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.

Qualitative Review of Clinical Guidelines for Medical and Surgical Management of Urolithiasis: Consensus and Controversy 2020.

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

Determining the Safety Threshold for the Passage of a Ureteral Access Sheath in Clinical Practice Using a Purpose-Built Force Sensor.

PURPOSE: Ureteral injury is a frequent complication of ureteral access sheath deployment. We sought to define the safe threshold of force for the passage of a ureteral access sheath using a novel ureteral access sheath force sensor. MATERIALS AND METHODS: Ureteral access sheath-force sensor measurements were recorded in 210 renal units. A 16Fr ureteral access sheath was deployed initially based on a prior porcine study. If 6 N was reached, the surgeon was advised to downsize the 16Fr ureteral access sheath. In each case, a post-ureteroscopic lesion scale was recorded. Regression models were used to estimate the impact of adjusted variables on post-ureteroscopic lesion scale grade, 16Fr ureteral access sheath deployment, and peak force. RESULTS: A 16Fr ureteral access sheath was deployed in 127 (61%) renal units with a mean peak force of 5.7 N. Two high-grade ureteral injuries occurred; in both cases >6 N of force was recorded. Post-ureteroscopic lesion scale grade correlated directly with peak insertion force (p <0.01). Bacteriuria within 60 days of the procedure (OR 2.009, p=0.034), combination of preoperative stent plus oral tamsulosin (OR 2.998, p=0.045), and prior ipsilateral stone surgery (OR 2.13, p=0.01) were independent predictors of successful 16Fr ureteral access sheath deployment. Among patients with neither prior ipsilateral stone surgery nor preoperative stent, preoperative tamsulosin facilitated passage of a 16Fr ureteral access sheath (OR 2.750, p=0.034). CONCLUSIONS: Ureteral access sheath associated ureteral injury can be averted by limiting the insertion force to ≤6 N. Prior stone surgery, preoperative indwelling ureteral stent plus oral tamsulosin, and recently treated bacteriuria favored passage of a 16Fr ureteral access sheath. In the naïve, unstented patient, preoperative tamsulosin favored deployment of a 16Fr ureteral access sheath.

Long-Term Antibiotic Treatment Prior to Laparoscopic Nephrectomy for Xanthogranulomatous Pyelonephritis Improves Postoperative Outcomes: Results from a Multicenter Study.

PURPOSE: Xanthogranulomatous pyelonephritis is a destructive bacterial infection typically necessitating nephrectomy. We hypothesized that long-term preoperative antibiotics would facilitate laparoscopic nephrectomy by reducing the renal inflammation. MATERIALS AND METHODS: We reviewed the records of all patients with histologically confirmed xanthogranulomatous pyelonephritis at 3 University of California institutions between 2005 and 2018. Patients were stratified by antibiotic treatment duration and surgical approach. Patients treated with long-term preoperative antibiotics (28 days or more of continuous treatment until surgery) were compared to patients treated with short-term antibiotics (less than 28 days) and those who only received single-dose prophylactic antibiotics before surgery. Patient demographics and operative outcomes were analyzed. Complications were assigned by Clavien-Dindo classification. RESULTS: Among the 61 patients, 51 (84%) were female and mean age was 50 years. There were 21 (34%) open procedures and 40 (66%) laparoscopic procedures. Median duration of antibiotic treatment was 5 days in those who received a short-term treatment and 87 days in those who received long-term treatment. Eleven patients received only prophylactic single-dose antibiotics. Using multivariate analysis among patients undergoing laparoscopic nephrectomy, controlling for preoperative drainage, long-term antibiotics resulted in a 6.5-day shorter length of stay (p=0.023) and less overall as well as milder postoperative complications (p <0.001). CONCLUSIONS: Greater than or equal to 4 weeks of preoperative antibiotics before laparoscopic nephrectomy for xanthogranulomatous pyelonephritis was associated with shorter length of stay and fewer, less severe postoperative complications.

Comparison of Conventional and Triple Bolus Computerized Tomographic Urography Protocols for Radiation Dose Reduction in Hematuria Evaluation: A Randomized Controlled Trial.

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

Characterization of intracalyceal pressure during ureteroscopy.

PURPOSE: To provide the first report of measuring intracalyceal pressures during ureteroscopy (URS). METHODS: A prospective single-center clinical study using a cardiac pressure guidewire to measure intracalyceal pressure during flexible URS was performed. Eight patients (45 calyces) undergoing URS for nephrolithiasis were included. A Verrata® pressure guide wire was passed through the working channel of a dual lumen flexible ureteroscope and into the calyces while irrigation was maintained at 150 mmHg. Pressure was measured in the renal pelvis, upper pole, interpolar, and lower pole calyces both with and without a ureteral access sheath (UAS). The pressure in each location with and without a UAS was compared. The correlation between calyceal pressure and infundibular dimensions (width, length) was determined. RESULTS: Intracalyceal pressure was significantly lower in each region when a UAS was used. Compared to patients with a 12/14Fr UAS, those with a 14/16Fr UAS had significantly lower pressure in the interpolar (25.3 ± 13.1 vs. 44.0 ± 27.5 mmHg, p = 0.03) and lower pole (16.2 ± 3.5 vs. 49.2 ± 40.3 mmHg, p = 0.004) calyces. Interpolar calyceal pressure in the presence of a UAS was significantly higher than the renal pelvis pressure (RPP) (30.8 ± 19.6 vs. 17.9 ± 11.0 mmHg, p = 0.004). CONCLUSIONS: During flexible URS, RPP strongly correlates with, but does not uniformly represent, the intracalyceal pressure. With a 14/16Fr UAS and an inflow pressure of 150 mmHg, RPP and intracalyceal pressure never exceed the threshold for renal backflow.

Smartphone technology and its applications in urology: a review of the literature.

PURPOSE: Smartphone technology has propelled the evolution of health-related mobile technology, referred to as mobile health (mHealth). With the rise of smartphone ownership and the growing popularity of health-related smartphone usage, mHealth offers potential benefits for both patients and health care providers. The objective of this review is to assess the current state of smartphone technology in urology. METHODS: A literature search of PubMed database was conducted to identify articles reporting on smartphone technology in urology. Publications were included if they focused on smartphone mHealth technology pertinent to the field of urology or included an evaluation of urological applications in digital stores. RESULTS: We identified 50 publications focused on the use of smartphones in urology. Studies were then grouped into the following categories: smartphones employing the built-in camera and light source, applications specific to prostate cancer, urolithiasis, pediatric urology, and as educational tools for urologists. In 23/50 (46%) studies, smartphone technology/intervention was compared to a control group or to standard of care. In this regard, smartphone technology did not demonstrate benefit over standard of care in 13 studies. In contrast, in 10 studies, smartphone interventions were proven beneficial over current practice. CONCLUSIONS: Smartphone technology is constantly evolving and has the potential to improve urological care and education. Of concern to consumer and urologist alike is that these downloadable programs are limited due to the accuracy of their content, risk of confidentiality breach, and the lack of central regulation and professional involvement in their development.

Effect of positioning on ureteric stone retropulsion: 'gravity works'.

OBJECTIVE: To evaluate the potential impact of alterations in 'patient' position on laser-induced ureteric stone retropulsion in an in vitro model. MATERIALS AND METHODS: A ceramic (phantom) stone was placed in a water-filled clear polymer tube and subjected to continuous laser energy until the stone had retropulsed a distance of 10 cm. The trial was stopped after 60 s if the stone had not reached 10 cm. The time and total energy needed to cause 10 cm of retropulsion were recorded at incline angles of 0°, 10°, 20°, and 40°; 10 trials at each angle were completed. The study was then repeated with pure calcium phosphate brushite stones. RESULTS: Retropulsion decreased with increasing incline angle of the saline-filled clear polymer tube. At 0° of incline the phantom stone reached a distance of 10 cm after 7.4 s. At 10°, 20° and 40°, the phantom stone migrated a mean maximum distance of 3.1, 1.2 and 0.7 cm, respectively, and the trial was stopped after 60 s. For the calcium phosphate stone, at 0° and 10° of incline, the stone reached 10 cm after 6.9 and 42.8 s, respectively (P < 0.05). At 20° and 40°, the calcium phosphate stone moved a mean maximum distance of 2.4 and 1 cm, and the trial was stopped after 60 s. CONCLUSION: Alterations in the angle of inclination reduced stone retropulsion during ureteroscopic lithotripsy in an in vitro model to <1 cm. Increasing the incline angle of a patient may effectively preclude retropulsion when performing laser lithotripsy of ureteric stones.

Ureteroscopic holmium laser-assisted retrograde nephrostomy access: a novel approach to percutaneous stone removal.

INTRODUCTION AND OBJECTIVES: Percutaneous nephrolithotomy remains a challenging procedure primarily due to difficulties obtaining access. Indeed, few urologists obtain their own access due to difficulties using a fluoroscopic or ultrasonic based antegrade puncture technique. Herein we report the first experience using holmium laser energy to obtain access in a retrograde fashion. METHODS: After a pretreatment week of tamsulosin 0.4 mg/day (one center only) and following a documented sterile urine, a total of ten patients underwent retrograde holmium laser-assisted endoscopic-guided nephrostomy access in a prone split leg position. RESULTS: In nine of ten patients, ureteroscopic guided, holmium laser access via an upper pole posterior calyx was achieved. In one patient, the laser tract could not be safely dilated and antegrade endoscopic and fluoroscopic guided access was performed. The mean operative time was 202 min; the mean fluoroscopy time was 32 s (6/9 cases). The mean pre-operative stone volume was 14,420 mm3. CT imaging on post-operative day 1 revealed 6/6 patients had residual stone fragments with total mean volume of 250 mm3 (96% reduction); there were no residual fragments in three patients who were evaluated with non-CT radiographic imaging (KUB). There was a single complication requiring angioembolization due to a subcapsular hematoma with associated secondary tearing of an inter-polar vessel remote from the nephrostomy site. CONCLUSIONS: Holmium laser-assisted endoscopic-guided retrograde access in a prone split-leg position was successfully performed at two institutions. The accuracy of nephrostomy placement and lessening of fluoroscopy time are two potential benefits of this approach.

Medical impulsive therapy (MIT): the impact of 1 week of preoperative tamsulosin on deployment of 16-French ureteral access sheaths without preoperative ureteral stent placement.

INTRODUCTION AND OBJECTIVES: Medical expulsive therapy is based on pharmacologic ureteral relaxation. We hypothesized this concept may facilitate the deployment of the large 16 French (F) ureteral access sheath (UAS) when patients are intentionally pre-treated with oral tamsulosin, i.e., medical impulsive therapy. METHODS: We retrospectively analyzed our experience with UAS deployment during endoscopic-guided percutaneous nephrolithotomy in prone position in patients pre-treated for 1 week with oral tamsulosin with a contemporary untreated cohort. Between January 2015 and September 2016, seventy-seven patients without a pre-existing ureteral stent met inclusion criteria. Demographic data, tamsulosin usage, UAS size, deployment failure, ureteral injuries, stone-free rates, and complications were recorded. Univariate and multivariate analysis was conducted to assess the impact of tamsulosin on deployment of the 16F UAS. RESULTS: There was no statistical difference between the tamsulosin (n = 40) group and non-tamsulosin (n = 37) group in regard to demographic data. The tamsulosin group had a significantly higher percentage of 16F UAS deployment, 87 vs. 43% (p < 0.001), and no significant difference in ureteral injuries (p = 0.228). Univariate and multivariate analysis revealed that tamsulosin significantly increased the odds ratio (9.3 and 19.4, respectively) for successful passage of a 16F UAS. Despite a larger stone volume, there was no significant difference in computed tomography scan complete stone-free rates (29 vs. 42%; p = 0.277) at median post-operative time of only 3 days. CONCLUSIONS: In this retrospective study, 1 week of preoperative tamsulosin was associated with an increase in the deployment of a 16F UAS in patients without preoperative ureteral stent placement.

Renal mass biopsy: an oncological conundrum.

PURPOSE OF REVIEW: We evaluate the reasons that the majority of urologists infrequently biopsy a T1a small renal mass (SRM). RECENT FINDINGS: The majority of urologists report that a renal mass biopsy will not change their management in patients with a SRM given concerns of safety and efficacy of the biopsy. However, when comparing the safety and efficacy of SRM biopsy with neoplasms in all other major organ systems (all of which require biopsy prior to treatment), renal mass biopsy results are favorable. In addition to being safe and effective, renal mass biopsy should be more cost-effective for the healthcare system. Finally, in properly selected patients, renal mass biopsy can be performed in the urologist's office, thereby further decreasing cost. SUMMARY: Renal mass biopsy is an essential clinical tool that needs to be incorporated into the decision-making process among patients with a T1a SRM. A biopsy-driven, tissue-specific diagnosis of SRMes should become the standard of care in urology to bring us to parity with standard practice to management of lesions identified in every other organ system.

Precise Characterization and 3-Dimensional Reconstruction of the Autonomic Nerve Distribution of the Human Ureter.

PURPOSE: We sought to characterize and 3-dimensionally reconstruct the distribution of the autonomic innervation of the human ureter. MATERIALS AND METHODS: Three male and 3 female pairs of ureters were evaluated at 2 mm serial transverse sections along the entire length of the ureter. The location of nerve tissue was immunohistochemically identified using the neuronal marker, S100 protein. ImageJ software was used to calculate nerve count and density in the adventitia and smooth muscle. Blender® graphics software was used to create a 3-dimensional reconstruction of autonomic nerve distribution. RESULTS: Within the adventitia nerve density was highest in the mid and distal ureter (females 2.87 and 2.71 nerves per mm2, and males 1.68 and 1.69 nerves per mm2) relative to the proximal ureter (females and males 1.94 and 1.22 nerves per mm2, respectively, p >0.0005). Females had significantly higher nerve density throughout the adventitia, especially in the distal ureter (2.87 vs 1.68 nerves per mm2, p <0.0005). In smooth muscle the nerve density progressively increased from the proximal to the distal ureter (p >0.0005). Smooth muscle nerve density was similar in the 2 genders (p = 0.928). However, in females nerve density was significantly higher in the first 2 cm of the distal ureter relative to the second 2 cm (3.6 vs 1.5 nerves per mm2, p <0.001) but not in males (3.0 vs 2.1 nerves per mm2, p = 0.126). CONCLUSIONS: Nerve density was highly concentrated at the distal ureter in the adventitia and smooth muscle of the male and female human ureters. The female ureter had greater nerve density in the adventitia, and in smooth muscle nerves were significantly concentrated at the ureteral orifice and the ureteral tunnel.

Laparoscopic Nephrectomy: Initial Case Report.

A tumor-bearing right kidney was completely excised from an 85-year-old woman using a laparoscopic approach. A newly devised method for intra-abdominal organ entrapment and a recently developed laparoscopic tissue morcellator made it possible to deliver the 190 gm. kidney through an 11 mm. incision.

Prone Versus Supine Percutaneous Nephrolithotomy: What Is Your Position?

PURPOSE OF REVIEW: Percutaneous nephrolithotomy (PCNL) is the gold standard surgical procedure for treating large, complex renal stones. Due to its challenging nature, PCNL has undergone many modifications in surgical technique, instruments, and also in patient positioning. Since the first inception of PCNL, prone position has been traditionally used. However, alternative positions have been proposed and assessed over the years. This is a comprehensive review on the latest developments related to positioning in the practice of PCNL. RECENT FINDINGS: The prone position and its modifications are the most widely used positions for PCNL, but with the introduction of various supine positions, the optimal position has been up for debate. Recent meta-analysis has shown a superior stone-free rate in the prone position and comparable complication rates to the supine position. The advantage of ease of access to the urethra for simultaneous retrograde techniques in the supine position is also possible with modifications in the prone position such as the split-leg technique. Modern-day PCNL has transformed from an operation traditionally undertaken in the prone position to a procedure in which a prone or supine position may be employed; however, published data have not shown significant superiority of either approach.

Treatment for T1a Renal Cancer Substratified by Size: "Less is More".

PURPOSE: Due to the widespread use of computerized tomography, the diagnosis of small renal cancers (3 cm or less) within the T1a classification continues to increase. Current treatment of these tumors includes radical nephrectomy, partial nephrectomy and thermal ablation. We used the SEER (Surveillance, Epidemiology, and End Results) Program to compare treatment modalities for these cancers based on 1 cm increments in tumor size. We examined overall survival, cancer specific survival, survival from cardiovascular disease and race based treatment disparities. MATERIALS AND METHODS: In the SEER database we identified 17,716 renal cancers 3 cm or less diagnosed from 2005 to 2010 treated with radical nephrectomy, partial nephrectomy or thermal ablation. Overall survival, cancer specific survival and cardiovascular survival were determined for each treatment group, and then substratified by size in centimeters, tumor grade, age, geographical location and ethnicity. Survival was analyzed using Kaplan-Meier methods, multivariate proportional hazards models and a propensity score weighted approach. RESULTS: Overall survival, cancer specific survival and cardiovascular survival were better for partial nephrectomy than radical nephrectomy in all circumstances. Thermal ablation showed equivalent overall survival to partial nephrectomy for tumors 2 cm or less. Notably, radical nephrectomy for renal tumors 3 cm or less was applied in a disparately larger number of black patients (OR 1.63, 95% CI 1.47-1.81) and Hispanic patients (OR 1.28, 95% CI 1.14-1.44). CONCLUSIONS: Radical nephrectomy should be avoided for all tumors 3 cm or less. For renal cancers 2 cm or less partial nephrectomy and thermal ablation are equally effective. For tumors 2.1 to 3 cm partial nephrectomy is better than thermal ablation. We identified significant racial treatment disparities that negatively impact survival in black and Hispanic patients.

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.