Sara Best

Durability of Flexible Ureteroscopes: A Randomized, Prospective Study

PURPOSE We performed a randomized, prospective, multi-institutional study evaluating the durability of commercially available flexible ureteroscopes. MATERIALS AND METHODS A total of 192 patients were randomized to the use of 7 less than 9Fr flexible ureteroscopes, including the Storz 11274AA and Flex-X, the ACMI DUR-8 and DUR-8 Elite, Wolf models 7330.170 and 7325.172, and the Olympus URF-P3. Information about total and lower pole use time, the number and method of ureteroscope insertion, and they type and duration of accessory instrumentation was recorded. Surgeons were asked to rate the visibility and maneuverability of the instrument on a scale of 0-poor to 10-excellent. RESULTS The indication for ureteroscopy was upper tract calculi in 87% of cases. Of ureteroscope insertions 97% were performed through an access sheath. The average of number of cases before repair ranged from 3.25 for the Wolf 7325 to 14.4 for the ACMI DUR-8 Elite. Average ureteroscope operative time was statistically longer for the DUR-8 Elite (494 minutes) than for the Flex-X (p = 0.047), and the Wolf 7325 and 7330 (p = 0.001 and 0.001, respectively). Duration of use before repair for the URF-P3 (373 minutes) was statistically longer than for the Wolf 7325 and 7330 (p = 0.016 and 0.017, respectively). Minutes of use with an instrument in the working channel were significantly more with the DUR-8 Elite and the URF-P3 than the Wolf 7330 (p = 0.017 and 0.008) and 7325 (p = 0.012 and 0.005, respectively). The ureteroscope that experienced the greatest average duration of lower pole use was the URF-P3, while the shortest was the Wolf 7325 (103 vs 20 minutes, p = 0.005). Average minutes of laser use before breakage was significantly longer for the DUR-8 Elite than for the Wolf 7325 (110 vs 21 minutes, p = 0.021) and 7330 (24 minutes, p = 0.025). CONCLUSIONS Currently available less than 9Fr flexible ureteroscopes remain fragile instruments. The DUR-8 Elite and Olympus URF-P3 proved to be the most durable devices.

Current practice patterns in the management of upper urinary tract calculi in the north central United States.

PURPOSE To determine the current practice patterns in the management of upper urinary tract calculi in a large group of urologists in the north central United States. MATERIALS AND METHODS An email survey was sent to 790 practicing members of the North Central Section of the American Urological Association. The survey consisted of questions pertaining to practice and training background, and case scenarios with treatment options for upper urinary tract calculi of different sizes at various locations. The responses were then statistically analyzed to determine practice trends. RESULTS Seven urologists did not fill out the survey, as they did not manage patients with stone disease. The overall response rate was 23% (167/783). Although more than 75% of urologists were trained to perform extracorporeal shockwave lithotripsy (SWL), ureteroscopy (URS), and percutaneous nephrolithotomy (PCNL) during their residency, only 61% and 17% were trained to perform open stone surgery (OSS) and medical expulsive therapy (MET), respectively. Twelve percent of respondents were fellowship trained in endourology. Observation was most commonly recommended for asymptomatic renal calculi <5 mm in size (92%). Although SWL continues to be the most commonly utilized therapy for renal (43%-92%) and proximal ureteral calculi <20 mm in size (29%-51%), and PCNL for renal calculi >20 mm in size (72%-92%), many urologists (48%) favored PCNL for lower pole calculi 10 to 20 mm in size. Use of URS was mostly favored for distal (44%-90%) and proximal ureteral calculi (23%-46%), while MET was recommended for small ureteral calculi <5 mm in size (25%-32%). Fellowship-trained endourologists, academic urologists, and urologists in practice for less than 5 years were more likely to utilize URS, PCNL, and MET, and less likely to utilize SWL for urinary calculi. CONCLUSION The results of this survey suggest that practice patterns for treatment of stone disease match the treatment approach recommended in the published literature. This information can be further utilized for assessment of guidelines for the treatment of stone disease.

Prospective Randomized Comparison of a Combined Ultrasonic and Pneumatic Lithotrite with a Standard Ultrasonic Lithotrite for Percutaneous Nephrolithotomy

PURPOSE To compare the efficiency and cost effectiveness of a combined pneumatic and ultrasonic lithotrite (Lithoclast Ultra) and a standard ultrasonic lithotrite, (LUS-1) during percutaneous nephrolithotomy. MATERIALS AND METHODS In a prospective randomized trial, 30 patients undergoing percutaneous nephrolithotomy (PCNL) were randomized to PCNL with either the combined pneumatic and ultrasonic lithotrite (PUL) or a standard ultrasonic lithotrite (SUL). Patient demographics, stone composition, location, pre- and post-operative stone burden, fragmentation rates, and device failures were compared. RESULTS There were 13 patients in the PUL group and 17 patients in the SUL group. Stone burden and location were equal. Overall, 64% of the PUL group had hard stones (defined as stones that were either pure or a mixture of cystine [3], calcium oxalate monohydrate [CaOxMono; 2], and calcium phosphate [CaPO4; 2]), and four had soft stones (3 struvite and 1 uric acid [UA]). In the SUL group, there were eight hard stones (5 CaOxMono and 3 CaPO4), and six soft stones (4 calcium oxalate dihydrate [CaOxDi] and 2 UA) (P = 0.51). Stone composition data were unavailable for five patients. Fragmentation time for the PAL was 37 minutes versus 31.5 minutes for the SUL (P = 0.22). Stone retrieval and mean operative times were similar for both groups. There were a total of three (23.1%) device-related problems in the PUL group, and eight (47%) in the SUL group. There was one (7.7%) device malfunction in the PUL group due to probe fracture. There were two (11.7%) device failures in the SUL group; one failure required the device to be reset every 30 minutes, and the second was an electrical failure. Suction tubing obstruction occurred twice (15.3%) in the PUL group and 35.3% in the SU group (P = 0.35). The stone-free rates for the PUL and SUL were 46% and 66.7%, respectively (P = 0.26). CONCLUSION Although the PUL was more costly, stone ablation and clearance rates were similar for both the combined pneumatic and ultrasonic device and the standard ultrasonic device. When stratified with respect to stone composition, the PUL was more efficient for harder stones, and the SUL was more efficient for softer stones.

Flexible ureteroscopy is effective for proximal ureteral stones in both obese and nonobese patients: a two-year, single-surgeon experience.

OBJECTIVE To report a retrospective series of proximal ureteral stone ureteroscopies (URS) by a single surgeon, using results presented in a recommended format from the American Urological Association Ureteral Stone Guideline panel, with an emphasis on outcomes related to obesity. METHODS A retrospective chart review of a single surgeons 2-year URS experience was performed. Of the 55 ureteroscopies for proximal ureteral calculi, 49 cases involving 43 patients had evaluable postoperative imaging. RESULTS Mean patient age was 56 years and average body mass index was 32.5 kg/m(2). Average ureteral stone size was 9.1 mm; 51% had been preoperatively stented and 93% were stented postoperatively. The overall ureteral stone-free rate was 86%. Overall, 5/43 patients (11%), none of whom were obese, required a second procedure. Obese patients had a 91% stone-free rate, statistically equivalent to the 81% rate in the nonobese. Three patients (7%) developed postoperative urinary tract infections. One patient came to the emergency department for stent-related discomfort. One patient treated in a staged setting for bilateral ureteral calculi developed urinary tract infection and systemic inflammatory response system complicated by alcohol withdrawal requiring a 3-day non-intensive care unit admission. CONCLUSIONS Proximal ureteral calculi can be successfully treated with URS most of the time, but the risk for persistent renal calculi and fragments exists. The complication rate is low and operative times are short. Obese patients can also be successfully treated ureteroscopically.

Patient and Tumor Characteristics can Predict Nondiagnostic Renal Mass Biopsy Findings

PURPOSE Identification of patient and tumor characteristics associated with nondiagnostic biopsies is necessary to improve prebiopsy counseling and patient selection. MATERIALS AND METHODS We reviewed the clinical records and prebiopsy imaging of all patients treated with percutaneous biopsy for a renal mass 7 cm or less. Univariate and multivariate logistic regression models were constructed to examine the association between biopsy outcome and clinical/radiographic features. RESULTS A total of 565 biopsies of renal tumors 7 cm or less in 525 patients were included in the study. There was no significant difference in age, body mass index, Charlson comorbidity score or gender between the patient cohorts with diagnostic and nondiagnostic biopsy. In 83 of 565 patients (14.7%) overall and in 72 of the 413 (17.4%) with a mass of 4 cm or less the biopsy findings were nondiagnostic. Overall 14.7% of masses were cystic and 85.3% were solid with a median tumor size of 2.75 cm (IQR 2.05-4.25). Independent predictors of nondiagnostic biopsy included cystic features, enhancement less than 20 HU, left tumor, tumor diameter and skin-to-tumor distance. The nondiagnostic rate of repeat biopsies was 20.8%, which did not statistically differ from the nondiagnostic rate at the initial renal mass biopsy attempt. Radiologist or pathologist experience was not associated with the biopsy nondiagnostic rate. In 7 of 565 patients (1.2%) hospital admission was required for adverse events after biopsy. CONCLUSIONS Nondiagnostic renal mass biopsies are more common in cystic, nonenhancing, small masses when patients have a skin-to-tumor distance of 13 cm or greater. Excluding patients with these criteria decreased the nondiagnostic rate from 14.7% to 8.7%.

Animal Protein and the Risk of Kidney Stones: A Comparative Metabolic Study of Animal Protein Sources

PURPOSE We compared the effect of 3 animal protein sources on urinary stone risk. MATERIALS AND METHODS A total of 15 healthy subjects completed a 3-phase randomized, crossover metabolic study. During each 1-week phase subjects consumed a standard metabolic diet containing beef, chicken or fish. Serum chemistry and 24-hour urine samples collected at the end of each phase were compared using mixed model repeated measures analysis. RESULTS Serum and urinary uric acid were increased for each phase. Beef was associated with lower serum uric acid than chicken or fish (6.5 vs 7.0 and 7.3 mg/dl, respectively, each p <0.05). Fish was associated with higher urinary uric acid than beef or chicken (741 vs 638 and 641 mg per day, p = 0.003 and 0.04, respectively). No significant difference among phases was noted in urinary pH, sulfate, calcium, citrate, oxalate or sodium. Mean saturation index for calcium oxalate was highest for beef (2.48), although the difference attained significance only compared to chicken (1.67, p = 0.02) but not to fish (1.79, p = 0.08). CONCLUSIONS Consuming animal protein is associated with increased serum and urine uric acid in healthy individuals. The higher purine content of fish compared to beef or chicken is reflected in higher 24-hour urinary uric acid. However, as reflected in the saturation index, the stone forming propensity is marginally higher for beef compared to fish or chicken. Stone formers should be advised to limit the intake of all animal proteins, including fish.

Extreme obesity does not predict poor cancer outcomes after surgery for renal cell cancer.

To assess whether extreme obesity (body mass index [BMI] ≥ 40 kg/m2) is associated with peri‐operative outcomes, overall survival (OS), cancer‐specific survival (CSS), or recurrence‐free survival (RFS) after surgical treatment for renal cell carcinoma (RCC).

Do Urinary Cystine Parameters Predict Clinical Stone Activity

Purpose: An accurate urinary predictor of stone recurrence would be clinically advantageous for patients with cystinuria. A proprietary assay (Litholink, Chicago, Illinois) measures cystine capacity as a potentially more reliable estimate of stone forming propensity. The recommended capacity level to prevent stone formation, which is greater than 150 mg/l, has not been directly correlated with clinical stone activity. We investigated the relationship between urinary cystine parameters and clinical stone activity. Materials and Methods: We prospectively followed 48 patients with cystinuria using 24‐hour urine collections and serial imaging, and recorded stone activity. We compared cystine urinary parameters at times of stone activity with those obtained during periods of stone quiescence. We then performed correlation and ROC analysis to evaluate the performance of cystine parameters to predict stone activity. Results: During a median followup of 70.6 months (range 2.2 to 274.6) 85 stone events occurred which could be linked to a recent urine collection. Cystine capacity was significantly greater for quiescent urine than for stone event urine (mean ± SD 48 ± 107 vs –38 ± 163 mg/l, p <0.001). Cystine capacity significantly correlated inversely with stone activity (r = –0.29, p <0.001). Capacity also correlated highly negatively with supersaturation (r = –0.88, p <0.001) and concentration (r = –0.87, p <0.001). Using the suggested cutoff of greater than 150 mg/l had only 8.0% sensitivity to predict stone quiescence. Decreasing the cutoff to 90 mg/l or greater improved sensitivity to 25.2% while maintaining specificity at 90.9%. Conclusions: Our results suggest that the target for capacity should be lower than previously advised.

Comparative Analysis of Surgery, Thermal Ablation, and Active Surveillance for Renal Oncocytic Neoplasms

OBJECTIVE To compare oncological and procedural outcomes for renal oncocytic tumors treated with surgery, thermal ablation, or active surveillance. METHODS Clinical and pathologic data were collected for consecutive patients with a histologic diagnosis of oncocytoma, oncocytic neoplasm, or chromophobe renal cell cancer (chRCC) from 2003 to 2016. Independent pathology and radiology reviews were performed for this study. RESULTS Of 171 patients, tumor histology included oncocytoma (n = 122), chRCC (n = 47), and oncocytic neoplasm not otherwise specified (n = 2). At the initial diagnosis, 67, 14, and 90 patients were treated with surgery, thermal ablation, and active surveillance. In 3 of 19 patients (16%) who had biopsy and subsequent surgery, diagnosis changed from oncocytoma to chRCC. The median follow-up was 39.9 months with no difference among choices of treatment modalities (P = .33). Of 90 patients who began active surveillance, 32 (36%) switched to active treatments (19 underwent thermal ablation and 13 underwent surgery). The median linear growth rate for patients on active surveillance was 1.2 mm/y. No patients who were managed with active surveillance developed metastatic renal cell cancer (mRCC). mRCC was identified in 3 patients and was the cause of death in 2 patients. Patients who developed metastatic disease presented with symptomatic tumors of >4 cm and were treated with immediate surgery. For oncocytic masses of ≤4 cm (n = 126), the 5-year cancer-specific survival was 100%. CONCLUSION Renal oncocytic neoplasms have favorable oncological outcomes. Active surveillance is safe and is the preferred management for small (≤4 cm) oncocytic renal tumors in selected patients.

A Critical Analysis of Perioperative Outcomes in Morbidly Obese Patients Following Renal Mass Surgery

OBJECTIVE To evaluate if body mass index (BMI) ≥ 40 is associated with risk of postoperative complications, receipt of perioperative blood transfusion (PBT), length of hospital stay (LOS), perioperative death, or hospital readmission rate following renal mass surgery. MATERIALS AND METHODS After Institutional Review Board approval, comprehensive information was collected for patients treated with surgery for renal mass from 2000 to 2015 at one institution. Univariable and multivariable analyses were used to evaluate the association of BMI ≥ 40 among other putative risk factors for perioperative outcomes. RESULTS A total of 1048 patients were treated surgically, including 115 (11%) with BMI > 40. Minimally invasive and open surgical approaches were used for 480 (45.8%) and 568 (54.2%) patients, respectively. Morbid obesity was not associated with risk of major complications, overall complications, receipt of PBT, LOS, hospital readmission rate, or perioperative death. Charlson comorbidity index was the only independent predictor of major complications following renal mass surgery, P = .0006, per point odds ratio 1.2 (95%C.I. 1.08-1.32). Surgical site infections (SSIs) were more common in patients with BMI ≥ 40 vs BMI < 40 (10.5% vs 4.8%, P = .01). Following multivariable analysis, BMI ≥ 40 was the only independent predictor of SSIs, odds ratio 2.6, 95% confidence interval 1.32-5.13; P = .006. CONCLUSION Morbid obesity (BMI ≥ 40) is an independent predictor of developing SSIs following renal mass surgery. Morbid obesity is not predictive of risk for major complications, receipt of PBT, hospital readmission, perioperative death, or LOS.