Illumination matters Part III: Impact of light obstruction on illuminance from flexible ureteroscopes - a comparative PEARLS analysis.

PURPOSE: Artifacts from poor ureteroscopes' light design with shadowing and dark areas in the field of view have been reported. The aim was to quantify effects of light obstruction in a kidney calyx model. METHODS: We evaluated a series of contemporary flexible ureteroscopes including the Storz Flex-Xc and Flex-X2s, Olympus V3 and P7, Pusen 7.5F and 9.2F, as well as OTU Wiscope using an enclosed 3D-printed pink in vitro kidney calyx model submerged in saline, where the field of light was intentionally partially obstructed alternatively at 12, 3, 6, and 9 o'clock. A color spectrometer was used for illuminance measurements at a 45° opening position in the background of the model. RESULTS: Overall and mean background illuminance for each obstructive situation were significantly different between scopes for both 50% and 100% brightness settings (ANOVA p < 0.001). At 50% brightness setting, almost all scopes had their highest and lowest background illuminance with the 6 o'clock and 3 o'clock obstructive situation, respectively. At 100% brightness setting, these became 6 o'clock and 12 o'clock obstructive situations. Considering each obstructive situation individually, the Flex-Xc was consistently the scope with highest background illuminance and the Pusen 7.5F the lowest. Background illuminance for each obstructive situation varied significantly for each scope individually, with the greatest range of variability for Pusen 7.5F and V3. CONCLUSIONS: Illuminance performance of ureteroscopes within an obstructed calyx model differ significantly for various obstructive situations. Urologists should be aware of this to help guide their choice of ureteroscope.

Pulsed Thulium:YAG laser - What is the lithotripsy ablation efficiency for stone dust from human urinary stones? Results from an in vitro PEARLS study.

BACKGROUND: The novel pulsed thulium:yttrium-aluminum-garnet (p-Tm:YAG) laser was recently introduced. Current studies present promising p-Tm:YAG ablation efficiency, although all are based on non-human stone models or with unknown stone composition. The present study aimed to evaluate p-Tm:YAG ablation efficiency for stone dust from human urinary stones of known compositions. METHODS: Calcium oxalate monohydrate (COM) and uric acid (UA) stones were subjected to lithotripsy in vitro using a p-Tm:YAG laser generator (Thulio®, Dornier MedTech GmbH, Germany). 200 J was applied at 0.1 J × 100 Hz, 0.4 J × 25 Hz or 2.0 J × 5 Hz (average 10W). Ablated stone dust mass was calculated from weight difference between pre-lithotripsy stone and post-lithotripsy fragments > 250 µm. Estimated ablated volume was calculated using prior known stone densities (COM: 2.04 mg/mm3, UA: 1.55 mg/mm3). RESULTS: Mean ablation mass efficiency was 0.04, 0.06, 0.07 mg/J (COM) and 0.04, 0.05, 0.06 mg/J (UA) for each laser setting, respectively. This translated to 0.021, 0.029, 0.034 mm3/J (COM) and 0.026, 0.030, 0.039 mm3/J (UA). Mean energy consumption was 26, 18, 17 J/mg (COM) and 32, 23, 17 J/mg (UA). This translated to 53, 37, 34 J/mm3 (COM) and 50, 36, 26 J/mm3 (UA). There were no statistically significant differences for laser settings or stone types (all p > 0.05). CONCLUSION: To our knowledge, this is the first study showing ablation efficiency of the p-Tm:YAG laser for stone dust from human urinary stones of known compositions. The p-Tm:YAG seems to ablate COM and UA equally well, with no statistically significant differences between differing laser settings.

Role, Cost, and Availably of Urinary pH Monitoring for Kidney Stone Disease-A Systematic Review of the Literature.

PURPOSE OF REVIEW: Urinary pH is an important factor related to renal stone disease, and it plays an essential role in stone prevention. Monitoring of urinary pH by patients at home provides information that can help to assess the treatment needed by each patient. We conducted a systematic review is to assess the available evidence concerning urinary pH monitoring methods along with their accuracy, cost, and usefulness by patients with urolithiasis. RECENT FINDINGS: A total of 9 articles were included (1886 urinary pH measurements). They reported information about urinary dipsticks, portable electronic pH meters and electronic strip readers, amongst other methods. Accuracy was compared with a laboratory pH meter (gold standard). Urinary dipsticks were found to be not accurate enough to guide clinical decision making and portable electronic pH meters showed promising results. Urinary dipsticks are neither precise nor accurate enough. Portable electronic pH meters seem to be more accurate, easy to use, and cost-effective. They are a reliable source for patients to use at home in order to prevent future episodes of nephrolithiasis.

Prospective Single-Center Study of SuperPulsed Thulium Fiber Laser in Retrograde Intrarenal Surgery: Initial Clinical Data.

INTRODUCTION: The objective of this study was to present our clinical experience of using the thulium fiber laser in retrograde intrarenal surgery (RIRS). METHODS: A prospective clinical study performed after the IRB approval (Sechenov University, Russia). Patients with stones <30 mm were treated with SuperPulsed thulium fiber laser (SP TFL) (NTO IRE-Polus, Russia) through a 200-µm-diameter fiber. Stone size, density, the duration of the operation, and laser on time (LOT) were measured. Based on the surgeon's feedback, retropulsion and intraoperative visibility were also assessed (Likert scale). Stone-free rates (SFRs) were assessed with a low-dose CT scan 90 days after the operation. RESULTS: Between January 2018 and December 2019, 153 patients (mean age 54 ± 2.8 years) underwent RIRS with SP TFL (mean stone density 1,020 ± 382 HU). Median stone volume was 279.6 (139.4-615.8) mm3. Median LOT was 2.8 (IQR 1.6-6.6) min with median total energy for stone ablation 4.0 (IQR 2.1-7.17) kJ, median ablation speed was 1.7 (1.0-2.8) mm3/s, median ablation efficacy was 13.3 (7.3-20.9) J/mm3, and energy consumption was 170.3 (59.7-743.3) J/s. Overall, the SFR (at 3 months) was 89%. The overall complication rate was 8.4%. Retropulsion was present in 23 (15.1%) patients. Visibility was estimated as optimal in most patients, with poor visibility reported in only 13 (8.5%) patients. CONCLUSION: The SP TFL is a safe and efficient tool in lithotripsy, irrespective of the stone type and density. Retropulsion is minimal and visibility is maintained with SP TFL. Nonetheless, further clinical studies are needed to ensure optimal comparison with conventional holmium:YAG lithotripsy.

Can the introduction of single-use flexible ureteroscopes increase the longevity of reusable flexible ureteroscopes at a high volume centre?

OBJECTIVES: To assess whether the introduction of single use flexibles ureteroscopes (su-fURS) at our high-volume centre had an advantageous impact on the turn-over and breakage rates of reusable fURS (re-fURS). METHODS: We analysed re-fURS number of usages and breakages at our centre between February 2015 and December 2018. We recorded the number of usages for analysed scope between the first usage until a breakage requiring reconditioning. Usage count was restarted following each reconditioning episode. Since su-fURS (Lithovue, Boston Scientific, USA) were introduced at our center in September 2016, we had the chance to compare different re-fURS life cycles according to both su-fURS availability and usage intensity (i.e., number of su-fURS used during each re-fURS life cycle). We then explored the relationship between su-fURS usage intensity and reusable scope survival (i.e., number of utilizations before any breakage requiring reconditioning) using locally weighted scatterplot smoothing (LOWESS) approach. RESULTS: Five different re-fURSs were employed at our centre, for a total of 1820 usages and 40 breakages requiring reconditioning. The overall mean (SD) number of usages before breaking was 40 (22). After su-fURS introduction, mean (SD) re-fURS number of usages increased from 35 (22) to 49 (20), (+ 40%, p = 0.02). The relationship between su-fURS usage intensity and reusable scopes survival showed a linear survival increase after 10 or more su-fURS scopes were used per life cycle. CONCLUSIONS: The life cycle of re-fURS increased by 40% after the introduction of su-fURS. Ten or more used su-fURS per life cycle were associated with increased re-fURS survival.

The Relationship between Modern Fad Diets and Kidney Stone Disease: A Systematic Review of Literature.

OBJECTIVES: Kidney stone disease (KSD) has a strong association with diet metabolic syndrome. This review aims at exploring the lithogenic risk posed by the current most popular diets. Our approach was to search for the effect of each diet type on the major urinary risk factors, to try to draw conclusions regarding the association of a specific diet type and KSD. METHODS: This systematic review searched for the available literature exploring the association between the existing popular fad diets and KSD. Articles in English, French and Spanish were included, without restriction of the search period with the final search done in August 2021. RESULTS: Total number of studies and studies for each diet type was as follows: 22 articles for the low carbohydrate diet, 20 articles for high protein diets, 26 articles for vegetarian and vegan diets. There exists a substantial variability in different low carbohydrate and high protein diets, and considerable overlap between modern popular fad diets. High carbohydrate intake might increase urine uric acid, calcium and oxalate levels. High protein diets increase urine calcium and uric acid and lower urine pH and citrate. Consumption of fruits and vegetables increases the urinary volume and urinary citrate. In vegan diets, sufficient daily calcium intake is important to avoid possible secondary hyperoxaluria. CONCLUSIONS: Few studies evaluated the direct relationship between modern fad diets and KSD. In general, the reduction of carbohydrate in the diet, and counterbalancing protein rich diets with sufficient intake of fruits and vegetables, seem to play a protective role against KSD formation. Maintaining sufficient calcium intake in vegan and vegetarian diets is important. Additional research is needed to directly evaluate the link between KSD and each diet type.

Role of Citrus Fruit Juices in Prevention of Kidney Stone Disease (KSD): A Narrative Review.

To explore the relationship between citrus fruit juices (oranges, grapefruits, and lemonades) and kidney stone disease (KSD). METHODS: A systematic review was performed using the Medline, EMBASE, and Scopus databases, in concordance with the PRISMA checklist for all English, French, and Spanish language studies regarding the consumption of citrus fruit juices and the relationship to urinary stone disease. The main outcome of interest was the association of citrus fruit juices with KSD. RESULTS: Thirteen articles met the criteria for inclusion in the final review. Three large epidemiological studies found that grapefruit juice was a risk factor for stone formation, while orange juice did not increase the risk for KSD. Ten small prospective clinical studies found that orange, grapefruit, and lemon juices all increased urinary citrate levels. Only orange and grapefruit juices had an alkalinizing effect and while lemon juice has a protective effect by raising urinary citrate levels, it lacked a significant alkalinizing effect on urine pH. Orange juice and grapefruit juices significantly increased urinary oxalate levels, while orange juice also had a high carbohydrate content. CONCLUSION: While orange juice seems to play a protective role against stone formation, grapefruit was found to raise the risk of KSD in epidemiological studies but had a protective role in smaller clinical studies. Lemon juice had a smaller protective role than orange juice. Larger amounts of, as well as more accurate, data is needed before recommendations can be made and a high carbohydrate content in these juices needs to be taken into consideration.

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.

Tea and coffee consumption and the risk of urinary stones-a systematic review of the epidemiological data.

OBJECTIVE: To explore the relationship between the consumption of coffee and tea with urolithiasis. We evaluated large epidemiological and small clinical studies to draw conclusions regarding their lithogenic risk. METHODS: A systematic review was performed using the Medline and Scopus databases, in concordance with the PRISMA statement. English, French, and Spanish language studies regarding the consumption of caffeinated and decaffeinated coffee and tea, and the relationship to urinary stone disease were reviewed. Case reports and letters, unpublished studies, posters, and comments were excluded. RESULTS: As per the inclusion criteria, 13 studies were included in the final review. Most studies, including four large prospective studies and one meta-analysis, reported a reduced risk of stone formation for coffee and tea. Caffeine has a diuretic effect and increases the urinary excretion of calcium, but if these losses are compensated for, moderate caffeine intakes may have little or no deleterious effects. Green and Herbal teas infused for short time had low oxalate content compared to black tea. CONCLUSION: There is no evidence that moderate consumption of coffee raises the risk for stone formation in healthy individuals, provided the recommended daily fluid intake is maintained. The currently available literature supports in general a protective role for tea against the stone formation, mainly for green tea. However, heterogeneity of published data and lack of standardization needs to be addressed before final and clear conclusions can be given to patients and to the public in general.

A systematic review of long-duration stents for ureteral stricture: which one to choose?

OBJECTIVE: To define which long-term stent would work best in malignant ureteral obstruction (MUO) and benign ureteral obstruction (BUO), focusing on their mechanisms of action, price and insertion approach. METHODS: A systematic review was developed using the MEDLINE and Scopus databases and in accordance with the PRISMA checklist. There were no language restrictions for the search. Studies describing the use of metallic ureteric stents for MUO and for BUO in humans were included. RESULTS: We analyzed five types of metallic stents (35 papers) and also the experience with the tumor and extra-anatomical stents. The Resonance, Memokath and Allium ureteral stents were found to be useful in BUO and MUO. The Uventa stent performed well in chronic ureteral obstruction. The Detour bypass stent was a recommended option in those patients who had complete obstruction of the ureter and were unfit for reconstructive surgery. There was no difference with regard to the insertion technique and both antegrade and retrograde approaches were equally successful. Although tumor stents showed a good performance, there were very few published studies on it. CONCLUSION: Metallic stents are a suitable option for MUO and BUO. When compared to standard double J stents, although they are relatively high priced, they show a financial benefit in the long-term. The Detour bypass stent seems to be an effective alternative for complete ureteral obstruction or patients unfit for surgery. Further prospective randomized studies should be done on the effectiveness of tumor stents versus metallic stents.

Ultrasound or Fluoroscopy for Percutaneous Nephrolithotomy Access, Is There Really a Difference? A Review of Literature.

Objective: To compare whether the outcomes of ultrasound-guided access percutaneous nephrolithotomy (USGA-PCNL) are similar to standard fluoroscopy-guided access percutaneous nephrolithotomy (FGA-PCNL). Methods: A review was developed by using the MEDLINE and Scopus databases and following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses protocol. Studies comparing the USGA-PCNL and the FGA-PCNL were included. Case reports, editorials and letters, unpublished studies, posters, and comments abstracts were excluded. Results: We found 12 published articles that compared USGA-PCNL and FGA-PCNL. These included six randomized controlled trials, three case-control trials, and three meta-analyses. The overall results showed no difference in the success of percutaneous access, bleeding, blood transfusion, operative time, postoperative complications, or hospital stay. Conclusion: The reported data demonstrate that there are no significant differences between the fluoroscopic-guided access PCNL and the ultrasonographic access PCNL. The choice of puncture depends on the surgeon's expertise in a particular technique and the patient and stone characteristics. Both approaches are equally safe and effective in experienced hands. It is important to recall that the use of one technique does not exclude the use of the other, and they can sometimes be complementary to each other.

A Novel Method for Repositioning Suboptimally Preoperatively Placed Nephrostomy Tubes for Percutaneous Nephrolithotomy Without Renal Repuncture.

Objective: Nephrostomy tubes (NTs) inserted in emergency settings by interventional radiologists are frequently unsuitable for subsequent percutaneous nephrolithotomy (PCNL). We report a novel method of adjusting these NTs to be used as PCNL tracts and avoid renal repuncture. Patients and Methods: A retrospective search of 981 consecutive PCNLs performed in our institution between 2002 and 2017 identified all patients with preoperatively inserted NTs. The NTs unsuitable for PCNL were adjusted by a novel approach in which a 5-mm incision was made at the ideal puncture location (IPL) as indicated under fluoroscopic guidance. The preinserted NT was removed after passing a guidewire into the kidney. A dissector clamp was introduced through the entry wound of the removed NTs to bluntly dissect a retroperitoneal tunnel and pull out the distal tip of guidewire through the IPL, while its proximal segment was maintained in the kidney. The newly positioned guidewire was used for PCNL tract preparation without repuncturing the kidney. Results: The NTs were located in the mid calix, lower calix, and renal pelvis in 6 (26%), 13 (57%), and 4 (17%) cases, respectively. The NT was suitable for PCNL in 5 (22%) cases, a new renal access was performed in 3 (13%), and the novel adjustment approach was used in 15 (65%), all successfully. The place of entry was moved an average of 6 cm (range 47) and the angle between the tract axis and the calix axis was reduced by 65° in average. The procedure was done uneventfully in an average of 4 minutes. Conclusions: The novel method of adjusting preoperatively inserted NTs for PCNL by repositioning their original entry location to the IPL offers the possibility of avoiding kidney repuncture. It is feasible, safe, and easy to implement, and it spares potential morbidity related to additional puncturing of the kidney.

Tea and coffee consumption and pathophysiology related to kidney stone formation: a systematic review.

OBJECTIVE: To explore the mechanisms behind the potential protective effect of coffee and tea consumption, regarding urinary stone formation, previously demonstrated in large epidemiological studies. METHODS: A systematic review was performed using the Medline, Cochrane library (CENTRAL) and Scopus databases, in concordance with the PRISMA statement. English, French and Spanish language studies, regarding the consumption of caffeinated and decaffeinated coffee and tea, and the relationship to urinary stone formation were reviewed. Meta-analyses, systematic reviews, case reports and letters, unpublished studies, posters and comments abstracts were excluded. RESULTS: As per the inclusion criteria, 13 studies were included in the final review. The major findings show that caffeine increases urinary excretion of calcium, sodium and magnesium, in addition to a diuretic action with consumption > 300-360 mg (approximately four cups of coffee). Together with other components of coffee, this beverage might have potential protective effects against the formation of urinary stones. Tea exerts many protective effects against stone formation, through the accompanying water intake, the action of caffeine and the effects of components with antioxidant properties. CONCLUSION: Caffeine has a hypercalciuric effect, balanced partially by a diuretic effect which appears after consumption of large quantities of caffeine. The current available literature supports in general, a potentially protective role for tea against stone formation, mainly for green tea. Additional standardization in this field of research, through specification of tea and coffee types studied, and their respective compositions, is needed for further clarification of the relation between coffee, tea and urinary stones.

Comparison of intrapelvic pressures during flexible ureteroscopy, mini-percutaneous nephrolithotomy, standard percutaneous nephrolithotomy, and endoscopic combined intrarenal surgery in a kidney model.

PURPOSE: To compare intrapelvic pressure (IPP) levels achieved during f-URS, mini-PCNL, standard PCNL, and endoscopic combined intrarenal surgery in a kidney model. METHODS: A silicone model simulating the complete urinary tract was used for all the experiments. We compared: a 9.5Fr f-URS, a 12Fr mini-nephroscope and a 26Fr nephroscope. The irrigation pressure was set at 40 and 193 cmH2O. We compared: f-URS-S ± ureteral access sheath (UAS, 10/12Fr, 11/13Fr, 12/14Fr) ± 273 µm laser fiber, Mini-PCNL with different sizes of operating sheath (15/16Fr, 16.5/17.5Fr, 21/22Fr) ± 365 µm laser fiber, Standard PCNL with an operating sheath of 30Fr ± Lithotripter LithoClast Master 11.4Fr. RESULTS: f-URS: IPP values ranged between 1.4 and 46.2 cmH2O. Factors reducing IPP were an irrigation pressure at 40 cmH2O, an occupied working channel, and the use of a UAS except with the 10/12Fr at 193 cmH2O. Mini-PCNL: IPP values ranged between 2.4 and 39.7 cmH2O. Factors reducing IPP were irrigation pressure at 40 cmH2O, a large operating sheath (> 15/16Fr). The occupation of the working channel did not affect the IPP at 40 cmH2O, while it decreased at 193 cmH2O. Standard PCNL: IPP values ranged between 1.4 and 7.3 cmH2O. Occupancy of the working channel did not affect IPP at 40 cmH2O, while it increased at 193 cmH2O. CONCLUSION: We recorded for the first time IPP values according to different endourological techniques and configurations. IPP never exceed 50 cmH2O irrespectively of the assessed technique/setup. The factors reducing IPP were a low irrigation pressure (40 cmH2O), the use of a UAS or a working sheath appropriate to the diameter of the endoscope, as well as the occupation of the working channel in the case of f-URS.

Long-Term Follow-Up of Yearly Replaced Double Internal Stents for Extrinsic Malignant Ureteral Obstruction.

Introduction: To assess long-term outcomes of double internal stents (DIS) for the relief of external malignant ureteral obstruction (MUO). Materials and Methods: DIS (7F each; 12-month indwelling time) were inserted under general anesthesia in 62 consecutive patients (75 renal units) with MUO during 2007-2018. Surveillance was performed every 3 months, and stents were exchanged routinely every year. The need for permanent stent retrieval was considered stent failure. Maintenance of stent patency and disease-specific survival (DSS) were estimated (Kaplan-Meier). Risk factors were also assessed (univariate and multivariable Cox regression analyses). Results: The median follow-up was 27 months (interquartile range [IQR] 20-27). The most frequent tumors causing obstruction were colorectal and ovarian cancers. Six patients (10%) had stent failure caused by sepsis, creatinine elevation, or hematuria. The average time to failure was 15 months (range 1-27). A history of radiation and an estimated glomerular filtration rate (eGFR) ≤45 mL/(min/1.73 m2) were associated with stent failure (p = 0.038 and p = 0.001, respectively). Thirty-nine patients died with a median DSS of 21 months (IQR 8.6-not reached). Multivariate analysis identified eGFR ≤60 mL/(min/1.73 m2) (hazard ratio [HR] 2.1, 95% confidence interval [CI] 1.1-4.2, p = 0.02) and need for balloon dilation (HR 2.1, 95% CI 1.1-4.1, p = 0.02) as independent predictors for disease-related mortality. Twenty-six patients (42%) had stent-related complications, for example, irritative symptoms, hematuria, and infections, of whom only two failed. Conclusions: One-year indwelling DIS provide effective long-term relief of MUO and represent a simple and effective alternative to other methods of urinary diversion. They avoid the need for external tubes and contribute to improved patient satisfaction.

Operator-assisted vs self-achieved basketing during ureteroscopy: results from an in vitro preference study.

OBJECTIVES: A recently introduced device (LithoVue Empower™ or LE, Boston Scientifics, USA) allows the surgeon to directly control the stone-retrieving basket without the need of an assistant during flexible ureteroscopy. We aimed to evaluate the stone-retrieval performance of this device. METHODS: We used a bench-training model for flexible ureteroscopy, the Key-box (K-Box®, Porgès-Coloplast, France), to compare the LE configured with a 1.9F stone-retrieval tipless basket (ZeroTip™, Boston Scientific, USA) and a traditional assistant-maneuvered 1.9F stone-retrieval tipless basket. Seven experienced endo-urologists and seven residents-in-training retrieved a fake stone from three different renal cavities of the K-Box with increasing access complexity first with the traditional basket and then with the LE device. We recorded retrieval time and all the operators filled in the NASA Task Load Index (TLI) for the self-evaluation of their performance. We then compared the use of LE in terms of retrieval time, failure rates, and NASA-TLI scores. RESULTS: Stone retrieval times and failure rates were similar according to the retrieval technique, although residents had non-statistically significant shorter times with the LE. NASA-TLI scores revealed lower frustration (p = 0.03) when LE was used by experienced urologists as compared to the traditional basketing. When stratifying the analyses according to surgical experience, fully trained urologists performed faster stone retrieval and showed lower effort scores than residents-in-training (p < 0.05). CONCLUSIONS: The individually controlled retrieval system is an effective device assisting stone retrieval and does not necessitate specific training among experienced endo-urologists. Young residents might benefit from LE during their learning curve.

Classification of Stones According to Michel Daudon: A Narrative Review.

CONTEXT: Morphoconstitutional analysis of urinary stones is perhaps the most important examination in the evaluation of a patient with urolithiasis. OBJECTIVE: A comprehensive stone classification system was developed in the early 1990s by Michel Daudon, which included the main types of stones and their possible physiopathogenic origin. EVIDENCE ACQUISITION: A narrative review of the articles published about this classification was conducted, without time limit. EVIDENCE SYNTHESIS: Two analytical steps are needed for the classification process: the microscopic examination, which gives the stone morphology, and the physical analysis, which provides the stone constitution. Upon completion of a full analysis, knowledge of the principal crystal species of the stone is acquired. In addition, this analysis highlights the possible causes of the lithogenic process, taking in account less frequent, but severe, pathologies. CONCLUSIONS: The aim of this report is to summarize the principal etiological causes for urinary stone formation thanks to the morphoconstitutional analysis and to present its contribution in the field of urinary stones. PATIENT SUMMARY: We looked at all types of stones and found that their origin varies according to the underlying pathology of the patient.