Avoiding "Needless" nephrectomy: What is the role of small renal mass biopsy in 2024?

Current guidelines do not mandate routine preoperative renal mass biopsy (RMB) for small renal masses (SRMs), which results in a considerable rate (18%-26%) of needless nephrectomy/partial nephrectomy for benign renal tumors. In light of this ongoing practice, a narrative review was conducted to examine the role of routine RMB for SRM. First, arguments justifying the current non-biopsy approach to SRM are critically reviewed and contested. Second, as a standalone procedure, RMB is critically assessed; RMB was found to have higher sensitivity, specificity, and an equal or lower complication rate when compared with other commonly preoperatively biopsied solid organ tumors (e.g., breast, prostate, lung, pancreas, thyroid, and liver). Based on the foregoing information, we propose a paradigm shift in SRM management, advocating for an updated policy in which partial nephrectomy or nephrectomy for SRM invariably occurs only after a preoperative biopsy confirms that a SRM is indeed malignant.

Surgical Force: Initial Study and Clinical Implications in the Assessment of Ureteral Access Sheath Induced Injury

Purpose: Ureteral access sheaths (UAS) pose the risk of severe ureteral injury. Our prior studies revealed forces ≤6 Newtons (N) prevent ureteral injury. Accordingly, we sought to define the force urologists and residents in training typically use when placing a UAS. Materials and Methods: Among urologists and urology residents attending two annual urological conferences in 2022, 121 individuals were recruited for the study. Participants inserted 12F, 14F, and 16F UAS into a male genitourinary model containing a concealed force sensor; they also provided demographic information. Analysis was completed using t-tests and Chi-square tests to identify group differences when passing a 16F sheath UAS. Participant traits associated with surpassing or remaining below a minimal force threshold were also explored through polychotomous logistic regression. Results: Participant force distributions were as follows: ≤4N (29%), >6N (45%), and >8N (32%). More years of practice were significantly associated with exerting >6N relative to forces between 4N and 6N; results for >8N relative to 4N and 8N were similar. Compared to high-volume ureteroscopists (those performing >20 ureteroscopies/month), physicians performing ≤20 ureteroscopies/month were significantly less likely to exert forces ≤4N (p = 0.017 and p = 0.041). Of those surpassing 6N and 8N, 15% and 18%, respectively, were high-volume ureteroscopists. Conclusions: Despite years of practice or volume of monthly ureteroscopic cases performed, most urologists failed to pass 16F access sheaths within the ideal range of 4N to 6N (74% of participants) or within a predefined safe range of 4N to 8N (61% of participants).

Utilization of Re-VASC, the Novel Retroperitoneal Neovascularity Scoring System, for Characterization of T1a Small Renal Masses

Purpose: Early characterization of small (T1a, <4 cm) renal masses is imperative for patient care and treatment planning. Renal biopsy is a sensitive and specific procedure that can accurately differentiate small renal masses as malignant or benign. However, it is an invasive procedure with a nonnegligible complication rate and is not performed routinely at most institutions. In this study, we sought to apply the Retroperitoneal Vascularity Assessment and Scoring in Carcinoma (Re-VASC) scoring system to T1a renal masses and analyzed whether it could differentiate these masses as benign or malignant. Methods: We obtained Institutional Review Board approval to retrospectively examine the records of all patients who presented to our single, urban academic referral center for surgical treatment of renal cell carcinoma (RCC). For the malignant group, patients with a diagnosis of T1a RCC from pathologic evaluation were included. Additionally, patients with a histopathological diagnosis of a T1a nonmalignant renal mass (fat poor-angiomyolipoma or oncocytoma) were included in our benign group. Results: This study includes 57 benign and 69 malignant T1a renal tumors. Average size for benign and malignant masses were 2.47 and 2.63, respectively (p = 0.267). Analysis demonstrated no significant difference between both groups in terms of sex, laterality, or size. The average Re-VASC score of benign and malignant masses was 0.175 and malignant masses was 0.784, respectively (p < 0.001). Additionally, the Re-VASC score was independently associated with malignancy with an odds ratio of 2.223 (p = 0.0109). Conclusion: The Re-VASC scoring system exhibits significantly greater values for malignant T1a renal masses when compared to benign masses. As a result, it shows promise as an adjunctive tool to renal biopsy for clinical decision-making. Further assessment of Re-VASC's true efficacy as a diagnostic marker will include prospective evaluation of a larger multicenter population.

Surgical Artificial Intelligence: Endourology

Endourology is ripe with information that includes patient factors, laboratory tests, outcomes, and visual data, which is becoming increasingly complex to assess. Artificial intelligence (AI) has the potential to explore and define these relationships; however, humans might not be involved in the input, analysis, or even determining the methods of analysis. Herein, the authors present the current state of AI in endourology and highlight the need for urologists to share their proposed AI solutions for reproducibility outside of their institutions and prepare themselves to properly critique this new technology.

Efficient and Accurate Computed Tomography-Based Stone Volume Determination: Development of an Automated Artificial Intelligence Algorithm

PURPOSE

Given the shortcomings of current stone burden characterization (maximum diameter or ellipsoid formulas), we sought to investigate the diagnostic accuracy and precision of a University of California, Irvine-developed artificial intelligence (AI) algorithm for determining stone volume determination.

MATERIALS AND METHODS

A total of 322 noncontrast CT scans were retrospectively obtained from patients with a diagnosis of urolithiasis. The largest stone in each noncontrast CT scan was designated the "index stone." The 3D volume of the index stone using 3D Slicer technology was determined by a validated reviewer; this was considered the "ground truth" volume. The AI-calculated index stone volume was subsequently compared with ground truth volume as well with the scalene, prolate, and oblate ellipsoid formulas estimated volumes.

RESULTS

There was a nearly perfect correlation between the AI-determined volume and the ground truth (R=0.98). While the AI algorithm was efficient for determining the stone volume for all sizes, its accuracy improved with larger stone size. Moreover, the AI stone volume produced an excellent 3D pixel overlap with the ground truth (Dice score=0.90). In comparison, the ellipsoid formula-based volumes performed less well (R range: 0.79-0.82) than the AI algorithm; for the ellipsoid formulas, the accuracy decreased as the stone size increased (mean overestimation: 27%-89%). Lastly, for all stone sizes, the maximum linear stone measurement had the poorest correlation with the ground truth (R range: 0.41-0.82).

CONCLUSIONS

The University of California, Irvine AI algorithm is an accurate, precise, and time-efficient tool for determining stone volume. Expanding the clinical availability of this program could enable urologists to establish better guidelines for both the metabolic and surgical management of their urolithiasis patients.

Alkaline Water: Help or Hype for Uric Acid and Cystine Urolithiasis?

PURPOSE

The consumption of alkaline water, water with an average pH of 8 to 10, has been steadily increasing globally as proponents claim it to be a healthier alternative to regular water. Urinary alkalinization therapy is frequently prescribed in patients with uric acid and cystine urolithiasis, and as such we analyzed commercially available alkaline waters to assess their potential to increase urinary pH.

MATERIALS AND METHODS

Five commercially available alkaline water brands (Essentia, Smart Water Alkaline, Great Value Hydrate Alkaline Water, Body Armor SportWater, and Perfect Hydration) underwent anion chromatography and direct chemical measurements to determine the mineral contents of each product. The alkaline content of each bottle of water was then compared to that of potassium citrate (the gold standard for urinary alkalinization) as well as to other beverages and supplements used to augment urinary citrate and/or the urine pH.

RESULTS

The pH levels of the bottled alkaline water ranged from 9.69 to 10.15. Electrolyte content was minimal, and the physiologic alkali content was below 1 mEq/L for all brands of alkaline water. The alkali content of alkaline water is minimal when compared to common stone treatment alternatives such as potassium citrate. In addition, several organic beverages, synthetic beverages, and other supplements contain more alkali content than alkaline water, and can achieve the AUA and European Association of Urology alkali recommendation of 30 to 60 mEq per day with ≤ 3 servings/d.

CONCLUSIONS

Commercially available alkaline water has negligible alkali content and thus provides no added benefit over tap water for patients with uric acid and cystine urolithiasis.

Electromotive Drug Administration in the Porcine Renal Pelvis: First Report

Introduction: Electromotive Drug Administration (EMDA) amplifies drug delivery deep into targeted tissues. We tested, for the first time, the ability of EMDA to deliver methylene blue into the urothelium of the renal pelvis. Materials and Methods: In an anesthetized female pig, both proximal ureters were transected two inches distal to the ureteropelvic junction. An 8F dual lumen catheter and a 5F fenestrated catheter with an indwelling silver wire were inserted into both renal pelvises following which methylene blue (0.1%) was infused at a rate of 5 mL/min for 20 minutes. In one pelvis, a 4 mA positive pulsed electrical current was applied to the silver wire. Results: In contrast to the control pelvis, the EMDA side macroscopically exhibited dense homogeneous staining; microscopy revealed penetration of methylene blue into the urothelium/lamina propria. Conclusion: In the porcine renal pelvis, application of EMDA increased the penetration of a charged molecule into the urothelium/lamina propria.

The Impact of Bilateral Stone Disease on Patients' Disease Progression and Health-Related Quality of Life

Purpose: Patients with recurring kidney stone events can expect significant morbidity and functional impairment. Few studies have evaluated the effect of bilateral kidney stones on disease progression and quality of life. We wanted to determine the association of bilateral stone disease on age of onset, and the impact on number of stone events and individual kidney stone disease-specific health-related quality of life (HRQOL) by analyzing the validated and prospectively collected Wisconsin Stone Quality of Life (WISQOL) database. Materials and Methods: We studied 2906 stone patients from 16 centers in North America after having completed the WISQOL questionnaire from 2014 to 2019. Kidney stone formers were assessed if kidney stones were bilateral or unilateral on imaging. Analysis with a chi-square test compared categorical variables. Bilateral kidney stone disease and its impact on HRQOL were evaluated through a multivariable linear regression model. Results: Of 2906 kidney stone formers, 1340 had unilateral kidney stones and 1566 had bilateral kidney stones. We observed more frequently that patients with bilateral stones had an increased number of depression/anxiety symptoms, renal tubular acidosis, and rheumatoid arthritis (all p < 0.05). Patients with bilateral stones had a younger mean (standard deviation [SD]) age of kidney stone disease onset (37.2 ± 15.8 vs 46.4 ± 15.9 years of age, p < 0.001). Bilateral kidney stone formers had a higher mean (SD) number of stone events (11.3 ± 21.8) than unilateral kidney stone formers (3.0 ± 5.1) (p < 0.001). Within our multivariable analysis, we found that HRQOL was negatively affected by the presence of bilateral stones for kidney stone patients (β = -11.2 [confidence interval: -19.5 to -3.0] points, p < 0.05). Conclusions: Bilateral kidney stone formers had a younger age of kidney stone disease onset and a higher number of stone events compared with unilateral kidney stone disease formers. The presence of bilateral kidney stone disease negatively impacted HRQOL.

The success rate of small renal mass core needle biopsy and its impact on lowering benign resection rate

BACKGROUND

Small renal mass (SRM) biopsy remains under-utilized due to stigma. Meanwhile, the alarmingly high benign findings in resected kidney masses highlight the need for improved preoperative diagnosis and patient selection.

METHODS

The purpose of this study is to review the success rate of SRM biopsy and to evaluate its impact on patient management. A total of 168 percutaneous image-guided core needle biopsies (CNBs) of SRMs were retrieved at a tertiary academic center between 2015 and 2019. Subsequent treatment choices, side effects and outcomes were retrospectively reviewed.

RESULTS

The diagnostic rate of CNB was 86.9%. Benign neoplasms accounted for a significant portion (14.3%) of SRM. Renal cell carcinomas (RCCs) were the most common diagnoses (69.6%) as expected. In biopsy-resection correlation, the positive predictive value of CNB was 100%. Tumor typing and subtyping by CNB were highly accurate, 100% and 98.3% respectively. Nuclear grading for clear cell RCC was accurate in 83.8% cases. The CNB results had significant impact on treatment. Most patients with RCCs underwent either resection (54.1%) or ablation (33.9%), in contrast to observation in benign neoplasms (90.5%). Most importantly, the benign resection rate (3.2%) in this series was much lower than the national average.

CONCLUSION

CNB provided accurate diagnoses for the majority of SRMs and revealed benign diagnoses in a subset of clinically suspicious lesions. Employment of CNB in suspicious SRM may help avoid overtreatment for benign lesions.

Evaluation of Renal Function and Stent Durability Following Resonance Stent Placement for Benign Disease

Introduction: The metal-based Resonance stent (RS) has traditionally been placed in patients with malignant ureteral obstruction; as such, the long-term utility of RS among patients with benign ureteral obstruction (BUO) remains underinvestigated. Methods: We retrospectively reviewed our database for patients with BUO who underwent RS placement between 2010 and 2020. The impact of chronic RS placement on renal function was evaluated by estimated serum creatinine-based glomerular filtration rate (eGFR), furosemide renal scan, and CT-based renal parenchymal volume measurement. The number of and reason for RS stent exchanges during the follow-up period, incidence of encrustation, and the average indwell time were recorded. A cost analysis of placing the RS vs a polymeric stent was performed. Results: Among 43 RS patients with BUO, at a mean follow-up of 26 months, there was no change in eGFR (p = 0.99), parenchymal volume (p = 0.44), or split renal function of the stent-bearing side on renal scan (p = 0.48). The mean RS indwell time was 9.7 months. Eleven patients (26%) underwent premature stent replacement (6 cases) or removal (5 cases). Stents in 9 patients (32%) were encrusted, of which 4 (44%) required laser lithotripsy. Overall, 25 patients (58%) and 12 patients (28%) had a mean stent indwell time of ≥6 months and ≥12 months, respectively. Placing an RS resulted in a 52%, 37%, and 5.6% cost reduction compared with a regular polymeric stent placement, where it was exchanged every 6, 4, or 3 months, respectively. Conclusions: RS deployment in the patient with a BUO results in cost-effective maintenance of renal function and of renal parenchymal volume at a mean follow-up of 2 years; however, only 28% of patients fulfilled the 1-year criterion for RS indwell time.

Comparison of Ureteral Stent Biomaterials: Encrustation Profile in Lithogenic Artificial Urine Models

Ureteral stent encrustation significantly limits indwelling time and can lead to downstream urological problems. However, no ideal polymeric biomaterials have been shown to completely resist encrustation in long-term urine exposure. Recently, 2-hydroxyethyl methacrylate (HEMA)-coated Pellethane was reported as a promising biomaterial resistant to encrustation. This study compared HEMA-coated Pellethane to commercially available stents under two different artificial urine environments. To evaluate the degree and composition of encrustation on HEMA-coated Pellethane, Boston Scientific Tria, Bard InLay Optima, Cook Universa Hydrogel, and Cook Black Silicone stents were used at various dwelling times in two different artificial urine environments. In a batch-flow model, samples of stents were suspended in an artificial urine solution (AUS) at 37 °C. Every 24 h for 11 weeks, 50% of the AUS would be replaced with fresh components using a programmable peristaltic pump system. The stent materials were removed at suitable time intervals and air-dried for 24 h under sterile conditions before follow-up analysis. SEM was used to assess the degree of encrustation, and inductively coupled plasma mass spectrometry (ICP-MS) was employed to quantify the encrusted compositions, specifically for calcium, magnesium, and phosphorus. We measured the weight gain over time due to encrusted deposits on the stents and quantified the amount of Ca, Mg, and P deposited on each encrusted stent. After the 11 week trial, HEMA-coated Pellethane showed the most average mass change. SEM showed that HEMA-coated Pellethane was fully encrusted in just 2 weeks in the AUS environments, and ICP-MS showed that Ca is the most abundant deposit. Among all the tested stents, Black Silicone performed the best. The two AUSs were formulated to encrust more rapidly than physiological conditions. HEMA-coated Pellethane is not an ideal stent material, while silicone is a promising material for advancing ureteral stents.

Electromotive Drug Administration in the Ureter in an In Vivo Animal Model: Initial Report

Introduction: Electromotive drug administration (EMDA) delivers a drug deeply into targeted tissues, such as the bladder. EMDA has never been applied to the ureter. Methods: In four in vivo porcine ureters, a unique EMDA catheter containing a silver conducting wire was advanced for the infusion of methylene blue. In two ureters, a pulsed current was delivered through an EMDA machine, whereas the other two ureters served as a control. After 20 minutes of infusion, the ureters were harvested. Results: In the EMDA ureter, there was diffuse staining of the urothelium; penetration of methylene blue occurred in the lamina propria and muscularis propria. In the control ureter, there was only patchy staining of the urothelium. Conclusion: In this first report of ureteral EMDA, a charged molecule penetrated beyond the urothelium into the lamina propria and muscularis propria of the porcine ureter.

A Review of the Recommendations and Strength of Evidence for Clinical Practice Guidelines on the Management of Small Renal Masses

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 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 in order to develop stronger, data-supported universal guideline for the management of SRMs.

The Changing Role of Renal Mass Biopsy

The incidence and prevalence of small renal masses (SRMs) continues to rise and with increased detection comes increases in surgical management, although the probability of an SRM being benign is upward of 30%. An extirpative treatment first diagnose-later strategy persists and clinical tools for risk stratification such as renal mass biopsy remain severely underutilized. The overtreatment of SRMs has multiple detrimental effects including surgical complications, psychosocial stress, financial loss, and reduced renal function leading to downstream effects such as the need for dialysis and cardiovascular disease.

Novel Retroperitoneal Neovascularity Scoring System in Renal Cell Carcinoma Tumor Staging

Purpose: Renal cell carcinoma (RCC) is the most common type of kidney cancer worldwide. Although radiologists assess enhancement patterns of renal tumors to predict tumor pathology report, to our knowledge, no formal scoring system has been created and validated to assess the level of neovascularity in RCC, despite its critical role in cancer metastases. In this study, we characterized and analyzed the level of angiogenesis in tumor-burdened kidneys and their benign counterparts. We then created and validated a scoring scale for neovascularity that can help predict tumor staging for RCC. Methods: After Institutional Review Board approval, the charts of patients who had undergone operation for RCC between January 13, 2014 and February 4, 2020 were retrospectively reviewed for inclusion in this study. Inclusion criteria were a diagnosis of RCC, simple/radical nephrectomy, preoperative contrast-enhanced CT scans, and complete pathology reports. Neovascularity was scored on a scale of 0-4 where 0 = no neovascularity detected, 1 = a single vessel <3 mm wide, 2 = a single vessel ≥3 mm wide, 3 = multiple vessels <3 mm wide, and 4 = multiple vessels ≥3 mm wide. Results: A total of 227 patients were included in this study. Most of the tumor pathology reports were clear cell carcinoma, regardless of tumor staging. The average neovascularity score was 1.07 for pT1x tumors, 2.83 for pT2x tumors, and 3.04 for pT3x tumors. There was a significant difference in neovascularity score between pT1x and pT2x tumors (p = 0.0046), pT1x and pT3x tumors (p < 0.0001), and benign kidneys and kidneys with RCC (p < 0.0001). Conclusion: Our novel vascular scoring system for RCC demonstrates significant correlation with RCC pathological tumor staging. This scoring system may be utilized as part of a comprehensive radiological assessment of renal tumors, potentially improving tumor characterization and clinical decision making.

Comparison of Superpulse Thulium Fiber Laser vs Holmium Laser for Ablation of Renal Calculi in an In Vivo Porcine Model

Introduction and Objectives: We sought to compare the effectiveness and efficiency of the superpulse thulium fiber laser (sTFL to the holmium: yttrium-aluminum-garnet [Ho:YAG] laser for ureteroscopic "dusting" of implanted renal stones in an in vivo porcine model. Methods: Twenty-four porcine kidneys (12 juvenile female Yorkshire pigs) were randomized to Ho:YAG or sTFL treatment groups. Canine calcium oxalate stones were scanned with computed tomography to calculate stone volume and stone density; the stones were randomized and implanted into each renal pelvis via an open pyelotomy. In all trials, a 14F, 35 cm ureteral access sheath was placed. With a 9.9F dual lumen flexible ureteroscope, laser lithotripsy was performed using dusting settings: Ho:YAG 200 μm laser fiber at 16 W (0.4 J, 40 Hz) or sTFL 200 μm laser fiber at 16 W (0.2 J, 80 Hz). Lithotripsy continued until no fragments over 1 mm were observed. No stone basketing was performed. Throughout the procedures, intrarenal and renal pelvis temperatures were measured using two percutaneously positioned K-type thermocouples, one in the upper pole calyx and one in the renal pelvis. After the lithotripsy, the ureteropelvic junction was occluded, the kidneys were bivalved, and all residual fragments were collected, dried, weighed, and then measured with an optical laser particle sizer. Results: Implanted stones were similar in volume and density in both groups. Intraoperative collecting system temperatures were similar for both groups (all <44°C). Compared to Ho:YAG, sTFL ablated stones faster (9 vs 27 minutes, p < 0.001) with less energy expenditure (8 vs 26 kJ, p < 0.001), and a greater stone clearance rate (73% vs 45%, p = 0.001). After sTFL lithotripsy, 77% of the remaining fragments were ≤1 mm vs 17% of fragments ≤1 mm after Ho:YAG treatment (p < 0.001). Conclusions: In an in vivo porcine kidney, using dusting settings, sTFL lithotripsy resulted in shorter ablation times, higher stone clearance rates, and markedly smaller stone fragments than Ho:YAG lithotripsy.

Porcine Bladder Replacement with a Bilayer Silk Fibroin Enhanced Prosthetic Reservoir: A Feasibility Study

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.

Novel retroperitoneal neovascularity scoring system in renal cell carcinoma tumor staging

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Background: Renal cell carcinoma (RCC) is the most common type of kidney cancer worldwide. While radiologists assess enhancement patterns of renal tumors to predict tumor pathology, to our knowledge, no formal scoring system has been created and validated to assess the level of neovascularity in RCC, despite its critical role in cancer metastases. In this study, we characterized and analyzed the level of angiogenesis in tumor-burdened kidneys and their benign counterparts. We then created and validated a scoring scale for neovascularity that can help predict tumor staging for RCC. Methods: After Institutional Review Board approval, the charts of patients who had undergone surgery for RCC between January 13, 2014 and February 4, 2020 were retrospectively reviewed for inclusion in this study. Inclusion criteria were a diagnosis of RCC, simple/radical nephrectomy, pre-operative contrast enhanced computed tomography (CT) scans, and complete pathology reports. Neovascularity was scored on a scale of 0 to 4 where 0= no neovascularity detected, 1= a single vessel <3mm wide, 2= a single vessel >3mm wide, 3=multiple vessels <3mm wide, and 4=multiple vessels >3mm wide Results: A total of 227 patients were included in the study. The majority of tumor pathology was clear cell carcinoma, regardless of tumor staging. The average neovascularity score was 1.07 for pT1x tumors, 2.83 for pT2x tumors, and 3.04 for pT3x tumors. There was a significant difference in neovascularity score between pT1x and pT2x tumors (p = 0.0046), pT1x and pT3x tumors (p < 0.0001), and benign kidneys and kidneys with RCC (p = <0.0001). Furthermore, we sought to address the ability of the Re-VASC score to predict up-staging or down-staging of clinically staged tumors. Only 5 total tumors were upstaged from cT1 to any pathological stage >1, with an average Re-VASC score of 2.33. There were 24 cases that were down-staged to pT1, with an average Re-VASC score of 1.73. Additionally, we specifically looked at cT3a tumors that were down-staged to p1x. The average Re-VASC scores were 0.82 and 2.11 for pT1a and pT1b tumors respectively. Conclusions: Our novel vascular scoring system for renal cell carcinoma demonstrates significant correlation with RCC pathological tumor staging. In future studies, we would like to further explore the ability of the scoring system to predict clinical up-staging and down-staging, as we had a limited sample size to analyze this function. This scoring system may be utilized as part of a comprehensive radiological assessment of renal tumors, potentially improving tumor characterization and clinical decision making.

Asymptomatic bacteriuria in candidates for active treatment of renal stones: results from an international multicentric study on more than 2600 patients

The occurrence of asymptomatic bacteriuria concomitant to urolithiasis is an issue for patients undergoing renal stone treatment. Disposing of a preoperative urine culture is essential to reduce the risk of septic events. The endpoint of the study is to report which characteristics of candidates for renal stone treatment are frequently associated with positive urine culture. 2605 patients were retrospectively enrolled from 14 centers; inclusion criteria were age > 18 and presence of a single renal stone 1-2 cm in size. The variables collected included age, gender, previous renal surgery, comorbidities, skin-to-stone distance, stone size, location, density, presence of hydronephrosis. After a descriptive analysis, the association between continuous and categorical variables and the presence of positive urine culture was assessed using a logistic regression model. Overall, 240/2605 patients (9%) had preoperative bacteriuria. Positive urine culture was more frequent in females, patients with previous renal interventions, chronic kidney disease, congenital anomalies, larger stones, increased density. Multivariate analysis demonstrated that previous renal interventions (OR 2.6; 95% CI 1.9-3.4; p < 0.001), renal-related comorbidities (OR 1.31; 95% CI 1.19-1.4; p < 0.001), higher stone size (OR 1.06; 95% CI 1.02-1.1; p = 0.01) and density (OR 1.00; 95% CI 1.0-1.00; p = 0.02) were associated with bacteriuria; male gender and lower caliceal location were inversely related to it. Beyond expected risk factors, such as female gender, other parameters are seemingly favoring the presence of positive urine culture. The awareness of variables associated with bacteriuria allows to assess which individuals are at increased risk of presenting bacteriuria and reduce the rate of septic complications.

Beyond Efficiency: Surface Electromyography Enables Further Insights into the Surgical Movements of Urologists

INTRODUCTION

Surgical skill evaluation while performing minimally invasive surgeries is a highly complex task. It is important to objectively assess an individual's technical skills throughout surgical training to monitor progress and to intervene when skills are not commensurate with the year of training. The miniaturization of wireless wearable platforms integrated with sensor technology has made it possible to non-invasively assess muscle activations and movement variability during performance of minimally invasive surgical tasks. Our objective was to use electromyography to deconstruct the motions of a surgeon during robotic suturing and distinguish quantifiable movements that characterize the skill of an experienced, expert urologic surgeon from trainees.

METHODS

Three skill groups of participants: novice (n=11), intermediate (n=12) and expert (n=3) were enrolled in the study. A total of 12 wireless wearable sensors consisting of surface electromyograms (EMGs) and accelerometers were placed along upper extremity muscles to assess muscle activations and movement variability, respectively. Participants then performed a robotic suturing task.

RESULTS

EMG-based parameters: total time, dominant frequency, cumulative muscular workload (CMW were significantly different across the three skill groups. We also found nonlinear movement variability parameters such as correlation dimension, Lyapunov exponent trended differently across the three skill groups.

CONCLUSIONS

These findings suggest that economy of motion variables and nonlinear movement variabilities are affected by surgical experience level. Wearable sensor signal analysis could make it possible to objectively evaluate surgical skill level periodically throughout the residency training experience.

The duration of stone disease and the impact of a stone event on patients' quality of life

INTRODUCTION

With a 5-year stone recurrence rate of 30-50%, kidney stone formers are subject to significant morbidity which negatively impacts their Health Related Quality of Life (HRQOL). We sought to determine the impact of age of kidney stone onset, duration of stone disease, and kidney stone event (surgery or stone passage) on patients' individual HRQOL by querying the validated and prospectively collected Wisconsin Stone Quality of Life (WISQOL) database.

MATERIALS AND METHODS

Cross-sectional data were obtained from a total of 2,438 kidney stone formers from 14 institutions in North America who completed the WISQOL questionnaire from 2014 to 2019. The 28-question survey has a 1-5 point scale for each item (total score range 0-140). Multivariable linear regression models assessed the impact of age of kidney stone onset, duration of stone disease and time since most recent surgery or stone passage on HRQOL.

RESULTS

Of 2,438 patients, older age at kidney stone onset and longer duration of disease were both independent predictors of better WISQOL (β=0.33 points/year; CI 0.17-0.49; p<0.001 and β=0.50 points/year; CI 0.32-0.68; p<0.001, respectively). Of 1,376 patients with surgery between 2010-2019, increased time since most recent surgery was an independent predictor of better WISQOL scores (β = 2.28 points/year; CI: 1.47-3.10; p=<0.001). Of 1,027 patients with spontaneous stone passage between 2010-2019, increased time since most recent stone passage was an independent predictor of better WISQOL scores (β = 1.59 points/year; CI: 0.59-2.59; p=<0.05).

CONCLUSION

Our study demonstrates that older age of onset, longer duration of disease, increase time from most recent surgery or stone passage were independent predictors of better HRQOL in kidney stone formers. Results of future studies that focus on optimizing stone related modifiable risk factors to decrease the amount of recurrent stone episodes and thus the need for recurrent surgeries will be essential.

Prospective, Randomized Comparison of Dual Lumen Versus Single Lumen Flexible Ureteroscopes in Proximal Ureteral and Renal Stone Management

INTRODUCTION

We sought to compare the safety, efficacy, efficiency and surgeon experience during upper urinary tract stone management with single-lumen versus dual-lumen flexible ureteroscopes.

MATERIALS AND METHODS

Seventy-nine patients with proximal ureteral or renal stone burden < 2 cm were randomized to a single-lumen or dual-lumen flexible ureteroscopy. We recorded times for ureteroscopy, laser lithotripsy, stone basketing, as well as intraoperative and postoperative complications. The rate of stone clearance and stone free status were calculated using computed tomography imaging. Surgeons completed a survey after each procedure rating various metrics regarding ureteroscope performance.

RESULTS

Thirty-five patients from the single-lumen group and forty-four patients from the dual-lumen group had comparable median ureteroscopy time (37 vs 35 minutes, p=0.984) and basketing time (12 vs 19 min; p=0.584). Median lithotripsy time was decreased in the dual-lumen group (single: 6 vs dual: 2 min, p=0.017). The stone clearance rate was superior in the dual-lumen group (single: 3.7 vs dual: 7.1 mm3/min, p=0.025). The absolute stone-free rate 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 stone free rate and superior surgeon ratings when compared to single-lumen flexible ureteroscopes.

Retrograde Cystonephroscopy for Complex Renal Calculi Using Novel Dual Action Aspiration, Irrigation Cystoscope: Initial Case Series

Introduction Percutaneous nephrolithotomy (PCNL) is the gold standard treatment for kidney stones ≥ 2 cm; however, it remains an invasive procedure with significant risks especially in individuals with severe medical co-morbidities. In contrast, while ureteroscopy is far less morbid, a major impediment to its use for larger calculi is the inability to evacuate the many fragments created during laser lithotripsy. Herein, we describe two patients with large volume calculi and a third high risk patient with a smaller stone that were treated with cystonephroscopy using a recently released, 16Fr flexible cystoscope equipped with dual aspiration and irrigation capabilities. Materials and Methods Three consecutive female patients underwent retrograde cystonephroscopy from June 2021 to July 2021 with a novel 16Fr aspiration enabled flexible cystoscope. Demographic data were collected. Pre-operative and post-operative CT-scan images were reviewed to determine linear stone dimensions and scalene ellipsoid volume. Results The three female patients had an average age of 72.3 years and an American Society of Anesthesiologists (ASA) physical status score of 3. The mean preoperative stone volume was 4950 mm³. The average post-cystonephroscopy stone volume was 217 mm³ resulting in a total stone clearance rate of 97%. No major complications occurred. Average procedure time was 176 minutes. Conclusions Among three high risk female patients, two with large volume calculi, retrograde cystonephroscopy with a novel aspiration-enabled cystoscope allowed for the procedure to be successfully completed solely via a retrograde approach.

The Impact of One Week of Pre-stenting on Porcine Ureteral Luminal Circumference

OBJECTIVES

Larger ureteral access sheaths (UAS) have the potential to improve ureteroscopic stone removal outcomes, but are often avoided by surgeons due to concerns of ureteral injury. Using our novel UAS force sensor and previously defined force thresholds for ureteral injury, we sought to evaluate the impact of one week of stenting on the maximum safe dilation of ureteral luminal circumference.

METHODS

Twelve juvenile female Yorkshire pigs (24 ureters) were evaluated. The inner (i.e. luminal) circumference of each ureter was determined using Cook urethral dilators ranging from 8-24Fr in 2Fr increments, 37cm in length. Each dilator was sequentially passed while applying the UAS force sensor to measure insertion force before and after one week of stent placement. Each ureter was randomized to receive either a 4.7Fr or 7.0Fr stent (20cm). Maximum ureteral luminal circumference was defined as successful passage of the dilator to the ureteropelvic junction with <6 newtons (N) of force (the force threshold previously defined by porcine and clinical studies to avoid ureteral damage). Following passage of the largest dilator at 6N, flexible ureteroscopy was performed and a post-ureteroscopic lesion score (PULS) was recorded.

RESULTS

After one week of stent placement, the median ureteral luminal circumference increased to 15Fr representing a mean increase of 3.8Fr + 2.8 (p<0.001). Twenty-one (88%) of the pre-stented ureters had an increase in luminal circumference, with 12 ureters (50%) dilated to >16Fr (p=0.032), six ureters (25%) dilated to >18Fr, and in two cases a maximum size of 24Fr was recorded. The PULS grade was < 2 in all cases, indicating no high grade ureteral injuries. Laterality and stent size did not impact ureteral luminal circumference after pre-stenting (p=0.232 and p=0.337, respectively).

CONCLUSIONS

One week of ureteral stenting resulted in nearly a 4Fr increase in the luminal circumference of porcine ureters.

Multidisciplinary Approach and Outcomes of Pretreatment Small (cT1a) Renal Mass Biopsy: Single-Center Experience

PURPOSE

We evaluated our experience of a multidisciplinary approach to renal mass biopsy (RMB) for small renal masses (SRM) employing in-office ultrasound (US) guided biopsy by urology (24%), computed tomography (CT) or US biopsy by interventional radiology (IR) (79%), and endoscopic ultrasound-guided biopsy by gastroenterology (GI) (4%).

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 non-diagnostic. Based on biopsy results, 71 patients (37%) elected active surveillance. Thirty-eight (20%) patients underwent cryoablation, 56 (29%) underwent partial nephrectomy (PN), 14 (7%) underwent radical nephrectomy (RN) 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 RCC 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 renal mass biopsy 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.

The Case for Laparoscopic Nephrectomy in Contemporary Practice

The first laparoscopic nephrectomy performed in 1990 laid the foundation for the use of minimally invasive surgery in treatment all major urologic pathology. Compared to the open technique, laparoscopy promised equivalent oncologic outcomes, shorter operating room times, less blood loss and shorter convalescence times. However, with the introduction of the Da Vinci Surgical System in the early 2000's there was a push to replace all forms of laparoscopy with robotic technique. Unlike laparoscopy, the adoption of the robotics was driven by aggressive marketing rather than evidence of superior outcomes. Although the robotic technique has many benefits in pelvic and reconstructive surgery, the same benefits do not necessarily translate to the radical renal surgery such as radical nephrectomy. The robotic platform is costly to acquire and maintain. Multiple studies show no superiority in oncologic outcomes, operating room times, blood loss or complications rates when comparing robotic to laparoscopic nephrectomy. Conversely, laparoscopic radical nephrectomy is a well established technique that is backbone of training in most residency programs. The equipment is readily available in most hospitals and the availability of staplers and alternate energy devices makes it safe and effective, especially in radical nephrectomy due to the extirpative nature of the procedure. In the absence of any measurable benefit of robotics over laparoscopy, there remains a role for laparoscopic radical nephrectomy in contemporary practice.

Crowd-Sourced Assessment of Surgical Skills of Urology Resident Applicants: Four-Year Experience

OBJECTIVE

To determine a) if surgical skills among urology resident applicants could be reliably assessed via crowdsourcing and b) to what extent surgical skills testing impacts resident selection.

DESIGN

Interviewees completed the following surgical skills tasks during their interview day: open knot tying (OKT), laparoscopic peg transfer (LPT), and robotic suturing (RS). Urology faculty and crowd-workers evaluated each applicant's video-recorded performance using validated scoring and were assessed for agreement using Cronbach's alpha. Applicants' USMLE scores, interview scores, and Jefferson Scale of Physician Empathy (JSPE-S) scores were assessed for correlation with skills testing scores and match rank. Additionally, a survey was distributed to interviewees assessing match outcomes.

SETTING

University of California Irvine Department of Urology, Surgical Skills Laboratory PARTICIPANTS: All 94 urology residency interviewees at the University of California Irvine Department of Urology from 2015-2018 were invited to complete the three surgical skills tasks on their interview day.

RESULTS

Survey responses were received from all 94 interviewees (100%). Crowd and expert agreement was good (α=0.88), fair (α=0.67), and poor (α=0.32) for LPT, RS, and OKT scores, respectively. The skills testing scores did not correlate with match rank, USMLE score, or JSPE-S score. On multivariate analysis, only interview score (r= -0.723; p<0.001) and faculty LPT score (r=-0.262; p=0.001) were significant predictors of match rank. Interviewees who reported matching into a top 3 residency choice had significantly higher faculty LPT scores than those who did not (11.9 vs. 9.7, p=0.03).

CONCLUSIONS

Surgical skills overall did not significantly impact match rank. Expert assessment of laparoscopic peg transfer skills and interview performance among urology resident applicants correlated with match rank.

Ex-vivo Renal Stone Dusting: Impact of Laser Modality, Ureteral Access Sheath, and Suction on Total Stone Clearance

INTRODUCTION AND OBJECTIVES

Conventional renal stone dusting is challenging; the holmium laser (Ho:YAG) and holmium with MOSES Effect (Ho:YAG-MOSES) fail to uniformly produce fragments <100 microns (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 six: laser type (Ho:YAG, Ho:YAG-MOSES, sTFL), ureteroscope (URS) with and without applied suction, and presence or absence of a 14Fr ureteral access sheath (UAS). Calcium oxalate stones were pre-weighed and implanted into each kidney via a pyelotomy. Stones were treated at 16 watts using dusting settings of 0.4Jx40Hz (Ho:YAG) 0.2Jx80Hz (Ho:YAG-MOSES), and 0.2Jx80Hz (sTFL) for up to 20 minutes. No stone basketing was performed. Kidneys were bi-valved and residual fragments were collected, dried, weighed, and sieved to determine fragment size and stone clearance.

RESULTS

Initial stone mass (mg), procedure time (sec), and laser energy expenditure (kJ) were similar in all 12 groups. The greatest stone clearance was seen with sTFL+suction+UAS (94%) compared to 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 laser, 14F ureteral access sheath, and aspiration. This combination resulted in 94% of stone fragments cleared; the 6% remaining fragments were all <2 mm. In all scenarios, deployment of a 14Fr UAS improved stone clearance.

Endoscopic Guided Percutaneous Nephrolithotomy

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.

Office-Based Renal Tumor Biopsy: a Paradigm Change in the Management of a Small Renal Mass?

PURPOSE OF REVIEW

The goal of this paper is to evaluate the use of an office-based renal mass biopsy (RMB), whose feasibility could represent a paradigm shift in clinical practice.

RECENT FINDINGS

Despite the earlier diagnosis of patients with renal masses, the lack of evidence showing a reduction in cancer-specific mortality warrants an examination in treatment practices. RMB is underutilized when compared to biopsy practice for all other neoplasms in every other solid organ (except testis), and the majority of RMB performed are outsourced to interventional radiologists. Performing an ultrasound-guided, office-based RMB is safe, reproducible, and has a meaningful impact on management decisions. The use of percutaneous RMB in clinical practice is growing, and the use of RMB has meaningful impact on management decisions for renal masses. Incorporating ultrasound-guided biopsy of a renal mass into clinical practice is feasible, and in contemporary practice, the urologist has the skill set to perform the procedure reliably, with low morbidity, and with minimal patient discomfort.

Can preoperative renal mass biopsy change clinical practice and reduce surgical intervention for small renal masses?

INTRODUCTION

The role of renal biopsy prior to surgical intervention for a renal mass remains controversial despite the fact that for all other urological organs except the testicle, biopsy inevitably precedes treatment as is true for all other specialties dealing with solid masses (e.g. thyroid, breast, colon, liver, etc.). Accordingly, we sought to determine the impact of a routine biopsy regimen on the course of patients with cT1a lesions in comparison with a contemporary series of cT1a individuals who went directly to treatment without a preoperative biopsy.

METHODS

We analyzed a multi-institutional, prospectively maintained database of patients who underwent an office-based, ultrasound-guided, renal mass biopsy (RMB) for a cT1a renal mass (i.e. ≤4cm in largest dimension). Controls were selected from all patients in the database who had a cT1a renal lesion but did not undergo RMB. Both groups were analyzed for differences in treatment modality and surgical pathology results.

RESULTS

A total of 72 RMB and 73 control patients were analyzed. The groups were similar in regards to their baseline characteristics. Overall RMB diagnostic rate was 75%. Surgical pathology revealed that excision of benign tumors was eight-fold less in the RMB cohort compared to the control group (3% vs. 23%; P < 0.001). Additionally, the rate of active surveillance in the RMB cohort was nearly three times higher at 35% vs. 14% for the controls (P < 0.001). Biopsy was concordant with surgical pathology in 97% of cases for primary histology (i.e. benign vs. malignant), 97% for histologic subtype, and 46% for low (I or II) vs. high (III or IV) grade. On multivariate analysis patients who underwent surgical intervention without preoperative RMB were 6.7 times more likely to have benign histopathology compared to patients who underwent preoperative RMB (OR 6.7, 95% CI = 0.714 - 63.626, P = 0.096). There were no procedural or post-procedural RMB complications.

CONCLUSIONS

For patients with cT1a lesions, the implementation of routine office-based RMB led to a significant decrease in the rate of surgical intervention for benign tumors. This practice also resulted in a higher rate of active surveillance for the management of renal cortical neoplasms with benign histopathology compared to a control group.

Global Assessments of the Endockscope System: Long-Term Impact of Cyber Endoscopy

INTRODUCTION

The disproportionate costs of state-of-the-art endoscopic equipment prohibit urologists from performing endoscopy in underserved countries. Given the global prevalence of smartphones, we engineered a $45 alternative endoscope utilizing three-dimensional (3D) printed attachments, an 8x lens, and a 1,000-lumen light-emitting diode (LED) cordless flashlight (Endockscope System (ES)).

MATERIALS AND METHODS

At the 34th World Congress of Endourology in Cape Town, South Africa (WCE 2016; 4-year group) and at the 39th Congress of the Société Internationale d'Urologie in Athens, Greece (SIU 2019; 8-month group), a total of 40 ES kits were distributed free of charge to an international group of urologists. Participants were given instructions and a hands-on demonstration of the device. Urologists given an ES were subsequently asked to complete a survey between June and September 2020 which included questions regarding user satisfaction, comfort, and comparability of the ES to standard endoscopic systems.

RESULTS

Urologists from 23 countries received ES kits. Overall, 10 of 22 urologists (10/22; 45%) from the 4-year group and 18 of 18 urologists (18/18; 100%) from the 8-month group completed the survey. The ES device was used by 80% (8/10) and 83% (15/18) of urologists from the 4-year and the 8-month groups, respectively. Of note, the greatest impact of ES usage was among urologists from the most impoverished countries. Of those who used the ES, 44% (4/9) of urologists from the 4-year cohort and 47% (8/17) from the 8-month cohort reported they were able to perform more endoscopic procedures directly because of the ES. Moreover, 57% (4/7) of the 4-year participants and 67% (10/15) of the 8-month participants found the ES equal or superior in quality to their standard endoscopic equipment.

CONCLUSION

The ES provided an effective and inexpensive system that enabled urologists in resource-challenged countries to successfully perform and expand their use of urological endoscopy.

Caveat Emptor: The Heat Is "ON": An In Vivo Evaluation of the Thulium Fiber Laser and Temperature Changes in the Porcine Kidney during Dusting and Fragmentation Modes

INTRODUCTION

We sought to examine the intrarenal fluid and tissue temperature during dusting and fragmentation with the Thulium fiber laser (TFL) in an in vivo porcine kidney.

METHODS

In two pigs, temperature was continuously measured within the upper, middle, and lower calyces and at the tip of the ureteroscope. Four experimental protocols were performed: dual lumen ureteroscope with both warmed (37°C) and room temperature (20-22ºC) irrigation and single lumen ureteroscope with warmed and room temperature irrigation. In each pig, one kidney had a 14F ureteral access sheath (UAS), other kidney had no UAS. A 200µm TFL was fired at three settings: dusting (0.5J, 80Hz, 40W) with continuous activation for 5 minutes or until a temperature reached 44⁰C; low power (1J, 10Hz, 10W) and high-power fragmentation (1.5J, 20Hz, 30W). For fragmentation, the laser was activated for 10 seconds with a 2 second intermission for 1 minute.

RESULTS

In the absence of an UAS, in all but one circumstance, temperatures exceeded 44ºC at all settings with the use of either warm or room temperature irrigation, regardless of the type of ureteroscope. Temperatures recorded at the ureteroscope tip were 4ºC - 22ºC less than the temperatures recorded in the renal calyces. In contrast, with a 14F UAS in place, 6 distinct groups had temperatures that did not exceed 44ºC, 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 at the ureteroscope tip with an UAS yielded temperature differences from 17ºC less to 19ºC more than the renal calyces.

CONCLUSIONS

Thulium fiber laser is a novel technology for lithotripsy. In the absence of a UAS, high-power TFL fragmentation settings, may create temperatures that could result in urothelial tissue injury.

Outcomes of Artificial Intelligence Volumetric Assessment of Kidneys and Renal Tumors for Preoperative Assessment of Nephron Sparing Interventions

Background Renal cell carcinoma is the most common kidney cancer and the 13th most common cause of cancer death worldwide. Partial nephrectomy and percutaneous ablation, increasingly utilized to treat small renal masses and preserve renal parenchyma, require precise preoperative imaging interpretation. We sought to develop and evaluate a convolutional neural network (CNN), a type of deep learning artificial intelligence, to act as a surgical planning aid by determining renal tumor and kidney volumes via segmentation on single-phase computed tomography (CT). Materials and Methods After institutional review board approval, the CT images of 319 patients were retrospectively analyzed. Two distinct CNNs were developed for (1) bounding cube localization of the right and left hemi-abdomen and (2) segmentation of the renal parenchyma and tumor within each bounding cube. Training was performed on a randomly selected cohort of 269 patients. CNN performance was evaluated on a separate cohort of 50 patients using Sorensen-Dice coefficients (which measures the spatial overlap between the manually segmented and neural network derived segmentations) and Pearson correlation coefficients. Experiments were run on a GPU-optimized workstation with a single NVIDIA GeForce GTX Titan X (12GB, Maxwell architecture). Results Median Dice coefficients for kidney and tumor segmentation were 0.970 and 0.816, respectively; Pearson correlation coefficients between CNN-generated and human-annotated estimates for kidney and tumor volume were 0.998 and 0.993 (p < 0.001), respectively. End-to-end trained CNNs were able to perform renal parenchyma and tumor segmentation on a new test case in an average of 5.6 seconds. Conclusions Initial experience with automated deep learning artificial intelligence demonstrates that it is capable of rapidly and accurately segmenting kidneys and renal tumors on single-phase contrast-enhanced CT scans and calculating tumor and renal volumes.

Analysis of Ureteral Diameter and Peristalsis in Response to Irrigant Fluid Temperature Changes in an In Vivo Porcine Model

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.

Interactive Virtual Reality Renal Models as an Educational and Preoperative Planning Tool for Laparoscopic Donor Nephrectomy

OBJECTIVE

To evaluate the efficacy of interactive virtual reality (iVR) in providing a three-dimensional (3D) experience with the donor's anatomy for surgeons and patients, we present a retrospective, case-controlled study assessing the impact of iVR renal models prior to LDN on both surgical outcomes and patients' understanding of the procedure.

MATERIALS AND METHODS

Twenty patients undergoing LDN were prospectively recruited; their contrast-enhanced CT scans were transformed into iVR models. An iVR platform allowed the surgeons to rotate and deconstruct the renal anatomy; patients could also view their anatomy as the procedure was explained to them. Questionnaires assessed surgeons' understanding of renal anatomy after CT alone and after CT+iVR. Surgeons also commented on whether iVR impacted their preoperative plan. Patients assessed their anatomical understanding and anxiety level before and after iVR. Surgical outcomes for the iVR cohort were compared to a retrospectively matched, non-iVR cohort of LDN patients.

RESULTS

Surgeons altered their preoperative plan in 18 of 20 LDNs after viewing iVR models. Patients reported better understanding of their anatomy (5/5) and noted decreased preoperative anxiety (5/5) after viewing iVR. When compared to the non-iVR group, the iVR group had a 25% reduction in median operative time (P < .001). In terms of surgical outcomes, patients in the iVR group had a 40% lower median relative change in postoperative creatinine (P < .001).

CONCLUSION

Preoperative viewing of iVR models altered the operative approach, decreased the operative time, and improved donor patient outcomes. iVR models also reduced patients' preoperative anxiety.

Evaluation of a Novel Female Gender Flexible Ureteroscope: Comparison of Flow and Deflection to a Standard Flexible Ureteroscope

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.

The impact of the number of lifetime stone events on quality of life: results from the North American Stone Quality of Life Consortium

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.

Initial Experience and Evaluation of a Nomogram for Outcome Prediction in Management of Medium-sized (1-2 cm) Kidney Stones

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.

Estimating the health-related quality of life of kidney stone patients: initial results from the Wisconsin Stone Quality of Life Machine-Learning Algorithm (WISQOL-MLA)

OBJECTIVE

To build the Wisconsin Stone Quality of Life Machine-Learning Algorithm (WISQOL-MLA) to predict urolithiasis patients' health-related quality of life (HRQoL) based on demographic, symptomatic and clinical data collected for the validation of the Wisconsin Stone Quality-of-Life (WISQOL) questionnaire, an HRQoL measurement tool designed specifically for patients with kidney stones.

MATERIAL AND METHODS

We used data from 3206 stone patients from 16 centres. We used gradient-boosting and deep-learning models to predict HRQoL scores. We also stratified HRQoL scores by quintile. The dataset was split using a standard 70%/10%/20% training/validation/testing ratio. Regression performance was evaluated using Pearson's correlation. Classification was evaluated with an area under the receiver-operating characteristic curve (AUROC).

RESULTS

Gradient boosting obtained a test correlation of 0.62. Deep learning obtained a correlation of 0.59. Multivariate regression achieved a correlation of 0.44. Quintile stratification of all patients in the WISQOL dataset obtained an average test AUROC of 0.70 for the five classes. The model performed best in identifying the lowest (0.79) and highest quintiles (0.83) of HRQoL. Feature importance analysis showed that the model weighs in clinically relevant factors to estimate HRQoL, such as symptomatic status, body mass index and age.

CONCLUSIONS

Harnessing the power of the WISQOL questionnaire, our initial results indicate that the WISQOL-MLA can adequately predict a stone patient's HRQoL from readily available clinical information. The algorithm adequately relies on relevant clinical factors to make its HRQoL predictions. Future improvements to the model are needed for direct clinical applications.

What is the relationship of stress to patients' kidney stone-related quality of life?

INTRODUCTION

Health-related quality of life (HRQOL) is decreased in patients with kidney stones at all stages of stone disease, even when asymptomatic. Stress is thought to contribute to HRQOL, although there has been minimal investigation into the effect of stress on stone-related quality of life (QOL). We used the Wisconsin Stone Quality of Life Questionnaire (WISQOL) to assess the relationship of stress to stone-related QOL in kidney stone patients.

METHODS

As part of the WISQOL Research Consortium, patients were approached in outpatient clinics and completed the WISQOL and the Perceived Stress Scale 10-item questionnaire (PSS-10). Patients with stones at enrollment were divided into those with symptoms and those without, while patients with no current stones formed another group. Questionnaire scores from each group were compared statistically and correlations between the groups were calculated.

RESULTS

Patients (n=704) were enrolled from six centers. The WISQOL successfully discriminated between patients with current stones and those without (p<0.0001), while the PSS-10 did not (p=0.0869). The PSS-10 revealed patients with symptomatic kidney stones experienced higher levels of general stress than asymptomatic subjects (p<0.0001). However, a Pearson correlation test comparing the responses from each instrument revealed no overall correlation between general stress and HRQOL (r=0.05).

CONCLUSIONS

Symptomatic kidney stones increase general stress, as these patients demonstrate higher PSS-10 scores. Despite this, no correlation exists between general stress and stone-related QOL in patients with stone disease regardless of their stone and symptom status. This implies the existence of other factors impacting QOL in these patients, which warrants further exploration.

In Vitro Evaluation of Stone Fragment Evacuation by Suction

Introduction: Contemporary, flexible stone baskets are unable to extract submillimeter stone fragments at the time of ureteroscopic laser lithotripsy. In this in vitro study, the feasibility of suctioning submillimeter fragments with a standard Luer Lock syringe through the working channel of a flexible ureteroscope was assessed. Materials and Methods: Phantom stones made from industrial plaster were mechanically fragmented into ≤1 and ≤0.5-mm groups. Both stone groups were divided into five preweighed trial samples. Each stone group was then mixed in a beaker filled with normal saline. A standard 10-mL Luer Lock syringe was connected to a fiber-optic ureteroscope with a 1.2-mm working channel. The syringe was then used to suction stone fragments from the beaker. The suctioned stone fragments and the stone fragments remaining in the beaker after removing the overlying solution were separated, centrifuged with supernatant removed, and dried in an incubator set at 33°C for 1 week. Dried weights were recorded. Results: Mean total weights for ≤0.5 and ≤1.0-mm stone groups at baseline were 0.807 and 0.806 g, respectively. The mean percentages of stone fragments suctioned through the ureteroscope for ≤0.5 and ≤1.0-mm groups were 86% and 86%, respectively (p = 0.973). During suctioning, 64% of stones in the ≤0.5-mm group were trapped in either the working channel of the ureteroscope or within the Luer Lock syringe compared with 78% of stones in the ≤1-mm group (p = 0.001) requiring cessation of the procedure to clear the channel. Conclusions: It is feasible to suction submillimeter stone fragments by connecting a Luer Lock syringe to the working channel of a flexible ureteroscope. The limiting factor for removing stone fragments appears to be the small working channel of flexible ureteroscopes as trapping of fragments during suctioning is common and requires time-consuming removal of the endoscope and clearing of the channel.

Metabolic Syndrome Negatively Impacts Stone-Specific Quality of Life

Purpose: Metabolic syndrome (MetS) is a cluster of metabolic diseases that is linked to atherosclerotic cardiovascular disease. MetS has also been linked to increased nephrolithiasis. However, limited research has been conducted on MetS and its impact on stone-specific health-related quality of life (HRQOL). This study aims to examine the hypothesis that the presence of MetS is associated with decreased HRQOL. Materials and Methods: The Wisconsin Stone Quality of Life Questionnaire, a stone-specific HRQOL questionnaire, was used to survey 3051 patients with kidney stones. Medical history was collected from patients. These data were used to distinguish MetS patients from non-MetS patients. Among patients with current stones, a Wilcoxon rank sum test was used to compare HRQOL scores from MetS patients and non-MetS patients. HRQOL from patients with and without individual MetS components were also compared, and a multivariate analysis was conducted. Results: Statistical comparison between MetS patients (median score 102/140) and non-MetS patients (median score 106/140) demonstrated a lower stone-specific HRQOL in patients with MetS (p = 0.049). Among individual MetS components, patients with diabetes mellitus (DM) or body mass index (BMI) >30 had significantly lower HRQOL than patients without DM or BMI <30 (p = 0.028 and p < 0.001, respectively). The multivariate analysis supported this trend as MetS remained a significant predictor of decreased HRQOL (p = 0.002) after controlling for other variables assessed. Conclusions: This study indicates an association between MetS and a lower stone-specific QOL. This has important implications for stone prevention strategies in patients with MetS. Clinical Trial Registration number: H14-01143.