Ureteral Wall Thickness Is an Effective Predictor of Ureteral Stone Impaction and Management Outcomes: A Systematic Review and Meta-analysis.

PURPOSE: Ureteral stone impaction is associated with unfavorable endourological outcomes; however, reliable predictors of stone impaction are limited. We aimed to assess the performance of ureteral wall thickness on noncontrast computed tomography as a predictor of ureteral stone impaction and failure rates of spontaneous stone passage, shock wave lithotripsy, and retrograde guidewire and stent passage. MATERIALS AND METHODS: This study was completed in accordance with the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-analyses) guidelines. A search was conducted in April 2022 for all adult, human, and English language studies investigating ureteral wall thickness using PROSPERO, OVID Medline, OVID EMBASE, Wiley Cochrane Library, Proquest Dissertations & Theses Global, and SCOPUS. A systematic review and meta-analysis using random effects model was conducted. Risk of bias was assessed using the MINORS (Methodological Index for Non-randomized Studies) score. RESULTS: Fourteen studies with a pooled population of 2,987 patients were included for quantitative analysis, and 34 studies were included in our qualitative review. Meta-analysis findings suggest that a thinner ureteral wall thickness is associated with more favorable subgroup stone outcomes. Thinner ureteral wall thickness suggests a lack of stone impaction and was associated with improved rates of spontaneous stone passage, successful retrograde guidewire and stent placement, and improved shock wave lithotripsy outcomes. Studies lack a standardized ureteral wall thickness measurement protocol. CONCLUSIONS: Ureteral wall thickness is a noninvasive measure that predicts ureteral stone impaction, and thin measurements are predictive of successful outcomes. Variability in measurement methods confirms that a standardized ureteral wall thickness protocol is needed, and the clinical utility of ureteral wall thickness is yet to be determined.

Litigation associated with 5-alpha-reductase-inhibitor use: A Canadian legal database review.

INTRODUCTION: 5α-reductase inhibitors (5ARI) are commonly prescribed medications. There is ongoing controversy about the adverse events of these medications. The aim of this study is to characterize lawsuits in Canada involving medical complications of 5ARIs use. MATERIALS AND METHODS: Legal cases were queried from CanLII. Cases were included if they involved a party taking a 5ARI who alleged an adverse event. Relevant full cases were retained, and pertinent characteristics were extracted with the help of a legal expert. RESULTS: Our deduplicated search yielded 67 unique legal documents from December 2013 to February 2019. Twelve of these documents met the inclusion criteria (representing 3 cases, considering each case had several hearings). The medical complaints filed by the plaintiffs were all related to medication side effects (n = 3, 100%). The plaintiffs were commonly patients themselves. Defendants were exclusively pharmaceutical companies. Persistent erectile dysfunction after stopping the medication was cited as a side effect in all complaints. The prescriptions were made for male pattern hair loss (n = 3, 100%) in all cases. All cases represent class actions brought by the plaintiffs, and they have been certified by their respective court. However, the cases are still ongoing. CONCLUSION: While 5ARI use has been linked to undesired sexual side effects, there have been few litigations on this issue in Canada. Persisting sexual dysfunction after stopping the medication is the only complaint presented in legal action. To date, no judgment against a physician or pharmaceutical company was identified. Cases are still ongoing.

Characterizing patients with multiple same-sided ureteric stones.

PURPOSE: Patients presenting with multiple same-sided ureteric stones (MSSUS) are a unique population with nuanced prognostic and treatment considerations, which have yet to be characterized in the literature. Therefore, our purpose was to examine outcomes of patients with MSSUS vs those with single ureteric stones (SUS). METHODS: A retrospective review of prospectively collected patients included adults (> 18yo) with [Formula: see text] 2 ipsilateral ureteral stones without prior treatment for their current stone burden. A historical comparison group was used as a control population. Univariate logistic regression analyses and descriptive statistics were performed with SPSS® 20.0 (p < 0.05). RESULTS: Seventy-nine MSSUS patients were compared to 101 SUS patients. MSSUS patients had 2.21 [Formula: see text] 0.66 ureteric stones and had significantly smaller lead stones (MSSUS 6.4 mm vs SUS 7.2 mm, p = 0.03). MSSUS patients were more likely to have had prior stones (66 vs 42%) and 5.9 times more likely to have had prior stone procedures. Conservative management was successful in 30% MSSUS vs 19% SUS (p = 0.073), and there were no differences in resolution time (p = 0.44). For patients proceeding to intervention, (MSSUS n = 52, SUS n = 78), ureteroscopy was performed on 58% MSSUS vs 51% SUS patients (p = 0.302), and shockwave lithotripsy in 10% MSSUS vs 26% SUS (p = 0.01). MSSUS were more likely to spontaneously pass a stone prior to planned intervention (OR = 41.1; 95% CI = 12.0-140.7; p = 0.0001). CONCLUSION: MSSUS patients are more likely recurrent stone formers with extensive stone histories and current stone burdens. Conservative management appears as successful between groups, with no difference in resolution time. When employed, ureteroscopy outcomes do not different between cohorts.

Patient Reported Outcomes Predicting Spontaneous Stone Passage May Not Have Acceptable Accuracy.

PURPOSE: We assessed the accuracy of patient reported outcomes for predicting spontaneous ureteral stone passage. MATERIALS AND METHODS: Patients with new unilateral ureteral calculi were prospectively assessed regarding current symptoms and whether they believed their stone had passed. The primary outcome was successful spontaneous stone passage as confirmed by ultrasound, and kidney, ureter and bladder x-ray. Spontaneous stone passage was compared to patient reported outcome responses to assess accuracy. RESULTS: Of the 212 patients 105 (49.5%) had successful spontaneous stone passage at a mean followup of 17.6 days. Compared to the unsuccessful spontaneous stone passage group, those with successful spontaneous stone passage had significantly smaller (mean 5.4 vs 7.6 mm), more distal (71.4% vs 34.6%) stones with slightly longer average time to followup at first visit (19.2 vs 16.0 days). Additionally, there was more patient reported cessation of pain (77.1% vs 44.9%) and perceived stone passage (55.2% vs 13.1%) in this group. Cessation of pain was 79.7% (95% CI 67.1-89.0) sensitive and 55.8% (95% CI 44.0-67.1) specific for successful spontaneous stone passage. Likewise, patient reported stone passage was 59.3% (95% CI 45.7-71.9) sensitive and 87.0% (95% CI 77.4-93.5%) specific. In the multivariable logistic regression analysis cessation of pain (OR 4.02, 95% CI 1.91-8.47, p <0.01) and reported stone passage (OR 3.79, 95% CI 1.73-8.28, p <0.01) were independent predictors of successful spontaneous stone passage. CONCLUSIONS: Cessation of pain and patient reported stone passage are independent predictors of successful spontaneous stone passage. However, both assessments may incorrectly gauge spontaneous stone passage, which raises concern for their validity as a sole clinical end point.

Accurately Diagnosing Uric Acid Stones from Conventional Computerized Tomography Imaging: Development and Preliminary Assessment of a Pixel Mapping Software.

PURPOSE: Preoperative determination of uric acid stones from computerized tomography imaging would be of tremendous clinical use. We sought to design a software algorithm that could apply data from noncontrast computerized tomography to predict the presence of uric acid stones. MATERIALS AND METHODS: Patients with pure uric acid and calcium oxalate stones were identified from our stone registry. Only stones greater than 4 mm which were clearly traceable from initial computerized tomography to final composition were included in analysis. A semiautomated computer algorithm was used to process image data. Average and maximum HU, eccentricity (deviation from a circle) and kurtosis (peakedness vs flatness) were automatically generated. These parameters were examined in several mathematical models to predict the presence of uric acid stones. RESULTS: A total of 100 patients, of whom 52 had calcium oxalate and 48 had uric acid stones, were included in the final analysis. Uric acid stones were significantly larger (12.2 vs 9.0 mm, p = 0.03) but calcium oxalate stones had higher mean attenuation (457 vs 315 HU, p = 0.001) and maximum attenuation (918 vs 553 HU, p <0.001). Kurtosis was significantly higher in each axis for calcium oxalate stones (each p <0.001). A composite algorithm using attenuation distribution pattern, average attenuation and stone size had overall 89% sensitivity, 91% specificity, 91% positive predictive value and 89% negative predictive value to predict uric acid stones. CONCLUSIONS: A combination of stone size, attenuation intensity and attenuation pattern from conventional computerized tomography can distinguish uric acid stones from calcium oxalate stones with high sensitivity and specificity.

Seasonal variations in urinary calcium, volume, and vitamin d in kidney stone formers.

OBJECTIVES: To investigate the seasonal variations in urinary calcium, serum vitamin D, and urinary volume in patients with a history of nephrolithiasis. MATERIALS AND METHODS: Patients included were those who completed a 24-hour urine metabolic evaluation on two occasions; one in summer (June-Aug) and one in winter (Nov-Jan), and who had not started any medications or been instructed on dietary modifications in the interval between the two tests that may have impacted the results. Patients were excluded if they were on thiazide diuretics or were taking calcium and / or Vitamin D supplementation. Welch's t-test was used to compare the difference in average summer and winter values. Unpaired Student t-test was used to compare baseline parameters (age, BMI), and Paired Student t-test was used to compare average seasonal measurements in men vs. women. RESULTS: 136 patients were identified who were not taking calcium or vitamin D supplements or thiazide diuretics, and who were not instructed on dietary modifications in the interval between the two measured parameters. No significant differences were observed when comparing male to female baseline parameters of age or BMI (Table-1). Average 24-hour urine calcium was higher (226.60) in the winter than in summer (194.18) and was significant in males (p = 0.014) and females (p < 0.001). No significant seasonal difference was seen in 24-hour urine volume or serum vitamin D levels. CONCLUSIONS: Urinary calcium is higher in winter months compared to summer months. As such, tailoring medical preventative strategies to the time of year may be helpful.

Multiple sclerosis and nephrolithiasis: a matched-case comparative study.

OBJECTIVE: To compare stone composition and serum/urine biochemistries in stone formers with multiple sclerosis (MS) against stone formers without MS and to examine the association between mobility, methods of bladder emptying, and stone formation. PATIENTS AND METHODS: In this retrospective case-control study, we identified patients diagnosed with MS and kidney stone disease who were seen at our institution between 2001 and 2016. For the first part of the study, up to two controls (stone formers without a history of MS) were identified for each case and matched on age, body mass index, and sex. For the second part of this study, matched controls (MS patients without a history of stones) were identified in a 1:1 ratio in a similar fashion. Results of 24-h urine biochemistry studies, stone compositions, serum laboratory measures, medications, history of stone surgeries, mobility, and method of bladder emptying were collected. RESULTS: In all, 587 patients were identified who had both MS and a history of stone disease. Of these, 118 patients had a stone composition available. When compared to matched controls, patients with MS were significantly more likely to have calcium phosphate stones (42% vs 15%, P < 0.001) and struvite stones (8% vs 3%, P = 0.03) and less likely to have calcium oxalate monohydrate stones (39% vs 64%, P < 0.001). Among those patients with a composition available, those with MS were more likely to have undergone a percutaneous nephrolithotomy (PCNL; 25% vs 12%, P = 0.005) or a cystolithopaxy (16% vs 3%, P < 0.001) compared to their matched controls. In all, 61 patients had a complete 24-h urinary stone panel. There were no significant differences in urinary pH, volume, creatinine, calcium, citrate, oxalate, sodium, and uric acid as well as rates of hypocitraturia, hyperoxaluria, hypercalciuria, and hyperuricosuria among patients with MS. Use of intermittent straight catheterisation [ISC; odds ratio (OR) 3.50, 95% confidence interval (CI) 1.89-6.47]; P < 0.001] or an indwelling catheter (OR 9.78, 95% CI 4.81-19.88; P < 0.001) for bladder emptying was significantly associated with stone disease. There was no association between level of mobility and stone disease (P = 0.10). CONCLUSIONS: Similar to findings seen in patients with spinal cord injuries, patients with MS have a high incidence of calcium phosphate stones and struvite stones when compared with matched controls. Additionally, they were more likely to undergo PCNL. The method of bladder management appears to be a risk factor in the development of stone disease. These findings suggest the importance of prompt treatment of urinary tract infections in this population and delay the use of ISC, suprapubic tube, or an indwelling Foley, when possible.

Accuracy of ultrasonography for renal stone detection and size determination: is it good enough for management decisions?

OBJECTIVES: To determine the sensitivity and specificity of ultrasonography (US) for detecting renal calculi and to assess the accuracy of US for determining the size of calculi and how this can affect counselling decisions. MATERIALS AND METHODS: We retrospectively identified all patients at our institution with a diagnosis of nephrolithiasis who underwent US followed by non-contrast computed tomography (CT) within 60 days. Data on patient characteristics, stone size (maximum axial diameter) and stone location were collected. The sensitivity, specificity and size accuracy of US was determined using CT as the standard. RESULTS: A total of 552 US and CT examinations met the inclusion criteria. Overall, the sensitivity and specificity of US was 54 and 91%, respectively. There was a significant association between sensitivity of US and stone size (P < 0.001), but not with stone location (P = 0.58). US significantly overestimated the size of stones in the 0-10 mm range (P < 0.001). Assuming patients with stones 0-4 mm in size will be selected for observation and those with stones ≥5 mm could be counselled on the alternative of intervention, we found that in 14% (54/384) of cases where CT would suggest observation, US would lead to a recommendation for intervention. By contrast, when CT results would suggest intervention as management, US would suggest observation in 39% (65/168) of cases. An average of 22% (119/552) of patients could be inappropriately counselled. Stones classified as 5-10 mm according to US had the highest probability (43% [41/96]) of having their management recommendation changed when CT was performed. The use of plain abdominal film of kidney, ureter and bladder and US increases sensitivity (78%), but 37% (13/35) of patients may still be counselled inappropriately to undergo observation. CONCLUSIONS: Using US to guide clinical decision-making for residual or asymptomatic calculi is limited by low sensitivity and inability to size the stone accurately. As a result, one in five patients may be inappropriately counselled when using US alone.

Robot-assisted ureteral reconstruction using a tubularized peritoneal flap: a novel technique in a chronic porcine model.

OBJECTIVE: To evaluate the feasibility and functional outcomes in porcine models of a novel robotic surgical technique for the treatment of complex ureteral injuries and strictures. MATERIALS AND METHODS: Six pigs underwent robotic ureteral reconstruction using a long tabularized peritoneal flap and followed for 6-9 weeks after the surgery. Ureteral flap vascularity, intra-renal pressure, patency of the conduct, endoscopic aspect of the flap, renal function and histopathology were evaluated. RESULTS: All animals successfully underwent ureteral reconstruction using a tubularized peritoneal flap. Median operative time was 223 min (162-360). Flap tubularization suture took 31 min (19-47), and proximal anastomosis took 20 min (15-38). Bladder mobilization with psoas hitch and distal anastomosis took 9 min (7-12) and 23 min (13-46), respectively. On follow-up, significant shrinkage of the ureteral flap in both length and width was observed. Antegrade pyelograms confirmed dilation and tortuosity of the proximal ureter, dilation of the renal pelvis, and major and minor calyxes without any definitive strictures. Microscopically, focal urothelial lining was seen in the neoureter. Creatinine level was significantly higher at the end of the follow-up period (p = 0.003). CONCLUSIONS: Robot-assisted ureteral reconstruction using a tubularized peritoneum flap is technically feasible and reproducible. The flap sustained abundant vascular supply after different intervals of follow-up and the peritoneal mesenchymal cells differentiated into urothelium and myofibroblasts. Further studies are needed to address the issue of functional obstruction to improve long-term renal function outcomes.

Quality of life and urolithiasis: the patient - reported outcomes measurement information system (PROMIS).

BACKGROUND: With a high rate of recurrence, urolithiasis is a chronic disease that impacts quality of life. The Patient Reported Outcomes Measurement Information System is an NIH validated questionnaire to assess patient quality of life. We evaluated the impact of urolithiasis on quality of life using the NIH-sponsored PROMIS-43 questionnaire. MATERIALS AND METHODS: Patients reporting to the kidney stone clinic were interviewed to collect information on stone history and demographic information and were asked to complete the PROMIS-43 questionnaire. Quality of life scores were analyzed using gender and age matched groups for the general US population. Statistical comparisons were made based on demographic information and patient stone history. Statistical significance was P<0.05. RESULTS: 103 patients completed the survey. 36% of respondents were male, the average age of the group was 52 years old, with 58% primary income earners, and 35% primary caregivers. 7% had never passed a stone or had a procedure while 17% passed 10 or more stones in their lifetime. Overall, pain and physical function were worse in patients with urolithiasis. Primary income earners had better quality of life while primary caregivers and those with other chronic medical conditions were worse. Patients on dietary and medical therapy had better quality of life scores. CONCLUSIONS: Urolithiasis patients subjectively have worse pain and physical function than the general population. The impact of pain on quality of life was greatest in those patients who had more stone episodes, underscoring the importance of preventive measures. Stone prevention measures improve quality of life.

Current practice of antibiotic utilization for renal colic in the emergency room.

INTRODUCTION: Urinalysis (UA) in the emergency setting for patients with nephrolithiasis produces potentially confusing results leading to treatment of presumed urinary tract infections (UTIs). Our objective was to evaluate the use of antibiotics in patients with nephrolithiasis in a large network of emergency departments (EDs). METHODS: A retrospective analysis of all ED visits associated with an ICD-9 diagnosis of nephrolithiasis and a CT scan between 2010 and 2013 was performed. Urinalysis data, the use of IV and PO antibiotics during the ED visit and at discharge were assessed. The presence of fever, elevated serum WBCs, >5 WBCs per hpf, and/or dip positive nitrites were used as appropriate criteria for antibiotic use. RESULTS: Urinalysis data were available for 3,518 (70%) of 5,035 patients with an ED diagnosis of nephrolithiasis and CT imaging. Of these visits, 237 patients had positive nitrites (6.7%) and 864 had >5 WBCs per hpf (24.6%) with 158 (4.5%) having both findings for a total of 943 patients. Intravenous antibiotics were given to 244 patients (25.9%) and oral antibiotics were given to 629 patients (66.7 %) with positive UA findings. Of the 2,440 patients with a negative UA and no leukocytosis or fever, 86 patients (3.5%) received IV antibiotics and 533 patients (21.8%) received PO antibiotics upon discharge. CONCLUSIONS: Proper treatment of nephrolithiasis in the ED includes the screening and diagnosis of concomitant UTIs. However, correct interpretation of UA studies is vital to the correct implementation of antibiotic therapy. This study suggests that 1/3 of patients were undertreated and 21.8% were over-treated.

Concurrent stone stabilization improves ultrasonic and pneumatic efficacy during cystolithopaxy: an in vitro analysis.

OBJECTIVE: To identify whether stabilization of larger bladder stones would improve the efficacy of combination (ultrasonic/pneumatic) lithotripsy in a phantom bladder stone model for percutaneous cystolithopaxy. MATERIALS AND METHODS: Using 1cm phantom Bego stones, a spherical model bladder was used to simulate percutaneous bladder access. A UroNet (US Endoscopy, USA) was placed alongside a Swiss Lithoclast probe through the working channel of a Storz 26Fr rigid nephroscope. Using a 30Fr working sheath, the stone was captured, and fragmented for 60 seconds. Resulting fragments and irrigation were filtered through a 1mm strainer, and recorded. Five trials were performed with and without the UN. Durability was then assessed by measuring net defects, and residual grasp strength of each instrument. Descriptive statistics (mean, standard deviations) were used to summarize the data, and Student's t-tests (alpha < 0.05) were used to compare trials. RESULTS: The mean time to stone capture was 12s (8-45s). After fragmentation with UN stabilization, there were significant improvements in the amount of residual stone (22% dry weight reduction vs 8.1% without UN, p < 0.001), number of fragments (17.5 vs 5.0 frag/stone, p=0.0029), and fragment size (3.6mm vs. 7.05 mm, p=0.035). Mesh defects were noted in all nets, ranging from 2-14 mm, though all but one net retained their original grip strength (36.8N). CONCLUSIONS: Bladder stone stabilization improved fragmentation when used in conjunction with ultrasonic/pneumatic lithotripsy. However, due to limitations in maneuverability and durability of the UN, other tools need to identified for this indication.

Detection of urolithiasis: comparison of 100% tube exposure images reconstructed with filtered back projection and 50% tube exposure images reconstructed with sinogram-affirmed iterative reconstruction.

PURPOSE: To compare images acquired with 50% tube exposure with a dual-source computed tomographic (CT) scanner and reconstructed with sinogram-affirmed iterative reconstruction (SAFIRE) with 100% exposure images reconstructed with filtered back projection (FBP) for reader ability to detect stones, reader confidence, and findings outside the urinary tract. MATERIALS AND METHODS: In this HIPAA-compliant, institutional review board-approved study, imaging examinations in 99 patients with urolithiasis were assessed. Data from both tubes were reconstructed with FBP; data from the primary tube only were reconstructed with SAFIRE. Seven readers evaluated randomized studies for calculi in nine regions. Reader confidence was scored by using a five-point scale. Ancillary findings were noted. Nonparametric methods for clustered data were used to estimate the area under the receiver operating characteristic curves with 95% confidence intervals to test for noninferiority of 50% exposure with SAFIRE. RESULTS: Calculi were found in 113 locations (pyelocalyceal ureter, 86; proximal ureter, seven; midureter, four; distal ureter, 15; bladder, one) and not found in 752 locations. Mean area under the receiver operating characteristic curve for FBP was 0.879 (range, 0.607-0.967) and for SAFIRE, 0.883 (range, 0.646-0.971; 95% confidence interval: -0.025, 0.031). The SAFIRE images were not significantly inferior to FBP images (P = .001). Reader confidence levels for images with stones were similar with FBP and SAFIRE (P = .963). For the 52 patients who had extraurinary findings, readers reported them correctly in 74.4% (271 of 364) and 72.0% (262 of 364) of cases (P = .215) for FBP and SAFIRE, respectively. For the nine patients with potentially important findings per the reference standard, the detection rates were 44% (28 of 63) and 33% (21 of 63, P = .024), respectively. For the 43 patients with unimportant or likely unimportant findings, the false detection rates were 15% (44 of 301) and 14% (43 of 301, P = .756), respectively. CONCLUSION: The 50% tube exposure CT images reconstructed with SAFIRE were not inferior to 100% exposure images reconstructed with FBP for diagnosis of urolithiasis, without decreases in reader confidence.

Dyslipidemia and kidney stone risk.

PURPOSE: We studied the impact of dyslipidemia on 24-hour urinalysis and stone composition. MATERIALS AND METHODS: We retrospectively identified patients with nephrolithiasis who underwent 24-hour urinalysis and lipid profile evaluation within 3 months. Patients were divided into groups based on total cholesterol, high density lipoprotein, nonhigh density lipoprotein and triglycerides. The groups were compared based on demographic data, diabetes, hypertension and each component of 24-hour urinalysis and stone composition. Multivariate analysis and linear regression were performed to control for potential confounders, including age, gender, body mass index, diabetes and hypertension. RESULTS: A total of 2,442 patients with a mean age of 51.1 years were included in study. On multivariate analysis patients with high total cholesterol had significantly higher urinary potassium and calcium, those with low high density lipoprotein or high triglycerides had significantly higher urinary sodium, oxalate and uric acid with lower pH, and those with high nonhigh density lipoprotein had higher urinary sodium and uric acid. Regarding stone composition, high total cholesterol and triglycerides were significantly associated with a higher uric acid stone rate (p = 0.006 and <0.001, respectively). Linear regression showed a significant association of nonhigh density lipoprotein with higher urinary sodium (p = 0.011) and uric acid (p <0.001) as well as triglycerides and higher uric acid (p = 0.017), and lower urinary pH (p = 0.005). CONCLUSIONS: There is a link between dyslipidemia and kidney stone risk that is independent of other components of metabolic syndrome such as diabetes and obesity. Specific alterations in the patient lipid profiles may portend unique aberrations in urine physicochemistry and stone risk.

Developing an Ex Vivo Pig Model for Teaching Ultrasound and Fluoroscopy-Guided Percutaneous Renal Access.

Introduction: Establishing percutaneous renal access is the key initial step to percutaneous nephrolithotomy; however, learning the technique during surgery for trainees is complicated by the number of approaches used to gain access, limited completion time during a breath hold. and attempt to minimize the number of passes through a kidney. There are many training models for percutaneous access commercially available all with their respective limitations. Our objective was to develop a low-cost, high-fidelity percutaneous access training model that addresses existing limitations and can be used with both ultrasound and fluoroscopy guidance. Methods: After a formal ethics exemption was attained, pig cadavers were harvested for flank, kidneys, and ureters. These were incorporated into a composite porcine tissue mould, created within a gelatin matrix. In the initial assessment, establishing percutaneous access under both ultrasound and fluoroscopy guidance was tested to refine usability. Once acceptable, its use during a training course was evaluated to assess impressions for use with ultrasound. Results: We were able to create a $45USD biodegradable model, which can facilitate percutaneous access using: fluoroscopy with intrarenal contrast; fluoroscopy with endoscopic guidance; and fluoro-less that is, ultrasound only. A cohort of 12 Canadian Postgraduate Year-3 residents who used the model for ultrasound access agreed that the model simulated a comparable tactile experience (58.33%) and anatomy (75%) to humans. Furthermore, majority of the residents agreed that model was easy to use with ultrasound guidance (91.67%), was a beneficial experience for their learning and future practice (83.33%) and if available would use to complement their intraoperative training (83.33%). Conclusion: We were able to develop a low-cost, preliminarily tested ex vivo pig model for percutaneous access compatible with multiple imaging modalities. We will continue refining our model and seek to understand its benefits when teaching percutaneous access to varying levels of learners.

Are renal stone protocol computed tomography reports giving us enough information?

INTRODUCTION: Non-contrast computed tomography (CT) is the gold-standard diagnostic test for urolithiasis. Little is published regarding which information needs to be included in the report for it to be most useful to the healthcare team for efficient triage and high-quality patient care. This study aimed to assess the quality and variability of CT scan reporting at a single Canadian tertiary academic medical center. METHODS: We completed a retrospective review of 100 consecutive renal colic CT scans. Descriptive statistics were used to report the frequency with which specific elements commonly used by urologists to triage and treat patients were included in radiology reports. RESULTS: Our sample had a mean age of 51.4±13.1 years. Stone size was universally reported for obstructing stones but was less frequently reported for non-obstructing stones (100% vs. 86.8%). A similar trend was observed for the exact stone number (100% vs. 93.4%). Non-obstructing stones were more likely than obstructing stones to be reported in one dimension (77.5% vs. 47%). Obstructing stones were reported in three dimensions 27% of the time. CT reports commonly include the presence or absence of hydronephrosis status (98%) but are less likely to include renal size (32%) and periureteral stranding (16%). Hounsfield units (HU) were reported in 3% of the reports, but skin-to-stone distance (SSD) and radiation dose were never reported. CONCLUSIONS: Reports routinely included assessments of stone size, location, and number (although not uniformly). HU, SSD, and radiation dose were rarely reported. This provides insight into opportunities for standardized reporting to optimize knowledge transfer that may result in clinical efficiency and improved quality of patient care.

Incidence and trends in the treatment of kidney stones in Canada: A population-based cohort study.

INTRODUCTION: Our objective was to assess the incidence of kidney stones requiring acute care, trends in the surgical treatment of stones, and the demographics of stone formers in Canada. METHODS: We conducted a population-based, retrospective cohort study using administrative data from the Canadian Institute for Health Information. We included Canadian residents age >18, outside of Quebec, who presented between January 1, 2013, and December 31, 2018, with a kidney stone episode. This was defined as a kidney stone resulting in hospital admission, emergency department visit, or stone intervention, specifically shockwave lithotripsy (SWL), ureteroscopy (URS), or percutaneous nephrolithotomy (PCNL). RESULTS: There were 471 824 kidney stone episodes, including 184 373 interventions. The number of kidney stone episode increased from 277/100 000 in 2013 to 290/100 000 in 2018. The median age was 53 (interquartile range 41-65) and 59.9% were male. The crude rate for stone intervention was 877/100 000. The age- and gender-standardized rate for interventions was highest in Nova Scotia and Newfoundland and Labrador and lowest in Prince Edward Island. The most common intervention in Canada was URS (73.5%), followed by SWL (19.8%) and PCNL (6.7%). The percent utilization of SWL was highest in Manitoba, whereas for URS, it was highest in Prince Edward Island and Alberta. CONCLUSIONS: Our study provides the first population-based data on the demographics of stone formers and treatment trends across Canada. There has been a 4.7% increase in kidney stone episodes over the study period. Those presenting to hospital or requiring intervention for a kidney stone are more likely to be male, age 41-65, and undergo URS.

Does stone entrapment with ″Uro-Net″ improve Ho:YAG laser lithotripsy efficiency in percutaneous nephrolithotomy and cystolithopaxy?: an in vitro study.

PURPOSE: to test the effect of stone entrapment on laser lithotripsy efficiency. MATERIALS AND METHODS: Spherical stone phantoms were created using the BegoStone® plaster. Lithotripsy of one stone (1.0 g) per test jar was performed with Ho:YAG laser (365 µm fiber; 1 minute/trial). Four laser settings were tested: I-0.8 J,8 Hz; II-0.2J,50 Hz; III-0.5 J,50 Hz; IV-1.5 J,40 Hz. Uro-Net (US Endoscopy) deployment was used in 3/9 trials. Post-treatment, stone fragments were strained though a 1mm sieve; after a 7-day drying period fragments and unfragmented stone were weighed. Uro-Net nylon mesh and wire frame resistance were tested (laser fired for 30s). All nets used were evaluated for functionality and strength (compared to 10 new nets). Student's T test was used to compare the studied parameters; significance was set at p < 0.05. RESULTS: Laser settings I and II caused less damage to the net overall; the mesh and wire frame had worst injuries with setting IV; setting III had an intermediate outcome; 42% of nets were rendered unusable and excluded from strength analysis. There was no difference in mean strength between used functional nets and non-used devices (8.05 vs. 7.45 lbs, respectively; p = 0.14). Setting IV was the most efficient for lithotripsy (1.9 ± 0.6 mg/s; p < 0.001) with or without net stabilization; setting III was superior to I and II only if a net was not used. CONCLUSIONS: Laser lithotripsy is not optimized by stone entrapment with a net retrieval device which may be damaged by high energy laser settings.

Success rate of repeat flexible ureteroscopy following previous failed access: An analysis of stent duration.

INTRODUCTION: Approximately 8% of patients that undergo therapeutic or diagnostic ureteroscopy will have the procedure aborted and ureter stented due to failed access. The primary objective of this study was to assess mean stent duration prior to repeat ureteroscopy and to calculate the associated successful access rate. METHODS: This retrospective, descriptive study evaluated all patients undergoing interval ureteroscopy following a failed procedure by endourologic surgeons at the University of Alberta from 2016-2018. Patients declining interval ureteroscopy, or those with malignant/known ureteral strictures were excluded from the study. The primary outcome measures were median time to salvage ureteroscopy and the rate of successful access of the repeat procedure. RESULTS: A total of 119 patients were identified as having a failed ureteroscopy during our study period. First-time and recurrent stone formers accounted for 64 (53.8%) and 47 (39.5%) patients, respectively. Median stent duration to second procedure was 17 days (average 20, range 10-84). Most patients had their repeat ureteroscopy at 14 days or greater (81.5%); 22 (18.5%) patients had their repeat ureteroscopy between 10 and 13 days. The success rate of a second ureteroscopy after stenting was 99.2% (118/119). CONCLUSIONS: Ureteric stenting following failed ureteroscopy leads to exceedingly high rates of successful access at interval procedure (99.2%). The standard duration of ureteric stenting employed at our institution is two weeks. Of the patients that underwent an accelerated second procedure (between 10-13 days of stenting), all had successful access at their interval procedure.

Understanding failures in getting it up: The prevalence and predictors of failed ureteral access in ureteroscopy.

INTRODUCTION: Failed access ureteroscopy (FA) describes the inability to gain adequate access to a stone to allow for treatment. The purpose of this study was to identify the prevalence of, and factors predicting FA in patients presenting with renal and ureteral stones. METHODS: We conducted a retrospective review of all ureteroscopy (URS) procedures performed for renal and ureteral stones by three endourologists over a six-month period at our center. All patients who underwent URS for the purpose of stone treatment were included. Patients were excluded if they underwent URS for non-stone diagnosis or treatment. FA was investigated in relation to demographics, medical history, stone-specific characteristics, procedure-specific characteristics, etc. Statistical analysis consisted of descriptive statistics, as well as Chi-squared and t-test analysis using SPSS statistical software version 24.0. RESULTS: A total of 188 cases were reviewed, with 8% of patients experiencing FA. Patient age, gender, body mass index (BMI), American Society of Anesthesiologists (ASA) score, emergency cases, previous stone treatment, use of computed tomography (CT) imaging, presence of hydronephrosis, and surgeon did not differ significantly between FA and successful access (SA) groups. Stone size (9.88±5.8 vs. 8.76±4.3 mm; p=0.361) was also not significantly different. However, a significant difference was noted in time from first diagnosis to URS (128 vs. 65 days, p=0.044) between the FA and SA groups, respectively. Similarly, for ureteral stones, the FA group had a significantly greater proportion of stones located in the proximal ureter (62.5% vs. 22.0%, p=0.043). CONCLUSIONS: Proximal ureteric stones were more likely to result in FA URS, and FA procedures were more likely to be preceded by extended time from first diagnosis to URS. Further investigation is necessary, and all endourology centers should track their own personal outcome data to allow for more meaningful analysis to be performed to improve patient outcomes.