Trends in the use of radiation protection and radiation exposure of European endourologists: a prospective trial from the EULIS-YAU Endourology Group.

INTRODUCTION: Due to the radiation exposure for the urology staff during endourology, our aim was to evaluate the trends of radiation protection in the operation room by endourologists from European centers and to estimate their annual radiation. METHODS: We conducted a multicenter study involving experienced endourologists from different European centers to evaluate whether the protection and threshold doses recommended by the International Commission on Radiation Protection (ICRP) were being followed. A 36-question survey was completed on the use of fluoroscopy and radiation protection. Annual prospective data from chest, extremities, and eye dosimeters were collected during a 4-year period (2017-2020). RESULTS: Ten endourologists participated. Most surgeons use lead aprons and thyroid shield (9/10 and 10/10), while leaded gloves and caps are rarely used (2/10 both). Six out of ten surgeons wear leaded glasses. There is widespread use of personal chest dosimeters under the apron (9/10), and only 5/10 use a wrist or ring dosimeter and 4 use an eye dosimeter. Two endourologists use the ALARA protocol. The use of ultrasound and fluoroscopy during PCNL puncture was reported by 8 surgeons. The mean number of PCNL and URS per year was 30.9 (SD 19.9) and 147 (SD 151.9). The mean chest radiation was 1.35 mSv per year and 0.007 mSv per procedure. Mean radiation exposure per year in the eyes and extremities was 1.63 and 11.5 mSv. CONCLUSIONS: Endourologists did not exceed the threshold doses for radiation exposure to the chest, extremities and lens. Furthermore, the ALARA protocol manages to reduce radiation exposure.

Impact of COVID-19 on the management and outcomes of ureteric stones in the UK: a multicentre retrospective study.

OBJECTIVES: To determine if management of ureteric stones in the UK changed during the coronavirus disease 2019 (COVID-19) pandemic and whether this affected patient outcomes. PATIENTS AND METHODS: We conducted a multicentre retrospective study of adults with computed tomography-confirmed ureteric stone disease at 39 UK hospitals during a pre-pandemic period (23/3/2019-22/6/2019) and a period during the pandemic (the 3-month period after the first severe acute respiratory syndrome coronavirus-2 case at individual sites). The primary outcome was success of primary treatment modality, defined as no further treatment required for the index ureteric stone. Our study protocol was published prior to data collection. RESULTS: A total of 3735 patients were included (pre-pandemic 1956 patients; pandemic 1779 patients). Stone size was similar between groups (P > 0.05). During the pandemic, patients had lower hospital admission rates (pre-pandemic 54.0% vs pandemic 46.5%, P < 0.001), shorter mean length of stay (4.1 vs 3.3 days, P = 0.02), and higher rates of use of medical expulsive therapy (17.4% vs 25.4%, P < 0.001). In patients who received interventional management (pre-pandemic 787 vs pandemic 685), rates of extracorporeal shockwave lithotripsy (22.7% vs 34.1%, P < 0.001) and nephrostomy were higher (7.1% vs 10.5%, P = 0.03); and rates of ureteroscopy (57.2% vs 47.5%, P < 0.001), stent insertion (68.4% vs 54.6%, P < 0.001), and general anaesthetic (92.2% vs 76.2%, P < 0.001) were lower. There was no difference in success of primary treatment modality between patient cohorts (pre-pandemic 73.8% vs pandemic 76.1%, P = 0.11), nor when patients were stratified by treatment modality or stone size. Rates of operative complications, 30-day mortality, and re-admission and renal function at 6 months did not differ between the data collection periods. CONCLUSIONS: During the COVID-19 pandemic, there were lower admission rates and fewer invasive procedures performed. Despite this, there were no differences in treatment success or outcomes. Our findings indicate that clinicians can safely adopt management strategies developed during the pandemic to treat more patients conservatively and in the community.

The Uniform grading tooL for flexIble ureterorenoscoPes (TULIP-tool): a Delphi consensus project on standardised evaluation of flexible ureterorenoscopes.

OBJECTIVE: To develop a standardised tool to evaluate flexible ureterorenoscopes (fURS). MATERIALS AND METHODS: A three-stage consensus building approach based on the modified Delphi technique was performed under guidance of a steering group. First, scope- and user-related parameters used to evaluate fURS were identified through a systematic scoping review. Then, the main categories and subcategories were defined, and the expert panel was selected. Finally, a two-step modified Delphi consensus project was conducted to firstly obtain consensus on the relevance and exact definition of each (sub)category necessary to evaluate fURS, and secondly on the evaluation method (setting, used tools and unit of outcome) of those (sub)categories. Consensus was reached at a predefined threshold of 80% high agreement. RESULTS: The panel consisted of 30 experts in the field of endourology. The first step of the modified Delphi consensus project consisted of two questionnaires with a response rate of 97% (n = 29) for both. Consensus was reached for the relevance and definition of six main categories and 12 subcategories. The second step consisted of three questionnaires (response rate of 90%, 97% and 100%, respectively). Consensus was reached on the method of measurement for all (sub)categories. CONCLUSION: This modified Delphi consensus project reached consensus on a standardised grading tool for the evaluation of fURS - The Uniform grading tooL for flexIble ureterorenoscoPes (TULIP) tool. This is a first step in creating uniformity in this field of research to facilitate future comparison of outcomes of the functionality and handling of fURS.

Silicone-hydrocoated ureteral stents encrustation and biofilm formation after 3-week dwell time: results of a prospective randomized multicenter clinical study.

OBJECTIVE: To explore the risk of encrustation and biofilm formation for silicone ureteral stents compared to percuflex polymer stents, through a randomized multicenter study. PATIENTS AND METHODS: Design, setting and participants: A Multicenter, prospective, randomized, single blind, comparative study of hydrocoated silicone stent (Coloplast Imajin® hydro) versus Percuflex™ Plus stent (Boston Scientific), in 141 patients treated by flexible URS for a kidney stone. The study had ethical committee approval in the respective hospitals. Outcome measurements and statistical analysis: Endpoints related to encrustation were biofilm formation and mineral encrustation after a period of 3-week indwelling time. They were evaluated at removal through a scoring scale of ureteral stents encrustation, infrared spectroscopy and optical microscopy of inner and outer surfaces of tips, angles and along the stent's body. Comparison was performed using ANOVA. RESULTS: 119 stents were available after removal for analysis, 56 in the silicone and 63 in the Percuflex TM Plus group. Mean dwelling duration was 21.8 days for silicone, 22.1 days for PercuflexTM Plus. There was significantly more biofilm on Percuflex™ Plus compared to silicone (1.24 ± 0.08 vs 0.93 ± 0.09, p = 0.0021), and more mineral encrustation (1.22 ± 0.10 vs 0.78 ± 0.11, p = 0.0048), respectively. CONCLUSIONS: This multicenter randomized study shows that silicone-hydrocoated stents are less prone to encrustation than PercuflexTM Plus after a 3-week dwelling period and confirms the low encrustation potential of silicone.

Effects of Silicone Hydrocoated Double Loop Ureteral Stent on Symptoms and Quality of Life in Patients Undergoing Flexible Ureteroscopy for Kidney Stone: A Randomized Multicenter Clinical Study.

PURPOSE: We compared the hydrocoated silicone stent (Coloplast Imajin® hydro) to Percuflex™ Plus stent (Boston Scientific) in terms of patient comfort and quality of life after flexible ureteroscopy for stone disease over a 5-week prospective followup. MATERIALS AND METHODS: This is a multicenter, single-blind, prospective, randomized trial of 141 patients treated with flexible ureteroscopy for renal stones. Primary outcome was Ureteral Stent Symptom Questionnaire (USSQ) Body Pain Index recorded before Double-J® stent removal at day (D) 20. Secondary endpoints were USSQ scores at intermediate dates (D2, D7, D20) and 2 weeks after stent withdrawal (D35), occurrence of adverse events and stent encrustation. RESULTS: The trial was completed by 113 (80.1%) patients. Mean (SD) USSQ body pain scores were 25% lower at D20 for the silicone stent at 18.7 (11.4) vs 25.1 (14.2) (p=0.015). No difference in terms of adverse events and safety profile was observed. USSQ urinary symptoms scores at D2, D7 and D20 were lower in the silicone stent group at 26.4 (7.7) vs 31.8 (8.1) at D20 (p <0.001). The use of USSQ self-questionnaires was associated with a limited number of missing or incomplete answers. CONCLUSIONS: The primary results of this large sample prospective randomized controlled study comparing the silicone Imajin hydro stents to the Percuflex Plus stent show that silicone stents are associated with significantly less patient discomfort. We would recommend their use in patients who require stenting for stone disease.

Qualitative exploration of the renal stone patients' experience and development of the renal stone-specific patient-reported outcome measure.

OBJECTIVES: To investigate the experience of patients living with renal calculi via a qualitative methodology, aiming to develop and validate a disease-specific patient-reported outcome measure (PROM) for renal stones, the Cambridge Renal Stone PROM (CReSP). PATIENTS, SUBJECTS AND METHODS: Patients with radiologically confirmed renal calculi who had undergone a range of management options were invited to focus groups or semi-structured interviews to elicit patient input and generate the PROM content. The developed renal stone PROM underwent validity studies included Cronbach's α for internal consistency, Spearman's and Pearson's correlation coefficients for test-retest reliability. Discriminant validity was assessed by Pearson's correlation coefficients vs the EuroQol five-dimensional five-level questionnaire (EQ-5D-5L). Our project has Health and Social Care Research Ethics Committee approval. RESULTS: A total of 106 subjects participated in creating the newly developed PROM. In all, 36 patients were invited to 22 semi-structured interviews and four focus groups, until reaching saturation. Major issues reported, and themes selected for the renal stone PROM included pain, anxiety, limitations to social life and tiredness, urinary symptoms, dietary changes' impacts, and gastrointestinal tract symptoms. Reliability analysis for 30 patients to determine internal consistency using Cronbach's α with a mean (range) of 0.91 (0.90-0.93) within domains and Cronbach's α between domains was 0.92. Average inter-item Pearson's and Spearman's correlation within domains was performed, with a Pearson's correlation mean (range) of 0.77 (0.73-0.85) and Spearman's correlation mean (range) of 0.72 (0.63-0.77). The test-retest Pearson's correlation mean (range) was 0.85 (0.57-0.95). Validity assessment was performed for 20 patients vs 20 controls. Pearson's correlation with EQ-5D-5L was -0.74, showing the newly developed PROM successfully discriminated patients with kidney stones. Our final renal stone PROM consists of 14 questions that are rated on a Likert scale; the higher the score, the worse the effect on a patient's quality of life. CONCLUSIONS: Although pain was the most frequent symptom, other health-related and social well-being issues significantly impacted patients' lives. Our validated patient-derived CReSP is a new instrument, specifically tailored to measure renal stone disease health outcomes from the patient's point of view.

Defining a national reference level for intraoperative radiation exposure in urological procedures: FLASH, a retrospective multicentre UK study.

OBJECTIVES: To define reference levels for intraoperative radiation during stent insertion, ureteroscopy (URS), and percutaneous nephrolithotomy (PCNL); to identify variation in radiation exposure between individual hospitals across the UK, between low- and high-volume PCNL centres, and between grade of lead surgeon. PATIENTS/SUBJECTS AND METHODS: In all, 3651 patients were identified retrospectively across 12 UK hospitals over a 1-year period. Radiation exposure was defined in terms of total fluoroscopy time (FT) and dose area product (DAP). The 75th percentiles of median values for each hospital were used to define reference levels for each procedure. RESULTS: Reference levels: ureteric stent insertion/replacement (DAP, 2.3 Gy/cm2 ; FT, 49 s); URS (DAP, 2.8 Gy/cm2 ; FT, 57 s); PCNL (DAP, 24.1 Gy/cm2 ; FT, 431 s). Significant variations in the median DAP and FT were identified between individual centres for all procedures (P < 0.001). For PCNL, there was a statistically significant difference between DAP for low- (<50 cases/annum) and high-volume centres (>50 cases/annum), at a median DAP of 15.0 Gy/cm2 vs 4.2 Gy/cm2 (P < 0.001). For stent procedures, the median DAP and FT differed significantly between grade of lead surgeon: Consultant (DAP, 2.17 Gy/cm2 ; FT, 41 s) vs Registrar (DAP, 1.38 Gy/cm2 ; FT, 26 s; P < 0.001). CONCLUSION: This multicentre study is the largest of its kind. It provides the first national reference level to guide fluoroscopy use in urological procedures, thereby adding a quantitative and objective value to complement the principles of keeping radiation exposure 'as low as reasonably achievable'. This snapshot of real-time data shows significant variation around the country, as well as significant differences between low- and high-volume centres for PCNL, and grade of lead surgeon for stent procedures.

Development and content validation of the percutaneous nephrolithotomy assessment score.

OBJECTIVES: To develop and content validate a percutaneous nephrolithotomy assessment score, taking into consideration the procedure-specific risks. METHODS: This prospective international study utilized the Healthcare Failure Mode and Effect Analysis to systematically outline percutaneous nephrolithotomy and failure modes for each step. A total of 25 h was spent observing percutaneous nephrolithotomy carried out by six expert surgeons. Hazard analysis scoring was carried out by 11 experts. It was determined if the steps were single point weaknesses. Single point weaknesses and those assigned a hazard score ≥4 were included in the percutaneous nephrolithotomy assessment score. The tool was then content validated by 16 experts from 10 countries. RESULTS: Application of the Healthcare Failure Mode and Effect Analysis identified 64 failure modes; 37 failure modes had a hazard score ≥4. After adaptations based on expert feedback the final percutaneous nephrolithotomy assessment score was developed containing 10 phases, 21 processes and 47 subprocesses. All participants agreed that the tool contained pertinent procedural steps. CONCLUSIONS: This study has developed and shown the international content validity of a novel percutaneous nephrolithotomy assessment score. The tool can be utilized in modular operating room training to quantify operator progress, and can be used in conjunction with other modules as part of a complete percutaneous nephrolithotomy curriculum for trainees.

Case 267: Cecureterocoele Manifesting in a Man with Infertility.

History A 28-year-old man presented with lifelong anejaculation, which had become an issue because of family planning. The patient had a history of normal erections and experienced the sensation of orgasm without ever ejaculating. On physical examination, both testes were present in the scrotum, with normal dimensions and a normal epididymis bilaterally. The patient had a slightly tender left testicle, and digital rectal examination findings were normal. The patient underwent further investigation for the possibility of retrograde ejaculation with urine cytology, the results of which were negative. Genetic testing was performed to exclude Y chromosome microdeletions. Serum-luteinizing and follicle-stimulating hormone levels were normal, with a borderline low level of testosterone (7.6 nmol/L; normal range, 8.0-29.0 nmol/L). All other pertinent laboratory results were noncontributory. Pelvic MRI was requested to exclude an anatomic cause of anejaculation. MRI was performed in accordance with the standard clinical prostate protocol, with a dynamic contrast material-enhanced study. CT of the upper abdomen was also performed. The patient subsequently underwent cystoscopy, which revealed an intravesicular fluid-filled mass near the left ureteric orifice.

Case 267.

History A 28-year-old man presented with lifelong anejaculation, which had become an issue because of family planning. The patient had a history of normal erections and experienced the sensation of orgasm without ever ejaculating. On physical examination, both testes were present in the scrotum, with normal dimensions and a normal epididymis bilaterally. The patient had a slightly tender left testicle, and digital rectal examination findings were normal. The patient underwent further investigation for the possibility of retrograde ejaculation with urine cytology, the results of which were negative. Genetic testing was performed to exclude Y chromosome microdeletions. Serum-luteinizing and follicle-stimulating hormone levels were normal, with a borderline low level of testosterone (7.6 nmol/L; normal range, 8.0-29.0 nmol/L). All other pertinent laboratory results were noncontributory. Pelvic MRI was requested to exclude an anatomic cause of anejaculation. MRI was performed in accordance with the standard clinical prostate protocol, with a dynamic contrast material-enhanced study ( Figs 1 - 3 ). CT of the upper abdomen was also performed ( Fig 4 ). The patient subsequently underwent cystoscopy, which revealed an intravesicular fluid-filled mass near the left ureteric orifice ( Fig 5 ). Figure 1a: (a) Coronal and (b, c) axial fast spin-echo T2-weighted MR images of the pelvis, with b being superior to c. Figure 1b: (a) Coronal and (b, c) axial fast spin-echo T2-weighted MR images of the pelvis, with b being superior to c. Figure 1c: (a) Coronal and (b, c) axial fast spin-echo T2-weighted MR images of the pelvis, with b being superior to c. Figure 2a: (a) Coronal T2-weighted (repetition time msec/echo time msec, 4574/86.5) MR image of the pelvis. (b) Axial T2-weighted (3000/85.4) MR image of the pelvis. Figure 2b: (a) Coronal T2-weighted (repetition time msec/echo time msec, 4574/86.5) MR image of the pelvis. (b) Axial T2-weighted (3000/85.4) MR image of the pelvis. Figure 3: Unenhanced axial fat-saturated T1-weighted (6.2/3.1) MR images. Figure 4: Coronal CT urogram. Figure 5: Image obtained at cystoscopy.

Percutaneous nephrolithotomy access by urologist or interventional radiologist: practice and outcomes in the UK.

OBJECTIVE: To compare outcomes of urologist vs interventional radiologist (IR) access during percutaneous nephrolithotomy (PCNL) in the contemporary UK setting. PATIENTS AND METHODS: Data submitted to the British Association of Urological Surgeons PCNL data registry between 2009 and 2015 were analysed according to whether access was obtained by a urologist or an IR. We compared access success, number and type of tracts, and perceived and actual difficulty of access. Postoperative outcomes, including stone-free rates, lengths of hospital stay and complications, including transfusion rates, were also compared. RESULTS: Overall, percutaneous renal access was undertaken by an IR in 3453 of 5211 procedures (66.3%); this rate appeared stable over the entire study period for all categories of stone complexity and in cases where there was predicted or actual difficulty with access. Only 1% of procedures were abandoned because of failed access and this rate was identical in each group. IRs performed more multiple tract access procedures than urologists (6.8 vs 5.1%; P = 0.02), but had similar rates of supracostal punctures (8.2 vs 9.2%; P = 0.23). IRs used ultrasonograhpy more commonly than urologists to guide access (56.6% vs 21.7%, P < 0.001). There were no significant differences in complication rates, lengths of hospital stay or stone-free rates. CONCLUSIONS: Our findings suggest that favourable PCNL outcomes may be expected where access is obtained by either a urologist or an IR, assuming that they have received the appropriate training and that they are skilled and proficient in the procedure.

Investigating upper urinary tract urothelial carcinomas: a single-centre 10-year experience.

OBJECTIVES: Evidence of the accuracy of predictive tests in confirming the presence and grade of upper urinary tract urothelial carcinomas (UUTUC) is limited. We present the largest series evaluating the diagnostic value of pre- and intra-operative parameters in the detection of UUTUC. MATERIALS AND METHODS: We retrospectively analysed records of patients who underwent diagnostic ureteroscopy between 2005 and 2014 for suspected UUTUC. Pre-operative workup included voided urine cytology and CT imaging. Intra-operative assessments involved ureteroscopy to directly visualise suspicious lesions, and where possible selective cytology and biopsy. Primary outcomes were the visualisation of UUTUC and histopathological confirmation of tumour. RESULTS: Hundred out of 160 (63 %) patients presenting with suspected upper tract malignancy had UUTUC. Voided and selective urine cytology and CT individually predicted UUTUC with a sensitivity/specificity of 63/67, 76/73, and 95/26 %, respectively. Forty out of 48 (83 %) patients who had abnormal CT and abnormal voided urine cytology had UUTUC, while 100 % of those with normal CT and normal voided cytology (investigated for ongoing symptoms) were normal. Comparing endoscopic biopsy to nephroureterectomy specimen grade, 19 (46 %), 18 (44 %), and 4 (10 %) were identical, upgraded, and downgraded, respectively. CONCLUSION: Pre-operative investigations can predict UUTUCs. When these investigations were normal, the risk of UUTUC is negligible. In selective patients with abnormal investigations, ureteroscopy should be performed to confirm and predict the grade of UUTUC, in order to guide future management. Selective cytology is unlikely to significantly contribute to the diagnostic workup of UUTUC.

First clinical evaluation of a new single-use flexible ureteroscope (LithoVue™): a European prospective multicentric feasibility study.

INTRODUCTION: We evaluated a new digital single-use flexible ureteroscope, LithoVue™ with respect to deflection, image quality and maneuverability. METHODS: A prospective cohort study was conducted in eight tertiary reference centers in Europe in December 2015 and January 2016. All consecutive patients included underwent flexible ureteroscopy and were 18 years or older. Deflection and image quality pre- and post-use and maneuverability were rated with a Likert scale. RESULTS: A total of 40 procedures were performed (five per institution). The indication for FURS was treatment of renal stones in 92.5 % of the cases. Before LithoVue™ usage, the median measured upward and downward deflections were both 270°. Image quality was rated as "very good" in 65 % of cases and "good" in 30 %. Maneuverability was "very good" in 77.5 % and "good" in 17.5 %. At the final evaluation, median upward and downward deflections were both 270°. Image quality was still "very good" in 65 % of cases and "good" in 30 % with no significant difference compared with preoperative data (p = 1). Maneuverability was "very good" in 72.5 % and "good" in 17.5 %, with no significant difference compared with preoperative data (p = 0.92). Two LithoVue™ broke during surgery (5 %): one occurring in extreme deflection with acute infundibulopelvic angle and spontaneous loss of vision for the second one. CONCLUSION: The LithoVue™ displayed good image quality, active deflection and maneuverability. Further evaluation of surgical outcomes and cost analysis will help to present the best utility of this single-use FURS in current practice.

Measuring stone volume - three-dimensional software reconstruction or an ellipsoid algebra formula?

OBJECTIVES: To determine the optimal method for assessing stone volume, and thus stone burden, by comparing the accuracy of scalene, oblate, and prolate ellipsoid volume equations with three-dimensional (3D)-reconstructed stone volume. Kidney stone volume may be helpful in predicting treatment outcome for renal stones. While the precise measurement of stone volume by 3D reconstruction can be accomplished using modern computer tomography (CT) scanning software, this technique is not available in all hospitals or with routine acute colic scanning protocols. Therefore, maximum diameters as measured by either X-ray or CT are used in the calculation of stone volume based on a scalene ellipsoid formula, as recommended by the European Association of Urology. METHODS: In all, 100 stones with both X-ray and CT (1-2-mm slices) were reviewed. Complete and partial staghorn stones were excluded. Stone volume was calculated using software designed to measure tissue density of a certain range within a specified region of interest. Correlation coefficients among all measured outcomes were compared. Stone volumes were analysed to determine the average 'shape' of the stones. RESULTS: The maximum stone diameter on X-ray was 3-25 mm and on CT was 3-36 mm, with a reasonable correlation (r = 0.77). Smaller stones (<9 mm) trended towards prolate ellipsoids ('rugby-ball' shaped), stones of 9-15 mm towards oblate ellipsoids (disc shaped), and stones >15 mm towards scalene ellipsoids. There was no difference in stone shape by location within the kidney. CONCLUSIONS: As the average shape of renal stones changes with diameter, no single equation for estimating stone volume can be recommended. As the maximum diameter increases, calculated stone volume becomes less accurate, suggesting that larger stones have more asymmetric shapes. We recommend that research looking at stone clearance rates should use 3D-reconstructed stone volumes when available, followed by prolate, oblate, or scalene ellipsoid formulas depending on the maximum stone diameter.

Use of the probability of stone formation (PSF) score to assess stone forming risk and treatment response in a cohort of Brazilian stone formers.

INTRODUCTION: The aim was to confirm that PSF (probability of stone formation) changed appropriately following medical therapy on recurrent stone formers. MATERIALS AND METHODS: Data were collected on 26 Brazilian stone-formers. A baseline 24-hour urine collection was performed prior to treatment. Details of the medical treatment initiated for stone-disease were recorded. A PSF calculation was performed on the 24 hour urine sample using the 7 urinary parameters required: voided volume, oxalate, calcium, urate, pH, citrate and magnesium. A repeat 24-hour urine sample was performed for PSF calculation after treatment. Comparison was made between the PSF scores before and during treatment. RESULTS: At baseline, 20 of the 26 patients (77%) had a high PSF score (> 0.5). Of the 26 patients, 17 (65%) showed an overall reduction in their PSF profiles with a medical treatment regimen. Eleven patients (42%) changed from a high risk (PSF > 0.5) to a low risk (PSF < 0.5) and 6 patients reduced their risk score but did not change risk category. Six (23%) patients remained in a high risk category (> 0.5) during both assessments. CONCLUSIONS: The PSF score reduced following medical treatment in the majority of patients in this cohort.

Acoustic emission of kidney stones: a medical adaptation of statistical breakdown mechanisms.

Kidney stones have a prevalence rate of > 10% in some countries. There has been a significant increase in surgery to treat kidney stones over the last 10 years, and it is crucial that such techniques are as effective as possible, while limiting complications. A selection of kidney stones with different chemical and structural properties were subjected to compression. Under compression, they emit acoustic signals called crackling noise. The variability of the crackling noise was surprisingly great comparing weddellite, cystine and uric acid stones. Two types of signals were found in all stones. At high energies of the emitted sound waves, we found avalanche behaviour, while all stones also showed signals of local, uncorrelated collapse. These two types of events are called 'wild' for avalanches and 'mild' for uncorrelated events. The key observation is that the crossover from mild to wild collapse events differs greatly between different stones. Weddellite showed brittle collapse, extremely low crossover energies (< 5 aJ) and wild avalanches over 6 orders of magnitude. In cystine and uric acid stones, the collapse was more complicated with a dominance of local "mild" breakings, although they all contained some stress-induced collective avalanches. Cystine stones had high crossover energies, typically [Formula: see text] 750 aJ, and a narrow window over which they showed wild avalanches. Uric acid stones gave moderate values of crossover energies, [Formula: see text] 200 aJ, and wild avalanche behaviour for [Formula: see text] 3 orders of magnitude. Further research extended to all stone types, and measurement of stone responses to different lithotripsy strategies, will assist in optimisation of settings of the laser and other lithotripsy devices to insight fragmentation by targeting the 'wild' avalanche regime.

International Alliance of Urolithiasis Guideline on Shockwave Lithotripsy.

Different international associations have proposed their own guidelines on urolithiasis. However, the focus is primarily on an overview of the principles of urolithiasis management rather than step-by-step technical details for the procedure. The International Alliance of Urolithiasis (IAU) is releasing a series of guidelines on the management of urolithiasis. The current guideline on shockwave lithotripsy (SWL) is the third in the IAU guidelines series and provides a clinical framework for urologists and technicians performing SWL. A total of 49 recommendations are summarized and graded, covering the following aspects: indications and contraindications; preoperative patient evaluation; preoperative medication; prestenting; intraoperative analgesia or anesthesia; intraoperative position; stone localization and monitoring; machine and energy settings; intraoperative lithotripsy strategies; auxiliary therapy following SWL; evaluation of stone clearance; complications; and quality of life. The recommendations, tips, and tricks regarding SWL procedures summarized here provide important and necessary guidance for urologists along with technicians performing SWL. PATIENT SUMMARY: For kidney and urinary stones of less than 20 mm in size, shockwave lithotripsy (SWL) is an approach in which the stone is treated with shockwaves applied to the skin, without the need for surgery. Our recommendations on technical aspects of the procedure provide guidance for urologists and technicians performing SWL.

Silicone vs. Polyurethane Stent: The Final Countdown.

Ureteric stents are conventionally used in daily urological practice. There is ongoing debate on the superiority of different stent materials, particularly in terms of patient tolerance. We conducted a literature review to compare silicone stents and stents made of other materials from a patient tolerability perspective. We conclude that silicone stents are better tolerated but further research is required.