PURPOSE:To evaluate if treating small asymptomatic renal stones with office-based burst wave lithotripsy (BWL) and ultrasonic propulsion (UP) prevents future stone growth, emergency department visits, and surgical procedures for stone care. METHODS:Participants with 2-7 mm asymptomatic renal stones were treated with BWL to break stones and UP to facilitate clearance of fragments. The primary outcome measure was relapse, defined as stone growth, an urgent or emergent medical visit, or operation for the randomized stones of interest within 14 months of the procedure. These events would include visits caused by the treatment and the presence of residual stones. Relapse data from untreated control groups with small stones or fragments from three published contemporaneous studies with similar protocols and 1- to 5-year follow-up were pooled and inverse probability weighted for comparison. The cumulative incidence of relapse was estimated using the Kaplan-Meier method. RESULTS:Between April 2023 and September 2024, 18 participants underwent treatment of 27 asymptomatic small stones; 7 (39%) participants underwent a second BWL procedure to complete treatment. The control group had significantly shorter time to relapse than the treatment group (p = 0.048 by weighted log-rank test). The hazard ratio for relapse in the treatment group, compared with the control group, was less than 0.01 (p < 0.001). There was no relapse in the treated group within 14 months. For comparison, the 1-year relapse rate was 26% in the control group. CONCLUSIONS:In a small feasibility study, no stone-related relapse events occurred within 14 months following treatment of small, asymptomatic renal stones with BWL and UP.

INTRODUCTION:Recent work has highlighted the renal papillary pathologies present in calcium stone formers. For example, evidence points to ductal plugging being especially damaging to the papillary tissue, and Randall's plaque has been correlated with stone recurrence. The objective of this study was to evaluate the reproducibility of a semiquantitative grading system that can be utilized in the operating room during endoscopic stone removal. MATERIALS AND METHODS:Clips of endoscopic video of single renal papillae, representing 3 papillae from each of 12 patients (6 majority calcium oxalate stone formers [CaOx SFs] and 6 majority apatite [CaP] SFs), were each triplicated in 3 rotations (original, 90° rotation, and vertical flip). Video clips were assessed by 4 graders who were blinded to any other data. Grades for plugging/dilated ducts, papillary pitting, loss of papillary contour, and Randall's plaque were evaluated for intra- and intergrader reproducibility. RESULTS:Graders were in almost perfect agreement on ductal plugging in the papillae (kappa = 0.84), and agreement was good with Randall's plaque (kappa = 0.68), moderate for papillary pitting (kappa = 0.56), and weakest for loss of contour scores (kappa = 0.40). There was substantial agreement of sum papillary scores (kappa = 0.65). CaP SFs had higher scores for ductal plugging, pitting, and loss of papillary contour, whereas CaOx SFs had higher scores for Randall's plaque. CONCLUSIONS:In this patient sample, papillary appearance differed between CaOx and CaP stone formers. Some of these differences can be reliably appreciated and quantified using the proposed papillary grading system. The grading system was reproducible across multiple graders and is designed to be used in the operating room in a manner that can be easily integrated into patient care.

Recent studies have shown that mechanisms of kidney stone growth can be analyzed at the microscopic level by leveraging modern fluorescence microscopy. The present study aims to utilize multimodal imaging techniques on multiple Randall’s plaque stones to observe native fluorescent patterns of mineral-matrix deposition and to compare them both within and between patients. Stones were removed by basket during endoscopic procedures and were verified by micro CT as having grown on Randall’s plaque. Each stone was mounted on polystyrene and ground down to a polished planar surface. Stones were grounded repeatedly to collect as many interior planes as possible, with micro CT verification of each plane of section. Mineral composition was confirmed in selected stones using scanning electron microscopy (SEM), elemental mapping by energy dispersive spectroscopy (EDS), and infrared (IR) microscopy. Stones were then imaged using confocal microscopy for native fluorescence. Randall’s plaque exhibited a characteristic blue autofluorescent signal, potentially indicating a unique protein composition compared to the overlying stone matrix. The apatite-rich layer adjacent to Randall’s plaque showed bright yellow fluorescence, a pattern conserved across patients, suggesting the presence of a distinct urinary protein profile that may facilitate calcium oxalate monohydrate (COM) crystal attachment and, therefore, initial stone propagation. COM regions overlying Randall’s plaque retained laminated layers with alternating autofluorescence signatures, allowing visualization of growth transitions. Our findings, visualized through integrated multimodal imaging, offer insight into early stone pathogenesis of Randall’s plaque stones, and show matrix and plaque fluorescence patterns consistent across patients.

Randall's plaques (RP) are located at the papillary tip, originating in the basement membranes of the thin loops of Henle, vasa recta and collecting ducts, and are associated with kidney stone retention. Disruption of the papillary epithelial layer exposes interstitial RP to calyceal urine, enabling calcium oxalate monohydrate (COM) overgrowth and papillary RP stone formation. This study aimed to analyze the surface and internal structures of RP stones using scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). Stones were collected from patients during percutaneous nephrolithotomy, ureteroscopy or both. Eighteen stones from nine patients were examined by stereoscopic microscopy, micro computed tomography (micro CT), SEM and EDS. Seven RP stones were sectioned for internal structure analysis. SEM revealed mineralized tubules potentially originating from thin loops, collecting ducts, ducts of Bellini, or vasa recta. These were frequently covered by collagen fibrils, and some were filled with dense or particulate mineral. Calcium phosphate (CaP) apatite was observed in various crystallized phases within RP regions. In three of the seven sectioned RP stones, monosodium urate monohydrate crystals were intercalated with RP, confirmed by EDS. Our multimodal imaging approach provides new insights into RP composition. This study suggests that sodium urate may precede RP formation in a subset of cases, potentially due to early, unexpected urinary pH shifts. Further studies are needed to validate this hypothesis and advance our understanding of RP stone pathophysiology, informing better diagnostic and therapeutic strategies for kidney stone disease.

PURPOSE:We tested feasibility of burst wave lithotripsy and ultrasonic propulsion to noninvasively fragment and expel small, asymptomatic renal stones in awake participants. MATERIALS AND METHODS:Adult patients suspected of having 2- to 7-mm stones were consented and screened for eligibility. Burst wave lithotripsy and ultrasonic propulsion were applied to up to 3 stones in 1 kidney of qualifying participants for a 30-minute total exposure. Participants completed a CT scan and the Wisconsin Stone Quality-of-Life (WISQOL) questionnaire within 90 days before and 120 days after the procedure. Participants were contacted weekly for 3 weeks after the procedure to assess adverse events (AEs). Outcomes included (1) no fragment > 2 mm, (2) unanticipated health care visits, (3) change in stone volume, (4) reported AEs, and (5) WISQOL score. RESULTS:Forty-one participants were enrolled between April 2023 and October 2024. Twenty-one participants failed screening because no stones were seen, stones were too large or small, stone visibility was too deep or obstructed, or they declined to participate. Twenty participants with 31 stones received the research procedure with 7 undergoing a single repeat procedure. Twenty-two of 31 stones (71%) met the primary effectiveness outcome of no fragment > 2 mm, with 17 of 31 stones (55%) reported as stone free. Median stone volume reduction (IQR) was 100% (88%-100%). No participants returned unexpectedly for care related to the procedure. AEs were all grade I by modified Clavien classification. WISQOL scores improved on 10 of 15 completed questionnaires. CONCLUSIONS:Small, asymptomatic renal stones were effectively and safely removed in awake participants in a clinic setting.

Introduction: Current American Urological Association guidelines recommend that patients with acute obstructive kidney stone requiring continuous anticoagulation/antiplatelet therapy should not be treated by shockwave lithotripsy or percutaneous nephrolithotomy because of the risk of catastrophic renal hemorrhage possible with those techniques. Currently, ureteroscopy is the only recommended surgical treatment. We evaluated if burst wave lithotripsy (BWL) could be used in these cases by treating pigs with BWL while undergoing anticoagulation therapy. Materials and Methods: Six pigs (31-37 kg) were given 200 units/kg porcine heparin, and then the right kidney of each animal was treated with a dose of BWL (18,000 ultrasound pulses at 10 Hz, 20 cycles/pulse, peak positive pressure of 12 MPa) known to fracture kidney stones. The contralateral kidney served as a control. Therapeutic anticoagulation was confirmed by evaluating activated partial thromboplastin time (aPTT). Microhematuria was checked by urine test strips. Kidneys were subsequently evaluated for hemorrhagic injury via MRI. Results: aPTT was significantly elevated (>100 seconds) throughout the entire treatment period (p = <0.001) indicating therapeutic anticoagulation. Gross hematuria was not observed in any of the pigs. After BWL, microhematuria averaged 145.8 red blood cells (RBC)/mu L in the BWL-treated kidney and 48 RBC/mu L in the control kidneys, and there was no statistically significant difference noted in microhematuria rates between the two groups (p = 0.16). Hemorrhagic injury measured only 0.10 +/- 0.02% of the tissue in the BWL-treated kidneys and 0.12 +/- 0.04% in the control side, with a paired difference of -0.03 +/- 0.05%, showing no significant difference (p = 0.58). Conclusions: A typical clinical dose of BWL causes no hemorrhagic injury to the kidney even during therapeutic anticoagulation therapy. This result suggests that BWL should be safe to use in patients with stone undergoing anticoagulation/antiplatelet therapy.

The goal of this retrospective study was to determine whether having added tiletamine–zolazepam to an anesthetic cocktail of ketamine and xylazine (KX) during an ongoing series of studies of renal function in domestic pigs changed baseline renal hemodynamics. Group A (10 pigs) had been anesthetized with KX, group B (25 pigs) was anesthetized with tiletamine–zolazepam combined with KX (TKX), and group C (10 pigs) was anesthetized with KX. Measurements of baseline glomerular filtration rate (GFR; inulin clearance), effective renal plasma flow (eRPF; para-aminohippuric acid clearance), and mean blood pressure (BP) were made during three 15-min urine collection periods. GFR and eRPF were lower in group B (TKX) than in groups A and C (KX only) by 34% to 40% and 39% to 49%, respectively. BP did not differ between the 3 groups. GFR and eRPF in groups A and C were not different from each other. These findings suggest that adding tiletamine–zolazepam to an anesthetic cocktail can cause an acute decline in GFR and eRPF independent of arterial BP in laboratory swine.

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.

You have accessJournal of UrologyStone Disease: Surgical Therapy (Including ESWL) III (MP29)1 May 2024MP29-11 FEASIBILITY OF BURST WAVE LITHOTRIPSY AND ULTRASONIC PROPULSION TO EXPEL SMALL, ASYMPTOMATIC, RENAL STONES Arturo E. Holmes, Mathew D. Sorensen, Barbrina Dunmire, Jeff Thiel, Barbara H. Burke, Christina Popchoi, John C. Kucewicz, Yak-Nam Wang, Stephanie Totten, Adam D. Maxwell, M. Kennedy Hall, James E. Lingeman, Alana C. Desai, Branda Levchak, Claire C. Yang, Michael R. Bailey, and Jonathan D. Harper Arturo E. HolmesArturo E. Holmes , Mathew D. SorensenMathew D. Sorensen , Barbrina DunmireBarbrina Dunmire , Jeff ThielJeff Thiel , Barbara H. BurkeBarbara H. Burke , Christina PopchoiChristina Popchoi , John C. KucewiczJohn C. Kucewicz , Yak-Nam WangYak-Nam Wang , Stephanie TottenStephanie Totten , Adam D. MaxwellAdam D. Maxwell , M. Kennedy HallM. Kennedy Hall , James E. LingemanJames E. Lingeman , Alana C. DesaiAlana C. Desai , Branda LevchakBranda Levchak , Claire C. YangClaire C. Yang , Michael R. BaileyMichael R. Bailey , and Jonathan D. HarperJonathan D. Harper View All Author Informationhttps://doi.org/10.1097/01.JU.0001008680.67760.37.11AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: The feasibility of burst wave lithotripsy (BWL) and ultrasonic propulsion to noninvasively fragment and expel small, asymptomatic, renal stones in awake subjects is being tested. A previous randomized control trial reported that removal of secondary, small, asymptomatic renal stones during surgery for a primary stone reduced relapse by 82% (Sorensen et al., NEJM, 2022;387:506-13). Our objective was to treat small asymptomatic stones with BWL and ultrasonic propulsion in a clinic-based setting without anesthesia. METHODS: Participants with up to three, 2-7 mm stones in one kidney seen on computerized tomography (CT) within 90 days were consented and screened to assure targetability with the ultrasound device. Untreated infection or inability to hold anticoagulation were exclusions. Transcutaneous ultrasound imaging with BWL therapy to break stones and ultrasonic propulsion to reposition fragments were applied to awake subjects for a 30-minute total exposure under continuous cardiac monitoring. Pain was assessed immediately before and after the procedure. Postoperative urine samples were graded on a published hematuria score (0-10). Participants were asked to strain their urine and they were contacted weekly for 3 weeks to assess for adverse events (AEs) and fragment passage. The primary outcome was stone free on CT 90 days post procedure. Secondary outcomes included change in stone volume, fragment passage, and AEs. RESULTS: Thirteen participants have been enrolled; 4 failed screening because no stones were seen (2), stones were too large (1), and the individual chose bilateral surgery instead (1). Nine participants with 11 stones received the research procedure: all tolerated treatment. Seven participants have received follow-up CT to date, 2 were stone free with 3 stones completely cleared. Mean reduction in stone volume was 70±25%. Video recordings of the research procedures showed stone fragmentation and repositioning. Six of 9 provided photographs of passed fragments. AEs were mild and self-resolving and included: hematuria (6, average score 2.0±1.6), renal colic (1), back pain (3), urinary urgency (1), and change in urinary frequency (1). One participant with a history of urinary tract infections was given antibiotics post procedure despite a negative urinalysis. All pain scores were zero, except one 2, which the participant attributed to positioning. CONCLUSIONS: It is feasible to remove small, asymptomatic, renal stones noninvasively in awake participants with only mild transient AEs. BWL and ultrasonic propulsion may in the not-too-distant future offer a way to prophylactically remove small stones before they require an emergency department visit or surgery. Source of Funding: Work supported by NIH NIDDK P01 DK043881 © 2024 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 211Issue 5SMay 2024Page: e485 Advertisement Copyright & Permissions© 2024 by American Urological Association Education and Research, Inc.Metrics Author Information Arturo E. Holmes More articles by this author Mathew D. Sorensen More articles by this author Barbrina Dunmire More articles by this author Jeff Thiel More articles by this author Barbara H. Burke More articles by this author Christina Popchoi More articles by this author John C. Kucewicz More articles by this author Yak-Nam Wang More articles by this author Stephanie Totten More articles by this author Adam D. Maxwell More articles by this author M. Kennedy Hall More articles by this author James E. Lingeman More articles by this author Alana C. Desai More articles by this author Branda Levchak More articles by this author Claire C. Yang More articles by this author Michael R. Bailey More articles by this author Jonathan D. Harper More articles by this author Expand All Advertisement PDF downloadLoading ...

You have accessJournal of UrologyEducation Research I (MP17)1 May 2024MP17-14 HOLEP MASTERCLASS: AN EVIDENCE-BASED EDUCATIONAL APPROACH FOR SKILL TRANSFER Ahmed Ghazi, Lauren Shepard, Michael Ayenew, Joel Funk, Smita De, Lori Lerner, James Lingeman, Mitchell Humphreys, Peter Gilling, and Akhil Das Ahmed GhaziAhmed Ghazi , Lauren ShepardLauren Shepard , Michael AyenewMichael Ayenew , Joel FunkJoel Funk , Smita DeSmita De , Lori LernerLori Lerner , James LingemanJames Lingeman , Mitchell HumphreysMitchell Humphreys , Peter GillingPeter Gilling , and Akhil DasAkhil Das View All Author Informationhttps://doi.org/10.1097/01.JU.0001008628.15460.84.14AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: Evidence shows that clinical skills acquired in simulation settings transfer directly to improved patient care. However, integration of simulation into postgraduate curricula has been challenging as most are based on experiential notions without a standardized approach to evaluate impact of curriculum design. We designed a 3-day HoLEP Masterclass using the 5E Inquiry-based instructional approach (engagement, exploration, explanation, elaboration and evaluation) that emphasizes active participation and learner's responsibility for discovering new knowledge. METHODS: 18 urologists with minimal to no HOLEP experience, completed a comprehensive curriculum (pre-course online didactics, 3 HoLEP simulations and interactive case presentations) designed to provide urologists with the necessary knowledge to overcome the initial learning curve and gain access to the tools required to initiate a HoLEP program (Figure 1). Assessment followed Kirkpatrick's 4 levels of training evaluation; (1) Reaction (trainee perception) via an exit survey , (2) Knowledge via an MCQ test, (3) Behavior via progression of simulation performance through 3 simulations evaluated using resected adenoma weights and a validated global evaluation metric (1-30), (4) Results via evaluation of post-masterclass patient cases. RESULTS: 94.4%, 88.9% & 88.9% of participants strongly agreed that the masterclass improved their knowledge of techniques, psychomotor skills, and confidence in performing a HoLEP. Pre to post course MCQ scores improved from 44.4% to 79.6%. Mean simulation performance scores and resected adenoma weights significantly improved from 1st to 3rd simulation (13.7±3.8 to 27.1± 2.9, p<0.001) and (31.6±15.3 to 53.7±15.8 gms, p<0.001) respectively (Figure 2). Video review of the 6 participants that completed a HOLEP case after the masterclass showed a mean score of 26.2±3.2. CONCLUSIONS: Our educational approach to a HOLEP masterclass provides promising evidence for successful transfer of simulated skill to live cases. Additional data is required to confirm our findings. Download PPTDownload PPT Source of Funding: none © 2024 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 211Issue 5SMay 2024Page: e296 Advertisement Copyright & Permissions© 2024 by American Urological Association Education and Research, Inc.Metrics Author Information Ahmed Ghazi More articles by this author Lauren Shepard More articles by this author Michael Ayenew More articles by this author Joel Funk More articles by this author Smita De More articles by this author Lori Lerner More articles by this author James Lingeman More articles by this author Mitchell Humphreys More articles by this author Peter Gilling More articles by this author Akhil Das More articles by this author Expand All Advertisement PDF downloadLoading ...

Endoscopic and biopsy findings have identified two distinct phenotypes among individuals with calcium oxalate (CaOx) kidney stones. The first type has normal renal papillae but shows interstitial mineral deposition, known as Randall's plaque. The other phenotype presents with collecting duct plugging and a higher incidence of loss of papilla tissue mass. With Randall’s plaque, renal papilla injury involves the loss of small patches of calcified tissue (Randall’s plaque detaching with the stone), which likely results in damage to only a few nephrons. In contrast, collecting duct mineral plugs are very large, causing obstruction to tubular flow. Since each terminal collecting duct drains thousands of nephrons, ductal plugs could lead to the degeneration of many nephrons and a significant loss of renal glomeruli. New visualization techniques for immune cells in papillary biopsies have revealed that the Randall's plaque phenotype is marked by the accumulation of macrophages around the plaque regions. In contrast, preliminary data on the plugging phenotype shows collecting duct damage with mineral plugs and increased T-lymphocytes throughout the papilla. These regions also show tubulitis, i.e., T-cell infiltration into nearby collecting duct epithelium. This suggests that while some CaOx stone formers may have some papillary inflammation but with minimal damage to nephrons, others suffer from obstruction to flow for many nephrons that may also include destructive inflammation in the renal tissue. We propose that CaOx stone formers with the plugging phenotype will have a higher long-term risk for loss of renal function.

Background: Holmium laser enucleation of the prostate (HoLEP) has been used as an effective minimally invasive technique for management of enlarged prostates. We aimed to report the role of HoLEP in prostate cancer (PCa) patients either on active surveillance with bothersome lower urinary tract symptoms (LUTS) or for prostate debulking before radiation therapy and the impact on PCa management plans.Methods: Prospectively maintained database in two institutions was reviewed for patients with localized PCa managed by HoLEP with at least a follow-up of 1 year. We assessed prostate-specific antigen (PSA) trends, effect on international prostate symptom score (IPSS) and further management of PCa.Results: Out of >2000 HoLEP patients, 117 patients with a median follow-up of 30 months were included. Mean (standard deviation) age was 72.3 (+/- 8.3) years with median (interquartile range, IQR) IPPS of 22 (16-28) and median (IQR) PSA at 7.6 (5.3-14.9) ng/mL. Gleason grade group was 1, 2, 3, and 4 in 47 (73.2%), 32 (27.35%), 7 (5.9%), and 4 (3.4%) patients, respectively. Median (IQR) PSA has significantly dropped to 1.3 (0.6-3.1), 1.4 (0.75-2.9), and 1.7 (0.86-2.75) ng/mL at 6-week, 3-month, and 1-year follow-up, respectively (p < 0.001). IPSS scores post-HoLEP obviously improved with mean (IQR) IPSS of 10 (5-13), 7 (3-12), and 3 (2-5) at 6-week, 3-month, and 1-year, respectively (p < 0.001). Eighty-eight (72%) patients stayed on active surveillance, whereas 27 (23%) patients had radiotherapy +/- androgen deprivation therapy for persistently high or relapsing PSA. Within 36 intermediate-risk patients, 15 (41.6%) and patients had radiotherapy, whereas 21 (58.3%) patients continued active surveillance.Conclusions: HoLEP is beneficial in debulking large prostate in PCa patients with bothersome LUTS on active surveillance or before radiotherapy. HoLEP reduces the contribution of large adenoma to PSA level, thus reflecting PSA level better and helping reduce overtreatment.

You have accessJournal of UrologyCME1 Apr 2023MP05-20 KIDNEY STONE GROWTH ‘RINGS’ VISUALIZED USING MICRO CT AND FLUORESCENCE MICROSCOPY: SIMILARITIES IN GROWTH OF RANDALL’S PLAQUE CALCIUM OXALATE STONES FROM THE SAME KIDNEYS Emily Wachter, Angela Sabo, Tarek El-Achkar, Elaine Worcester, James Lingeman, and James Williams Emily WachterEmily Wachter More articles by this author , Angela SaboAngela Sabo More articles by this author , Tarek El-AchkarTarek El-Achkar More articles by this author , Elaine WorcesterElaine Worcester More articles by this author , James LingemanJames Lingeman More articles by this author , and James WilliamsJames Williams More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000003216.20AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: Recent work has shown that mechanisms of stone growth can be demonstrated at the microscopic level using fluorescence microscopy. The objective here was to study multiple stones to observe patterns of mineral and organic deposition within and between patients. METHODS: Stones were removed by basket during endoscopic procedure, and a total of 12 stones were studied from 3 patients. All stones were verified by micro CT as having grown on Randall’s plaque by residue visible on the stone. Each stone was mounted on polystyrene and ground down to reveal a planar surface inside the stone. The stone was then imaged using confocal microscopy (Leica SP8) with a water immersion lens (20x, 0.75 NA). Each stone was ground repeatedly to collect as many interior planes as possible, with micro CT verification of each plane of section and mineral regions exposed. RESULTS: Within a patient, similarities of layering (both thickness and color) were apparent in stones from the same kidney, but stones from different patients had different fluorescent features. Several stones showed evidence of episodic growth by deposition of aggregates of calcium oxalate dihydrate crystals, and these stones with evidence of dihydrate aggregates tended to be larger stones within a given patient. Regions of apatite adjacent to Randall’s plaque showed yellow fluorescence distinctly different from apatite in later stone overgrowth. CONCLUSIONS: The unique fluorescence of apatite laid down as the first overgrowth on Randall’s plaque is suggestive of special urine molecules deposited at the initiation of stone growth. Outside of this consistent finding, fluorescent molecules laid down with mineral in calcium oxalate stones are not universal among patients, but stones from the same kidney showed similar fluorescence patterns. Source of Funding: NIH R01 DK124776, NIH P01 DK056788 © 2023 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 209Issue Supplement 4April 2023Page: e52 Advertisement Copyright & Permissions© 2023 by American Urological Association Education and Research, Inc.MetricsAuthor Information Emily Wachter More articles by this author Angela Sabo More articles by this author Tarek El-Achkar More articles by this author Elaine Worcester More articles by this author James Lingeman More articles by this author James Williams More articles by this author Expand All Advertisement PDF downloadLoading ...