT FROM AUTHOR]

Purpose: To predict successful dusting of kidney stones during retrograde intrarenal surgery (RIRS) using stone density parameters and histograms measured with non-contrast computed tomography imaging. Methods: Medical records of 49 patients who underwent retrograde intrarenal surgery between January 2018 and January 2019 at Kyung Hee University Hospital were reviewed, and the data of 55 stones were evaluated. Patient age, sex, mean stone density, the highest and lowest measured Hounsfield unit (HU), standard deviation and range of the measured HUs, volume of the most measured HU, and success of dusting were evaluated. Histograms of the measured HUs were created and cutoff values for successful dusting were analyzed. Results: Thirty-two stones were successfully dusted during surgery. Dusted stones had a wider range of HU and higher standard deviation. The volume of the most measured HU was smaller in the dusted stones. Successful dusting could be predicted when the volume of the most measured HU was < 8.9 mm3, with range ≥ 853, or when the volume of the most measured HU was < 8.9 mm3, with range < 853, and the mean stone density was < 355. The histograms of HUs of the dusted stones were wide and rugged, while those of dusting failed stones were narrow and peaked. Conclusion: Evaluation of stone HU histograms showed differences in distribution and proportion. This will help predict surgical outcomes and prepare for intraoperative complications. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the outcomes of complete supine percutaneous nephrolithotomy (csPCNL) for staghorn stones and multiple large non-staghorn stones. Methods: The records of 886 patients who underwent csPCNL from September 2009 to October 2019 were considered. Out of them, 201 cases met the eligibility criteria and they were divided into three groups: 63 cases of staghorn, 68 cases of multiple medium (20 mm < diameter ≤ 30 mm) non-staghorn and 70 cases of multiple large non-staghorn (> 30 mm) stones. Almost all outcomes and stone-related factors were analyzed. Results: There was not any significant difference regarding age, body mass index, history of urinary tract infection, transfusion rate, complication rate, pre and post-surgery serum creatinine, hemoglobin drop and total hospital stay between the three groups. Stone free rate was 98.5% in multiple medium group, 97.1% in multiple large group and 84.1% in staghorn group (P = 0.001). The operation duration was significantly shorter for the multiple medium group (P < 0.001) but it was not significantly different between the multiple large non-staghorn and staghorn group. Conclusion: The results demonstrated that almost all outcomes were not significantly different between the three groups (especially between staghorn and larger non-staghorn ones). These findings reveal that surgeons could choose csPCNL for treatment of staghorn stones and multiple large non-staghorn stones and consider staghorn stones as challenging as multiple large (especially diameter > 30 mm) non-staghorn stones. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the ability of a semi-automated radiomic analysis software in predicting the likelihood of spontaneous passage of urinary stones compared with manual measurements.Methods: Symptomatic patients visiting the emergency department with suspected stones in either kidney or ureters who underwent a CT scan were included. Patients were followed for up to 6 months for the outcome of a trial of passage. Maximum stone diameters in axial and coronal images were measured manually. Stone length, width, height, max diameter, volume, the mean and standard deviation of the Hounsfield units, and morphologic features were also measured using automated radiomic analysis software. Multivariate models were developed using these data to predict subsequent spontaneous stone passage, with results expressed as the area under a receiver operating curve (AUC).Results: One hundred eighty-four patients (69 females) with a median age of 56 years were included. Spontaneous stone passage occurred in 114 patients (62%). Univariate analysis demonstrated an AUC of 0.83 and 0.82 for the maximum stone diameter determined manually in the axial and coronal planes, respectively. Multivariate models demonstrated an AUC of 0.82 for a model including manual measurement of maximum stone diameter in axial and coronal planes. The same AUC was found for a model including automatic measurement of maximum height and diameter of the stone. Further addition of morphological parameters measured automatically did not increase AUC beyond 0.83.Conclusion: The semi-automated radiomic analysis of urinary stones shows similar accuracy compared with manual measurements for predicting urinary stone passage. Further studies are needed to predict clinical impacts of reporting the likelihood of urinary stone passage and improving inter-observer variation using automatic radiomic analysis software. [ABSTRACT FROM AUTHOR]

Calcium oxalate monohydrate (COM) crystals are the primary constituent of most kidney stones, but urine proteins in stone matrix are believed to be critical elements for stone formation from these crystals. Recent data have shown that hundreds of proteins appear in the stone matrix with no explanation for inclusion of so many proteins. We have proposed a stone formation model with protein stimulated COM aggregation based on polyanion–polycation aggregation, which is supported by finding that matrix is highly enriched in strongly anionic and strongly cationic proteins. Many other proteins may be drawn to such aggregates due to their limited solubility in water or charge effects. Finding similar protein enrichment in both polyarginine (pR) induced aggregates of urine proteins and COM stone matrix would support this hypothesis. Purified proteins (PP) were obtained from random urine samples of six healthy adults by ultradiafiltration. Protein aggregation was induced by adding pR to PP solutions at two concentrations; 0.25 and 0.5 µg pR/µg of PP. Samples of each fraction and the original PP mixture were lyophilized and analyzed by tandem mass spectrometry. Aggregates induced by pR addition to PP samples collected a protein mixture that mimicked the protein distribution observed in COM matrix, supporting our hypothesis. The apparently discordant behavior of certain abundant anionic proteins preferentially joining the pR aggregate, when they had demonstrated reduced abundance in COM stone matrix, suggests that this model was overdriven to aggregate. The reversal of aggregate preference of albumin at low pR addition supports this interpretation. [ABSTRACT FROM AUTHOR]

The aim of the study is to compare the effects of varying frequency rates (60, 90, and 120 SWs/min) on the stone free rate and complication rates of pediatric SWL. 75 children with renal stones were divided into 3 groups depending on the SW frequency applied. Group 1. low (60 SWs/min), Group 2. intermediate (90 SWs/min) and Group 3. high (120 SWs/min) frequency. Patient demographics (age, gender, BMI), stone (location, size, laterality), and SWL (total number of sessions, shock waves, anesthesia time) related parameters were documented. Postoperative success, complication rates, and the need for additional interventions were comparatively evaluated. There was no significant difference regarding the patient demographics, stone characteristics, SWL parameters, postoperative complication rates, need for additional interventions as well as efficacy quotient between all (p > 0.05). The stone free rates were significantly lower in cases with high frequency, whereas there was no statistically significant difference between the intermediate and low frequency groups (p > 0.05). Although not statistically significant; low frequency application may be more advantageous than intermediate as lower number of high energy shock waves required which may cause less tissue damage. On the other hand, despite lack of a statistically significant difference, relatively longer anesthesia time may constitute a disadvantage for lower frequency. We believe that considering the growing nature of the child kidney application of low frequency (60 SWs/min) will be advantageous. However, we believe that further studies with larger series of cases are needed to make a clear-cut differentiation between low and intermediate SW applications. [ABSTRACT FROM AUTHOR]

To evaluate the impact of chronic stone recurrence on an individual's quality of life using the validated Wisconsin Stone Quality of Life (WISQOL) questionnaire. We collected cross-sectional data on patients with kidney stones from 14 institutions in North America. A stone event was defined as renal colic, stone-related procedure or emergency department visit. The regression analyses using general linear models and pairwise comparison determined the impact of the number of stone events on quality of life. The median number of stone events among the 2205 patients who completed the questionnaire was 3 (IQR 1–6). The mean total score was 107.4 ± 28.7 (max 140 points). The number of lifetime stone events was an independent predictor of lower quality of life (p < 0.001), specifically, score declined significantly beyond five events. Compared with patients who experienced a single stone event, there was a 0.4, 2.5, and 6.9 point decline in the adjusted mean WISQOL score after 2–5, 6–10, or > 10 events, respectively. The cumulative number of lifetime stone events was associated with a lower quality of life when more than five stone events were occurred. These findings underscore the importance of efforts to determine the underlying metabolic etiology of urolithiasis in the recurrent stone former, and the institution of a regimen to place their stone disease in remission. [ABSTRACT FROM AUTHOR]

Purpose of Review: To present the latest evidence related to the outcomes and cost of single-use, disposable ureteric stent removal system (Isiris). Recent Findings: Our review suggests that compared to a reusable flexible cystoscope (re-FC), a disposable flexible cystoscope (d-FC) with built-in grasper (Isiris) significantly reduced procedural time and provided a cost benefit when the latter was used in a ward or outpatient clinic-based setting. The use of d-FC also allowed endoscopy slots to be used for other urgent diagnostic procedures. Summary: Disposable FCs are effective and safe for ureteric stent removal. They offer greater flexibility and, in most cases, have been demonstrated to be cost-effective compared to re-FCs. They are at their most useful in remote, low-volume centres, in less well-developed countries and in centres where large demand is placed on endoscopy resources. [ABSTRACT FROM AUTHOR]

Purpose: To assess the effect of our new classification on surgical outcomes after flexible ureteroscopy (fURS) for kidney stones. Methods: We retrospectively examined 128 patients after single renal fURS procedures performed using ureteral access sheaths (UASs) with the fragmentation technique. Based on the gap (calculated by subtracting the ureteroscope diameter from the UAS diameter), enrolled patients were divided into three groups: small (< 0.6 mm), medium (0.6 to < 1.2 mm), and large space groups (≥ 1.2 mm). Stone-free (SF) status was defined as either complete absence of stones (SF) or the presence of stones < 4 mm in diameter on non-contrast computed tomography (NCCT). Results: The SF rate was significantly lower in the small space group (50% in small, 97.9% in medium, 89.2% in large; p = 0.001). Perioperative complications over Clavien–Dindo Grade I were observed in 16.7%, 4.2%, and 8.1% of patients, respectively (p = 0.452). The ratio of stone volume and operative time (efficiency of stone removal) was significantly higher in the large space group compared to the small and medium space groups (0.009 ± 0.003 ml/min, 0.013 ± 0.005 ml/min, 0.027 ± 0.012 ml/min, respectively; p < 0.001). Conclusion: Our findings that gaps > 0.6 mm (1.8 Fr), including the combination of a 9.5-Fr UAS and a small caliber ureteroscope, improve SF rates, and larger gaps facilitate stone removal efficiency providing the basis for future development of clinical protocols aimed at improving outcomes. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the balance between existing evidence and expert opinions on the safety and efficacy of new technological improvements in lithotripsy techniques for percutaneous nephrolithotomy (PCNL). Methods: A scoping review approach was applied to search literature in Pubmed, Embase, and Web of Science. Consensus by key opinion leaders was reached at a 2-day meeting entitled "Consultation on Kidney Stones: Aspects of Intracorporeal Lithotripsy" held in Copenhagen, Denmark, in September 2019. Results: New-generation dual-mode single-probe lithotripsy devices have shown favourable results compared with use of ballistic or ultrasonic lithotripters only. However, ballistic and ultrasonic lithotripters are also highly effective and safe and have been the backbone of PCNL for many years. Compared with standard PCNL, it seems that mini PCNL is associated with fewer bleeding complications and shorter hospital admissions, but also with longer operating room (OR) time and higher intrarenal pressure. Use of laser lithotripsy combined with suction in mini PCNL is a promising alternative that may improve such PCNL by shortening OR times. Furthermore, supine PCNL is a good alternative, especially in cases with complex renal stones and large proximal ureteric stones; in addition, it facilitates endoscopic combined intrarenal surgery (ECIRS). Conclusion: Recent technological improvements in PCNL techniques are promising, but there is a lack of high-level evidence on safety and efficacy. Different techniques suit different types of stones and patients. The evolution of diverse methods has given urologists the possibility of a personalized stone approach, in other words, the right approach for the right patient. [ABSTRACT FROM AUTHOR]

Purpose: To compare noise texture and accuracy to differentiate uric acid from non-uric acid urinary stones among four different single-source and dual-source DECT approaches in an ex vivo phantom study. Methods: Thirty-two urinary stones embedded in gelatin were mounted on a Styrofoam disk and placed into a water-filled phantom. The phantom was imaged using four different DECT approaches: (A) dual-source DECT (DS-DE); (B) 1st generation split-filter single-source DECT (SF1-TB); (C) 2nd generation split-filter single-source DECT (SF2-TB) and (D) 2nd generation split-filter single-source DECT using serial acquisitions (SF2-TS). Two different radiation doses (3 mGy and 6 mGy) were used. Noise texture was compared by assessing the average spatial frequency (fav) of the normalized noise power spectrum (nNPS). ROC curves for stone classification were computed and the accuracy for different dual-energy ratio cutoffs was derived. Results: NNPS demonstrated comparable noise texture among A, C, and D (fav-range 0.18–0.19) but finer noise texture for B (fav = 0.27). Stone classification showed an accuracy of 96.9%, 96.9%, 93.8%, 93.8% for A, B, C, D for low-dose, respectively, and 100%, 96.9%, 96.9%, 100% for routine dose. The vendor-specified cutoff for the dual-energy ratio was optimal except for the low-dose scan in D for which the accuracy was improved from 93.8 to 100% using an optimized cutoff. Conclusion: Accuracy to differentiate uric acid from non-uric acid stones was high among four single-source and dual-source DECT approaches for low- and routine dose DECT scans. Noise texture differed only slightly for the first-generation split-filter approach. [ABSTRACT FROM AUTHOR]

Purpose: To identify risk factors by developing and internally validating a nomogram for preventing perioperative complications in overnight ureteral catheterization cases after fURS for kidney stones. Methods: We retrospectively examined 309 patients with overnight ureteral catheterization after single fURS procedures for renal stones. fURS procedures were performed based on the fragmentation technique. The ureteral catheter was removed on postoperative day 1. Within this group, patients who experienced perioperative complications (complication group) were compared with those who did not experience complications (non-complication group). The complication group included 77 patients whose Clavien–Dindo classification score was I, II, III, or IV and/or those whose body temperature during hospitalization was over 37.5 °C. Results: The overall stone volume, stone-free rate, incidence of perioperative complications, and procedure duration were 1.39 mL, 94.8%, 24.9%, and 62 min, respectively. Severe complications of a Clavien–Dindo level III or IV were observed in only four cases (1.3%). Multivariate assessment revealed five independent predictors of perioperative complications after fURS with overnight catheterization: age (p = 0.11), sex (p = 0.067), stone volume (p = 0.33), Hounsfield units (p = 0.16), and narrow ureter (p = 0.018). We developed a nomogram to predict perioperative complications after fURS using these parameters. Conclusions: We developed a predictive model for perioperative complications of patients with overnight catheterization after fURS for renal stones. This model could select patients who were at a low risk of complications. [ABSTRACT FROM AUTHOR]

This study aimed at illustrating our experience with the retrograde nephrostomy access technique for percutaneous nephrolithotomy (PCNL).This retrospective study was conducted between June 1997 and September 2018 for 648 patients who underwent PCNL with retrograde nephrostomy access. Included in the study were the patient demographic, operative time, site of the access, fluoroscopic exposure time, stone clearance rate, additional procedures and complications. A total of 648 patients aged between 25 and 70 years had renal stones and were included in this study. Retrograde nephrostomy access was achieved through the upper calyx in 252 patients (38.9%), middle calyx in 348 patients (53.7%) and lower calyx in 48 patients (7.4%). Among those patients, 108 (16.7%) required supracostal access. The average time for the retrograde access and PCNL was 14.4 min and 40 min, respectively. The average fluoroscopic exposure time for the retrograde access was 3.2 min. There were 12 failures (1.9%) as a result of severe hydronephrosis. Complete stone clearance was achieved in 91.8%. Small stone fragments (4 mm or less) were detected in 7.4%. Median hospital stay was 3.5 days (range 3–7). Complications occurred in 39 patients (6%). Eight patients (1.2%) developed significant postoperative hemorrhage that was controlled by transfusion and angioembolization. There were no recorded cases of colonic injuries, pneumothorax or hemothorax, demonstrating that the retrograde access technique is safe and reliable. It provides control over both ends of the wire eliminating the risk of accidental wire displacement. Radiation exposure is minimal. There are low failure and complication rates. [ABSTRACT FROM AUTHOR]

Objectives: To predict the main component of pure and mixed kidney stones using dual-energy computed tomography and machine learning.Methods: 200 kidney stones with a known composition as determined by infrared spectroscopy were examined using a non-anthropomorphic phantom on a spectral detector computed tomography scanner. Stones were of either pure (monocrystalline, n = 116) or compound (dicrystalline, n = 84) composition. Image acquisition was repeated twice using both, normal and low-dose protocols, respectively (ND/LD). Conventional images and low and high keV virtual monoenergetic images were reconstructed. Stones were semi-automatically segmented. A shallow neural network was trained using data from ND1 acquisition split into training (70%), testing (15%) and validation-datasets (15%). Performance for ND2 and both LD acquisitions was tested. Accuracy on a per-voxel and a per-stone basis was calculated.Results: Main components were: Whewellite (n = 80), weddellite (n = 21), Ca-phosphate (n = 39), cysteine (n = 20), struvite (n = 13), uric acid (n = 18) and xanthine stones (n = 9). Stone size ranged from 3 to 18 mm. Overall accuracy for predicting the main component on a per-voxel basis attained by ND testing dataset was 91.1%. On independently tested acquisitions, accuracy was 87.1-90.4%.Conclusions: Even in compound stones, the main component can be reliably determined using dual energy CT and machine learning, irrespective of dose protocol.Key Points: • Spectral Detector Dual Energy CT and Machine Learning allow for an accurate prediction of stone composition. • Ex-vivo study demonstrates the dose independent assessment of pure and compound stones. • Lowest accuracy is reported for compound stones with struvite as main component. [ABSTRACT FROM AUTHOR]

Development of surgical expertise and technology has affected the way renal tract stones are treated. Our hypothesis was that flexible ureteroscopy (FURS) for upper tract stones in children produces good results. Our outcomes were reviewed. A retrospective case note review was performed for children with upper tract calculi who were treated by FURS. There were 56 stone episodes in 36 patients. Median age was 10.6 years. Stones were 3–23 mm (median 8 mm); 64.3% had multiple calculi. Median follow-up was for 17.1 months. After the first FURS there was stone clearance in 42/56 (75%). Although there were no immediate complications, two required re-admission; one with stent symptoms, the other with urinary infection. A second FURS was performed in 11, bringing the cumulative clearance to 89%, although this was often done as "another look" before stent removal. There was no statistically significant difference in stone clearance after first FURS for those with single stones (81.0%) compared to those with multiple stones (72.2%). Clearance rates of more than 70% after first FURS were achieved with stones of up to 17 mm. Unexpected disease was found and treated during FURS in 9 (16.1%) children. FURS is safe in children and good clearance rates are achieved. Multiple stones at different sites may be treated during the same treatment. In addition, FURS allows diagnosis and treatment of unexpected problems. [ABSTRACT FROM AUTHOR]