Comparison of metabolic parameters between pure-uric acid and mixed-uric acid kidney stone formers.

PURPOSE: We seek to compare clinical and 24-h urine parameters between pure-uric acid (UA) and UA-CaOx stone formers in our practice and explore how any differences in metabolic profiles could suggest different prevention strategies between the two groups. METHODS: We retrospectively reviewed patients with either pure- or mixed-UA nephrolithiasis from 2020 to 2023 at a tertiary care center. We included patients with a 24-h urine collection and a stone analysis detecting any amount of UA. Patients were organized into two cohorts: (1) those with 100% UA stones and (2) < 100% UA stones. Differences in demographic characteristics were compared between pure-UA and UA-CaOx stone formers. Twenty-four hour urine metabolic parameters as well as metabolic abnormalities were compared between the pure-uric acid and mixed-uric acid groups. RESULTS: We identified 33 pure-UA patients and 33 mixed-UA patients. Patient demographics were similar between the groups (Table 1). Pure- and mixed-UA patients had a similar incidence of metabolic syndrome, diabetes, history of stones, and stone burden. Table 1 Demographic and baseline characteristics among pure- and mixed-uric acid stone formers Pure-uric acid stones (n = 33) Mixed-uric acid stones (n = 33) p-value Median age [IQR] 63.00 [58.00-72.50] 63.00 [53.50-68.00] 0.339 Median BMI [IQR] 28.79 [25.81-33.07] 27.96 [25.81-29.55] 0.534 Gender, n (%) 1.000  Male 21 (63.6) 21 (63.6)  Female 12 (36.4) 12 (36.4) Metabolic syndrome, n (%) 17 (51.5) 16 (48.5) 0.806 Diabetes, n (%) 13 (39.4) 12 (36.4) 0.800 History of stones, n (%) 23 (69.7) 22 (66.7) 0.792 Median total stone burden, mm [IQR] 12.00 [6.00-26.50] 13.00 [7.05-20.00] 0.995 Median serum uric acid, mg/dL [IQR] 6.20 [4.80-7.15] 5.90 [4.98-6.89] 0.582 IQR Interquartile range BMI Body Mass Index n number We found the pure-UA cohort to have 24-h lower urine volume (1.53 vs. 1.96 L/day, p = 0.045) and citrate levels (286 vs. 457 mg/day, p = 0.036). UA-CaOx stone formers had higher urinary calcium levels (144 vs. 68 mg/day, p = 0.003), higher urinary oxalate levels (38 vs. 30 mg/day, p = 0.017), and higher median urinary calcium oxalate super-saturation (3.97 vs. 3.06, p = 0.047). CONCLUSIONS: Pure-UA kidney stone formers have different urinary metabolic parameters when compared with UA-CaOx stone formers, thus requiring different and tailored medical management.

Displacement of Lower Pole Stones During Retrograde Intrarenal Surgery Improves Stone-free Status: A Prospective Randomized Controlled Trial.

PURPOSE: Lower pole renal stones are associated with the lowest stone-free status of any location in the urinary tract during retrograde intrarenal surgery. Prior work has suggested displacing lower pole stones to a more accessible part of the kidney to improve stone-free status. We sought to prospectively compare the efficacy of laser lithotripsy in situ vs after displacement during retrograde intrarenal surgery for lower pole stones. MATERIALS AND METHODS: Between July 2017 and May 2022 patients undergoing retrograde intrarenal surgery for lower pole stones were randomized into an in situ or displacement group. Demographics, comorbidities, and operative parameters were documented. Primary outcome was stone-free status, determined by combination of abdominal x-ray and renal ultrasound at 30-day follow-up. Secondary outcomes included operative time, 30-day complications, emergency department visits, and readmissions. RESULTS: A total of 138 patients (69 per group) were enrolled and analyzed. Baseline characteristics were similar between groups. Stone-free status significantly favored the displacement group over the in situ group (95% vs 74%, P = .003, n=62 in each group). Operative time, total laser energy usage, 30-day complications, and 30-day emergency department visits or hospital readmissions were similar between groups. On multivariate analysis only study group allocation was significantly associated with stone-free status (P = .024). CONCLUSIONS: Basket displacement of lower pole stones results in a significantly higher stone-free status compared to in situ lithotripsy. The technique is simple, atraumatic, and requires no additional equipment costs and little additional operative time, making it a practical tool in the treatment of lower pole stones.

Opioid-free percutaneous nephrolithotomy: an initial experience.

INTRODUCTION: The opioid epidemic in the United States is an ongoing public health crisis that is in part fueled by excessive prescribing by physicians. Percutaneous nephrolithotomy (PCNL) is a procedure that conventionally involves opioid prescriptions for adequate post-operative pain control. We aimed to evaluate the feasibility of a non-opioid pain regimen by evaluating post-operative outcomes in PCNL patients discharged without opioids. MATERIALS AND METHODS: As a quality improvement measure to reduce opioid consumption our department began routinely prescribing oral ketorolac instead of oxycodone-acetaminophen for pain control after PCNL. We retrospectively compared patients undergoing PCNL who had received ketorolac prescriptions (NSAID) to those who received oxycodone-acetaminophen prescriptions (NARC). Demographic, operative, and post-operative factors were obtained and compared in both groups. Peri-operative factors and demographics were compared using either Chi-squared tests, Mann-Whitney U tests. Surgical outcomes were compared between the two groups using Chi-squared tests and Fisher's exact tests. Multivariate logistic regression analysis was performed to determine whether ketorolac use was an independent predictor of post-surgical pain-related encounters. Primary outcome was unplanned pain-related healthcare encounters inclusive of office phone calls, unscheduled office visits, and emergency department (ED) visits. Secondary outcome measures were non-pain-related healthcare encounters, hospital readmissions, pain-related rescue medications prescribed, and post-op complications. RESULTS: There were similar demographics and peri-operative characteristics amongst patients in both cohorts. There was no significant difference identified between NSAID and NARC regarding unplanned pain-related encounters (8/70, 11.4% vs. 10/70, 14.3%, p = 0.614). However, NARC experienced more unplanned phone calls (42, 60% vs. 24, 34.3%, p = 0.004). Multivariate analysis revealed only prior stone surgery was predictive of pain-related encounters after PCNL (p = 0.035). CONCLUSION: Our results show that there were no significant differences in pain-related encounters between those who received ketorolac and oxycodone-acetaminophen following PCNL. A non-opioid pathway may mitigate the potential risk associated with opioid prescription without compromising analgesia. Prospective comparative studies are warranted to confirm feasibility.

Drivers of calcium oxalate stone formation in the octogenarian population.

INTRODUCTION: American Urological Association (AUA) guidelines suggest metabolic testing via 24-h urine studies in high-risk, interested first-time stone formers, and recurrent stone formers. If metabolic testing is not available or otherwise not feasible, clinicians may need to utilize empiric therapy. Debility and social barriers, particularly in the elderly population, may limit the practicality of metabolic testing, and therefore, empiric therapy is of particular importance. The aim of this study is to identify whether unique urinary metabolic abnormality profiles exist for octogenarians with calcium oxalate kidney stones, as this may guide empiric stone prevention therapy more precisely in this population. MATERIALS AND METHODS: Patients with calcium oxalate stones from a single academic kidney stone center in New York, NY, were retrospectively identified in our prospectively managed database. Patient data, including demographic, clinical information, and baseline 24-h urine studies, were collected before initiating any treatment. Subjects were stratified by age (≤ 40, 41-59, 60-79, and ≥ 80 years) to compare the metabolic urinary abnormality profiles between octogenarians and other age groups. Subgroup analyses were also performed to compare results by gender and by the presence of underlying kidney dysfunction. Comparative statistical analysis was carried out using Chi-square tests, Mann-Whitney U tests, and t-tests where appropriate. RESULTS: Hypocitraturia, low urine pH, and low urine volume were most common in older patients, particularly in octogenarians. Hypercalciuria, hypernatriuria, and hyperuricosuria were more apparent in younger groups. CONCLUSION: With increasing age, hypocitraturia, low urine pH, and low urine volume were more prevalent on 24-h urine metabolic testing. We hypothesize increased comorbidity, including medical renal disease, polypharmacy, and dehydration are possible factors contributing to this unique profile. We suggest that empiric therapy targeted towards this profile is important in very elderly stone formers in whom 24-h urine testing may not be possible. Increased hydration, increased fruit and vegetable intake, and low-dose alkali therapy are easy measures to accomplish this.

A prospective randomized study evaluating the necessity of narcotics following ureteroscopy for urinary stone disease.

PURPOSE: To evaluate the efficacy of non-narcotic analgesics and preoperative counseling in managing postoperative pain and narcotic use following ureteroscopic laser lithotripsy (URS). METHODS: Adult patients at a single academic center undergoing URS for nephrourolithiasis were recruited. After informed consent, subjects were randomized into three groups: NARC-15 tablets oxycodone-acetaminophen 5/325 mg (A-OXY), 2. NSAID-15 tablets ibuprofen (IBU) 600 mg, 3. CNSL-15 tablets A-OXY, 15 tablets IBU, and preoperative counseling from the surgeon to avoid narcotic if possible. Patients who did not receive an intraoperative stent were excluded. At the time of stent removal subjects completed the Universal Stent Symptom Questionnaire (USSQ), and a pill count was performed. USSQ pain indices were the primary study endpoint. RESULTS: Of 115 patients enrolled, 104 met the primary endpoint and were included in the analysis. No significant differences were noted in patient demographic, clinical, or operative characteristics. No differences were noted in median USSQ pain indices. The CNSL group used a significantly lower median number of A-OXY pills compared to the NARC group (2.4 vs. 5.4, p = 0.001) and less IBU compared to the NSAID group (3.1 vs. 5.9, p = 0.008). No differences in median total pill count, office calls, medication requests, nor ED visits were noted. CONCLUSION: Our data suggest that patients can achieve equivalent postoperative analgesic satisfaction with non-narcotics compared to opiates following URS. Further, counseling patients on postoperative pain before surgery can reduce the total number of postoperative narcotic and non-narcotic medications taken. We suggest surgeons strongly consider omission of narcotic prescriptions following non-complicated URS.

Use of the Quick Sequential Organ Failure Assessment Score for Prediction of Intensive Care Unit Admission Due to Septic Shock after Percutaneous Nephrolithotomy: A Multicenter Study.

PURPOSE: Recent studies have demonstrated that quick sequential organ failure assessment criteria may be more accurate than systemic inflammatory response syndrome criteria to predict postoperative sepsis. In this study we evaluated the ability of these 2 criteria to predict septic shock after percutaneous nephrolithotomy. MATERIALS AND METHODS: We performed a retrospective multicenter study in 320 patients who underwent percutaneous nephrolithotomy at a total of 8 institutions. The criteria for quick sequential organ failure assessment and systemic inflammatory response syndrome were collected 24 hours postoperatively. The study primary outcome was postoperative septic shock. Secondary outcomes included 30 and 90-day emergency department visits, and the hospital readmission rate. RESULTS: Three of the 320 patients (0.9%) met the criteria for postoperative septic shock. These 3 patients had positive criteria for quick sequential organ failure assessment and systemic inflammatory response syndrome. Of the entire cohort 23 patients (7%) met quick sequential organ failure assessment criteria and 103 (32%) met systemic inflammatory response syndrome criteria. Specificity for postoperative sepsis was significantly higher for quick sequential organ failure assessment than for systemic inflammatory response syndrome (93.3% vs 68.4%, McNemar test p <0.001). The positive predictive value was 13% for quick sequential organ failure assessment criteria and 2.9% for systemic inflammatory response syndrome criteria. On multivariate logistic regression systemic inflammatory response syndrome criteria significantly predicted an increased probability of the patient receiving a transfusion (ß = 1.234, p <0.001). Positive quick sequential organ failure assessment criteria significantly predicted an increased probability of an emergency department visit within 30 days (ß = 1.495, p <0.05), operative complications (ß = 1.811, p <0.001) and transfusions (p <0.001). The main limitation of the study is that it was retrospective. CONCLUSIONS: Quick sequential organ failure assessment criteria were superior to systemic inflammatory response syndrome criteria to predict infectious complications after percutaneous nephrolithotomy.

The Role of Media in Non-Directed (Altruistic) Living Kidney Donation.

This study seeks to characterize how non-directed living kidney donors use media and informational resources over the course of their kidney donation journey. We conducted semi-structured interviews with non-directed donors (NDDs) who initiated kidney transplant chains. Interview transcripts were reviewed and references to media or informational resources were classified by type and pattern of use. More than half (57%) of NDDs reported that an identifiable media or informational resource resulted in their initial interest in donation. Two-thirds (67%) of NDDs cited the influence of stories and personal narratives on their decision to donate. After transplant, media and informational resources were used to promote organ donation, connect with other donors or recipients, and reflect on donation. From the study's findings, we conclude that media and informational resources play an important role in the process of donation for NDDs, including inspiring interest in donation through personal narratives. Media sources provide emotionally and intellectually compelling discussions that motivate potential donors. The results of this study may facilitate the development of more targeted outreach to potential donors through use of personal narratives in articles and television programming about donation.

Evaluation of the Current Status of Artificial Intelligence for Endourology Patient Education: A Blind Comparison of ChatGPT and Google Bard Against Traditional Information Resources.

Introduction: Artificial intelligence (AI) platforms such as ChatGPT and Bard are increasingly utilized to answer patient health care questions. We present the first study to blindly evaluate AI-generated responses to common endourology patient questions against official patient education materials. Methods: Thirty-two questions and answers spanning kidney stones, ureteral stents, benign prostatic hyperplasia (BPH), and upper tract urothelial carcinoma were extracted from official Urology Care Foundation (UCF) patient education documents. The same questions were input into ChatGPT 4.0 and Bard, limiting responses to within ±10% of the word count of the corresponding UCF response to ensure fair comparison. Six endourologists blindly evaluated responses from each platform using Likert scales for accuracy, clarity, comprehensiveness, and patient utility. Reviewers identified which response they believed was not AI generated. Finally, Flesch-Kincaid Reading Grade Level formulas assessed the readability of each platform response. Ratings were compared using analysis of variance (ANOVA) and chi-square tests. Results: ChatGPT responses were rated the highest across all categories, including accuracy, comprehensiveness, clarity, and patient utility, while UCF answers were consistently scored the lowest, all p < 0.01. A subanalysis revealed that this trend was consistent across question categories (i.e., kidney stones, BPH, etc.). However, AI-generated responses were more likely to be classified at an advanced reading level, while UCF responses showed improved readability (college or higher reading level: ChatGPT = 100%, Bard = 66%, and UCF = 19%), p < 0.001. When asked to identify which answer was not AI generated, 54.2% of responses indicated ChatGPT, 26.6% indicated Bard, and only 19.3% correctly identified it as the UCF response. Conclusions: In a blind evaluation, AI-generated responses from ChatGPT and Bard surpassed the quality of official patient education materials in endourology, suggesting that current AI platforms are already a reliable resource for basic urologic care information. AI-generated responses do, however, tend to require a higher reading level, which may limit their applicability to a broader audience.

Review of efficacy and safety of same-day discharge after percutaneous nephrolithotomy.

PURPOSE: Prior literature reviews have assessed the efficacy and safety of outpatient percutaneous nephrolithotomy (PCNL) with "outpatient" defined as discharge within twenty-four hours of surgery. To our knowledge, this is the first literature review analyzing ambulatory PCNLs (aPCNL) defined as hospital discharge on the same day as surgery. This review aims to assess the efficacy and safety of same-day discharge after PCNL. METHODS: We conducted a search in the PubMed database for key search terms including "ambulatory PCNL", "ambulatory percutaneous nephrolithotomy", "outpatient PCNL", "outpatient percutaneous nephrolithotomy", and "day surgery percutaneous nephrolithotomy". We reviewed articles defining "ambulatory" as discharge the same day the PCNL was performed. 13 papers were identified in our search. RESULTS: Overall, we found no difference in complication rates, emergency department visits, and postoperative admissions when comparing outpatient PCNL to inpatient PCNL, and to previously published statistics for inpatient PCNL. Some studies even showed lower rates of adverse outcomes in ambulatory cohorts when compared to inpatient cohorts. Additionally, ambulatory PCNL conferred significant healthcare savings over inpatient PCNL. CONCLUSION: This literature review suggests that ambulatory PCNL can be safely performed in both optimal and suboptimal surgical candidates with no significant increase in complications. Additional high-quality studies are warranted to further the evidence surrounding outpatient PCNL and its outcomes.

Predicting Septic Shock After Emergent Ureteral Stenting in Stone-Related Obstruction and Presumed Infections.

Introduction: Systemic inflammatory response syndrome (SIRS) criteria have long been used to predict septic shock. The sequential organ failure assessment and quick sequential organ failure assessment (qSOFA) scores have been suggested to be more accurate predictors. This study aims to compare SIRS and qSOFA for predicting of septic shock in the setting of retrograde ureteral stenting for obstructing stones and concomitant urinary tract infection. Methods: A retrospective review of records at two centers of consecutive patients was performed. Patients with unilateral ureteral obstruction by a stone who underwent ureteral stent placement and suspicion of urinary tract infection were identified. Primary endpoints were SIRS and qSOFA positive scores, intensive care unit admission, and vasopressor requirements. Results: A total of 187 patients were included. SIRS criteria were met in 103 patients (55.1%) and in 30 patients who experienced septic shock. qSOFA criteria were met for 24 patients (12.8%) and in 18 patients who experienced septic shock. Specificity for postoperative septic shock was significantly higher for qSOFA than for SIRS criteria (75 vs 29.1%, McNemar test p < 0.001). Both SIRS and qSOFA had significant areas under the curve (AUC), qSOFA had a fair AUC of 0.750, p = 0.001, whereas SIRS had a poor AUC of 0.659, p = 0.008. Univariate logistic regression of SIRS and qSOFA for septic shock showed: qSOFA (odds ratio [OR] 46 [0.25-228], p = 0.001) and SIRS (OR 2.29 [0.716-7.37], p = 0.162). Conclusion: Although SIRS offers higher sensitivity, qSOFA score may offer advantages over SIRS criteria in evaluation of risk for septic shock for patients who present with obstructing ureteral stone and urinary tract infection.

Comprehensive analysis of factors associated with significant blood loss during percutaneous nephrolithotomy.

INTRODUCTION: The objective of this study is to conduct a thorough investigation of the risk factors associated with blood loss during PCNL, within the setting of a US urban tertiary care center. MATERIALS AND METHODS: We conducted a retrospective analysis of our endourology database to identify adult patients who underwent PCNL for stone extraction at our tertiary stone center between October 2014 and December 2022. Patients were categorized into two groups based on the extent of blood loss: significant blood loss (SBL) and no significant blood loss (NSBL). The cut-off value for SBL was determined as the median change in hematocrit levels from preoperative to postoperative among patients who required postoperative transfusions. Several factors were evaluated, including stone dimensions, operative details, the presence of preoperative drains, patient position, type of access, access site, number of accesses, tract size, tract length, stone location, number of stones, operative time, and the S.T.O.N.E. Nephrolithometry Scoring System. RESULTS: Our analysis included a total of 695 procedures performed on 674 distinct patients who met our inclusion criteria. Of these, 102 patients (14.7%) were included in the SBL group. Patients in the SBL group had a higher mean number of accesses (1.57 vs. 1.29, P<0.001), were positioned prone more often (96.0% vs. 88.6%, P = 0.025), and underwent fluoroscopic-guided access more frequently (89.9% vs. 64.8%, P<0.001). Additionally, significant differences were observed in stone morphology, with the SBL group having higher rates of complete staghorn stones (42.2% vs. 27.0%, P = 0.019) and lower rates of partial staghorn stones (27.7% vs. 36.8%, P = 0.019). A larger proportion of patients in the SBL group required a 16 French nephrostomy tube for postoperative drainage (13.3% vs. 10.4%, P = 0.041). Lastly, the SBL group had a longer mean operative time compared to the NSBL group (P<0.001). Multiple logistic regression analysis identified stone volume (P = 0.039), number of accesses (P = 0.047), and operative time (P = 0.006) as independent risk factors associated with SBL status. CONCLUSION: Surgical complexity factors such as stone volume, number of accesses, and operative time are linked to a higher risk of SBL during PCNL. Stone volume and the requirement for multiple accesses can usually be estimated with reasonable accuracy before surgery.

Adjuvant intraluminal therapies for upper tract urothelial carcinoma.

Upper urinary tract urothelial carcinomas (UTUCs) are often identified and first treated endoscopically. After proper risk stratification, adjuvant treatment may be recommended. Consequently, as adjuvant therapy becomes more common place in the oncological armamentarium, we seek to better characterize its existing and future therapeutic landscape. In this article, we present an overview of the most up-to-date information about intracavitary instillations as an adjuvant therapy in the context of UTUC. We reviewed the current literature on the epidemiology, disease characteristics, treatment, and outcomes of UTUC with a particularly focus on intraluminal adjuvant therapy for UTUC. This review provides a comprehensive overview of the most recent available data regarding adjuvant therapies used for UTUC. Intraluminal therapy plays an increasingly important role in the management of UTUC. Mitomycin C is the most common adjuvant treatment for UTUC with bacillus Calmette-Guerin (BCG) being utilized to a lesser extent. UGN-101 is a novel topical gel-based therapy that has shown promising results and thus recently garnered Food and Drug Administration (FDA) approval for UTUC. Other treatments such as BCG-IFN, gemcitabine, docetaxel, and drug-eluting stents (DES) may play a future role in UTUC treatment given further research. It is important to caveat that current studies on topical adjuvant treatments demonstrate varying degrees of effectiveness. This is largely due to limited research on UTUC, consisting of small sample sizes, and mostly retrospective experiences. Accordingly, further clinical trials are needed to evaluate the true benefit of these treatments.

Selecting an Endourology Society Fellowship Program: The Candidates' Perspectives.

Introduction: Understanding the factors that influence the decision of urology residents to pursue an Endourology Society (ES) fellowship and the criteria used by applicants to rank programs may help residents and program directors (PDs) optimize the match process. In the present study, we surveyed current ES fellows to gain better insight surrounding their decision-making process. Materials and Methods: A survey was emailed to all ES fellows, comprising Endourology and Stone Disease (ESD), Laparoscopic and Robotic Surgery (MIS), and combination of ESD/MIS (COM) programs. A Likert scale ranging from 1 to 5 was used. The survey captured demographics such as geographic region, program type, duration, applicants' reasons for pursuing fellowship, criteria for ranking programs, and perceived improvements in surgical comfort levels at the end of their training. Results: Out of the 60 fellows who were surveyed, 40 (66.7%) responded. Among the respondents, 9 (22.5%) pursued ESD, 10 (25%) pursued MIS, and 21 (52.5%) pursued COM programs. The primary reason for seeking a fellowship was to improve surgical skills while increasing earning potential and enhancing research opportunities were deemed the least important. Fellows enrolled in 1-year programs were less likely to pursue fellowships for academic reasons. The two most significant factors in selecting a program were both related to gaining operative experience. Lastly, there was an increase in the level of comfort performing all endourological surgeries independently after fellowship. Conclusions: ES fellowship is seen as an opportunity to hone surgical skills and increase job competitiveness. When selecting a program, operative experience is the most important factor, and fellowship improves operative confidence. The information obtained from this study may mutually help guide future applicants and PDs in the decision process of the Endourology Match.

Reverse Trendelenburg Positioning Minimizes Stone Retropulsion During Ureteroscopic Laser Lithotripsy: A Prospective Randomized Study.

Purpose: Retropulsion of stone fragments during ureteroscopic laser lithotripsy (URSLL) remains a challenge for urologists and is associated with increased operative time and reduced stone-free rate (SFR). In this study, we compared the rate of retropulsion of ureteral stones during URSLL between the standard dorsal lithotomy (SDL) position and dorsal lithotomy position with reverse Trendelenburg (RT). Materials and Methods: Patients with ureteral stones requiring surgical intervention between May 2019 and January 2022 were randomized to undergo URSLL in either SDL or RT positions. The primary outcome of this study was stone retropulsion. Secondary outcomes included retropulsion to the kidney, SFR, operative time, 30-day emergency department visits and complications, and the need for conversion from semirigid to flexible ureteroscope. Differences between groups were evaluated using the chi-square test, Fisher exact test, Kruskal-Wallis test, or t-test. Results: A total of 114 patients were included in the study, with 57 patients in each group. There were no differences between groups in terms of baseline demographics or stone characteristics. Retropulsion was significantly less frequent in the RT group (68.4% vs 10.5%, p < 0.01). Similarly, the RT group was favored for lower risk of retropulsion into the kidney (40.4% vs 5.3%, p < 0.01), operative time (43.5 vs 33.0 minutes, p = 0.02), and need for ureteroscope conversion (16.7% vs 2.2%, p = 0.04). There was no difference in the SFR (100% vs 95%, p = 0.49). Conclusions: RT positioning during URSLL for ureteral stones significantly decreases the rate of stone retropulsion, operative time, and the need for conversion from semirigid to flexible ureteroscope.

The effects of continuing aspirin on blood loss and postoperative outcomes in percutaneous nephrolithotomy.

BACKGROUND: Percutaneous nephrolithotomy (PCNL) is an effective surgery for complex kidney stones yet with inherent bleeding risks. It remains unclear whether aspirin should be discontinued prior to PCNL. We aimed to further substantiate the safety of continuing aspirin during PCNL surgery and to determine whether aspirin status affects postoperative outcomes following PCNL. METHODS: We retrospectively queried our endourology database for patients who underwent PCNL from October 2017 to December 2022 at our high-volume tertiary referral center. The three groups were based on aspirin status at the time of PCNL: no aspirin (NA), discontinued aspirin (DA), and continued aspirin (CA). Data collected included demographics, preoperative characteristics, operative parameters, pre and postoperative lab values, transfusions, and complications. RESULTS: A total 648 patients were divided into these study groups: 525 NA patients (81.0%), 55 DA (8.5%), and 68 CA (10.5%). The DA and CA groups were of similar comorbidities, and both were more comorbid at baseline than NA. Postoperative change in lab values and complications did not differ significantly. Rates of postoperative blood transfusion were higher in the CA and DA groups compared to NA and approached statistical significance. There were no significant differences in any postoperative outcomes between the DA and CA groups alone. CONCLUSIONS: In patients on chronic aspirin therapy, continuing aspirin appears equally safe to discontinuing aspirin prior to PCNL. Most patients should not forego the benefits of continuous aspirin for the theoretical risk of bleeding. Patients on prolonged aspirin therapy may be more likely than those who are not on chronic aspirin therapy to require blood transfusions. However, regardless of whether aspirin use is stopped, this may be caused by patient comorbidities rather than higher rates of blood loss.

Comparative proteomic profiling of uric acid, ammonium acid urate, and calcium-based kidney stones.

INTRODUCTION: Kidney stone matrix proteins may help explain cellular mechanisms of stone genesis. However, most existing proteomic studies have focused on calcium oxalate stones. Here, we present a comparative proteomic analysis of different kidney stone types. METHODS: Proteins were extracted from the stones of patients undergoing percutaneous nephrolithotomy (PCNL). Approximately 20 µg of protein was digested into tryptic peptides using filter aided sample preparation, followed by liquid chromatography tandem-mass-spectrometry using an EASY-nLC 1200 and Orbitrap Fusion Lumos mass spectrometer. A standard false discovery rate cutoff of 1% was used for protein identification. Stone analysis was used to organize stone samples into similar groups. We selected the top 5% of proteins based on total ion intensities and used DAVID and Ingenuity Pathway Analysis to identify and compare significantly enriched gene ontologies and pathways between groups. RESULTS: Six specimens were included and organized into the following four groups: 1) mixed uric acid (UA) and calcium-based, 2) pure UA, 3) pure ammonium acid urate (AAU), and 4) pure calcium-based. We identified 2,426 unique proteins (1,310-1,699 per sample), with 11-16 significantly enriched KEGG pathways identified per group and compared via heatmap. Based on number of unique proteins identified, this is the deepest proteomic study of kidney stones to date and the first such study of an AAU stone. CONCLUSIONS: The results indicate that mixed UA and calcium-based kidney stones are more similar to pure UA stones than pure calcium-based stones. AAU stones appear more similar to pure calcium-based stones than UA containing stones and may be related to parasitic infections. Further research with larger cohorts and histopathologic correlation is warranted.