Removal of Small, Asymptomatic Kidney Stones and Incidence of Relapse.

BACKGROUND: The benefits of removing small (≤6 mm), asymptomatic kidney stones endoscopically is unknown. Current guidelines leave such decisions to the urologist and the patient. A prospective study involving older, nonendoscopic technology and some retrospective studies favor observation. However, published data indicate that about half of small renal stones left in place at the time that larger stones were removed caused other symptomatic events within 5 years after surgery. METHODS: We conducted a multicenter, randomized, controlled trial in which, during the endoscopic removal of ureteral or contralateral kidney stones, remaining small, asymptomatic stones were removed in 38 patients (treatment group) and were not removed in 35 patients (control group). The primary outcome was relapse as measured by future emergency department visits, surgeries, or growth of secondary stones. RESULTS: After a mean follow-up of 4.2 years, the treatment group had a longer time to relapse than the control group (P<0.001 by log-rank test). The restricted mean (±SE) time to relapse was 75% longer in the treatment group than in the control group (1631.6±72.8 days vs. 934.2±121.8 days). The risk of relapse was 82% lower in the treatment group than the control group (hazard ratio, 0.18; 95% confidence interval, 0.07 to 0.44), with 16% of patients in the treatment group having a relapse as compared with 63% of those in the control group. Treatment added a median of 25.6 minutes (interquartile range, 18.5 to 35.2) to the surgery time. Five patients in the treatment group and four in the control group had emergency department visits within 2 weeks after surgery. Eight patients in the treatment group and 10 in the control group reported passing kidney stones. CONCLUSIONS: The removal of small, asymptomatic kidney stones during surgery to remove ureteral or contralateral kidney stones resulted in a lower incidence of relapse than nonremoval and in a similar number of emergency department visits related to the surgery. (Funded by the National Institute of Diabetes and Digestive and Kidney Diseases and the Veterans Affairs Puget Sound Health Care System; ClinicalTrials.gov number, NCT02210650.).

Integrated Cytometry With Machine Learning Applied to High-Content Imaging of Human Kidney Tissue for In Situ Cell Classification and Neighborhood Analysis.

The human kidney is a complex organ with various cell types that are intricately organized to perform key physiological functions and maintain homeostasis. New imaging modalities, such as mesoscale and highly multiplexed fluorescence microscopy, are increasingly being applied to human kidney tissue to create single-cell resolution data sets that are both spatially large and multidimensional. These single-cell resolution high-content imaging data sets have great potential to uncover the complex spatial organization and cellular makeup of the human kidney. Tissue cytometry is a novel approach used for the quantitative analysis of imaging data; however, the scale and complexity of such data sets pose unique challenges for processing and analysis. We have developed the Volumetric Tissue Exploration and Analysis (VTEA) software, a unique tool that integrates image processing, segmentation, and interactive cytometry analysis into a single framework on desktop computers. Supported by an extensible and open-source framework, VTEA's integrated pipeline now includes enhanced analytical tools, such as machine learning, data visualization, and neighborhood analyses, for hyperdimensional large-scale imaging data sets. These novel capabilities enable the analysis of mesoscale 2- and 3-dimensional multiplexed human kidney imaging data sets (such as co-detection by indexing and 3-dimensional confocal multiplexed fluorescence imaging). We demonstrate the utility of this approach in identifying cell subtypes in the kidney on the basis of labels, spatial association, and their microenvironment or neighborhood membership. VTEA provides an integrated and intuitive approach to decipher the cellular and spatial complexity of the human kidney and complements other transcriptomics and epigenetic efforts to define the landscape of kidney cell types.

Fragmentation of Stones by Burst Wave Lithotripsy in the First 19 Humans.

PURPOSE: We report stone comminution in the first 19 human subjects by burst wave lithotripsy (BWL), which is the transcutaneous application of focused, cyclic ultrasound pulses. MATERIALS AND METHODS: This was a prospective multi-institutional feasibility study recruiting subjects undergoing clinical ureteroscopy (URS) for at least 1 stone ≤12 mm as measured on computerized tomography. During the planned URS, either before or after ureteroscope insertion, BWL was administered with a handheld transducer, and any stone fragmentation and tissue injury were observed. Up to 3 stones per subject were targeted, each for a maximum of 10 minutes. The primary effectiveness outcome was the volume percent comminution of the stone into fragments ≤2 mm. The primary safety outcome was the independent, blinded visual scoring of tissue injury from the URS video. RESULTS: Overall, median stone comminution was 90% (IQR 20, 100) of stone volume with 21 of 23 (91%) stones fragmented. Complete fragmentation (all fragments ≤2 mm) within 10 minutes of BWL occurred in 9 of 23 stones (39%). Of the 6 least comminuted stones, likely causative factors for decreased effectiveness included stones that were larger than the BWL beamwidth, smaller than the BWL wavelength or the introduction of air bubbles from the ureteroscope. Mild reddening of the papilla and hematuria emanating from the papilla were observed ureteroscopically. CONCLUSIONS: The first study of BWL in human subjects resulted in a median of 90% comminution of the total stone volume into fragments ≤2 mm within 10 minutes of BWL exposure with only mild tissue injury.

A Randomized Trial Evaluating the Use of a Smart Water Bottle to Increase Fluid Intake in Stone Formers.

OBJECTIVE: The aim of this study is to evaluate if the use of a smart water bottle improves urine volume in stone forming patients. METHODS: Adults with nephrolithiasis and low urine volume (<1.5 L) documented on a 24-hour urinalysis (24 hr U) were randomized to receive either standard dietary recommendations to increase fluid intake (DR arm), or DR and a smart water bottle (HidrateSpark®; Hydrate Inc., Minneapolis, MN) that recorded fluid intake, synced to the user's smartphone, and provided reminders to drink (SB arm). Participants completed baseline surveys assessing barriers to hydration. They then repeated a 24 hr U and survey at 6 and 12 weeks, respectively. RESULTS: Eighty-five subjects (44 DR, 41 SB) were enrolled. The main baseline factor limiting fluid intake was not remembering to drink (60%). Follow-up 24 hr Us were available for 51 patients. The mean increase in volume was greater in the SB arm (1.37 L, 95% confidence interval -0.51 to 3.25) than the DR arm (0.79 L, 95% confidence interval -1.15 to 2.73) (P = .04). A smaller percentage of subjects in the SB arm reported not remembering to drink as the main factor limiting fluid intake in the follow-up questionnaire compared to baseline (45.4% vs. 68.4%, P < .05). This was not true for the DR arm (40.0% vs. 51.2%, P = .13). CONCLUSIONS: Difficulty remembering to drink is a barrier to achieving sufficient fluid intake in stone formers. The use of a smart bottle was associated with greater increases in 24 hr U volumes and less difficulty remembering to drink.

Using micro computed tomographic imaging for analyzing kidney stones.

Stone analysis is a critical part of the clinical characterization of urolithiasis. This article reviews the strengths and limitations of micro CT in the analysis of stones. Using micro CT alone in a series of 757 stone specimens, micro CT identified the 458 majority calcium oxalate specimens with a sensitivity of 99.6% and specificity of 95.3%. Micro CT alone was also successful in identifying majority apatite, brushite, uric acid, and struvite stones. For some minor minerals-such as apatite in calcium oxalate or calcium salts in uric acid stones-micro CT enables the detection of minute quantities well below 1%. The addition of a standard for calibrating X-ray attenuation values improves the ability of micro CT to identify common stone minerals. The three-dimensional nature of micro CT also allows for the visualization of surface features in stones, which is valuable for the study of stone formation.

The Role of Prostate Specific Antigen Monitoring after Holmium Laser Enucleation of the Prostate.

PURPOSE: Prostate specific antigen screening for prostate cancer has recently been challenged due to poor sensitivity. In addition to prostate cancer, a number of conditions elevate prostate specific antigen, of which benign prostatic hyperplasia is most common. The objective of this study was to assess the positive predictive value of prostate specific antigen and prostate specific antigen density for prostate cancer risk following holmium laser enucleation of the prostate. MATERIALS AND METHODS: We queried an institutional review board approved database of holmium laser enucleation of the prostate performed at Indiana University from 1999 to 2018 to identify 1,147 patients with prostate specific antigen data available after holmium laser enucleation. A total of 55 biopsies after enucleation were recorded. Demographics, prostate specific antigen, prostate volume and oncologic details were analyzed. The primary outcome was biopsy proven prostate cancer. RESULTS: A total of 55 patients underwent transrectal ultrasound prostate biopsy for cause after holmium laser enucleation of the prostate. Cancer was identified in more than 90% of biopsied cases. Men with prostate specific antigen above 1 ng/ml at biopsy had a 94% probability of cancer detection and an 80% risk of clinically significant disease. Prostate specific antigen density above 0.1 ng/ml2 was associated with a 95% risk of cancer and an 88% risk of clinically significant cancer. Prostate specific antigen greater than 5.8 ng/ml or prostate specific antigen density greater than 0.17 ng/ml2 was universally associated with biopsy proven cancer. CONCLUSIONS: Prostate specific antigen and prostate specific antigen density have high positive predictive value for prostate cancer risk after holmium laser enucleation of the prostate. Thresholds for biopsy should be lower than in patients who do not undergo holmium laser enucleation. Those who undergo that procedure and have prostate specific antigen above 1 ng/ml or prostate specific antigen density above 0.1 ng/ml2 are at higher risk for harboring clinically significant disease and should undergo biopsy. Referring physicians should be aware of these significant risk shifts.

Operative time comparison of aquablation, greenlight PVP, ThuLEP, GreenLEP, and HoLEP.

INTRODUCTION: The BPH surgical armamentarium is composed of a rapidly expanding number of technologies and techniques. These include greenlight photovaporization of the prostate (PVP), greenlight enucleation of the prostate (GreenLEP), holmium laser enucleation of the prostate (HoLEP), thulium laser enucleation of the prostate (ThuLEP) and, more recently, the aquablation procedure. To the best of our knowledge, no direct comparison in operative time has been performed. METHODS: Data for this study were pooled from five sources. For aquablation, patient-level data from four studies of the aquablation procedure were provided by the device manufacturer as well as from a high-volume commercial user. PVP, GreenLEP, HoLEP, and ThuLEP were performed by high-volume, experienced experts. Endpoints included total operative time, resection time, and proportion of total operative time for resection. General linear models were used to evaluate the relationship between prostate volume (or other continuous predictors) and procedure time. RESULTS: Total procedure time was related to prostate size. Except for the small prostate size range (size < 40 cc), at any given prostate volume, procedure time was highest for PVP, intermediate for LEPs, and lowest for Aquablation. The relationship between procedure time and prostate size (i.e., slope of the fitted lines) was 0.16 min/g for aquablation, 0.32 min/g, 0.28 min/g and 0.32 min/g for GreenLEP, HoLEP and ThuLEP, respectively, and 0.63 min/g for PVP. CONCLUSION: In our analysis of pooled data of multi-surgical techniques and technologies, aquablation provided the lowest operative time across all prostate volumes. PVP had the longest procedure time for prostates > 40 cc.

Aquablation for benign prostatic hyperplasia in large prostates (80-150 cc): 2-year results.

INTRODUCTION: To report 2-year safety and effectiveness of the Aquablation procedure for the treatment of men with symptomatic benign prostatic hyperplasia (BPH) and large-volume 80-150 cc prostates. MATERIALS AND METHODS: Between September-December 2017, 101 men with moderate-to-severe BPH symptoms and prostate volumes of 80-150 cc underwent an ultrasound-guided robotically executed Aquablation procedure in a prospective multicenter international clinical trial (WATER II). Baseline, procedural and follow up parameters were recorded at baseline and scheduled postoperative visits. Herein we report 2-year safety and efficacy for this cohort. RESULTS: Mean prostate volume was 107 cc (range 80-150 cc). Mean IPSS improved from 23.2 at baseline to 5.8 at 2 years (17-point improvement, p < .0001). Mean IPSS quality of life improved from 4.6 at baseline to 1.1 at 2 years (p < .0001). Maximum urinary flow increased from 8.7 to 18.2 cc/sec. Two subjects underwent a repeat procedure for BPH symptoms over the 2-year follow up period. By 2 years or study exit, all but 2 of 74 subjects stopped taking alpha blockers. Similarly, all but 4 of 32 subjects stopped taking 5α-reductase inhibitors. CONCLUSIONS: Two-year prospective multicenter follow up demonstrated that the Aquablation procedure is safe and effective in the treatment of men with LUTS due to BPH and prostates 80-150 cc with durable treatment efficacy, acceptable safety profile and a low retreatment rate. ClinicalTrials.gov number, NCT03123250.

Aquablation for benign prostatic hyperplasia in large prostates (80-150 mL): 6-month results from the WATER II trial.

OBJECTIVE: To present 6-month safety and effectiveness data from a multicentre prospective study of aquablation in men with lower urinary tract symptoms (LUTS) attributable to benign prostatic hyperplasia (BPH) with prostate volumes between 80 and 150 mL. METHODS: Between September and December 2017, 101 men with LUTSattributable to BPHwere prospectively enrolled at 16 centres in Canada and the USA. RESULTS: The mean prostate volume was 107 mL. The mean length of hospital stay after the aquablation procedure was 1.6 days (range: same day to 6 days). The primary safety endpoint (Clavien-Dindo grade 2 or higher or any grade 1 event resulting in persistent disability) at 3 months occurred in 45.5% of men, which met the study design goal of < 65% (P < 0.001). At 6 months, 22% of the patients had experienced a Clavien-Dindo grade 2, 14% a grade 3 and 5% a grade 4 adverse event. Bleeding complications requiring intervention and/or transfusion were recorded in eight patients prior to discharge and in six patients after discharge. The mean International Prostate Symptom Score improved from 23.2 ± 6.3 at baseline to 6.7 ± 5.1 at 3 months, meeting the study's primary efficacy endpoint goal (P < 0.001). The maximum urinary flow rate increased from 8.7 to 18.8 mL/s (P < 0.001) and post-void residual urine volume decreased from 131 at baseline to 47 at 6 months (P < 0.0001). At 6 months, prostate-specific antigen concentration reduced from 7.1 ± 5.9 ng/mL at baseline to 4.0 ± 3.9 ng/mL, a 44% reduction. CONCLUSIONS: Aquablation is safe and effective in treating men with larger prostates (80-150 mL), without significant increase in procedure or resection time.

WATER II (80-150 mL) procedural outcomes.

OBJECTIVES: To present early safety and feasibility data from a multicentre prospective study (WATER II) of aquablation in the treatment of symptomatic men with large-volume benign prostatic hyperplasia (BPH). METHODS: Between September and December 2017, 101 men with moderate-to-severe BPH symptoms and prostate volume of 80-150 mL underwent aquablation in a prospective multicentre international clinical trial. Baseline demographics and standardized postoperative management variables were carefully recorded in a central independently monitored database. Surgeons answered analogue scale questionnaires on intra-operative technical factors and postoperative management. Adverse events up to 1 month were adjudicated by an independent clinical events committee. RESULTS: The mean (range) prostate volume was 107 (80-150) mL. The mean (range) operating time was 37 (15-97) min and aquablation resection time was 8 (3-15) min. Adequate adenoma resection was achieved with a single pass in 34 patients and with additional passes in 67 patients (mean 1.8 treatment passes), all in a single operating session. Haemostasis was achieved using either a Foley balloon catheter placed in the bladder under traction (n = 98, mean duration 18 h) or direct tamponade using a balloon inflated in the prostate fossa (n = 3, mean duration 15 h). No patient required electrocautery for haemostasis at the time of the primary procedure. The mean length of stay after the procedure was 1.6 days (range same day to 6 days). The Clavien-Dindo grade ≥2 event rate observed at 1 month was 29.7%. Bleeding complications were recorded in 10 patients (9.9%) during the index procedure hospitalization prior to discharge, and included six (5.9%) peri-operative transfusions. CONCLUSIONS: Aquablation is feasible and safe in treating men with men with large prostates (80-150 mL). The 6-month efficacy data are being accrued and will be presented in future publications (ClinicalTrials.gov number, NCT03123250).

Randall's plaque in stone formers originates in ascending thin limbs.

Randall's plaque, an attachment site over which calcium oxalate stones form, begins in the basement membranes of thin limbs of the loop of Henle. The mechanism of its formation is unknown. Possibly, enhanced delivery of calcium out of the proximal tubule, found in many stone formers, increases reabsorption of calcium from the thick ascending limb into the interstitium around descending vasa recta, which convey that calcium into the deep medulla, and raises supersaturations near thin limbs ("vas washdown"). According to this hypothesis, plaque should form preferentially on ascending thin limbs, which do not reabsorb water. We stained serial sections of papillary biopsies from stone-forming patients for aquaporin 1 (which is found in the descending thin limb) and the kidney-specific chloride channel ClC-Ka (which is found in the ascending thin limb). Plaque (which is detected using Yasue stain) colocalized with ClC-Ka, but not with aquaporin 1 (χ2 = 464, P < 0.001). We conclude that plaque forms preferentially in the basement membranes of ascending thin limbs, fulfilling a critical prediction of the vas washdown theory of plaque pathogenesis. The clinical implication is that treatments such as a low-sodium diet or thiazide diuretics that raise proximal tubule calcium reabsorption may reduce formation of plaque as well as calcium kidney stones.

Papillary Ductal Plugging is a Mechanism for Early Stone Retention in Brushite Stone Disease.

PURPOSE: Mechanisms of early stone retention in the kidney are under studied and poorly understood. To date attachment via Randall's plaque is the only widely accepted theory in this regard, which is best described in idiopathic calcium oxalate stone formers. Brushite stone formers are known to have distinct papillary morphology relative to calcium oxalate stone formers. As such we sought to determine whether stone attachment mechanisms in such patients may be similarly unique. MATERIALS AND METHODS: Patients undergoing percutaneous and or ureteroscopic procedures for stone removal consented to endoscopic renal papillary examination and individual stone collection. Each removed stone was processed using micro computerized tomography to assess the 3-dimensional microstructure and the minerals contained, and search for common structural features indicative of novel mechanisms of early growth and attachment to renal tissue. RESULTS: A total of 25 intact brushite stones were removed from 8 patients and analyzed. Video confirmed attachment of 13 of the 25 stones with the remainder believed to have been accidently dislodged during the procedure. Microscopic examination by light and computerized tomography failed to show evidence of Randall's plaque associated with any stone containing brushite. Conversely each brushite stone demonstrated microstructural evidence of having grown attached to a ductal plug formed of apatite. CONCLUSIONS: Three-dimensional analysis of small brushite stones suggests overgrowth on ductal apatite plugs as a mechanism of early stone growth and retention. Such findings represent what is to our knowledge the initial supporting evidence for a novel mechanism of stone formation which has previously been hypothesized but never verified.

Urine kidney injury markers do not increase following gastric bypass: a multi-center cross-sectional study.

INTRODUCTION: To determine if markers of kidney injury correlate with urinary oxalate excretion. If so, such biomarkers might be early predictors of oxalate nephropathy. Gastric bypass surgery for obesity is known to be associated with postoperative hyperoxaluria, which can lead to urolithiasis and kidney damage. MATERIALS AND METHODS: Patients were recruited from four large academic centers > 6 months following completion of gastric bypass surgery. Patients provided a spot urine sample for analysis of three markers of kidney injury: 8-iso-Prostaglandin F2 α, N-acetyl- ß -D-Glucosaminidase, and Neutrophil gelatinase-associated lipocalin. Patients also provided 24 hour urine samples for stone risk analysis. RESULTS: A total of 46 study patients provided samples, the average age was 48.4 +/- 11.3. There were 40 women and 6 men. There was no difference in the level of any of the three inflammatory markers between the study group and the reference range generated from healthy non-hyperoxaluric subjects. Neither oxalate excretion nor supersaturation of calcium oxalate correlated with any of the injury markers. There was no difference noted between those with hyperoxaluria (n = 17) and those with normoxaluria (n = 29) with respect to any of the injury markers. CONCLUSIONS: Though hyperoxaluria was common after bypass surgery, markers of kidney injury were not elevated after surgery. No correlation was found between urine oxalate excretion and any of the injury markers.

Outcomes of Holmium Laser Enucleation of the Prostate in the Re-Treatment Setting.

PURPOSE: Holmium laser enucleation of the prostate can also be applied in the re-treatment setting when other benign prostatic hyperplasia therapies fail. We compared outcomes in men who underwent holmium laser enucleation of the prostate in the primary vs the re-treatment setting. MATERIALS AND METHODS: We retrospectively reviewed the records of 2,242 patients who underwent holmium laser enucleation of the prostate at a total of 4 academic hospitals between 2003 and 2015. Patient demographics, and operative and perioperative outcomes were compared between re-treatment and primary holmium laser enucleation of the prostate. RESULTS: Of the 360 of 2,242 men (16%) who underwent re-treatment holmium laser enucleation of the prostate the procedure was done for residual urinary symptoms in 71%. The most common primary procedure was transurethral resection of the prostate in 42% of cases. Mean time between prior benign prostatic hyperplasia surgery and re-treatment was 68 months (range 1 to 444). There were no significant differences in age, prostate size, AUA (American Urological Association) symptom score or average flow rate between the cohorts. Perioperatively, re-treatment holmium laser enucleation of the prostate was associated with significantly shorter operative time, reduced blood loss, lower specimen weight and shorter length of stay. The AUA symptom score improved in both groups, although it remained higher in men who underwent re-treatment (6.5 vs 5.0, p <0.001). The likelihood of clot retention (4.7% vs 1.8%, p = 0.01) and urethral stricture (3.3% vs 1.5%, p = 0.043) was slightly higher in the re-treatment group. CONCLUSIONS: Immediate perioperative outcomes of holmium laser enucleation of the prostate performed in the re-treatment setting were no different from those in the primary setting. While re-treatment was associated with an increased likelihood of clot retention, urethral stricture and higher AUA symptom score, these minimal differences must be considered against the overall favorable symptom improvement across both cohorts.

Holmium Laser Enucleation of the Prostate in Patients Requiring Anticoagulation.

PURPOSE OF REVIEW: This is to evaluate and discuss the literature surrounding holmium laser enucleation of the prostate (HoLEP) in patients on anticoagulation. RECENT FINDINGS: The relationship of benign prostatic hyperplasia (BPH) to bothersome lower urinary tract symptoms (LUTS) is well established with a majority of men over the age of 60 having significant symptoms. Patients with severe enough symptoms often require surgery and with cardiovascular disease ranking as the primary cause of death in the USA, a growing number will be taking antiplatelet (AP) or anticoagulation (AC) for primary or secondary prevention of disease. A review of the recent literature focusing on patients on AP/AC undergoing HoLEP noted minimal adverse effects in the postoperative course aside from prolonged bleeding requiring catheterization with continuous bladder irrigation. Although patients with BPH and bothersome LUTS undergoing HoLEP are at a slightly greater risk for prolonged bladder irrigation secondary to bleeding, surgical outcomes are similar to men not on AP/AC. The literature surrounding newer direct oral anticoagulants (DOACs) and HoLEP is limited, and therefore, conclusions regarding continuation of DOACs cannot be drawn. However, HoLEP appears to be a safe and effective procedure for BPH-related LUTS in patients on AP/AC therapy.

Wolf Piranha Versus Lumenis VersaCut Prostate Morcellation Devices: A Prospective Randomized Trial.

PURPOSE: Holmium laser enucleation of the prostate for the management of benign prostatic hyperplasia involves the 2 steps of enucleation and morcellation. Few prostate morcellation devices are available. In this study we compare the Wolf Piranha and Lumenis® VersaCut™ prostate morcellation devices. MATERIALS AND METHODS: After institutional review board approval and patient informed consent, a prospective, randomized trial was initiated for patients with symptomatic benign prostatic hyperplasia undergoing holmium laser enucleation of the prostate. All procedures were performed by a single surgeon (JEL) at Indiana University Health Methodist Hospital using the Piranha or VersaCut prostate morcellation device. Patient demographics, and preoperative, intraoperative and postoperative data for patients in the 2 treatment groups were analyzed and compared in a prospective fashion. RESULTS: A total of 74 patients were enrolled and randomized for the treatment device. Both groups were comparable in terms of age, prostate specific antigen and prostate size. There was no difference in patient demographic and preoperative characteristics. The Piranha achieved a slightly higher morcellation rate at 5.6 gm per minute (range 1.4 to 18), compared to the VersaCut at 4.8 gm per minute (range 1.3 to 9.5). However, the difference was not statistically significant (p = 0.14). Cost analysis (USD per patient) favored the VersaCut ($241 vs $471, p <0.001). CONCLUSIONS: Morcellation rates for the Piranha and VersaCut prostate morcellation devices are comparable, with the Piranha having a statistically significant increased cost. The Wolf Piranha also has a more complicated design, making it less user-friendly for the operating room staff and, therefore, more difficult to troubleshoot than the Lumenis VersaCut. Nevertheless, 75% of urology faculty, fellows and residents preferred the Piranha over the VersaCut, reporting that when working properly, it was more efficient in tissue removal.

Preoperative Bladder Urine Culture as a Predictor of Intraoperative Stone Culture Results: Clinical Implications and Relationship to Stone Composition.

PURPOSE: We examine the relationship between urine and stone cultures in a large cohort of patients undergoing percutaneous stone removal and compare the findings in infectious vs metabolic calculi. MATERIALS AND METHODS: A total of 776 patients treated with percutaneous nephrolithotomy who had preoperative urine cultures and intraoperative stone cultures were included in the study. Statistical analysis used chi-square or logistic fit analysis as appropriate. RESULTS: Preoperative urine culture was positive in 352 patients (45.4%) and stone cultures were positive in 300 patients (38.7%). There were 75 patients (9.7%) with negative preoperative cultures who had positive stone cultures, and in patients with both cultures positive the organisms differed in 103 (13.3%). Gram-positive organisms predominated in preoperative urine and stone cultures. CONCLUSIONS: Preoperative urine cultures in patients undergoing percutaneous nephrolithotomy are unreliable as there is a discordance with intraoperative stone cultures in almost a quarter of cases. There has been a notable shift toward gram-positive organisms in this cohort of patients.

Salvage Percutaneous Nephrolithotomy: Analysis of Outcomes following Initial Treatment Failure.

PURPOSE: Percutaneous nephrolithotomy has high potential for morbidity or failure. There are limited data regarding risk factors for failure and to our knowledge no published reports of surgical outcomes in patients with prior failed attempts at percutaneous stone removal. MATERIALS AND METHODS: We identified patients referred to 3 medical centers after prior failed attempts at percutaneous nephrolithotomy. A retrospective chart review was performed to analyze reasons for initial failure and outcomes of salvage percutaneous nephrolithotomy. Outcomes were compared to those in a prospectively maintained database of more than 1,200 patients treated with a primary procedure. RESULTS: Salvage percutaneous nephrolithotomy was performed in 31 patients. Unsuitable access to the stone was the reason for failure in 80% of cases. Other reasons included infection, bleeding and inadequate instrument availability in 6.5% of cases each. Compared to patients who underwent primary percutaneous nephrolithotomy those treated with salvage were more likely to have staghorn calculi (61.3% vs 31.4%, p <0.01) and a larger maximum stone diameter (3.7 vs 2.5 cm, p <0.01), and require a secondary procedure (65.5% vs 42.1%, p <0.01). There was no significant difference between the cohorts in the remaining demographics or perioperative outcomes. All patients were deemed completely stone free except one who elected observation for a 3 mm nonobstructing fragment. CONCLUSIONS: Despite the more challenging nature and prior unsuccessful attempts at treatment, the outcomes of salvage percutaneous nephrolithotomy were no different from those of primary percutaneous nephrolithotomy when performed by experienced surgeons.