Jonathan D. Harper

Comparison of accuracy of 14-, 18- and 20-G needles in ex-vivo renal mass biopsy: a prospective, blinded study

Study Type – Diagnostic (exploratory cohort)
 Level of Evidence 2b

Adult UrologyOncology: Adrenal/Renal/Upper Tract/BladderRisk Factors for Renal Cell Carcinoma in the VITAL Study

PURPOSE The incidence of renal cell carcinoma is increasing worldwide. Cited risk factors include obesity, smoking and hypertension but few others have been confirmed in prospective studies. We used a prospective cohort to validate established renal cell carcinoma risk factors and evaluate more controversial risk factors for incident renal cell carcinoma. MATERIALS AND METHODS A total of 77,260 residents of Washington 50 to 76 years old completed a questionnaire between 2000 and 2002 on demographic, lifestyle and health data. Incident renal cell carcinoma cases were determined by linkage to the regional cancer registry through December 31, 2009. Multivariate methods using covariates and cutoffs selected a priori were applied to analyze the association between renal cell carcinoma and previously studied factors related to lifestyle (body mass index, smoking and alcohol/fruit/vegetable consumption) and health (hypertension, diabetes, kidney disease and viral hepatitis). RESULTS There were 249 incident cases of renal cell carcinoma. Independent renal cell carcinoma risk factors in the fully adjusted model were body mass index (35 or greater vs less than 25 kg/m2 HR 1.71, 95% CI 1.06-2.79), smoking (greater than 37.5 pack-years vs never HR 1.58, 95% CI 1.09-2.29), hypertension (HR 1.70, 95% CI 1.30-2.22), kidney disease (HR 2.58, 95% CI 1.21-5.50) and viral hepatitis (HR 1.80, 95% CI 1.03-3.14). Diabetes was associated with renal cell carcinoma (HR 1.83, 95% CI 1.26-2.65) in a base model adjusting for age and gender but not in the multivariate model. We found no association between alcohol, fruit or vegetable intake and renal cell carcinoma. CONCLUSIONS We identified a significant association of renal cell carcinoma with obesity, smoking, hypertension, renal disease and viral hepatitis. Identifying risk factors offers an opportunity for targeted education and intervention.

Focused Ultrasound to Expel Calculi From the Kidney

PURPOSE A persistent stone burden after renal stone treatment may result in future patient morbidity and potentially lead to additional surgery. This problem is particularly common after treatment of lower pole stones. We describe a potential noninvasive therapeutic option using ultrasound waves to create a force sufficient to aid in stone fragment expulsion. MATERIALS AND METHODS Human stones were implanted by retrograde ureteroscopy or antegrade percutaneous access in a live porcine model. The calibrated probe of a system containing ultrasound imaging and focused ultrasound was used to target stones and attempt displacement. To assess for injury an additional 6 kidneys were exposed for 2 minutes each directly to the output used for stone movement. Another 6 kidneys were exposed to more than twice the maximum output used to move stones. Renal tissue was analyzed histologically with hematoxylin and eosin, and nicotinamide adenine dinucleotide staining. RESULTS Stones were moved to the renal pelvis or ureteropelvic junction by less than 2 minutes of exposure. Stone velocity was approximately 1 cm per second. There was no tissue injury when tissue was exposed to the power level used to move stones. Localized thermal coagulation less than 1 cm long was observed in 6 of 7 renal units exposed to the level above that used for ultrasonic propulsion. CONCLUSIONS Transcutaneous ultrasonic propulsion was used to expel calculi effectively and safely from the kidney using a live animal model. This study is the first step toward an office based system to clear residual fragments and toward use as a primary treatment modality in conjunction with medical expulsive therapy for small renal stones.

Fragmentation of Urinary Calculi In Vitro by Burst Wave Lithotripsy

PURPOSE We developed a new method of lithotripsy that uses short, broadly focused bursts of ultrasound rather than shock waves to fragment stones. We investigated the characteristics of stone comminution by burst wave lithotripsy in vitro. MATERIALS AND METHODS Artificial and natural stones (mean ± SD size 8.2 ± 3.0 mm, range 5 to 15) were treated with ultrasound bursts using a focused transducer in a water bath. Stones were exposed to bursts with focal pressure amplitude of 6.5 MPa or less at a 200 Hz burst repetition rate until completely fragmented. Ultrasound frequencies of 170, 285 and 800 kHz were applied using 3 transducers, respectively. Time to fragmentation for each stone type was recorded and fragment size distribution was measured by sieving. RESULTS Stones exposed to ultrasound bursts were fragmented at focal pressure amplitudes of 2.8 MPa or greater at 170 kHz. Fractures appeared along the stone surface, resulting in fragments that separated at the surface nearest to the transducer until the stone was disintegrated. All natural and artificial stones were fragmented at the highest focal pressure of 6.5 MPa with a mean treatment duration of 36 seconds for uric acid stones to 14.7 minutes for cystine stones. At a frequency of 170 kHz the largest artificial stone fragments were less than 4 mm. Exposure at 285 and 800 kHz produced only fragments less than 2 mm and less than 1 mm, respectively. CONCLUSIONS Stone comminution with burst wave lithotripsy is feasible as a potential noninvasive treatment method for nephrolithiasis. Adjusting the fundamental ultrasound frequency allows for stone fragment size to be controlled.

Focused Ultrasound to Expel Calculi from the Kidney: Safety and Efficacy of a Clinical Prototype Device

PURPOSE Focused ultrasound has the potential to expel small stones or residual stone fragments from the kidney, or move obstructing stones to a nonobstructing location. We evaluated the efficacy and safety of ultrasonic propulsion in a live porcine model. MATERIALS AND METHODS Calcium oxalate monohydrate kidney stones and laboratory model stones (2 to 8 mm) were ureteroscopically implanted in the renal pelvicalyceal system of 12 kidneys in a total of 8 domestic swine. Transcutaneous ultrasonic propulsion was performed using an HDI C5-2 imaging transducer (ATL/Philips, Bothell, Washington) and the Verasonics® diagnostic ultrasound platform. Successful stone relocation was defined as stone movement from the calyx to the renal pelvis, ureteropelvic junction or proximal ureter. Efficacy and procedure time was determined. Three blinded experts evaluated histological injury to the kidney in the control, sham treatment and treatment arms. RESULTS All 26 stones were observed to move during treatment and 17 (65%) were relocated successfully to the renal pelvis (3), ureteropelvic junction (2) or ureter (12). Average ± SD successful procedure time was 14 ± 8 minutes and a mean of 23 ± 16 ultrasound bursts, each about 1 second in duration, were required. There was no evidence of gross or histological injury to the renal parenchyma in kidneys exposed to 20 bursts (1 second in duration at 33-second intervals) at the same output (2,400 W/cm(2)) used to push stones. CONCLUSIONS Noninvasive transcutaneous ultrasonic propulsion is a safe, effective and time efficient means to relocate calyceal stones to the renal pelvis, ureteropelvic junction or ureter. This technology holds promise as a useful adjunct to surgical management for renal calculi.

Overuse of Antimicrobial Prophylaxis in Community Practice Urology

PURPOSE We examined index urological surgeries to assess utilization patterns of antimicrobial prophylaxis in a large, community based population. MATERIALS AND METHODS From the Premier Perspectives Database we identified patients who underwent inpatient urological surgeries that are considered index procedures by the ABU (American Board of Urology), including radical prostatectomy, partial or radical nephrectomy, radical cystectomy, ureteroscopy, shock wave lithotripsy, transurethral resection of the prostate, percutaneous nephrostolithotomy, transvaginal surgery, inflatable penile prosthesis, brachytherapy, transurethral resection of bladder tumor and cystoscopy. Procedures were identified based on ICD-9 procedure codes for 2007 to 2012. Antimicrobial administration, class and duration were abstracted from patient billing data. The class and duration of antimicrobials concordant with the 2008 AUA Best Practice Policy Statement was used to determine compliance. RESULTS The overall compliance rate was 53%, ranging from 0.6% for radical cystectomy to 97% for shock wave lithotripsy. Antimicrobial use consistent with AUA Best Practices included the appropriate class in 67% of cases (range 34% to 80%) and the recommended duration in 78% (range 1.2% to 98%). Average prophylaxis duration for procedures for which it is recommended ranged from 1.1 days after brachytherapy to 10.3 days after radical cystectomy. The compliance rate increased from 46% overall in 2007 to 59% overall in 2012. CONCLUSIONS We documented considerable variation in antimicrobial prophylaxis for urological surgery. Compliance with AUA Best Practices increased with time but overall rates remain less than 60%. Efforts are needed to better understand the reasons for variation from recommended antimicrobial prophylaxis for common inpatient urological procedures to help decrease resultant complications and improve outcomes.

Crowd-sourced assessment of technical skills: an adjunct to urology resident surgical simulation training.

Abstract Background: Crowdsourcing is the practice of obtaining services from a large group of people, typically an online community. Validated methods of evaluating surgical video are time-intensive, expensive, and involve participation of multiple expert surgeons. We sought to obtain valid performance scores of urologic trainees and faculty on a dry-laboratory robotic surgery task module by using crowdsourcing through a web-based grading tool called Crowd Sourced Assessment of Technical Skill (CSATS). Methods: IRB approval was granted to test the technical skills grading accuracy of Amazon.com Mechanical Turk™ crowd-workers compared to three expert faculty surgeon graders. The two groups assessed dry-laboratory robotic surgical suturing performances of three urology residents (PGY-2, -4, -5) and two faculty using three performance domains from the validated Global Evaluative Assessment of Robotic Skills assessment tool. Results: After an average of 2 hours 50 minutes, each of the five videos received 50...

B-mode Ultrasound Versus Color Doppler Twinkling Artifact in Detecting Kidney Stones

PURPOSE To compare color Doppler twinkling artifact and B-mode ultrasonography in detecting kidney stones. PATIENTS AND METHODS Nine patients with recent CT scans prospectively underwent B-mode and twinkling artifact color Doppler ultrasonography on a commercial ultrasound machine. Video segments of the upper pole, interpolar area, and lower pole were created, randomized, and independently reviewed by three radiologists. Receiver operator characteristics were determined. RESULTS There were 32 stones in 18 kidneys with a mean stone size of 8.9±7.5 mm. B-mode ultrasonography had 71% sensitivity, 48% specificity, 52% positive predictive value, and 68% negative predictive value, while twinkling artifact Doppler ultrasonography had 56% sensitivity, 74% specificity, 62% positive predictive value, and 68% negative predictive value. CONCLUSIONS When used alone, B-mode is more sensitive, but twinkling artifact is more specific in detecting kidney stones. This information may help users employ twinkling and B-mode to identify stones and developers to improve signal processing to harness the fundamental acoustic differences to ultimately improve stone detection.

Fluoroless ureteroscopy: zero-dose fluoroscopy during ureteroscopic treatment of urinary-tract calculi.

PURPOSE Fluoroscopy usage during endoscopic procedures exposes the patient and operating room staff to ionizing radiation. Pooled mean fluoroscopy usage time during ureteroscopy reported from recent literature is 144 seconds per case. The purpose of this study was to evaluate radiation exposure using a minimal-use fluoroscopy protocol during ureteroscopic treatment of urinary-tract calculi and determine patient and perioperative factors associated with increased fluoroscopy time. MATERIALS AND METHODS A protocol was developed to access the ureter with the ureteroscope without fluoroscopy usage, and minimize radiation utilization during each portion of the case. Over a 16-month period, fluoroscopy usage and radiation dose for all cases involving retrograde ureteroscopy for a single surgeon were prospectively recorded. A chart review was performed on patient factors and intraoperative events. RESULTS In 162 consecutive ureteroscopic procedures for nephrolithiasis, there were 156 renal units with fluoroscopic usage data, of which total mean and median fluoroscopy time, including stent placement, was 3.3 and 2.0 seconds (0-35 seconds), respectively. Excluding fluoroscopy usage to confirm ureteral stent placement, 75% of all cases did not require any fluoroscopy time (fluoroless), and 85% required 2 seconds or less. Of the 98 renal units with radiation dosage data, the total mean and median radiation dose measured as air kerma was estimated at 1.1 and 0.6 mGy (0.0-17.5 mGy), respectively. Reasons for utilization of total fluoroscopy time more than 5 seconds included stone impaction, ureteral tortuosity or narrowing, collecting system aberrant anatomy, and difficult ureteral stent placement. CONCLUSIONS The reduced fluoroscopy protocol resulted in minimal fluoroscopy time and radiation exposure, significantly lower than reported in the literature. Fluoroless ureteroscopy is safe and feasible in the majority of ureteroscopic cases and lessens exposure to patients and staff.

Focused Ultrasonic Propulsion of Kidney Stones: Review and Update of Preclinical Technology

INTRODUCTION A noninvasive tool to reposition kidney stones could have significant impact in the management of stone disease. Our research group has developed a noninvasive transcutaneous ultrasound device. A review and update of the current status of this technology is provided. DISCUSSION OF TECHNOLOGY: Stone propulsion is achieved through short bursts of focused, ultrasonic pulses. The initial system consisted of an eight-element annular array transducer, computer, and separate ultrasound imager. In the current generation, imaging and therapy are completed with one ultrasound system and a commercial probe. This generation allows real-time ultrasound imaging, targeting, and propulsion. Safety and effectiveness for the relocation of calyceal stones have been demonstrated in the porcine model. ROLE IN ENDOUROLOGY: This technology may have applications in repositioning stones as an adjunct to lithotripsy, facilitating clearance of residual fragments after lithotripsy, expelling de novo stones, and potentially repositioning obstructing stones. Human trials are in preparation.