Initial Experience with an Absorbable Urologic Scaffold to Mitigate Early Urinary Incontinence following Radical Prostatectomy: A Report of 2 Cases.

INTRODUCTION: Stress urinary incontinence (SUI) is a frequent, known complication following robot-assisted radical prostatectomy (RARP) for prostate cancer. Urethral shortening and reduced urethral support following RARP are contributing factors. CASE PRESENTATIONS: Herein, we describe a surgical approach using a novel absorbable urologic scaffold to mitigate SUI in 2 patients enrolled in an ongoing single-arm prospective study. The scaffold is designed to relieve the burden on the urinary sphincter by lengthening the effective urethra following RARP. The scaffold is placed at the anastomotic site, overlying the bladder neck and urethral stump following prostate removal and prior to the creation of the anastomosis. Both patients successfully underwent the prostatectomy and urologic scaffold placement with no reported perioperative complications. Neither patient suffered from early SUI following RARP as measured by pad weight and usage at 1 and 3 months following the procedure. CONCLUSION: Early experience with the absorbable urologic scaffold suggests it could safely and effectively prevent SUI following RARP. Early and long-term results derived from the ongoing prospective study with this device will better define its potential role in the prevention of SUI.

Over half of contemporary clinical Gleason 8 on prostate biopsy are downgraded at radical prostatectomy.

INTRODUCTION: Contemporary clinical guidelines utilize the highest Gleason sum (HGS) in any one core on prostate biopsy to determine prostate cancer treatment. Here, we present a large discrepancy between prostate cancer risk stratified as high risk on biopsy and their pathology after radical prostatectomy. MATERIALS AND METHODS: We retrospectively reviewed 1424 men who underwent either open or robotic-assisted prostatectomy between 2004 and 2015. We analyzed 148 men who were diagnosed with HGS 8 on prostate biopsy. Biopsy and prostatectomy pathology were compared in aggregate and over 1 year time intervals. Chi-squared test, Fisher's exact test, Student's t-test, and Wilcoxon Rank-Sum test were used for statistical analysis. RESULTS: A total of 61.5% (91/148) of clinical HGS 8 diagnoses were downgraded on prostatectomy, with 58.8% (87/148) downgraded to Gleason 7 (Gleason 4 + 3 n = 59; Gleason 3 + 4 n = 28). Factors associated with downgrading include lower prostate-specific antigen (PSA) at biopsy (median 6.8 ng/mL versus 9.1 ng/mL, p < 0.001), number of Gleason 8 biopsy cores (median 1 versus 2, p < 0.02), presence of Gleason pattern 3 on biopsy cores (67.9% versus 44.8%, p < 0.03), pT2 staging (72.4% versus 55.1%, p < 0.04), positive margins (53.9% versus 69.1%, p < 0.04), extracapsular extension (53.4% versus 74.1%, p < 0.02), and smaller percent tumor (median 10% versus 15%, p < 0.004). CONCLUSION: The large percentage of pathology downgrading of biopsy-diagnosed HGS 8 suggests suboptimal risk-stratification that may lead to suboptimal treatment strategies and much patient distress. Our study adds great urgency to the efforts refining prostate cancer clinical assessment.

Effect of positive end-expiratory pressure on blood loss during retropubic and robot-assisted laparoscopic radical prostatectomy.

OBJECTIVES: To study the effect of end-expiratory pressure used during anesthesia on blood loss during radical prostatectomy. METHODS: We evaluated 247 patients who underwent either radical retropubic prostatectomy or robot-assisted laparoscopic prostatectomy at a single institution from 2008 to 2013 by one of four surgeons. Patient characteristics were compared using t-tests, rank sum or χ(2) -tests as appropriate. The association between positive end-expiratory pressure and estimated blood loss was tested using linear regression. RESULTS: Patients were classified into high (≥4 cmH2 O) and low (≤1 cmH2 O) positive-end expiratory pressure groups. Estimated blood loss in radical retropubic prostatectomy was higher in the high positive end-expiratory pressure group (1000 mL vs 800 mL, P = 0.042). Estimated blood loss in robot-assisted laparoscopic prostatectomy was lower in the high positive end-expiratory pressure group (150 mL vs 250 mL, P = 0.015). After adjusting for other factors known to influence blood loss, a 5-cmH2 O increase in positive end-expiratory pressure was associated with a 34.9% increase in estimated blood loss (P = 0.030) for radical retropubic prostatectomy, and a 33.0% decrease for robot-assisted laparoscopic prostatectomy (P = 0.038). CONCLUSIONS: In radical retropubic prostatectomy, high positive end-expiratory pressure was associated with higher estimated blood loss, and the benefits of positive end-expiratory pressure should be weighed against the risk of increased estimated blood loss. In robot-assisted laparoscopic prostatectomy, high positive end-expiratory pressure was associated with lower estimated blood loss, and might have more than just pulmonary benefits.

Complications of surgical management of upper tract calculi in spina bifida patients: analysis of nationwide data.

PURPOSE: The management of upper urinary tract stones in patients with spina bifida is challenging but poorly described in the literature. We compared urolithiasis interventions and related complications in patients with spina bifida to those in other stone formers using a national database. MATERIALS AND METHODS: We retrospectively reviewed the NIS to identify hospital admissions for renal and ureteral stones from 1998 to 2011. We used ICD-9-CM codes to identify urological interventions, including shock wave lithotripsy, ureteroscopy, percutaneous nephrolithotomy and ureteral stent placement. NSQIP data were used to identify postoperative complications. RESULTS: We identified 4,287,529 weighted stone hospital admissions, including 12,315 (0.3%) of patients with spina bifida. Compared to those without spina bifida the patients with spina bifida who had urolithiasis were significantly younger (mean age 34 vs 53 years), more likely to have public insurance (72% vs 44%) and renal vs ureteral calculi (81% vs 58%), and undergo percutaneous nephrolithotomy (27% vs 8%). After adjusting for age, insurance, comorbidity, treatment year, surgery type, stone location and hospital factors patients with spina bifida were more likely to have urinary tract infections (OR 2.5), urinary complications (OR 3.1), acute renal failure (OR 1.9), respiratory complications (OR 2.0), pneumonia (OR 1.5), respiratory insufficiency (OR 3.2), prolonged mechanical ventilation (OR 3.2), sepsis (OR 2.7), pulmonary embolism (OR 3.0), cardiac complications (OR 2.4) and bleeding (OR 1.6). CONCLUSIONS: Compared to those without spina bifida the patients with spina bifida who were hospitalized for urolithiasis were younger, and more likely to have renal stones and undergo percutaneous nephrolithotomy. Urolithiasis procedures in patients with spina bifida were associated with a significantly higher risk of in-hospital postoperative complications.

Radiation Exposure during the Evaluation and Management of Nephrolithiasis.

PURPOSE: There is rising concern over the increasing amount of patient radiation exposure from diagnostic imaging and medical procedures. Patients with nephrolithiasis are at potentially significant risk for radiation exposure due to the need for imaging to manage recurrent stone disease. We reviewed the literature in an attempt to better characterize actual risks and discussed methods to reduce radiation exposure for adult patients with nephrolithiasis. MATERIALS AND METHODS: A PubMed search was performed using the key words nephrolithiasis, stones, radiation, fluoroscopy, ureteroscopy, percutaneous nephrolithotomy, computerized tomography and shock wave lithotripsy. Additional citations were identified by reviewing reference lists of pertinent articles. RESULTS: A total of 50 relevant articles were included in this review. Patients with a first time acute stone event are exposed to a significant amount of radiation. Most radiation is from computerized tomography. Patients undergoing percutaneous nephrolithotomy are exposed to an equal or greater amount of radiation than they received from computerized tomography. Risk factors for increased exposure during percutaneous nephrolithotomy include obesity, multiple tracts and a larger stone burden. Ureteroscopy exposes patients to approximately the same amount of radiation as plain x-ray of the kidneys, ureters and bladder. Risk factors for increased exposure during ureteroscopy include obesity and ureteral dilation. During shock wave lithotripsy the amount of radiation exposure is not well characterized. Interventions to reduce exposure to patients include using ultrasound when possible and implementing low dose computerized tomography protocols. The as low as reasonably achievable principle of radiation exposure should always be followed when fluoroscopy is performed. The use of an air retrograde pyelogram may also reduce exposure during percutaneous nephrolithotomy. Fluoroscopy time during ureteroscopy may be decreased by a laser guided C-arm, a dedicated C-arm technician, stent placement under direct vision and tactile feedback to help guide wire placement. CONCLUSIONS: Patients with nephrolithiasis are at significant risk for increased radiation exposure from the imaging and fluoroscopy used during treatment. The true risks of low radiation exposure remain uncertain. It is important to be aware of these risks to provide better counseling for patients. Urologists must also be familiar with techniques to decrease radiation exposure for patients with nephrolithiasis.

Balloon Dilation of the Ureter: A Contemporary Review of Outcomes and Complications.

PURPOSE: During ureteroscopy ureteral balloon dilation may be necessary to allow for passage of endoscopic instruments or access sheaths. We assessed the efficacy and complications associated with ureteral balloon dilation. MATERIALS AND METHODS: We retrospectively reviewed the records at 2 institutions from 2000 to 2012 to identify patients who underwent ureteral balloon dilation during ureteroscopic treatment of upper tract stones. An 18Fr balloon dilator was used in all cases. Patients with documented ureteral stricture, radiation therapy or urothelial cancer were excluded from analysis. Primary outcomes were the stone-free rate, operative complications, balloon dilation failure and the postoperative ureteral stricture rate. Complications were divided into intraoperative and postoperative groups according to the Satava and Clavien-Dindo classifications, respectively. RESULTS: A total of 151 patients fulfilled study criteria. Median followup was 12 months. The stone-free rate was 72% and median time to first postoperative imaging was 2.8 months. Balloon dilation failed in only 8 patients (5%). Eight intraoperative ureteral perforations (5%) were identified, which were managed by a ureteral stent in 7 patients and a percutaneous tube in 1. Endoscopic re-treatment was required in 4 patients with Satava 2b postoperative complications. The postoperative complication rate was 8% (11 cases). A single ureteral stricture was attributable to balloon dilation. CONCLUSIONS: In this contemporary review balloon dilation of the ureter before endoscopic treatment of stone disease was associated with a high success rate and few complications. Ureteral balloon dilation may decrease the need for a secondary procedure in patients undergoing ureteroscopy to manage proximal ureteral and intrarenal stones.

Does body mass index impact the outcomes of tubeless percutaneous nephrolithotomy?

OBJECTIVE: To evaluate whether body mass index (BMI) has an impact on the outcomes of tubeless percutaneous nephrolithotomy (PCNL). PATIENTS AND METHODS: We retrospectively reviewed patients who underwent tubeless PCNL at our institution from 2006 to 2011. Specifically, stone-free rates, complications, and hospital length of stay (LOS) were assessed. Patients were divided into four groups based on BMI: <25, 25-29.9, 30-34.9 and ≥35 kg/m(2) . Baseline characteristics and outcomes were compared between BMI groups. Multivariable logistic regressions were used to evaluate the independent contribution of BMI as a predictor of outcomes. RESULTS: We identified 268 patients who fulfilled study requirements. The overall stone-free and complication rates were 52.5% and 19.0%, respectively. Minor and severe complication comprised 10.4% and 8.6%, respectively. Univariate and multivariable analyses showed no association between BMI and stone-free or complication rates. However, patients with a normal BMI had significantly higher transfusion rates (P = 0.005), and were significantly more likely to have a prolonged LOS (≥2 days), when compared with an overweight BMI (P = 0.032) CONCLUSIONS: BMI did not impact the stone-free, or complication rates of tubeless PCNL. Normal BMI was found to be a risk factor for prolonged LOS, which may be due to an increase in clinically significant bleeding in this patient population. Tubeless PCNL appears to be a safe and effective procedure for the treatment of complex renal calculi, independent of BMI.

Small renal mass biopsy--how, what and when: report from an international consensus panel.

To discuss the use of renal mass biopsy (RMB) for small renal masses (SRMs), formulate technical aspects, outline potential pitfalls and provide recommendations for the practicing clinician. The meeting was conducted as an informal consensus process and no scoring system was used to measure the levels of agreement on the different topics. A moderated general discussion was used as the basis for consensus and arising issues were resolved at this point. A consensus was established and lack of agreement to topics or specific items was noted at this point. Recommended biopsy technique: at least two cores, sampling different tumour regions with ultrasonography being the preferred method of image guidance. Pathological interpretation: 'non-diagnostic samples' should refer to insufficient material, inconclusive and normal renal parenchyma. For non-diagnostic samples, a repeat biopsy is recommended. Fine-needle aspiration may provide additional information but cannot substitute for core biopsy. Indications for RMB: biopsy is recommended in most cases except in patients with imaging or clinical characteristics indicative of pathology (syndromes, imaging characteristics) and cases whereby conservative management is not contemplated. RMB is recommended for active surveillance but not for watchful-waiting candidates. We report the results of an international consensus meeting on the use of RMB for SRMs, defining the technique, pathological interpretation and indications.

Obesity triples the radiation dose of stone protocol computerized tomography.

PURPOSE: Patients with recurrent nephrolithiasis are often evaluated and followed with computerized tomography. Obesity is a risk factor for nephrolithiasis. We evaluated the radiation dose of computerized tomography in obese and nonobese adults. MATERIALS AND METHODS: We scanned a validated, anthropomorphic male phantom according to our institutional renal stone evaluation protocol. The obese model consisted of the phantom wrapped in 2 Custom Fat Layers (CIRS, Norfolk, Virginia), which have been verified to have the same radiographic tissue density as fat. High sensitivity metal oxide semiconductor field effect transistor dosimeters were placed at 20 organ locations in the phantoms to measure organ specific radiation doses. The nonobese and obese models have an approximate body mass index of 24 and 30 kg/m(2), respectively. Three runs of renal stone protocol computerized tomography were performed on each phantom under automatic tube current modulation. Organ specific absorbed doses were measured and effective doses were calculated. RESULTS: The bone marrow of each model received the highest dose and the skin received the second highest dose. The mean ± SD effective dose for the nonobese and obese models was 3.04 ± 0.34 and 10.22 ± 0.50 mSv, respectively (p <0.0001). CONCLUSIONS: The effective dose of stone protocol computerized tomography in obese patients is more than threefold higher than the dose in nonobese patients using automatic tube current modulation. The implication of this finding extends beyond the urological stone population and adds to our understanding of radiation exposure from medical imaging.

Radiation exposure in urology: a genitourinary catalogue for diagnostic imaging.

PURPOSE: Computerized tomography use increased exponentially in the last 3 decades, and it is commonly used to evaluate many urological conditions. Ionizing radiation exposure from medical imaging is linked to the risk of malignancy. We measured the organ and calculated effective doses of different studies to determine whether the dose-length product method is an accurate estimation of radiation exposure. MATERIALS AND METHODS: An anthropomorphic male phantom validated for human organ dosimetry measurements was used to determine radiation doses. High sensitivity metal oxide semiconductor field effect transistor dosimeters were placed at 20 organ locations to measure specific organ doses. For each study the phantom was scanned 3 times using our institutional protocols. Organ doses were measured and effective doses were calculated on dosimetry. Effective doses measured by a metal oxide semiconductor field effect transistor dosimeter were compared to calculated effective doses derived from the dose-length product. RESULTS: The mean±SD effective dose on dosimetry for stone protocol, chest and abdominopelvic computerized tomography, computerized tomography urogram and renal cell carcinoma protocol computerized tomography was 3.04±0.34, 4.34±0.27, 5.19±0.64, 9.73±0.71 and 11.42±0.24 mSv, respectively. The calculated effective dose for these studies Was 3.33, 2.92, 5.84, 9.64 and 10.06 mSv, respectively (p=0.8478). CONCLUSIONS: The effective dose varies considerable for different urological computerized tomography studies. Renal stone protocol computerized tomography shows the lowest dose, and computerized tomography urogram and the renal cell carcinoma protocol accumulate the highest effective doses. The calculated effective dose derived from the dose-length product is a reasonable estimate of patient radiation exposure.

Lithotrites and postoperative fever: does lithotrite type matter? Results from the Clinical Research Office of the Endourological Society Percutaneous Nephrolithotomy Global Study.

OBJECTIVE: To compare the risks of fever from different lithotrites after percutaneous nephrolithotomy (PNL). MATERIALS AND METHODS: The Clinical Research Office of the Endourological Society (CROES) PNL database is a prospective, multi-institutional, international PNL registry. Of 5,803 total patients, 4,968 received preoperative antibiotics, were supplied with complete information and included in this analysis. The lithotrites assessed included no fragmentation, ultrasonic, laser, pneumatic and combination ultrasonic/pneumatic. Risk of fever was estimated using multivariate logistic regression with adjustment for diabetes, steroid use, a history of positive urine culture, the presence of staghorn calculi or preoperative nephrostomy, stone burden and lithotrite. RESULTS: The overall fever rate was 10%. Pneumatic lithotrites were used in 43% of the cohort, followed by ultrasonic (24%), combination ultrasonic/pneumatic (17.3%), no fragmentation (8.4%) and laser (7.3%). Fever rates were no different between patients who underwent no or any fragmentation (p = 0.117), nor among patients when stratified by lithotrite (p = 0.429). On multivariate analysis, fragmentation was not significantly associated with fever [Odds Ratio (OR) 1.17, p = 0.413], while diabetes (OR 1.32, p = 0.048), positive urine culture (OR 2.08, p < 0.001), staghorn calculi (OR 1.80, p < 0.001) and nephrostomy (OR 1.65, p < 0.001) increased fever risk. Fever risk among lithotrites did not differ (p ≥ 0.128). CONCLUSIONS: Risk of post-PNL fever was not significantly different among the various lithotrites used in the CROES PNL study.

Determination of patient radiation dose during ureteroscopic treatment of urolithiasis using a validated model.

PURPOSE: We measured organ specific radiation dose rates and determined effective dose rates during simulated ureteroscopy using a validated model. To calculate the effective dose, patients were exposed to ureteroscopic management of stones at our institution. MATERIALS AND METHODS: A validated anthropomorphic male phantom was placed on a fluoroscopy table and underwent simulated ureteroscopy. High sensitivity metal oxide semiconductor field effect transistor dosimeters were placed at 20 organ sites in the phantom and used to measure organ specific radiation doses. These dose rates were multiplied by the appropriate tissue weighting factor and summed to calculate effective dose rates. Also, we retrospectively reviewed the charts of patients who underwent ureteroscopy at our institution. A total of 30 nonobese males with data on fluoroscopy time were included in analysis. The median effective dose was determined by multiplying median fluoroscopy time by the effective dose rate. RESULTS: The skin entrance was exposed to the highest absorbed dose rate, followed by the small intestine (mean ± SD 0.3286 ± 0.0054 and 0.1882 ± 0.0194 mGy per second, respectively). The mean effective dose rate was 0.024 ± 0.0019 mSv per second. Median fluoroscopy time was 46.95 seconds (range 12.9 to 298.8). The median effective dose was 1.13 mSv (range 0.31 to 7.17). CONCLUSIONS: The fluoroscopy used during ureteroscopy contributes to overall radiation exposure in patients with nephrolithiasis. Nonobese males are exposed to a median of 1.13 mSv during ureteroscopy, similar to that of abdominopelvic x-ray. More data are needed to determine clinical implications but urologists must be aware and decrease patient radiation during ureteroscopy.

Outcomes of metallic stents for malignant ureteral obstruction.

PURPOSE: Malignant ureteral obstruction often necessitates chronic urinary diversion and is associated with high rates of failure with traditional ureteral stents. We evaluated the outcomes of a metallic stent placed for malignant ureteral obstruction and determined the impact of risk factors previously associated with increased failure rates of traditional stents. MATERIALS AND METHODS: Patients undergoing placement of the metallic Resonance® stent for malignant ureteral obstruction at an academic referral center were identified retrospectively. Stent failure was defined as unplanned stent exchange or nephrostomy tube placement for signs or symptoms of recurrent ureteral obstruction (recurrent hydroureteronephrosis or increasing creatinine). Predictors of time to stent failure were assessed using Cox regression. RESULTS: A total of 37 stents were placed in 25 patients with malignant ureteral obstruction. Of these stents 12 (35%) were identified to fail. Progressive hydroureteronephrosis and increasing creatinine were the most common signs of stent failure. Three failed stents had migrated distally and no stents required removal for recurrent infection. Patients with evidence of prostate cancer invading the bladder at stent placement were found to have a significantly increased risk of failure (HR 6.50, 95% CI 1.45-29.20, p = 0.015). Notably symptomatic subcapsular hematomas were identified in 3 patients after metallic stent placement. CONCLUSIONS: Failure rates with a metallic stent are similar to those historically observed with traditional polyurethane based stents in malignant ureteral obstruction. The invasion of prostate cancer in the bladder significantly increases the risk of failure. Patients should be counseled and observed for subcapsular hematoma formation with this device.

Low dose computerized tomography for detection of urolithiasis--its effectiveness in the setting of the urology clinic.

PURPOSE: Low dose noncontrast computerized tomography is becoming a common imaging tool to diagnose urolithiasis. We investigated its usefulness as a diagnostic tool in the outpatient setting. MATERIALS AND METHODS: A total of 62 patients with suspected urolithiasis underwent standard renal stone protocol computerized tomography with a tube current of 160 mA. Images were modified by adding image noise to simulate tube currents of 70, 100 and 130 mA. Three urologists independently interpreted the original and simulated dose scans for stone number, location and associated signs of obstruction. In addition, the investigators rated the ease of interpreting the scans and their overall level of confidence. RESULTS: There were no statistically significant differences in interobserver and intra-observer variability for stone detection or obstruction signs except significant interobserver variability in hydronephrosis and intra-observer variability in stranding categories. Each 1 mm increase in stone size increased the likelihood of a concordant response 3.55, 2.7 and 2-fold when reducing the tube current level by 19%, 38% and 56%, respectively (p=0.001, 0.008 and 0.021, respectively). Multiple stones or index stone location were not associated with agreement. The overall level of confidence decreased with lower simulated doses, particularly in the bony pelvis (p<0.02). CONCLUSIONS: Low dose computerized tomography may serve as an effective tool in the setting of the urology clinic in patients with urolithiasis. This imaging tool can better assess urolithiasis and associated obstruction than plain abdominal radiographs, but it may be problematic with small stones (less than 2 mm) and evidence of distal ureteral obstruction. Its effectiveness as a long-term followup tool requires further prospective trials.

Predictors of prolonged operative time during robot-assisted laparoscopic radical prostatectomy.

OBJECTIVE: To determine risk factors for prolonged operative time (OT) during robot-assisted laparoscopic radical prostatectomy (RALP). Being able to predict prolonged OT is of pivotal importance both to the physician for patient counseling and to the hospital management. PATIENTS AND METHODS: Retrospective review of patient records undergoing RALP between 2003 and 2009 at a tertiary academic center with a structured teaching program. The following variables were recorded: age, race, body-mass index (BMI), previous abdominal surgery (yes/no), nerve-sparing technique (yes/no), lymph nodes dissection (yes/no), pathological stage (organ-confined versus non), cumulative surgical experience with RALP (expressed as number of years since introduction of RALP at our center), prostate weight and OT calculated skin-to-skin by the anesthesiologists. Prolonged OT was defined as the upper quintile (20%) according to the distribution. Multivariate regression model was generated to assess potential predictors of prolonged OT. RESULTS: A total of 523 records were retrieved. Caucasians accounted for 77.8% of the cohort. Median age was 60.3 years (interquartile range, IQR, 55.0-64.6 years), median BMI 28.1 (25.8-30.7 kg/m²), prostate weight 46.0 g (37.0-57.8 g). Eighty-six (16.4%) patients had previous abdominal surgery, lymph nodes dissection was performed in 341 (65.2%) and nerve-sparing technique was done in 310 (59.3%) cases. Median OT was 175 min (IQR 146-220 min). Prolonged OT was set at > 230 min, thereby 105 (20.1%) records were classified as such. On multivariate analysis, cumulative surgical experience with RALP (P < 0.001), nerve sparing (P = 0.023) and prostate weight (P < 0.001) were independent predictors of prolonged OT. CONCLUSIONS: Larger prostates are associated with longer OT and this effect is maintained independently of cumulative robotic experience that represents another independent factor in determining OT.

Evaluation of a Novel Single-Use Flexible Ureteroscope.

Introduction: A novel single-use flexible ureteroscope promises the optical characteristics and maneuverability of a reusable fourth-generation flexible ureteroscope. In this study, the LithoVue Single-Use Digital flexible ureteroscope was directly compared with contemporary reusable flexible ureteroscopes, with regard to optics, deflection, and irrigation flow. Methods: Three flexible ureteroscopes such as the LithoVue (Single Use; Boston Scientific), Flex-Xc (Karl Storz, Germany), and Cobra (Richard Wolf, Germany) were assessed in vitro for image resolution, distortion, color representation, grayscale imaging, field of view, and depth of field. Ureteroscope deflection was tested with an empty channel followed by placement of a 200 µm laser fiber and a 1.9F wire basket, a 2.0F nanoelectric pulse lithotripsy (NPL) probe, and a 2.4F NPL probe. Ureteroscope irrigation flow was measured using normal saline at 100 cm, with an empty channel followed by a 200 µm laser fiber, a 1.9F wire basket and a 2.0F NPL probe. Results: The LithoVue showed the largest field of view, with excellent resolution, image distortion, and depth of field. No substantial difference was demonstrated in color reproducibility or in the discernment of grayscales between ureteroscopes. The LithoVue maintained full deflection ability with all instruments in the working channel, although the Flex-Xc and Cobra ureteroscopes showed loss of deflection ranging from 2° to 27°, depending on the instrument placed. With an empty channel, the LithoVue showed an absolute flow rate similar to the Flex-Xc ureteroscope (p = 0.003). It maintained better flow with instruments in the channel than the Flex-Xc ureteroscope. The Cobra ureteroscope has a separate 3.3F instrument channel, keeping flow rates the same with instrument insertion. Conclusion: The LithoVue Single-Use Digital ureteroscope has comparable optical capabilities, deflection, and flow, making it a viable alternative to standard reusable fourth-generation flexible digital and fiberoptic ureteroscopes.

Factors affecting patient radiation exposure during percutaneous nephrolithotomy.

PURPOSE: We identified patient and stone characteristics that may contribute to increased radiation exposure during percutaneous nephrolithotomy and offer technique modifications to limit the radiation dose. MATERIAL AND METHODS: We reviewed the records of 96 patients who underwent percutaneous nephrolithotomy in the last 2 years. The effective radiation dose was calculated using accepted conversion tables. We performed multivariate linear regression to determine the association of the effective radiation dose with specific patient, stone and procedural characteristics. RESULTS: Mean±SD patient age was 51.5±13.4 years and 62.5% of the patients were female. Median body mass index was 32.0±9.7 kg/m2 (range 16.2 to 59.6) and the median stone burden was 4 cm2. Increased body mass index (p<0.001), higher stone burden (p=0.013), stone nonbranched configuration (p=0.002) and a greater number of percutaneous access tracts (p=0.040) were significantly associated with an increased effective radiation dose. Specifically obese patients with a body mass index of 30 to 39.9 kg/m2 had a more than 2-fold increase in the mean adjusted effective radiation dose and morbidly obese patients with a body mass index of 40 kg/m2 or greater had a greater than 3-fold increase vs that in normal weight patients with a body mass index of less than 25 kg/m2 (6.49 and 9.13 mSv, respectively, vs 2.66, p<0.001). Other stone specific parameters, including site and composition, percutaneous access site and estimated blood loss were not associated with the effective radiation dose. CONCLUSIONS: Patients with higher body mass index, greater stone burden, nonbranched stones and multiple nephrostomy access tracts are at risk for increased radiation exposure during percutaneous nephrolithotomy. Urologists must seek alternative strategies to minimize radiation exposure, such as tighter collimation to the region of interest, judicious use of magnification and the acquisition of as few images as possible during stone removal.

The impact of new methods of imaging on radiation dosage delivered to patients.

PURPOSE OF REVIEW: Ionizing radiation is produced by many of the imaging studies used in the diagnosis, management, and follow-up of patients with urolithiasis. Knowing the small, but significant, risks of solid and hematological malignancies associated with increased radiation exposure, our purpose is to discuss new imaging modalities that limit radiation exposure without compromising the valuable information needed by clinicians for appropriate management. RECENT FINDINGS: Recent studies suggest that many patients with urolithiasis may be subjected to relatively high doses of ionizing radiation during acute stone episodes and throughout the management of their disease, due, in large part, to the rapidly increasing usage of computed tomography (CT). Certain imaging modalities, most notably low-dose CT, have shown promise in reducing radiation dose to patients while maintaining comparable sensitivity and specificity to standard CT, under most conditions. SUMMARY: Urologists who use radiographic imaging in the care of their patients, must be aware of the risks of ionizing radiation. Accordingly, every effort must be made to limit radiation exposure, especially in the most susceptible populations. In our view, low-dose CT is currently the best imaging modality for patients with urolithiasis, as it offers adequate image quality with much reduced radiation exposure.

Reaching Nonmember Advanced Practice Providers and Allied Health Care Professionals.

INTRODUCTION: The AUA (American Urological Association) partners with several organizations. However, past efforts to effectively collaborate with advanced practice provider associations, particularly SUNA (the Society of Urologic Nurses and Associates), have been unsuccessful. We define a path forward for the AUA to achieve the goal of mutually beneficial partnership. METHODS: We analyzed surveys commissioned by the AUA to determine the number of advanced practice providers in urology and the procedures performed. We then designed a survey to determine the prevalence and engagement of advanced practice providers in contemporary urological practice. We also contacted SUNA leadership to ascertain engagement with the AUA. RESULTS: The 2017 AUA Census included 172 advanced practice provider respondents, of whom 72 (41.9%) were physician assistants and 88 (51.2%) nurse practitioners. The most highly valued resources for advanced practice providers were discounted products and services (66.7%) and a sense of professional pride (62.9%). The overall response rate to the AUA member online survey was 10.5%. The majority (87%) of respondents reported having advanced practice providers in their practice. Discussions with SUNA and a survey proposal were hampered by prior disagreement with the AUA, revealing a historical divide between the organizations. CONCLUSIONS: The true number and scope of advanced practice providers in urology are not well-defined. Additionally, there is a lack of engagement and support from AUA members on a sectional and national level. The AUA should strongly consider incentivizing advanced practice provider membership through certification, job opportunities and board membership.

Assessment of conservative dietary management as a method for normalization of 24-h urine pH in stone formers.

Low urine pH is a metabolic risk factor for stone formation. While medical therapy is typically prescribed (as urinary alkalinization), patients typically prefer dietary modifications. We aimed to assess capacity to alter urine pH with dietary management alone. We analyzed a retrospective cohort of stone formers seen between 2000 and 2015 with multiple 24-h urine collections (24hUC). Patients ≥ 18 years old with low urine pH (< 6.0) were included; those prescribed alkalinizing agents or thiazides were excluded. Demographic data, 24hUC parameters, and medications were abstracted. 24hUC was utilized to calculate gastrointestinal alkali absorption (GIAA). The primary outcome was urine pH ≥ 6.0 on second 24hUC. Predictors were selected utilizing multivariable logistic regression. The database consisted of 2197 stone formers; 224 of these met inclusion criteria. On second 24hUC, 124 (55.4%) achieved a favorable pH ≥ 6.0. On univariable analysis, a second pH ≥ 6.0 was associated with high initial pH, low initial sulfate, younger age, increase in citrate/GIAA/urine volume, and decrease in ammonium (P < 0.02). On multivariable analysis, high initial pH (OR = 23.64, P < 0.001), high initial GIAA (OR = 1.03, P = 0.001), lower initial sulfate (OR = 0.95, P < 0.001), increase in urine volume (OR = 2.19, P = 0.001), increase in GIAA (OR = 8.6, P < 0.001), increase in citrate (OR = 2.7, P = 0.014), decrease in ammonium (OR = 0.18, P < 0.001), and younger age (OR = 0.97, P = 0.025) were associated with a second pH ≥ 6.0. The analysis demonstrated a corrected AUC of 0.853. These data suggest that certain dietary recommendations (increases in urine volume, citrate, GIAA, and decreased acid load) may normalize urine pH in a select group of patients. This may allow urologists to counsel patients with low urine pH on possibility of success with dietary modification alone.