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Introduction: With the rise in the detection of incidental small renal masses (SRM), the management paradigm for these patients has become an issue of increasing concern. We aim to identify areas of consensus, controversy, and opportunities for improvement among recently published guidelines and assess the strength of evidence for the management of SRMs. Methods: We reviewed practice guidelines for SRMs promulgated by the American Urological Association, European Association of Urology, National Comprehensive Cancer Network, American Society of Clinical Oncology, European Society for Medical Oncology, and the Chinese Society of Clinical Oncology. Levels of evidence and strength of recommendations for evaluation, management and follow-up were analyzed with regard to consensus, conflict, and neglect. Results: There is consensus among guidelines for the initial evaluation and treatment of SRMs; however, discrepancies exist with regard to indications for active surveillance, thermal ablation, and timing/method of follow-up after treatment. Routine renal mass biopsy is not recommended by any guideline. Overwhelmingly, guideline statements are based on low to moderate levels of evidence; only 23% of the reviewed guidelines were based on high-level evidence, 38% based on moderate-level, and 39% on low-level evidence or expert opinion. Conclusions: Despite all six guidelines sharing a consensus on most management topics regarding SRMs, the ongoing lack of high-level evidence precludes gold standard recommendations in the areas of diagnosis, treatment, and follow-up. More high-quality studies are needed to develop a stronger, data-supported universal guideline for the management of SRMs.

Introduction: The creation of synthetic reservoirs for bladder replacement has been limited by challenges of interfacing synthetic materials and native tissue. We sought to overcome this challenge by utilizing a novel bilayer silk fibroin scaffold (BLSF) as an intermediary toward the development of an acellular prosthetic reservoir. Methods: Under institutionally approved protocols, 3D-printed reservoirs were implanted in six juvenile female pigs after cystectomy. BLSF was attached to the in situ prosthetic reservoir serving as an intermediary to native ureteral and urethral tissue anastomoses. Our first protocol allowed four pigs to be survived up to 7 days, and the second protocol allowed two pigs to be survived for up to 1 year. At the first sign of functional decline or the end of the study period, the animals were euthanized, and kidneys, ureters, prosthetic bladder, and urethra were harvested en bloc for histopathology analysis. Results: The first two pigs had anastomotic urine leaks because of design flaws resulting in early termination. The third pig had acute renal failure resulting in early termination. The artificial bladder design was modified in subsequent iterations. The fourth pig survived for 7 days and, upon autopsy, had intact urethral and ureteral anastomoses. The fifth and sixth pigs survived for 11 and 12 weeks, respectively, before they were sacrificed because of failure to thrive. One animal developed an enteric fistula. The other animal had an intact anastomosis, and the BLFS was identified at the ureteral and urethral anastomoses on histopathologic analysis. Conclusions: Replacing the porcine bladder with a prosthetic bladder was achieved for up to 3 months, the second longest survival period for a nonbiologic bladder alternative. BLSF was used for the first time to create an interface between synthetic material and biologic tissue by allowing ingrowth of urothelium onto the acellular alloplastic bladder.

Introduction: We sought to compare the safety, efficacy, efficiency, and surgeon experience during upper urinary tract stone management with single-lumen (SLFU) vs dual-lumen flexible ureteroscopes (DLFU). Materials and Methods: Seventy-nine patients with proximal ureteral or renal stone burden <2 cm were randomized to a SLFU or DLFU. We recorded times for ureteroscopy (URS), laser lithotripsy, stone basketing, as well as intraoperative and postoperative complications. The rate of stone clearance and stone free status were calculated using CT imaging. Surgeons completed a survey after each procedure rating various metrics regarding ureteroscope performance. Results: Thirty-five patients from the single-lumen group and 44 patients from the dual-lumen group had comparable median URS time (37 vs 35 minutes, p  = 0.984) and basketing time (12 vs 19 minutes; p  = 0.584). Median lithotripsy time was decreased in the dual-lumen group (single: 6 vs dual: 2 minutes, p  = 0.017). The stone clearance rate was superior in the dual-lumen group (single: 3.7 vs dual: 7.1 mm 3 /min, p  = 0.025). The absolute stone-free rate (SFR) was superior for the dual-lumen group (single: 26% vs dual: 48%, p  = 0.045). No differences in intraoperative (single: 0% vs dual: 2%; p  = 0.375) and postoperative complications (single: 7% vs dual: 11%, p  = 0.474) were observed. Surgeons' ratings of the dual-lumen ureteroscope was superior for visibility, comfort, ease of use, and overall performance. Conclusions: The use of the dual-lumen ureteroscope in patients with renal and proximal ureteral stones <2 cm provided shorter lithotripsy time, higher stone clearance rates, improved SFR, and superior surgeon ratings when compared with SLFUs.

Purpose: We evaluated our experience of a multidisciplinary approach to renal mass biopsy (RMB) for small renal masses (SRMs) employing in-office ultrasound (US)-guided biopsy by urology (24%), CT, or US biopsy by interventional radiology (IR) (79%), and endoscopic ultrasound (EUS)-guided biopsy by gastroenterology (GI) (4%). Materials and Methods: A single-institution retrospective review of patients who underwent RMB for SRM from May 2013 to August 2019 was conducted. Data regarding patient demographics, tumor characteristics, biopsy technique, histopathology, and management were collected. Diagnostic rates, concordance with final pathology, complications, and outcomes were analyzed. Results: Of the 192 biopsies reviewed, 63% biopsies were malignant, 20% were benign, and 17% were nondiagnostic. Based on biopsy results, 71 patients (37%) elected active surveillance. Thirty-eight (20%) patients underwent cryoablation, 56 (29%) underwent partial nephrectomy, 14 (7%) underwent radical nephrectomy, and the remaining patients were treated elsewhere. The rate of surgery for benign pathology after pretreatment RMB was 3%. The concordance rate between biopsy and final pathology was 99% for malignancy, 96% for specific pathology subtype, and 85% for renal cell carcinoma grade. Median time from diagnosis to definitive treatment was 97 days (urology: 76, IR: 110 and GI: 54, p  = 0.002). Three (1.6%) Clavien I complications were reported. Conclusion: Our multidisciplinary approach to RMB for clinical stage T1a demonstrated favorable safety and diagnostic rates, which effectively directed management strategies and minimized surgery for benign disease. Urologist-performed office biopsies significantly shortened the time from diagnosis to definitive treatment. Our experience with GI EUS biopsy has demonstrated feasibility and safety for tumors that were otherwise not accessible percutaneously.

Introduction and Objectives: Conventional renal stone dusting is challenging; the holmium (Ho:YAG) laser and holmium with MOSES effect (Ho:YAG- MOSES ) fail to uniformly produce fragments ≤100 μm (i.e., dust). The superpulse thulium fiber laser (sTFL) may more effectively render uroliths into "dust," and may thus improve stone-free rates. Accordingly, we performed ex vivo evaluations with all three laser modalities, assessing stone fragments and stone clearance. Methods: Seventy-two ex vivo porcine kidney-ureter models were divided into 12 groups of 6: laser type (Ho:YAG, Ho:YAG- MOSES , sTFL), ureteroscope with and without applied suction, and the presence or absence of a 14F ureteral access sheath (UAS). Calcium oxalate stones were preweighed and implanted into each kidney via a pyelotomy. Stones were treated at 16W using dusting settings of 0.4J × 40Hz (Ho:YAG), 0.2J × 80Hz (Ho:YAG- MOSES ), and 0.2J × 80Hz (sTFL) for up to 20 minutes. No stone basketing was performed. Kidneys were bivalved and residual fragments were collected, dried, weighed, and sieved to determine fragment size and stone clearance. Results: Initial stone mass (mg), procedure time (seconds), and laser energy expenditure (kJ) were similar in all 12 groups. The greatest stone clearance was seen with sTFL + suction + UAS (94%) compared with a conventional technique (Ho:YAG + no suction + no UAS) (65%, p  < 0.01). The use of sTFL provided greater stone clearance than Ho:YAG or Ho:YAG- MOSES . Aspiration improved stone clearance for sTFL ( p  = 0.01), but not for Ho:YAG or Ho:YAG- MOSES , consistent with the creation of smaller fragments with sTFL. Presence of a 14F UAS improved stone clearance in all scenarios ( p  < 0.01). Conclusions: In this ex vivo study, stone clearance was optimized under the following conditions: sTFL, 14F UAS, and aspiration. This combination resulted in 94% of stone fragments being cleared; the 6% remaining fragments were all <2 mm. In all scenarios, deployment of a 14F UAS improved stone clearance.

Background: The gold standard treatment for solitary medium-sized (1-2 cm) renal stones is not defined by recent guidelines, since management modalities including shockwave lithotripsy (SWL), retrograde intrarenal surgery (RIRS), and percutaneous nephrolithotomy (PNL) are recommended. Improved ability to predict patient outcomes would aid in patients' counseling and decision-making., Objective: To develop a nomogram predicting treatment failure, based on preoperative clinical variables, to be used in the preplanning setting., Design, Setting, and Participants: We recruited 2605 patients from 14 centers and carried out a multicenter retrospective analysis of 699 SWL, 1290 RIRS, and 616 PN L procedures performed as first-line treatment for 1-2-cm kidney stones. The variables evaluated included age, gender, previous renal surgery, body mass index, stone size, location, stone density, skin-to-stone distance, presence of urinary tract infections (UTIs), and hydronephrosis., Outcome Measurements and Statistical Analysis: Multivariate logistic regression was fitted to predict treatment failure, defined as the presence of residual fragments >4 mm. A nomogram was developed based on the coefficients of the logit function., Results and Limitations: A total of 2431 (93.3%) patients were stone free; 174 (6.7%) treatment failures were recorded and considered the event to be predicted. On univariate analysis, type of procedure, preoperative hydronephrosis, stone density, stone location, and laterality turned out to be statistically significant. Skin-to-stone distance, UTIs, and previous renal surgery were predictors of failure on multivariate analysis. Each variable was given a score based on statistical relevance. The main limitation of the current study is its retrospective nature., Conclusions: This nomogram provides a prediction of treatment failure and need of reintervention for medium-sized kidney stones. External validation is needed to determine its reproducibility and validity., Patient Summary: We developed a preoperative model of treatment outcomes for 1-2-cm kidney stones. Its application may assist urologists to counsel patients with regard to stone management modality., (Copyright © 2020. Published by Elsevier B.V.)

Introduction: We sought to examine the intrarenal fluid and tissue temperature alterations during dusting and fragmentation with the thulium fiber laser (TFL) in an in vivo porcine kidney. Materials and Methods: In two female Yorkshire pigs, temperature was continuously measured within the upper, interpolar, and lower calices along with the renal pelvis using multipoint thermal sensor probes; another temperature probe was situated at the tip of the ureteroscope. Four experimental protocols were performed for each animal: dual lumen ureteroscope with both warmed (37°C) irrigation and room temperature (20°C-22°C) irrigation and single lumen ureteroscope with warmed and room temperature irrigation. Of note, in each pig, one kidney underwent ureteroscopy (URS) with a 14F ureteral access sheath (UAS) in place, whereas the other kidney had no UAS placed. A 200-μm TFL fiber was fired at three laser settings: (1) dusting at 0.5 J, 80 Hz (40 W) with continuous activation until 5 minutes expired or a temperature of 44°C was reached, (2) low-power fragmentation 1 J, 10 Hz, (10 W), and (3) high-power fragmentation at 1.5 J, 20 Hz (30 W). In all cases, the pulse width was 1 ms. For fragmentation, the laser was activated for 10 seconds with a 2-second intermission for a 1-minute period (five cycles). Results: In the absence of a UAS, in all but one circumstance, temperatures reached or exceeded 44°C at all laser settings with the use of either warm or room temperature irrigation fluid, regardless of the type of ureteroscope used. Of concern, temperatures recorded at the tip of the URS were 4°C to 22°C less than the temperatures recorded in the renal calices. In contrast, with a 14F UAS in place, six distinct groups had temperatures that did not exceed 44°C, specifically at low- and high-power fragmentation settings with room temperature irrigation for both sets of ureteroscopes and at dusting and low-power fragmentation settings with warm temperature irrigation solely for the single lumen ureteroscope. Temperatures recorded at the tip of the ureteroscope with the deployment of a UAS yielded temperature differences ranging from 17°C less to 19°C more than the renal calices. Conclusions: TFL is a novel laser technology for lithotripsy. In the absence of a UAS, high-power TFL fragmentation settings in particular may create temperatures within the collecting system that could result in urothelial tissue injury. Of note, peak temperatures recorded at the tip of the ureteroscope may misrepresent the actual intrarenal temperature during TFL laser lithotripsy.

Percutaneous nephrolithotomy (PCNL) is the treatment of choice for kidney stones >2 cm in size. Obtaining a nephrostomy tract to access the kidney is a key step in this procedure that ultimately determines the patient's outcome. We describe each step of the endoscopic guided approach to PCNL as performed at the University of California, Irvine. Each step of the endoscopic guided PCNL is described and depicted in the video. Surgical steps depicted in the video are from various recorded PCNL procedures from our institution. This guide outlines the indications, preoperative preparation, patient positioning, surgical steps, and postoperative care for patients undergoing PCNL using the endoscopic guided approach. Direct observation of nephrostomy puncture, tract dilation using the balloon, and passing of the Amplatz sheath allow for proper access to the kidney and lower risk of injury. By following this systematic module of endoscopic guided PCNL, a nephrostomy tract can be created and accessed under direct observation, facilitating the routine steps of PCNL.

Objective: It has been previously reported that warming irrigation fluid higher than body temperature may decrease ureteral spasm and thereby facilitate ureteroscopic access to the proximal ureter. Our objective was to examine the effects on ureteral peristalsis and ureteral diameter if the irrigant was warmed to just under the biological threshold for injury. Materials and Methods: Two female adult Yorkshire pigs were studied in this pilot study. In the first pig, a dilute mixture of contrast and irrigation fluid at 37°C and then at 43°C was instilled for 30 minutes into each renal pelvis through a ureteral catheter at 40 mm Hg. Retrograde pyelogram images were captured for each trial and the caliber of the ureter was measured using Vitrea ® software. In the second pig, a lumbotomy was performed, and a magnetic sensor was placed on the extraluminal surface of the ureter to monitor ureteral peristalsis while repeating the aforedescribed regimen. Thirty minutes after the first regimen, the force exerted during placement of a 16F ureteral access sheath (UAS) was recorded at both temperatures using the University of California, Irvine Ureteral Force Sensor. Results: There was no statistically significant difference in ureteral caliber along the length of the ureter at 43°C ( p  = 0.87, p  = 0.32, p  = 0.66 for proximal, middle, and distal ureter, respectively). Indeed, there was an increase in peristalsis from baseline with fluid irrigation at 37°C and at 43°C (59% and 65%, respectively). There was no significant difference in the force exerted for UAS placement at either temperature. On histologic analysis, there were no significant changes in ureteral histology or luminal diameter. Conclusions: In a porcine model, warming irrigation fluid to just under the biological threshold for injury did not increase ureteral caliber, decrease ureteral peristalsis, or facilitate UAS placement. As such, during ureteroscopy, we continue to warm our irrigation fluid just to body temperature.

Purpose: Computerized tomographic urography is the diagnostic tool of choice for evaluating hematuria. In keeping with the ALARA (As Low As Reasonably Achievable) principle, we evaluated a triple bolus computerized tomography protocol designed to reduce radiation exposure., Materials and Methods: Patients with macroscopic or microscopic hematuria were prospectively randomized to conventional computerized tomography (100) or triple bolus computerized tomography (100). The triple bolus computerized tomography protocol entails 2 scans: pre-contrast scan followed by 3 contrast injections at 40 seconds, 60 seconds and 20 minutes prior to the second scan to capture all 3 phases. The conventional computerized tomography protocol requires 4 scans: pre-contrast scan, and 3 post-contrast scans at the corticomedullary, nephrographic and excretory phases. Radiation exposure and the detection of urological pathology were recorded based on radiology reports., Results: There were no differences in patient demographics or body mass index between the 2 groups. Triple bolus computerized tomography exposed patients to 33% less radiation (1,715 vs 1,145 mGy*cm for conventional vs triple bolus computerized tomography; p <0.001). For macroscopic hematuria, the pathology detection rates were 70% for triple bolus and 73% for conventional computerized tomography (p=0.72). For microscopic hematuria, the detection rates were 59% for triple bolus and 50% for conventional computerized tomography (p=0.68). In both groups, the rates of detection of urolithiasis, renal cysts, urological masses, bladder pathology and prostate pathology were no different between triple bolus and conventional computerized tomography., Conclusions: In both the settings of macroscopic and microscopic hematuria evaluation, triple bolus computerized tomography significantly reduces radiation exposure while providing equivalent detection of genitourinary pathology compared to conventional computerized tomography. The ability to detect upper tract filling defects was not specifically tested.

Introduction: The advent of single-use disposable flexible ureteroscopes allows for rapid prototyping of novel endoscopes. In this regard, we sought to develop a female-specific ureteroscope, with a shorter working length, to account for the female anatomy. We hypothesized that the shorter, female-specific single-use flexible ureteroscope would engender higher irrigation flow at a given pressure than that of the standard-length ureteroscope. Methods: An in vitro analysis of a standard 65 cm Dornier Axis™ ureteroscope and a shorter, 45 cm female-specific Dornier Axis ureteroscope was performed. All other aspects of the endoscopes were identical. Each ureteroscope was oriented vertically and connected to a Thermedx ® irrigation system to provide uniform pressurized flow. The average flow rate was computed over five, 2-minute periods at pressure settings of 50, 100, 150, and 200 mm Hg. Data were collected with the working channel unoccupied, after placement of a 200 μm (0.6F) holmium laser fiber and after passage of a 1.7F stone basket. The procedure was then repeated with the endoscopes at maximum deflection. Results: The female gender ureteroscope had significantly higher irrigation flow rates than the standard-length ureteroscope under all conditions by an average of 11% ( p  < 0.02). The highest average percent increase, 17% ( p  < 0.001), was seen with the 1.7F NGage ® basket in the working channel with the endoscope straight. The maximum angle of deflection was not significantly different between the female gender and standard ureteroscopes with an open working channel (314° vs 315°, p  = 0.86), with the 1.7F NGage basket in place (314° vs 315°, p  = 0.15), and with the 200 μm holmium laser in place (316° vs 309°, p  = 0.09). Conclusions: A 45 cm female gender ureteroscope allows for a higher irrigation flow rate than the standard-length ureteroscope under all test conditions. There is no added benefit with regard to deflection capabilities.

Purpose: Many major guidelines across the globe address the medical and surgical management of urolithiasis. We elected to compare and contrast the recommendations among the 5 most highly cited guidelines on stone disease to offer insights on where evidence has created a consensus and where there remains ongoing controversy and hence a need for the pursuit of studies that will provide a higher level of evidence., Materials and Methods: We reviewed the American Urological Association 2019 medical and 2016 surgical guidelines, the 2016 Canadian Urological Association guidelines, the 2020 European Association of Urology guidelines, the 2019 National Institute for Health and Care Excellence and the 2019 Urological Association of Asia guidelines. Tables correlating guideline statements by topic were created, and a comparative analysis was conducted to ascertain consensus and discordance., Results: Comparative analysis of recommendations from the American Urological Association guidelines to the Canadian Urological Association, European Association of Urology, National Institute for Health and Care Excellence guidelines and Urological Association of Asia revealed a high consensus surrounding the medical management of stones. In terms of the surgical management of stones, there is high consensus regarding the treatment of ureteral stones including medical expulsive therapy using alpha blockers, not prestenting for uncomplicated ureteroscopy and employment of either ureteroscopy or shockwave lithotripsy as first line treatment. There is high consensus among the American Urological Association, European Association of Urology, National Institute for Health and Care Excellence and Urological Association of Asia guidelines regarding renal stone treatment. The Canadian Urological Association does not have guidelines on the management of renal stones. Unlike the American Urological Association and National Institute for Health and Care Excellence, the Canadian Urological Association and European Association of Urology make specific recommendations regarding selection of patients for shockwave lithotripsy procedures, including stone density, skin-to-stone distance, treatment rate, acoustic coupling and postshockwave lithotripsy use of medical expulsive therapy., Conclusions: There are many areas of consensus and only minor areas of conflict among the most up-to-date American Urological Association, Canadian Urological Association, European Association of Urology, National Institute for Health and Care Excellence and Urological Association of Asia guidelines on the medical and surgical management of stone disease. Conflicts among guidelines and areas of low evidence, such as followup imaging strategies and stone surveillance, the use of a ureteral access sheath in ureteroscopy and guidance on the use of miniaturized percutaneous nephrolithotomy, are opportunities for novel, impactful high grade clinical studies.