HoLEP Learning Curve-Resident Perspective: Survey of Senior Residents from High-Volume Tertiary Center.

Objective: We aim to report the learning curve and experience performing holmium laser enucleation of the prostate (HoLEP) from a resident standpoint trained at a tertiary high-volume center. Methods: An electronic survey was distributed to 10 surveyees that included recently graduated chief residents trained at Indiana University in the past 3 years i.e., between 2020 and 2022 with a 100% response rate. The questionnaire focused on HoLEP training experience based on a recently established mentorship curriculum in training the residents through each individual step of the surgery. Results: The average learning curve for performing HoLEP was reported to be greater than 25 cases with 50% of the residents reporting >50 cases to master the technique. The surgical difficulty of steps of the HoLEP were rated on a subjective scale of 1-5: 1 = very easy, 2 = easy, 3 = neutral, 4 = hard, and 5 = very hard. The common challenging steps in decreasing the order of difficulty as reported are performing apical enucleation, joining anterior and posterior planes, and dividing anterior commissure with a mean rating of 3.5, 3.1, and 3.1, respectively. The most difficult aspect of the surgery to master was performing apical dissection (60%). Comparing operative parameters for HoLEP with transurethral resection of the prostate in aspects of resection volume and times, 70% of candidates reported it better for HoLEP whereas 20% had similar times for both procedures. A total of 90% of the residents felt confident to offer HoLEP as part of their practice without the need for any further training. Regarding the initial challenge of including HoLEP surgery in practice, the majority (60%) reported difficulty with equipment set up in their practice while 20% reported difficulty maintaining efficient operating room (OR) times and turnover. Conclusion: We believe HoLEP can be performed immediately after residency training and incorporated into practice with high volume, repeated exposure to HoLEP surgery throughout residency based on study results. The average learning curve reported for performing HoLEP was greater than 25 cases.

Heterogeneity in stone culture protocols and endourologist practice patterns: a multi-institutional survey.

Kidney stone cultures can be beneficial in identifying bacteria not detected in urine, yet how stone cultures are performed among endourologists, under what conditions, and by what laboratory methods remain largely unknown. Stone cultures are not addressed by current clinical guidelines. A comprehensive REDCap electronic survey sought responses from directed (n = 20) and listserv elicited (n = 108) endourologists specializing in kidney stone disease. Questions included which clinical scenarios prompt a stone culture order, how results influence post-operative antibiotics, and what microbiology lab protocols exist at each institution with respect to processing and resulting stone cultures. Logistic regression statistical analysis determined what factors were associated with performing stone cultures. Of 128 unique responses, 11% identified as female and the mean years of practicing was 16 (range 1-46). A specific 'stone culture' order was available to only 50% (64/128) of those surveyed, while 32% (41/128) reported culturing stone by placing a urine culture order. The duration of antibiotics given for a positive stone culture varied, with 4-7 days (46%) and 8-14 days (21%) the most reported. More years in practice was associated with fewer stone cultures ordered, while higher annual volume of percutaneous nephrolithotomy was associated with ordering more stone cultures (p < 0.01). Endourologists have differing practice patterns with respect to ordering stone cultures and utilizing the results to guide post-operative antibiotics. With inconsistent microbiology lab stone culture protocols across multiple institutions, more uniform processing is needed for future studies to assess the clinical benefit of stone cultures and direct future guidelines.

Cost-Effectiveness of 90-day Single-use Flexible Cystoscope Trial: Single Center Micro-Costing Analysis and User Satisfaction.

OBJECTIVE: To evaluate cost-effectiveness and user satisfaction of a single-use flexible cystoscope at a tertiary care center we conducted a 90-day trial. Single-use flexible cystoscope advancements have introduced alternative options to reusable scopes. However, there is a paucity of cost-effectiveness and provider satisfaction studies examining the implementation of a hospital-based transition to single-use cystoscopes. METHODS: Following institutional device-approval we initiated a 90-day trial period (November 1, 2020-January 29, 2021) where all flexible, transurethral, and percutaneous, urologic care was provided with a disposable AMBU aScope. We performed a micro-costing analysis examining payor per case cost of the reusable flexible cystoscope (including servicing and processing) to the disposable units. Provider surveys assessed visual quality, deflection, ease of working channel and overall satisfaction on a 10-point Likert scale. RESULTS: Over the 90-day period, we encountered 84 cases (78 operative, 5 inpatient, 1 emergency department) where flexible cystoscopy was required. One disposable flexible cystoscope was successfully used in 78 of 84 (93%) cases. Of the 6 failures, 2 were due to an inability to access a disposable scope/monitor. Per use cost of the reusable flexible cystoscope at our center was $272.41 versus $185.00 for the single use. Extrapolating our average case volume and conservative failure rate (3 single use failures/month, requiring reusable), transitioning to predominately single use scopes results in $39,142.84 annual cost savings. CONCLUSIONS: This single center 90-day trial of disposable flexible cystoscopy identified per-use costs to be less when a single-use flexible cystoscope was utilized at a high-volume tertiary care center.

Ambulatory Percutaneous Nephrolithotomy May Be Cost-Effective Compared to Standard Percutaneous Nephrolithotomy.

Background: Coronavirus disease 2019 (COVID-19) changed the practice of medicine in America. During the March 2020 lockdown, elective cases were canceled to conserve hospital beds/resources resulting in financial losses for health systems and delayed surgical care. Ambulatory percutaneous nephrolithotomy (aPCNL) has been shown to be safe and could be a strategy to ensure patients receive care that has been delayed, conserve hospital resources, and maximize cost-effectiveness. We aimed to compare the safety and cost-effectiveness of patients undergoing aPCNL against standard PCNL (sPCNL). Materials and Methods: Ninty-eight patients underwent PCNL at Indiana University Methodist Hospital, a tertiary referral center, by three expert surgeons from January 2020 to September 2020. The primary outcome of the study was to compare the 30-day rates of emergency department (ED) visits, readmissions, and complications between sPCNL and aPCNL. Secondary outcomes included cost analysis and stone-free rates (SFRs). Propensity score matching was performed to ensure the groups were balanced. Statistical analyses were performed using SAS 9.4 using independent t-tests for continuous variables and chi-square analyses for categorical variables. Results: Ninety-eight patients underwent PCNL during the study period (sPCNL = 75 and aPCNL = 23). After propensity score matching, 42 patients were available for comparison (sPCNL = 19 and aPCNL = 23). We found no difference in 30-day ED visits, readmissions, or complications between the two groups. aPCNL resulted in cost savings of $5327 ± 442 per case. SFRs were higher for aPCNL compared with sPCNL. Conclusions: aPCNL appears safe to perform and does not have a higher rate of ED visits or readmissions compared with sPCNL. aPCNL may also be cost-effective compared with sPCNL.

Same Day Discharge is a Successful Approach for the Majority of Patients Undergoing Holmium Laser Enucleation of the Prostate.

BACKGROUND: Limited research has focused on success with hospital discharge on the same day of surgery after holmium laser enucleation of the prostate (HoLEP). OBJECTIVE: To determine the success of same-day discharge in our HoLEP cohort and factors associated with this approach. DESIGN, SETTING, AND PARTICIPANTS: A retrospective review of our prospectively maintained HoLEP database demonstrated that 473 adult males underwent HoLEP from July 2018 to December 2019 at a tertiary referral center and high-volume HoLEP hospital. Patients were divided into groups according to planned inpatient admission (PIA), successful same-day discharge (SDD), or unplanned admission (UA). OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: The PIA, SDD, and UA groups were assessed for differences in preoperative demographic data, perioperative surgical data, and postoperative follow-up data. SDD and UA were then compared to determine if any specific factors predicted UA, including univariate and multivariate logistic regression analyses. RESULTS AND LIMITATIONS: Age (p = 0.0049), use of anticoagulation (p = 0.037), American Society of Anesthesiologists score of 3-4 (p = 0.0017), and enucleation time (p=0.0178) were significantly higher in the PIA group. Morcellation time (p = 0.0059) and the rate of bedside catheter irrigation (p = 0.04) were higher in the UA group. The SDD group had the highest rate of successful voiding trial (p = 0.0001). Among the three groups, there was no difference in the rate of postoperative complications (p = 0.141). In a comparison of the SDD and UA groups, morcellation time (p = 0.041), the rate of bedside clot evacuation (p = 0.004), and successful voiding trial (p = 0.003) all favored SDD. There was no difference in 90-d complications (p = 0.536). A limitation is the retrospective nature of this study. CONCLUSIONS: HoLEP can be successfully performed as day surgery without an increase in postoperative complications. HoLEP as day surgery is possible for any patient who does not require admission for medical comorbidities. PATIENT SUMMARY: Same-day discharge (SDD) after holmium laser enucleation of the prostate (HoLEP) is possible and is successful in 87.4% of patients. Patients with longer morcellation times and with post-procedure hematuria with clots are more likely to have an unplanned admission. Use of a 120-W modulated-pulse laser resulted in a higher rate of SDD success. The culture change to day surgery is time-intensive owing to education of the postsurgical care units and clinic staff, and in our experience took approximately 9 mo to seamlessly integrate SDD as our HoLEP standard of care.

Comparison of Newly Optimized Moses Technology vs Standard Holmium:YAG for Endoscopic Laser Enucleation of the Prostate.

Introduction: The purpose of this study was to describe our initial experience of using a newly optimized Moses technology that is part of the second-generation Moses platform specifically designed for holmium laser enucleation of the prostate (M2-HoLEP) and compare it with patients undergoing HoLEP using standard holmium:YAG technology (S-HoLEP). Materials and Methods: We retrospectively collected data on patients who underwent M2-HoLEP and compared it with the last 50 patients in whom we performed S-HoLEP. Specifically, we compared preoperative symptom scores for lower urinary tract symptoms (LUTS) and erectile dysfunction (ED), preoperative objective voiding metrics, as well as intraoperative characteristics, perioperative characteristics, postoperative complications, postoperative symptom scores for LUTS and ED, and postoperative objective voiding metrics. Additionally, we evaluated the ability for same-day discharge following surgery in the M2-HoLEP group. Results: We included 104 total patients for analysis. We compared the first 54 patients undergoing M2-HoLEP with 50 patients undergoing S-HoLEP. Both groups had similar age, body mass index, use of anticoagulation medication, LUTS and ED scores, and objective voiding metrics. Operations performed with M2-HoLEP had faster mean hemostasis time (8.7 vs 10.6 ± 6 minutes, p = 0.03) as well as hemostasis rate (0.13 vs 0.30 min/g, p = 0.01). Same-day discharge was achieved in 69.4% of patients in the M2-HoLEP group. Postoperatively, both groups also had similar and low rates of urinary retention and complications. At follow-up, both groups had similar symptom scores for LUTS and ED, as well as similar objective voiding metrics. Conclusions: The newly optimized Moses pulse modulation technology is safe and efficient for the treatment of benign prostate hyperplasia. Such technologic improvements in the laser have greatly enhanced the feasibility of same-day discharge of patients undergoing HoLEP.

Opioid Free Ureteroscopy: What is the True Failure Rate?

OBJECTIVE: To determine the true failure rate of opioid free ureteroscopy (OF-URS) and rates of new-persistent opioid use utilizing a national prescription drug monitoring program. MATERIAL AND METHODS: We identified 239 patients utilizing our retrospective stone database who underwent OF-URS from Februrary 2018-March 2020. In Feb 2018, we initiated a OF-URS pathway (diclofenac, tamsulosin, acetaminophen, pyridium and oxybutynin). Patients who had a contraindication to NSAIDs were excluded from primary analyses. A prescription drug monitoring program was then utilized to determine the number of patients who failed OF-URS (defined as receipt of an opioid within 31 days of surgery) as well as rates of new-persistent opioid use (defined as receipt of opioid 91-180 days after surgery). All statistical analyses were performed using SAS 9.4. Tests were 2-sided and statistical significance was set at P<0.05. RESULTS: We found a OF-URS failure rate of 16.6% and 14.0% in the total and opioid naïve cohorts, respectively. Rates of new-persistent opioid use were 0.9% and 1.2%, respectively (lower than published expected rate of ~6% after URS with postoperative opioids). 91% of patients obtained opioid from alternative sources. Uni/multivariate analyses were performed for both cohorts. In the total cohort, benzodiazepine users had a lower risk of OF-URS failure on multivariate analysis. No variables were associated with OF-URS failure in the opioid naïve cohort. CONCLUSION: The true failure rate of OF-URS is higher than previously thought at 16.6% and 14.0%. However, efforts to reduce opioid prescriptions with OF-URS pathways have successfully reduced new-persistent opioid use.

Next generation sequencing in patients with nephrolithiasis: how does it perform compared with standard urine and stone cultures?

BACKGROUND: Our aim was to compare microorganism detection between standard culture (Ctx) and next generation sequencing (NGS) in patients undergoing surgery for nephrolithiasis; we prospectively compared both urine and stone culture results using these two techniques. METHODS: We prospectively compared microorganism detection of urine and stone cultures using Ctx versus NGS in patients undergoing surgery for nephrolithiasis. We analyzed preoperative voided urine (Voided) using both Ctx and NGS. Intraoperatively, renal stone (Stone) cultures were analyzed with Ctx and NGS. The primary outcome was concordance in microorganism detection between Voided Ctx and Stone NGS, as well as between Stone Ctx and Stone NGS. RESULTS: We prospectively evaluated 84 patients. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of Voided Ctx predicting Stone Ctx were 66.7%, 73.7%, 54.5%, and 82.4%, respectively. Concordance of Voided Ctx microorganisms to Stone microorganisms decreased when NGS was used for the Stone compared with Ctx. The sensitivity, specificity, PPV, and NPV of Voided NGS to predict Stone Ctx microorganisms were 85.2%, 24.6%, 34.8%, and 77.8%, respectively. The concordance of Voided NGS to Stone microorganisms improved when the Stone was analyzed via NGS compared with Ctx. CONCLUSION: NGS has a higher detection rate of microorganisms than standard culture for both preoperative urine and stone cultures. Voided NGS was the most sensitive in predicting a positive Stone sample, but the specificity and PPV were, overall, low. Further correlation of NGS microorganism detection with patient outcomes will determine which clinical situations may benefit most from NGS versus standard culture in patients with urinary-tract stones.

Same-Day Discharge Following Holmium Laser Enucleation in Patients Assessed to Have Large Gland Prostates (≥175 cc).

Background: Holmium laser enucleation of the prostate (HoLEP) is a highly effective and durable minimally invasive surgery for benign prostatic hyperplasia. Historically, alternative treatments for large glands (≥175 cc) are associated with prolonged length of stay (LOS) and postoperative catheterization. However, advances in laser technology combined with surgical technique optimization have early evidence supporting same-day discharge. We look to examine contemporary same-day discharge outcomes for large glands. Materials and Methods: With Institutional Review Board (IRB) approval we queried our electronic medical record and retrospective clinical registry to examine perioperative outcomes of large gland (≥175 cc) prostates that underwent HoLEP with consideration for same-day discharge. Results: From December 10, 2019 to September 29, 2020 we identified 55 patients with a preoperative prostate size ≥175 cc (39 CT, 12 MRI, 4 transrectal ultrasound), of which 45 were scheduled for same-day discharge and 10 for admission. Mean preoperative prostate size was 229.9 cc (range 175-535 cc) and 36 (65.5%) were in urinary retention. Mean preoperative prostate-specific antigen (PSA) was 8.58 ng/mL, American Urological Association Symptom Score (AUASS) 22.3, and Qmax 8.8 mL/second. At 3 months postoperative follow-up mean AUASS was 6.7, PSA 0.87 ng/mL and Qmax 20.4 mL/second. All comer same-day discharge rate was 70% (38/55). Of patients planned for same-day discharge 38/45 (84%) were effective. Average LOS for all patients was 11.8 hours with catheterization of 21.2 hours. When compared with 2010 published large gland outcomes, our current LOS represents a 220% reduction. Looking specifically at patients planned for same-day discharge, average LOS and catheter duration was 8.8 and 17.0 hours, whereas LOS and catheter duration for patients planned for admission was 25.7 and 39.4 hours, respectively. Conclusions: We report the first outcomes of preoperatively planned same-day discharge for HoLEP in large glands (≥175 cc). A combination of technologic advances and optimization of technique have allowed for a safe adoption of same-day discharge, providing additional advantages over alternative large gland treatments.

In Vivo Entombment of Bacteria and Fungi during Calcium Oxalate, Brushite, and Struvite Urolithiasis.

Background: Human kidney stones form via repeated events of mineral precipitation, partial dissolution, and reprecipitation, which are directly analogous to similar processes in other natural and manmade environments, where resident microbiomes strongly influence biomineralization. High-resolution microscopy and high-fidelity metagenomic (microscopy-to-omics) analyses, applicable to all forms of biomineralization, have been applied to assemble definitive evidence of in vivo microbiome entombment during urolithiasis. Methods: Stone fragments were collected from a randomly chosen cohort of 20 patients using standard percutaneous nephrolithotomy (PCNL). Fourier transform infrared (FTIR) spectroscopy indicated that 18 of these patients were calcium oxalate (CaOx) stone formers, whereas one patient formed each formed brushite and struvite stones. This apportionment is consistent with global stone mineralogy distributions. Stone fragments from seven of these 20 patients (five CaOx, one brushite, and one struvite) were thin sectioned and analyzed using brightfield (BF), polarization (POL), confocal, super-resolution autofluorescence (SRAF), and Raman techniques. DNA from remaining fragments, grouped according to each of the 20 patients, were analyzed with amplicon sequencing of 16S rRNA gene sequences (V1-V3, V3-V5) and internal transcribed spacer (ITS1, ITS2) regions. Results: Bulk-entombed DNA was sequenced from stone fragments in 11 of the 18 patients who formed CaOx stones, and the patients who formed brushite and struvite stones. These analyses confirmed the presence of an entombed low-diversity community of bacteria and fungi, including Actinobacteria, Bacteroidetes, Firmicutes, Proteobacteria, and Aspergillus niger. Bacterial cells approximately 1 µm in diameter were also optically observed to be entombed and well preserved in amorphous hydroxyapatite spherules and fans of needle-like crystals of brushite and struvite. Conclusions: These results indicate a microbiome is entombed during in vivo CaOx stone formation. Similar processes are implied for brushite and struvite stones. This evidence lays the groundwork for future in vitro and in vivo experimentation to determine how the microbiome may actively and/or passively influence kidney stone biomineralization.

Real-World Experience of Holmium Laser Enucleation of the Prostate with Patients on Anticoagulation Therapy.

Background: Holmium laser enucleation of the prostate (HoLEP) is a highly effective procedure for benign prostatic hyperplasia that is size independent and has been recommended for patients necessitating antiplatelet (AP) and anticoagulant (AC) medications. Although HoLEP is feasible in AP/AC patients, there is a lack of published results on real-world outcomes of patients on AP/AC therapy undergoing HoLEP. Patients and Methods: We performed a retrospective review of our institutional HoLEP database of demographics, perioperative and postoperative data, and outcomes of patients on AP and AC therapy compared with none. We also further stratified patients on warfarin compared with direct oral anticoagulants (DOACs). Results: Of 472 patients who underwent HoLEP at our institution from July 2018 to December 2019 with data on AP/AC drugs, 30 (6.3%) were on AP and 65 (17.2%) were on AC. One patient continued AP (3.3%), six patients (9.2%) were bridged on AC, and one patient (1.5%) continued AC through the time of HoLEP at the discretion of the prescribing provider. Preoperatively, only age was significantly different among the three groups (p < 0.001). There were no intraoperative differences. Postoperatively, there was a higher 90-day complication rate in AP and AC groups (p = 0.035), but not an increase in emergency department (ED) visits (p = 0.557) or Clavien ≥3 complications (p = 0.16). In comparison of patients on warfarin with DOAC, there was a lower rate of successful voiding trial (p = 0.009), higher 90-day complications (p = 0.003), and more ED visits (p = 0.003) in the warfarin group. Conclusions: HoLEP is safe and effective for patients who require AP or AC therapy. There is no increase in serious complications or worsened postoperative voiding parameters. Of patients on AC, those on DOAC have better outcomes compared with warfarin.

Catheter Removal on the Same Day of Holmium Laser Enucleation of the Prostate: Outcomes of a Pilot Study.

OBJECTIVE: To determine if same day catheter removal is feasible in a select population after holmium laser enucleation of the prostate (HoLEP). METHODS: We performed an analysis of patients undergoing HoLEP at our institution who underwent same-day catheter removal after HoLEP. All HoLEPs were performed with Moses 2.0 Optimized for BPH. Patients were dismissed from postoperative recovery unit to the clinic for catheter removal and voiding trial. RESULTS: To date, 30 patients have undergone same day catheter removal. Median age is 68.6 years (interquartile range [IQR] 61.8-73.3) and preoperative prostate volume 81 mL (IQR 53-114.8). Median enucleation time was 39.5 minutes (IQR 30.5-53), morcellation time was 5 minutes (IQR 4-12 minutes), and enucleated specimen weight was 52.5 g (IQR 33-81). Twenty-seven (90%) patients successfully voided on the same day without requiring catheter replacement. All patients were catheter free by POD1. For patients who successfully passed their voiding trial, the median time from the end of the procedure to hospital discharge was 2.6 hours (IQR [2.1-2.9]) and from the end of the HoLEP to catheter removal was 4.9 hours (IQR [3.5-6.0]). CONCLUSION: We present for the first time that same day catheter removal is a feasible option in a select population of patients undergoing HoLEP. With more study, this has the potential for transforming the management of BPH, especially larger glands.

Correlating Patient Anxiety with Urinary Symptoms Before and After Holmium Laser Enucleation of the Prostate.

Introduction and Objective: Preoperative anxiety has been shown to correlate with certain urinary symptoms in patients with certain types of voiding dysfunction, particularly overactive bladder. The purpose of this study was to evaluate if patient-reported anxiety correlates with pathologic characteristics, voiding symptoms, and objective metrics of bladder emptying in male patients undergoing holmium laser enucleation of the prostate (HoLEP). Patients and Methods: We began collecting patient-reported anxiety scores (generalized anxiety disorder 7-item or GAD-7) in addition to patient-reported scores of lower urinary tract symptoms (LUTS) and erectile dysfunction (ED) starting in November 2018 for men with LUTS due to benign prostate hyperplasia (BPH). We retrospectively evaluated the relationship between preoperative GAD-7 score with preoperative age, body mass index (BMI), preoperative urine flow metrics, preoperative postvoid residual (PVR), and preoperative symptom scores for LUTS (American Urological Association, BPH impact index [BII], and Michigan incontinence symptom index [MISI]) and ED (sexual health inventory for men and male sexual health questionnaire for ejaculatory dysfunction [MSHQ-EjD]). We then compared preoperative GAD-7 score with enucleated prostate weight, postoperative GAD-7 scores, postoperative urine flow metrics, postoperative PVR, and postoperative symptom scores for LUTS and ED. Results: We included 139 patients for analysis. The preoperative GAD-7 score positively correlated with preoperative BII scores (rs = 0.202, p = 0.019), MISI total (rs = 0.260, p = 0.002), and MISI bother (rs = 0.345, p < 0.001) scores. Preoperative GAD-7 negatively correlated with preoperative MSHQ-EjD (rs = -0.191, p = 0.031). Following HoLEP, all four of these correlations disappear. The GAD-7 score did not correlate with age, BMI, preoperative urine flow metrics, preoperative PVR, or other preoperative LUTS and ED symptom scores. In addition, preoperative GAD-7 score showed no correlation with enucleated prostate weight, postoperative urine flow metrics, postoperative PVR, and postoperative LUTS and ED symptom scores. Conclusions: Higher preoperative anxiety correlated with more severe preoperative urinary LUTS, particularly incontinence symptoms, in patients undergoing HoLEP. Following HoLEP, these symptoms improve regardless of patient anxiety level.

Variability in stone composition and metabolic correlation between kidneys in patients with bilateral nephrolithiasis.

PURPOSE: To evaluate the clinical significance of discordant stone analyses in patients undergoing bilateral ureteroscopy. MATERIALS AND METHODS: A retrospective chart review was performed for all patients undergoing stone extraction with bilateral ureteroscopy at our institution in an aim to identify patients who had bilateral stone analysis and 24-h urine chemistry data available. Stones were then classified based upon the dominant present (> 50%). Twenty-four hour urinalysis results were reviewed and statistical analysis performed comparing discordant and concordant patient populations, assessing significant differences that would potentially influence clinical management. RESULTS: We identified 79 patients (158 renal units) who had bilateral stones removed at the time of ureteroscopy. The majority of stones were classified as calcium oxalate (CaOx) (60.1%) followed by calcium phosphate (CaP) (27.8%), brushite (5.1%), uric acid (UA) (4.4%), and cystine (2.5%). Discrepancies in stone classifications were present 24% of the time. Evaluation of 24-h urinalysis results demonstrated that patients with CaOx:CaP stone discordance compared to CaOx:CaOx concordant stone formers were more likely to have an elevated pH (p = 0.02) and lower uric acid supersaturation (p = 0.01). CONCLUSIONS: Discrepancies in stone mineral content are common in patients with bilateral stone disease. A single stone analysis from one side in the setting of bilateral stone disease is insufficient for management of patients with bilateral renal stones, and may lead to mismanagement when this misrepresented information is utilized in addition to 24-h urinalysis results. At least one stone analysis should be performed from both sides during a bilateral stone extraction procedure.

Treatment of non-obstructive, non-struvite urolithiasis is effective in treatment of recurrent urinary tract infections.

PURPOSE: To determine if treatment of non-obstructing urolithiasis is effective in management of recurrent UTI. MATERIALS AND METHODS: A retrospective review was performed of patients undergoing elective management of non-struvite upper tract urinary calculi with recurrent UTI from 2009 to 2016. Recurrent UTI was defined at ≥ 3 UTI in 12 months, with symptoms and documented urine culture. Preoperative CT was performed in all patients to determine stone burden. All patients had postoperative imaging and ≥ 12 months of follow-up. Pre- and postoperative variables were between patients who had recurrent UTI after treatment versus those who did not. RESULTS: 46 patients met inclusion criteria. 42 (91.3%) were female. Median age was 63.7 years (IQR 49.1, 73.4) and median total stone burden was 20 mm (IQR 14-35). Within the cohort, 20 (43.5%) underwent ureteroscopy only, 26 (56.5%) underwent PCNL ± URS, and none underwent ESWL. Median postoperative follow-up was 2.9 years (IQR 2.0, 4.3). Only five patients (10.9%) had recurrent UTI after treatment. 80% were with the preoperative pathogen. The presence of residual stone was an independent risk factor for recurrent UTI after treatment (p < 0.046). Diabetes, hypertension, immunosuppression and chronic kidney disease were not. CONCLUSIONS: Stone removal for patients with recurrent UTIs was associated with a high rate of success (89.1%) in elimination of further recurrent UTIs. Residual fragments are independently associated with persistent recurrent UTIs and thus, complete stone removal is of paramount importance in treatment of this patient population.

Electromagnetic Guided Percutaneous Renal Access Outcomes Among Surgeons and Trainees of Different Experience Levels: A Pilot Study.

OBJECTIVE: To determine feasibility of an electromagnetic (EM) guidance system (Auris Health, Redwood City, CA) in obtaining percutaneous renal access among urologists and trainees of different experience levels. EM-guidance is appealing for access as it allows real time, 3-dimensional targeting without radiation. Few studies have explored this for percutaneous nephrolithotomy (PCNL) and none have assessed its potential to decrease the learning curve in obtaining access using traditional techniques. METHODS: Institutional Animal Care and Use Committee approval was obtained to compare EM-guided percutaneous access to fluoroscopic guided access in a porcine model. Voluntary participants included urology trainees and faculty. They were categorized as beginner (no prior primary percutaneous nephrolithotomyexperience), intermediate (10-100 prior) and advanced (>100). Each participant attempted an EM and fluoroscopic guided puncture. Primary outcome was successful puncture. Secondary outcomes included access time, fluoroscopy time, and number of attempts. Participants were limited to 3 attempts and 10 minutes total to obtain access using each technique. RESULTS: Fourteen participants (6 beginners, 4 intermediates, and 4 experts) attempted 28 punctures. Overall success using EM-guidance was 93% compared to 71% using fluoroscopy (P = .33). EM punctures had shorter access times (85 vs 255 seconds, P <.01) required fewer attempts (1 vs 2, P = .04) and had decreased associated fluoroscopy times (1 vs 96 seconds, P <.01) excluding the initial retrograde pyelogram and guidance of the ureteroscope to the desired calyx. Beginners showed comparable success rates and outcomes relative to experts despite higher access times. CONCLUSION: EM-guidance is a promising new technique to decrease the learning curve of percutaneous access with high success rates and minimal radiation.

Urinary extracellular vesicle-associated MCP-1 and NGAL derived from specific nephron segments differ between calcium oxalate stone formers and controls.

Randall's plaque (RP; subepithelial calcification) appears to be an important precursor of kidney stone disease. However, RP cannot be noninvasively detected. The present study investigated candidate biomarkers associated with extracellular vesicles (EVs) in the urine of calcium stone formers (CSFs) with low (<5% papillary surface area) and high (≥5% papillary surface area) percentages of RP and a group of nonstone formers. RPs were quantitated via videotaping and image processing in consecutive CSFs undergoing percutaneous surgery for stone removal. Urinary EVs derived from cells of different nephron segments of CSFs (n = 64) and nonstone formers (n = 40) were quantified in biobanked cell-free urine by standardized and validated digital flow cytometer using fluorophore-conjugated antibodies. Overall, the number of EVs carrying surface monocyte chemoattractant protein (MCP)-1 and neutrophil gelatinase-associated lipocalin (NGAL) were significantly lower in CSFs compared with nonstone former controls (P < 0.05) but did not differ statistically between CSFs with low and high RPs. The number of EVs associated with osteopontin did not differ between any groups. Thus, EVs carrying MCP-1 and NGAL may directly or indirectly contribute to stone pathogenesis as evidenced by the lower of these populations of EVs in stone formers compared with nonstone formers. Validation of EV-associated MCP-1 and NGAL as noninvasive biomarkers of kidney stone pathogenesis in larger populations is warranted.