Unsupervised Machine Learning to Identify Risk Factors of Pyeloplasty Failure in Ureteropelvic Junction Obstruction.

Introduction: In adult patients with ureteropelvic junction obstruction (UPJO), little data exist on predicting pyeloplasty outcome, and there is no unified definition of pyeloplasty success. As such, defining pyeloplasty success retrospectively is particularly vulnerable to bias, allowing researchers to choose significant outcomes with the benefit of hindsight. To mitigate these biases, we performed an unsupervised machine learning cluster analysis on a dataset of 216 pyeloplasty patients between 2015 and 2023 from a multihospital system to identify the defining risk factors of patients that experience worse outcomes. Methods: A KPrototypes model was fitted with pre- and perioperative data and blinded to postoperative outcomes. T-test and chi-square tests were performed to look at significant differences of characteristics between clusters. SHapley Additive exPlanation values were calculated from a random forest classifier to determine the most predictive features of cluster membership. A logistic regression model identified which of the most predictive variables remained significant after adjusting for confounding effects. Results: Two distinct clusters were identified. One cluster (denoted as "high-risk") contained 111 (51.4%) patients and was identified by having more comorbidities, such as old age (62.7 vs 35.7), high body mass index (BMI) (26.9 vs 23.8), hypertension (66.7% vs 17.1%), and previous abdominal surgery (72.1% vs 37.1%) and was found to have worse outcomes, such as more frequent severe postoperative complications (7.2% vs 1.0%). After adjusting for confounding effects, the most predictive features of high-risk cluster membership were old age, low preoperative estimated glomerular filtration rate (eGFR), hypertension, greater BMI, previous abdominal surgery, and left-sided UPJO. Conclusions: Adult UPJO patients with older age, lower eGFR, hypertension, greater BMI, previous abdominal surgery, and left-sided UPJO naturally cluster into to a group that more commonly suffers from perioperative complications and worse outcomes. Preoperative counseling and perioperative management for patients with these risk factors may need to be thought of or approached differently.

POCUS-first for nephrolithiasis: A Monte Carlo simulation illustrating cost savings, LOS reduction, and preventable radiation.

OBJECTIVES: Non-contrast computed tomography (NCCT) is the gold standard for nephrolithiasis evaluation in the emergency department (ED). However, Choosing Wisely guidelines recommend against ordering NCCT for patients with suspected nephrolithiasis who are <50 years old with a history of kidney stones. Our primary objective was to estimate the national annual cost savings from using a point-of-care ultrasound (POCUS)-first approach for patients with suspected nephrolithiasis meeting Choosing Wisely criteria. Our secondary objectives were to estimate reductions in ED length of stay (LOS) and preventable radiation exposure. METHODS: We created a Monte Carlo simulation using available estimates for the frequency of ED visits for nephrolithiasis and eligibility for a POCUS-first approach. The study population included all ED patients diagnosed with nephrolithiasis. Based on 1000 trials of our simulation, we estimated national cost savings in averted advanced imaging from this strategy. We applied the same model to estimate the reduction in ED LOS and preventable radiation exposure. RESULTS: Using this model, we estimate a POCUS-first approach for evaluating nephrolithiasis meeting Choosing Wisely guidelines to save a mean (±SD) of $16.5 million (±$2.1 million) by avoiding 159,000 (±18,000) NCCT scans annually. This resulted in a national cumulative decrease of 166,000 (±165,000) annual bed-hours in ED LOS. Additionally, this resulted in a national cumulative reduction in radiation exposure of 1.9 million person-mSv, which could potentially prevent 232 (±81) excess cancer cases and 118 (±43) excess cancer deaths annually. CONCLUSION: If adopted widely, a POCUS-first approach for suspected nephrolithiasis in patients meeting Choosing Wisely criteria could yield significant national cost savings and a reduction in ED LOS and preventable radiation exposure. Further research is needed to explore the barriers to widespread adoption of this clinical workflow as well as the benefits of a POCUS-first approach in other patient populations.

Initial Safety and Feasibility of Steerable Ureteroscopic Renal Evacuation: A Novel Approach for the Treatment of Urolithiasis.

Background: There is a need to reliably render urolithiasis patients completely stone free with minimal morbidity. We report on the initial safety and feasibility with steerable ureteroscopic renal evacuation (SURE) in a prospective study using basket extraction as a comparison. Materials and Methods: A pilot randomized controlled study was conducted comparing SURE with basket extraction postlaser lithotripsy. SURE is performed using the CVAC™ Aspiration System, a steerable catheter (with introducer). The safety and feasibility of steering CVAC throughout the collecting system under fluoroscopy and aspirating stone fragments as it was designed to do were evaluated. Fluoroscopy time, change in hemoglobin, adverse events through 30 days, total and proportion of stone volume removed at 1 day, intraoperative stone removal rate, and stone-free rate (SFR) at 30 days through CT were compared. Results: Seventeen patients were treated (n = 9 SURE, n = 8 Basket). Baseline demographics and stone parameters were not significantly different between groups. One adverse event occurred in each group (self-limiting ileus for SURE and urinary tract infection for Basket). No mucosal injury and no contrast extravasation were observed in either group. The CVAC catheter was steered throughout the collecting system and aspirated fragments. There was no significant difference in fluoroscopy time, procedure time, change in hemoglobin, or stone removal rate between groups. SURE removed more and a greater proportion of stone volume at day 1 vs baskets (202 mm3 vs 91 mm3, p < 0.01 and 84% vs 56%, p = 0.022). SURE achieved 100% SFR at 30 days vs 75% for baskets, although this difference was not statistically significant (p = 0.20). Conclusions: This initial study suggests SURE is safe, feasible, and may be more effective in stone removal postlaser lithotripsy compared to basketing. More development is needed, and larger clinical studies are underway.

Determining Variable Costs in the Acute Urolithiasis Cycle of Care Through Time-Driven Activity-Based Costing.

OBJECTIVE: To characterize full cycle of care costs for managing an acute ureteral stone using time-driven activity-based costing. METHODS: We defined all phases of care for patients presenting with an acute ureteral stone and built an overarching process map. Maps for sub-processes were constructed through interviews with providers and direct observation of clinical spaces. This facilitated calculation of cost per minute for all aspects of care delivery, which were multiplied by associated process times. These were added to consumable costs to determine cost for each specific step and later aggregated to determine total cost for each sub-process. We compared costs of eight common clinical pathways for acute stone management, defining total cycle of care cost as the sum of all sub-processes that comprised each pathway. RESULTS: Cost per sub-process included $920 for emergency department (ED) care, $1665 for operative stent placement, $2368 for percutaneous nephrostomy tube placement, $106 for urology clinic consultation, $238 for preoperative center visit, $4057 for ureteroscopy with laser lithotripsy (URS), $2923 for extracorporeal shock wave lithotripsy, $169 for clinic stent removal, $197 for abdominal x-ray, and $166 for ultrasound. The lowest cost pathway ($1388) was for medical expulsive therapy, whereas the most expensive pathway ($8002) entailed a repeat ED visit prompting temporizing stent placement and interval URS. CONCLUSION: We found a high degree of cost variation between care pathways common to management of acute ureteral stone episodes. Reliable cost accounting data and an understanding of variability in clinical pathway costs can inform value-based care redesign as payors move away from pure fee-for-service reimbursement.

Changing the Status Quo: Developing a Virtual Sub-Internship in the Era of COVID-19.

PROBLEM: Subinternships are integral to medical education as tools for teaching and assessing fourth-year medical students. Social distancing due to COVID-19 has precluded the ability to offer in-person subinternships - negatively impacting medical education and creating uncertainty surrounding the residency match. With no precedent for the development and implementation of virtual subinternships, the Society of Academic Urologists (SAU) developed an innovative and standardized curriculum for the Virtual Subinternship in Urology (vSIU). METHODS: The vSIU committee's mandate was to create a standardized curriculum for teaching foundational urology and assessing student performance. Thirty-three members from 23 institutions were divided into working groups and given 3 weeks to develop 10 modules based on urologic subspecialties, Accreditation Council for Graduate Medical Education core competencies, technical skills training and student assessment. Working groups were encouraged to develop innovative learning approaches. The final curriculum was assembled into the "vSIU Guidebook." RESULTS: The vSIU Guidebook contains 212 pages - 64 pages core content and 2 appendices (patient cases and evaluations). It outlines a detailed 4-week curriculum with a sufficient volume of resources to offer a completely adaptable virtual course with the same rigor as a traditional subinternship. Modules contain curated teaching resources including journal articles, lectures, surgical videos and simulated clinical scenarios. Innovative learning tools include reflective writing, mentorship guidelines, videoconference-based didactics, surgical simulcasting and virtual technical skills training. The guidebook was disseminated to program directors nationally. NEXT STEPS: The vSIU is the first virtual subinternship in any specialty to be standardized and offered nationally, and it was implemented by at least 19 urology programs. This curriculum serves as a template for other specialties looking to develop virtual programs and feedback from educators and students will allow the curriculum to evolve. As the pandemic continues to challenge our paradigm, this rapid and innovative response exemplifies that the medical community will continue to meet the needs of an ever-changing educational landscape.

Racial disparities in analgesic use amongst patients presenting to the emergency department for kidney stones in the United States.

INTRODUCTION: We sought quantify racial disparities in use of analgesia amongst patients seen in Emergency Departments for renal colic. METHODS: We identified all individuals presenting to the Emergency Department with urolithiasis from 2003 to 2015 in the nationally representative Premier Hospital Database. We included patients discharged in ≤1 day and excluded those with chronic pain or renal insufficiency. We assessed the relationship between race/ethnicity and opioid dosage in morphine milligram equivalents (MME), and ketorolac, through multivariable regression models adjusting for patient and hospital characteristics. RESULTS: The cohort was 266,210 patients, comprised of White (84%), Black (6%) and Hispanic (10%) individuals. Median opioid dosage was 20 MME and 55.5% received ketorolac. Our adjusted model showed Whites had highest median MME (20 mg) with Blacks (-3.3 mg [95% CI: -4.6 mg to -2.1 mg]) and Hispanics (-6.0 mg [95% CI: -6.9 mg to -5.1 mg]) receiving less. Blacks were less likely to receive ketorolac (OR: 0.72, 95% CI: 0.62-0.84) while there was no difference between Whites and Hispanics. CONCLUSIONS: Black and Hispanic patients in American Emergency Departments with acute renal colic receive less opioid medication than White patients; Black patients are also less likely to receive ketorolac.

Care Setting as a Modifiable Predictor of Perioperative Cost and Outcomes following Elective Urinary Stone Surgery.

INTRODUCTION: We sought to identify predictors of index surgical care setting and to determine if care setting influences risk adjusted perioperative costs and/or 30-day revisits following elective surgery for urinary stones. METHODS: Using 2014 HCUP (Healthcare Cost and Utilization Project) all payer claims data from New York and Florida, we retrospectively identified 29,433 patients undergoing index ureteroscopy or shock wave lithotripsy. We used inverse probability of treatment weighting adjusted multivariable logistic and gamma regression to assess the association between index surgical care setting and 30-day revisits and total costs, respectively. RESULTS: Most urinary stone procedures (70.8%) were performed in the ambulatory setting. Underinsurance was associated with lower odds of undergoing surgery in the ambulatory setting (Medicaid vs private: OR 0.44, 95% CI 0.37-0.53; p <0.001; self-pay vs private: OR 0.21, 95% CI 0.17-0.26; p <0.001). Adjusted mean index surgical and 30-day acute care costs were significantly lower among ambulatory vs inpatient/emergency department cases ($4,746.10 vs $10,669.26 and $5,434.42 vs $11,729.39, both p <0.001), respectively. Ambulatory surgery was independently associated with lower odds of experiencing a 30-day revisit (OR 0.82, 95% CI 0.72-0.94; p=0.005). CONCLUSIONS: Urinary stone cases managed surgically in an ambulatory setting had lower risk adjusted costs and odds of a 30-day revisit compared to those managed in an inpatient setting. Our findings support use of ambulatory rather than inpatient based elective surgery for uncomplicated urinary stones. We invite clinicians and policymakers alike to reconsider clinical and nonclinical factors that influence pathways of care.

Testosterone replacement therapy is associated with an increased risk of urolithiasis.

PURPOSE: To determine whether TRT in men with hypogonadism is associated with an increased risk of urolithiasis. METHODS: We conducted a population-based matched cohort study utilizing data sourced from the Military Health System Data Repository (a large military-based database that includes beneficiaries of the TRICARE program). This included men aged 40-64 years with no prior history of urolithiasis who received continuous TRT for a diagnosis of hypogonadism between 2006 and 2014. Eligible individuals were matched using both demographics and comorbidities to TRICARE enrollees who did not receive TRT. The primary outcome was 2-year absolute risk of a stone-related event, comparing men on TRT to non-TRT controls. RESULTS: There were 26,586 pairs in our cohort. Four hundred and eighty-two stone-related events were observed at 2 years in the non-TRT group versus 659 in the TRT group. Log-rank comparisons showed this to be a statistically significant difference in events between the two groups (p < 0.0001). This difference was observed for topical (p < 0.0001) and injection (p = 0.004) therapy-type subgroups, though not for pellet (p = 0.27). There was no significant difference in stone episodes based on secondary polycythemia diagnosis, which was used as an indirect indicator of higher on-treatment testosterone levels (p = 0.14). CONCLUSION: We observed an increase in 2-year absolute risk of stone events among those on TRT compared to those who did not undergo this hormonal therapy. These findings merit further investigation into the pathophysiologic basis of our observation and consideration by clinicians when determining the risks and benefits of placing patients on TRT.

Validation of a novel, tissue-based simulator for robot-assisted radical prostatectomy.

PURPOSE: To create a tissue-based simulator that allows practice of key steps of robot-assisted radical prostatectomy (RARP) in a sequential fashion. MATERIALS AND METHODS: A model was created from female porcine genitourinary tract tissue to represent the male pelvic genitourinary anatomy. The following steps of RARP were simulated: dorsal venous complex ligation, division of bladder neck, seminal vesicle dissection, prostatic pedicle ligation with nerve sparing, urethral division, bladder neck reconstruction, and vesicourethral anastomosis. Ten novices and 10 experts performed RARP on the model. Face validity was calculated by ratings of realism. Content validity was calculated by experts' rating of usefulness of the model as a training tool. Construct validity was calculated by comparison of time to complete the simulator and rating of performance on the objective structured assessment of technical skill (OSATS) questionnaire, between novices and experts. RESULTS: The model was determined to have good face and content validity with an average score of 3.7/5 and 4.8/5, respectively. The mean time for completion of the simulator was 121.5 minutes for the novice and 62 minutes for the expert group (P<0.001), and the mean overall OSATS performance ratings were 4.6/5 for experts and 2.6/5 for novices (P<0.001), yielding good construct validity. CONCLUSIONS: We created and validated a realistic, tissue-based simulator to allow for training of key surgical steps of RARP in a sequential fashion. Ultimately, this simulator could be incorporated into urology training, credentialing, and facilitate surgeon transitioning from open prostatectomy to RARP.

Nanostructured polyurethane-poly-lactic-co-glycolic acid scaffolds increase bladder tissue regeneration: an in vivo study.

Although showing much promise for numerous tissue engineering applications, polyurethane and poly-lactic-co-glycolic acid (PLGA) have suffered from a lack of cytocompatibility, sometimes leading to poor tissue integration. Nanotechnology (or the use of materials with surface features or constituent dimensions less than 100 nm in at least one direction) has started to transform currently implanted materials (such as polyurethane and PLGA) to promote tissue regeneration. This is because nanostructured surface features can be used to change medical device surface energy to alter initial protein adsorption events important for promoting tissue-forming cell functions. Thus, due to their altered surface energetics, the objective of the present in vivo study was to create nanoscale surface features on a new polyurethane and PLGA composite scaffold (by soaking the polyurethane side and PLGA side in HNO3 and NaOH, respectively) and determine bladder tissue regeneration using a minipig model. The novel nanostructured scaffolds were further functionalized with IKVAV and YIGSR peptides to improve cellular responses. Results provided the first evidence of increased in vivo bladder tissue regeneration when using a composite of nanostructured polyurethane and PLGA compared with control ileal segments. Due to additional surgery, extended potentially problematic healing times, metabolic complications, donor site morbidity, and sometimes limited availability, ileal segment repair of a bladder defect is not optimal and, thus, a synthetic analog is highly desirable. In summary, this study indicates significant promise for the use of nanostructured polyurethane and PLGA composites to increase bladder tissue repair for a wide range of regenerative medicine applications, such as regenerating bladder tissue after removal of cancerous tissue, disease, or other trauma.

Prostate abscess: MRSA spreading its influence into Gram-negative territory: case report and literature review.

Prostate abscess is a rare complication of an ascending urinary tract infection (UTI). Its incidence has reduced secondary to routine and early use of antibiotics for treatment of UTIs. Prostate abscess has been reported in patients with uncontrolled diabetes, prolonged indwelling urinary catheters, prostate biopsy or other instrumentation of lower urinary tract. Prostate abscess is most commonly associated with Gram-negative bacteria. Staphylococcus aureus is rarely implicated and has been reported in patients with underlying risk factors like long-term or uncontrolled diabetes, intravenous drug abuse or bacteraemia. We present a rare case of prostate abscess due to methicillin resistant S aureus without obvious risk factors.

An updated report on complications following robotic prostatectomy: results of an unbiased prospective database.

INTRODUCTION: The application of robotic-assisted radical prostatectomy has increased considerably over the past decade, but there remains a paucity of standardized complications reporting associated with this procedure. The complications literature regarding robotic prostatectomy is wrought with limitations, variability, and bias making meaningful comparisons between surgical series difficult. MATERIALS AND METHODS: From November 2006 to December 2010, a total of 575 patients were evaluated. Data were assimilated through an IRB-approved blinded prospective database by an independent third party committee. Patients were followed prospectively for 30 days postoperatively. The Modified Clavien system was utilized to grade complications. Grade I and II complications were classified as minor, while grade III, IV, and V were considered major complications. Multiple complications in individual patients were recorded as separate events. Our initial experience and that of our most recent were compared. Age, body mass index, American Society of Anesthesiologists score, Gleason grade, prostate specific antigen, prostate volume, and complications were evaluated. RESULTS: Of the 575 patients, 482 (83.8%) had an ideal perioperative course. In the remaining 93 (16.2%) patients, there were 117 complications. Minor complications occurred in 84 (14.6%) and major complications arose in 15 (2.6%) patients. When the first 500 patients were divided into subsets of 100 patients, a linear regression analysis demonstrated no significant difference in overall complications among the five quintiles (p=0.17). The first quintile was found to have a significantly higher major complication rate compared with the second quintile (p=0.05). The subsequent quintiles exhibited no significant change in major complication rate. CONCLUSIONS: As a surgeon progresses through the learning curve, there is a stable overall complication rate with a drop in major complications after the first 100 cases.

Hand-assisted laparoscopic versus robot-assisted laparoscopic partial nephrectomy: comparison of short-term outcomes and cost.

INTRODUCTION: Robot-assisted laparoscopic partial nephrectomy (RALPN) and laparoscopic partial nephrectomy (LPN) have become standard for the surgical management of small renal masses (SRMs). However, no studies have evaluated the short-term outcomes or cost of RALPN as compared with hand-assisted laparoscopic partial nephrectomy (HALPN) in a standardized fashion. METHODS: A retrospective review of all patients who underwent HALPN or RALPN from 2006 to 2010 were assessed for patient age, body mass index (BMI), American Society of Anesthesiologists (ASA) score, radiographic tumor size, nephrometry (radius, endo/exophytic, nearness to collecting system, anterior/posterior, lines of polarity [RENAL]) scores, operative and room times, hospital length of stay (LOS), estimated blood loss (EBL), requirement of hilar vessel clamping, warm ischemia time (WIT), pre- and postprocedural creatinine and hemoglobin levels, and complications. Total costs of the procedures were estimated based on operating room component (operative staff time, anesthesia, and supply) and hospital stay cost (room and board, pharmacy). A robotic premium cost, estimated based on the yearly overall cost of the da Vinci S surgical system divided by the annual number of cases, was included in the RALPN cost. Cost figures were obtained from hospital administration and applied to the mean HALPN and RALPN patient. RESULTS: Forty-seven patients underwent HALPN since 2006 and 21 patients underwent RALPN since 2008. ASA, BMI, EBL, tumor size, nephrometry score, positive margin rate, change in creatinine, change in hemoglobin, morphine equivalents used, and complication rate were all similar in both groups (p>0.05). Room time and operative time were significantly shorter for the HALPN cohort (p=0.001) whereas LOS was significantly shorter in the RALPN cohort (p=0.019). Despite the shorter LOS, RALPN was associated with a $1165 increased cost, mainly due to increased operating room time and premium cost of the robot. CONCLUSIONS: While early in our experience, RALPN offered no significant advantage in short-term outcomes over HALPN and was associated with an increased cost of over $1150.

Dedicated robotics team reduces pre-surgical preparation time.

CONTEXT: Robot-Assisted Laparoscopic Radical Prostatectomy (RALRP) requires significant preoperative setup time for the room, staff, and surgical platform. The utilization of a dedicated robotics operating room (OR) staff may facilitate efficiency and decrease costs. AIMS: We sought to determine the degree to which preoperative time decreased as experience was gained. MATERIALS AND METHODS: A total of 476 patients with a mean age of 60.2 years were evaluated (11/2006 to 1/2010). Data was assimilated through an institutional review board approved blinded, prospective database. Utilizing time from patient arrival in the OR to robot docking as preoperative preparation, our experience was evaluated. Age, body mass index (BMI), and American Society of Anesthesiologists risk scores (ASA) were compared. STATISTICAL ANALYSIS USED: Analysis of variance; Two-sample t-test for unequal variances. RESULTS: The first and last 100 cases were found to have similar age (P=0.27), BMI (P=0.11), and ASA (P=0.09). The average preoperative times were 66. 4 and 53.4 min, respectively (P<0.05). The second 100 patients treated were found to have a significantly shorter preoperative time when compared to the first 100 patients (P<0.05). When the first 100 cases were divided into cohorts of 10 cases the mean preoperative time for the first through fourth cohorts were 80.5, 69.3, 78.8, and 64.7 min, respectively. After treatment of our first 30 patients we found a significant drop in preoperative time. This persisted throughout the remainder of our experience. CONCLUSIONS: From the time of patient arrival a number of tasks are accomplished by the non-physician operating room staff during RALRP. The use of a consistent staff can decrease preoperative setup times and, therefore, the overall length of surgery.

Relationship between serum vitamin D and 24-hour urine calcium in patients with nephrolithiasis.

OBJECTIVE: To examine the relationship between serum 25-OH vitamin D and 24-hour urine calcium in patients with nephrolithiasis. METHODS: A retrospective review was performed. Patients evaluated in 2 metabolic stone clinics were included for analysis. Multivariate linear regression models were adjusted for known risk factors for stone disease (age, gender, body mass index, hypertension, diabetes mellitus, gout, relevant medications, and 24-hour urine composition). RESULTS: One-hundred sixty-nine patients were included in the study. Female to male ratio was 69:100, mean age was 50.9 years (SD 13.7), and mean body mass index was 27.4 (SD 6.4). Vitamin D deficiency (25-OH vitamin D <20 ng/mL) was present in 18.9% of patients, vitamin D insufficiency (>20, <30 ng/mL) was present in 34.9% of patients, and vitamin D was within normal limits (≥ 30 ng/mL) in 46.1% of patients. On age-adjusted and multivariate linear regression, serum 25-OH vitamin D was not related to 24-hour urine calcium (age adjusted ß = -0.31 m 95% CI -1.9 to 1.3; multivariate adjusted ß = 0.08, 95% CI -1.3 to 1.5). CONCLUSION: Although 25-OH vitamin D is involved in the body's calcium homeostasis, our study does not show a relationship between serum vitamin D level and 24-hour urine calcium excretion in stone-formers. This information may have implications regarding the safety of vitamin D repletion in patients with nephrolithiasis.

Histopathologic changes after bipolar resection of the prostate: depth of penetration of bipolar thermal injury.

BACKGROUND AND PURPOSE: While the power needed to initiate bipolar vaporization is higher than conventional monopolar resection, the energy needed to maintain bipolar vaporization is significantly lower and may result in less thermal tissue injury. This may have implications for hemostasis, scarring, and perioperative morbidity. The objective of this study is to assess histopathologic changes in prostatic tissue after bipolar transurethral vaporization of the prostate. PATIENTS AND METHODS: Male patients older than 40 years with a diagnosis of benign prostatic hyperplasia (BPH) who elected to undergo bipolar transurethral vaporization of the prostate were included in this study. Patients were excluded if they had a previous transurethral resection of the prostate (TURP) or prostate radiation therapy. An Olympus button vaporization electrode was used to vaporize prostate tissue. A loop electrode was then used to obtain a deep resection specimen. The vaporized and loop resection surfaces were inked and sent for pathologic analysis to determine the presence of gross histologic changes and the depth of penetration of the bipolar vaporization current. RESULTS: A total of 12 men underwent bipolar TURP at standard settings of 290 W cutting and 145 W coagulation current. Mean patient age was 70±10.2 years (range 56-88 years). Mean surgical time was 48.7±20.2 minutes (range 30-89 min). Mean depth of thermal injury was 2.4±0.84 mm (range 0.3-3.5 mm). Histopathologic evaluation demonstrated thermal injury in all specimens, but no gross char was encountered. CONCLUSIONS: In bipolar systems, resection takes place at much lower peak voltages and temperatures compared with monopolar systems. Theoretically, this leads to less collateral thermal damage and tissue char. Our tissue study illustrates that the button vaporization electrode achieves a much larger depth of penetration than previous studies of bipolar TURP. This may be because thermal injury represents a gradual continuum of histologic changes.

Stone forming risk factors in patients with type Ia glycogen storage disease.

PURPOSE: Patients with type Ia glycogen storage disease have an increased recurrent nephrolithiasis rate. We identified stone forming risk factors in patients with type Ia glycogen storage disease vs those in stone formers without the disease. MATERIALS AND METHODS: Patients with type Ia glycogen storage disease were prospectively enrolled from our metabolic clinic. Patient 24-hour urine parameters were compared to those in age and gender matched stone forming controls. RESULTS: We collected 24-hour urine samples from 13 patients with type Ia glycogen storage disease. Average +/- SD age was 27.0 +/- 13.0 years and 6 patients (46%) were male. Compared to age and gender matched hypocitraturic, stone forming controls patients had profound hypocitraturia (urinary citrate 70 vs 344 mg daily, p = 0.009). When comparing creatinine adjusted urinary values, patients had profound hypocitraturia (0.119 vs 0.291 mg/mg creatinine, p = 0.005) and higher oxalate (0.026 vs 0.021 mg/mg creatinine, p = 0.038) vs other stone formers. CONCLUSIONS: Patients with type Ia glycogen storage disease have profound hypocitraturia, as evidenced by 24-hour urine collections, even compared to other stone formers. This may be related to a recurrent nephrolithiasis rate greater than in the overall population. These findings may be used to support different treatment modalities, timing and/or doses to prevent urinary lithiasis in patients with type Ia glycogen storage disease.