Ralph V. Clayman

Objective: Retrograde intrarenal surgery is limited by the narrow caliber of the human ureter, resulting in both reluctance to deploy larger ureteral access sheaths and, at times, failed primary ureteral access, requiring placement of a ureteral stent and a delayed second procedure. In this study, we sought to evaluate the application of electromotive drug administration (EMDA) to deliver smooth muscle relaxants to the porcine ureter to facilitate acute ureteral dilation. Methods: Eighteen juvenile female Yorkshire pigs were randomized into three treatment groups (alfuzosin, aminophylline, or isoproterenol; n = 6 per group). Within each animal, one ureter received an intraureteral drug infusion with EMDA, while the contralateral ureter served as a control, receiving 0.9% normal saline (NS). Ureteral size was assessed before and after treatment by passing sequentially larger urethral dilators starting at 10 Fr, with a maximum insertion force of 3.5 N. Results: Only alfuzosin with EMDA increased ureteral size compared with NS alone (alfuzosin vs NS, 0.8 Fr vs 0.1 Fr, p = 0.031). Neither aminophylline nor isoproterenol with EMDA resulted in a significant increase in ureteral size compared with their respective NS controls (aminophylline vs NS, 0.3 Fr vs −0.6 Fr, p = 0.344; isoproterenol vs NS, 0.1 Fr vs −0.4 Fr, p = 0.125). Conclusion: In this first report, EMDA-mediated in vivo delivery of alfuzosin into the porcine ureter acutely increased ureteral distensibility.

Prior laser studies have demonstrated that as the temperature of a medium increases, the amount of energy delivered to the target increases. We sought to investigate the role of irrigation fluid temperature on Thulium fiber laser (TFL) urolith ablation. 360 calculi were divided in vitro according to chemical composition: calcium oxalate monohydrate (COM), cystine (CYS), struvite (STR), calcium phosphate (CAP), uric acid (UA), and calcium oxalate dihydrate (COD). A 200 μm TFL was placed directly on each stone, while immersed in 0.9% NaCl at four different temperatures (25 C, 37 C, 44 C, 60 C) and a single laser pulse administered at distinct energy settings (0.1 J, 0.5 J, 1.5 J). Optical coherence tomography assessed the resulting ablation cone volume. Mean stone volume and porosity were evaluated through ANOVA and Tukey post-hoc analysis. A multivariate generalized model for each composition accounted for the impact of fluid temperature and laser energy on stone ablation. Warmer fluid temperatures yielded greater ablation cone volumes for most energy settings, excluding UA stones. When accounting for chemical composition, higher tensile strength stones (COM, CYS) benefited most from warmer fluid in comparison to frangible stones (CAP, STR). The effects of increasing fluid temperature are modest relative to laser pulse energy as a large temperature increase (i.e. 7ºC) is equivalent to a minor energy increase (i.e. 0.1 J). For non-UA stones, TFL ablation efficiency increases with warmer irrigation fluid. The effect, albeit modest compared to laser pulse energy, was most notable for COM and CYS stones.

Purpose: Retrograde intrarenal surgery is the gold-standard treatment for most kidney stones. During ureteroscopy, ureteral access sheath insertion at forces greater than 8.0 Newtons (N) risks high-grade ureteral injury. To monitor force, our institution utilizes a unique, Bluetooth-equipped device (i.e., the University of California—Irvine Force Sensor). Given the unique nature of the force sensor, we sought to develop an inexpensive and accessible force sensor based on Boyle’s law and the specific amount of force required to compress an occluded 1.0 mL syringe. Materials and Methods: We evaluated three brands of 1.0 mL syringes. After setting the plunger at 1.0 mL, the syringe was occluded, and the syringe plunger was compressed. The syringe volume was recorded when the applied force on the plunger reached 4.0 N, 6.0 N, and 8.0 N. Multiple trials were performed to assess reliability and reproducibility. A method for applying this clinically was also developed. Results: The precise force thresholds identified for a 1.0 mL Luer-Lok™ Syringe (Becton Dickinson, Franklin Lakes, NJ) were 0.30 mL for 4.00 N, 0.20 mL for 6.00 N, and 0.15 mL for 8.00 N. The 1.0 mL Tuberculin Syringe and 1.0 mL Luer Slip Syringe were less precise, but compression from 1.0 to 0.40 mL, 0.25 mL, and 0.20 mL corresponded to force sensor readings that did not exceed 4.00 N, 6.00 N, and 8.00 N, respectively. Conclusions: Based on volume changes, 4.00 N, 6.00 N, and 8.00 N of force can be reliably and reproducibly achieved using an occluded 1.0 mL syringe.

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).

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 8Fr dual lumen catheter and a 5Fr 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 4mA 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.

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.

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.

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 via an EMDA machine, while 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.

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 printed attachments, an 8 × lens, and a 1000-lumen light-emitting diode 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 (SIU) 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 that 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 effectively perform and expand their use of urologic endoscopy.