Effect of outflow resistance on intrarenal pressure at different irrigation rates during ureteroscopy: in vivo evaluation.

To maintain visualization and control temperature elevation during ureteroscopy, higher irrigation rates are necessary, but this can increase intrarenal pressure (IRP) and lead to adverse effects like sepsis. The IRP is also dependent on outflow resistance but this has not been quantitatively evaluated in a biological system. In this study, we sought to characterize the IRP as a function of irrigation rate in an in vivo porcine model at different outflow resistances. Ureteroscopy was performed in a porcine model with a 9.5 Fr prototype ureteroscope containing a pressure sensor. A modified ureteral access sheath (UAS) (11/13 Fr, 36 cm) was configured to adjust outflow resistance. IRP-irrigation rate curves were generated at four different outlet resistances representing different outflow scenarios. At lower irrigation rates, the pressure change in response to increased irrigation was gradual and non-linear, likely reflecting a "compliant" phase of the renal collecting system. Once IRP reached the range of 35-50 cm H2O, the pressure increased in a linear fashion with irrigation rate, suggesting that the distensibility of the collecting system had become saturated. The relationship between IRP and irrigation rate becomes linear during in vivo porcine studies once the initial compliance of the system is saturated. IRP is more sensitive to changes in irrigation rate in systems with higher outflow resistance. The modified UAS is a novel research tool which allows variance of outflow resistance to mimic different clinical scenarios. Knowledge of outflow resistance may simplify the decision to use an UAS.

Preoperative risk factors for complications after flexible and rigid ureteroscopy for stone disease: A French multicentric study.

BACKGROUND: With an increasing prevalence in industrialized countries, lithiasis represents a public health problem with significant economic cost. Ureteroscopy is nowadays the main treatment for kidney and ureteral stones with increasingly broad indications. While this treatment is relatively safe and effective, the complications can be severe. AIM: The aim of this study was to investigate the preoperative risk factors of complication in the 30 days following a rigid or flexible ureteroscopy in a large cohort of patients. METHODS: A retrospective multicenter study was conducted in 5 French centers between January 1st 2017 and 31st December 2018. All flexible and rigid ureteroscopies performed were included. All preoperative and per operative data were collected in an electronic database. Outcomes and complications within 30 days of the procedure were also collected. Univariate and multivariable analyses evaluated for potential predictors of postoperative complications. RESULTS: 1124 procedures were included. According to the occurrence of a postoperative complication, patients were divided into two groups, 109 in the group with complications. The majority of complications were minor, with only 13.7% classified as Clavien 3-4. In univariate analysis, ASA score>2 (odd ratio, OR=1.68, P=0.04), WHO performance status≥1 (OR=1.50, P=0.04) and neurologic disease (OR=2.78, P=0.005) were predictors of postoperative complications. In multivariable analysis, Charlson's score (OR=0.79, P=0.01) and ASA score>2 (OR=1.48, P=0.03) were independents risk factors of postoperative complication. Concerning major complications, in univariate analysis, cardiovascular disease (OR=3.71, P=0.032) and BMI (OR=0.87, P=0.02) were the only predictors of major complications after ureteroscopy. Only BMI was found In multivariable analysis (OR=0.86, P=0.01) CONCLUSION: Baseline characteristics and comorbidities of the patients, especially neurological diseases, were the main risk factors for short-term complications after ureteroscopy. Ureteroscopy remains a relatively safe and effective procedure. However, we advise surgeons to take precautions with fragile patients with multiple comorbidities or neurological disease.

Safety and Outcomes of using ureteric access sheath (UAS) for treatment of Pediatric renal stones: Outcomes from 2 tertiary endourology centers.

OBJECTIVE: To look at the safety and outcomes of using ureteral access sheath (UAS) for pediatric renal stones. The use of UAS is variable in urological practice with very little clinical work on their use in pediatric kidney stone disease. PATIENTS AND METHODS: Data was retrospectively collected from 2 large European tertiary endourology centers for all pediatric patients (≤16 years) with renal stones who underwent flexible ureteroscopy and lasertripsy (FURSL) via UAS. Data was collected on patient details, stone demographics and clinical outcomes of the FURSL procedure. RESULTS: Forty-eight patients with a mean age of 10.7 years were treated with FURSL for a mean single and cumulative stone size of 10.4 mm and 15 mm respectively, with two-third having multiple stones and stones in the lower pole. The initial and final stone free rate (SFR) was 66.7% and 100% respectively with 1.3 procedures/patient. One patient each had intra-operative grade 1 ureteric injury and post-operative UTI, with no other injuries or complications noted. Over a mean follow-up of 17 months, no other complications were noted. CONCLUSION: Ureteral access sheath is safe for treatment of pediatric renal stones with excellent outcomes and are especially useful for larger or multiple stones. While there does not seem to be any medium-term sequalae, to avoid risk of ureteral injury, we would suggest using the smallest size sheath possible. We would argue these procedures are best done in specialist high-volume endourology units for optimal results.

Risk Factors for a Complicated Postoperative Course in Flexible Ureteroscopy.

INTRODUCTION: The goal was to determine risk factors for Clavien-Dindo (CD) grade ≥2 complications, with special focus on early postoperative systemic inflammatory response syndrome (SIRS), for flexible ureteroscopy (fURS). MATERIALS AND METHODS: A retrospective monocentric statistical analysis relating to 32 factors was performed with the χ2 test, Mann-Whitney U tests, and multivariate logistic regression. RESULTS: In total, 416 consecutive fURS performed between September 2013 and June 2017 were analyzed; 283 (68.03%) of these were for stone surgery and 133 (31.97%) for diagnostic purposes. In 43 cases (10.34%), CD ≥2 occurred; 31 cases (72.09%) of these were SIRS. On multivariate logistic regression, positive preoperative urine culture and steep pyelographic and CT-based infundibulopelvic angle (IPA) have been confirmed as independent risk factors for both CD ≥2 and SIRS. Greater maximal median stone diameter and female gender were significantly associated only with a higher CD ≥2 prevalence, but not with SIRS. The influence of ureteral access sheath (UAS) on CD ≥ 2 or SIRS occurrence could not be confirmed on multivariate analysis. Perioperative antibiotic prophylaxis for patients with negative urine culture showed no difference regarding SIRS prevalence. CONCLUSION: Steep CT-based IPA can be considered as a new radiologic predictor of complicated postoperative course and SIRS. The role of UAS as well as indications for perioperative antibiotic prophylaxis should be determined in prospective studies.

The feasibility of one-stage flexible ureteroscopy lithotripsy in solitary kidney patients with 1-3 cm renal stones and risk factors of renal function changes.

PURPOSE: To compare perioperative outcomes and long-term renal function changes between prior stenting (PS) and not prior stenting (NPS) before flexible ureteroscopy lithotripsy (f-URS) for solitary kidney patients. METHODS: Solitary kidney patients with 10-30 mm renal stones were enrolled in this historical control study. Perioperative parameters and complications were compared. Stone-free was defined as the absence of any residual stones on a CT scan. Renal function changes were evaluated by estimated glomerular filtration rate (eGFR) and adjusted for body surface area. A decrease in the eGFR over 20% was identified as 'deterioration' in renal function. The follow-up period was at least 6 months. Logistic regression was used to identify risk factors of renal function deterioration. RESULTS: Of the 76 patients included, 40 cases experienced prior stenting before f-URS. The average stone diameter was 16.8 ± 4.7 mm, ranging from 10.0 to 28.4 mm. Initial SFR was 85.0 and 83.3% in the PS and NPS groups, respectively (p = 0.842), while SFR after the second procedure was 97.5 and 94.4% (p = 0.926). Seven PS and 5 NPS patients developed complications (p = 0.666). At the postoperative 6 months, seven patients showed a deteriorated renal function. Surgical time in minutes was identified as a risk factor for renal function deterioration after the operation (OR = 1.061, 95% CI: 1.015-1.109, p = 0.009, per minute). CONCLUSION: It appears that one-stage f-URS without PS could be feasible for 10-30 mm renal stones in solitary kidney patients, and less surgical time might be beneficial to protect renal function.

The effectiveness and safety of Sun tip-flexible ureterorenoscope for the management of kidney stones: A protocol for systematic review and meta-analysis of randomized controlled trials.

INTRODUCTION: Kidney stone is one of the urinary system diseases with a high incidence. In this study, we will evaluate the effectiveness and safety of Sun tip-flexible ureterorenoscope treating patients with kidney stone. METHODS AND ANALYSIS: English and Chinese literature about Sun tip-flexible ureterorenoscope treatment for kidney stones published before October 31, 2020 will be systematic searched in PubMed, Embase, Web of Science, Cochrane Library, Open Grey, Clinicaltrials.gov, Chinese Clinical Trial Registry, WANFANG, VIP Chinese Science and Technology Journal Database, CNKI, Chinese biomedical document service system (SinoMed). Only randomized controlled trials (RCTs) of patients with kidney stones will be included. Literature screening, data extraction, and the assessment of risk of bias will be independently conducted by 2 reviewers, and the 3rd reviewer will be consulted if any different opinions existed. Systematic review and meta-analysis will be produced by RevMan 5.3 and Stata 14.0. This protocol reported in accordance with the Preferred Reporting Items for Systematic Review and Meta-analysis Protocols (PRISMA-P) statement, and we will report the systematic review by following the PRISMA statement. RESULTS: The current study is a protocol for systematic review and meta-analysis without results, and data analysis will be carried out after the protocol. We will share our findings in the fourth quarter of 2021. CONCLUSION: This study will provide recommendations for the effectiveness and safety of Sun tip-flexible ureterorenoscope for patients with kidney stones (KS), which may help to guide clinician. ETHICS AND DISSEMINATION: Ethical approval is not required as the review is a secondary study based on published literature. The results of the study will be published in peer-reviewed publications and disseminated electronically or in print. PROTOCOL REGISTRATION NUMBER: INPLASY2020110099.

In-vitro and in-vivo new evidence for Flexor® Vue™ deflecting endoscopic system use: optimization of the stone free rate (SFR) after flexible ureteroscopy and Ho:YAG laser lithotripsy.

To test in-vitro and in-vivo the Flexor® Vue™ deflecting endoscopic system (FVDES) as a new technology able to improve the removal of residual intrarenal fragments.This is an observational prospective "proof of concept" study performed in patients with renal calculi treated with flexible ureteroscopy and Ho:YAG laser lithotripsy (f-URS) in Humanitas Research Hospital (Rozzano, Italy). We assessed feasibility, efficacy and safety of FVDES as an in-vivo tool for removing residual fragments after f-URS. The stone-free rate (SFR) at 30 days post-operatively was evaluated using CT. An in-vitro model was developed to evaluate the FVDES when used for this purpose.Eleven patients (M/F ratio: 7/4, mean age 63.5 ± 8.3) were treated. The stones were located in the lower calyces and the renal pelvis in 3 and 8 patients, respectively. Mean stone size was 18 ± 3.2 mm. The procedure with FVDES was feasible and effective in all the patients. Mean operative time was 82 ± 13.7 min and median hospitalization was of 1.5 days. The SFR after 90 days was 81% (9/11). We reported no relevant complications (Clavien-Dindo > 2); one patient had fever and was treated with antibiotics. The experimental in-vitro model demonstrated the efficacy of FVDES, allowing the removal of about 90% of fragments.Our study showed that FVDES is effective when used as a tool for retrieval of residual fragments at the end of f-URS. This technology could ensure a complete cleaning of the intrarenal collecting system and represent a safe alternative to basketing.

Device profile of the LithoVue single-use digital flexible ureteroscope in the removal of kidney stones: overview of safety and efficacy.

Introduction: Flexible ureteroscopy is a commonly performed urologic procedure for visualization and treatment of the upper urinary tracts. Traditionally, ureteroscopy has been performed with reusable scopes, which have large initial purchasing costs. LithoVue was the first widely adopted single-use flexible ureteroscope clinically available in 2016 and has caused reevaluation of this paradigm. Areas covered: This review is an objective assessment of the LithoVue single-use ureteroscope based on available studies at the time of publication. The authors searched major databases for papers that included the term 'LithoVue' and included relevant papers. The state of the market, technical specifications, results from clinical studies and cost analyses, and competitors are discussed. Expert opinion: The LithoVue single-use flexible ureteroscope has comparable clinical performance to existing reusable ureteroscopes based on available data. Direct clinical comparisons to competing single-use ureteroscopes, many of which are relatively new, are limited. In numerous pre-clinical studies LithoVue performed favorably compared to available competitors. Cost analyses suggest that benefit of single-use ureteroscopes is institution-specific, and will likely be favorable at a low volume of cases and with high local costs for repairs of reusable scopes.

Semi-rigid ureteroscope as a dilator in renal stone ureteroscopic treatment.

INTRODUCTION: To determine the efficacy and safety of using the semi-rigid ureteroscope as the only ureteral dilator for primary ureteroscopy (URS) in the treatment of renal stones. MATERIALS AND METHODS: A retrospective review of primary URS for renal stone disease was performed on consecutive patients treated by a single provider from 2013 to 2017. Utilizing wire placement under fluoroscopic guidance and direct visual ureteroscopic dilation with a semi-rigid ureteroscope, primary outcome was successful completion of stone treatment. In addition, perioperative safety was evaluated. RESULTS: A total of 126 consecutive cases of primary URS using the semi-rigid ureteroscope as the only ureteral dilator were attempted for renal stone treatment. The renal stones were treated in 124 (98.4%) patients without other forms of active ureteral dilation. Two (1.6%) patients required ureteral stent placement for passive dilation despite attempted other dilating techniques. No intraoperative ureteral perforations were identified. Postoperative radiographic follow up was available for 67% patients with a 91% stone free rate and no hydronephrosis or ureteral strictures were detected. CONCLUSION: Utilizing direct visual semi-rigid ureteroscopic dilation with a semi-ridged ureteroscope prior to flexible ureteroscopy leads to successful primary ureteroscopy for renal stone treatment in most patients. This technique is an effective, safe and possibly cost-effective method of obtaining ureteral access to facilitate primary URS for renal stone treatment.

The Impact of Ureteral Access Sheath Use on the Development of Abnormal Postoperative Upper Tract Imaging after Ureteroscopy.

PURPOSE: Ureteral access sheaths are commonly used during ureteroscopy to facilitate stone removal, improve visibility and maintain low intrarenal pressures. However, the use of a ureteral access sheath can cause ureteral wall ischemia and ureteral tears, potentially increasing the risk of postoperative ureteral stricture and obstruction. We studied the impact of ureteral access sheath use on postoperative imaging studies. Secondary objectives included studying the impact of other intraoperative parameters on postoperative imaging studies. MATERIALS AND METHODS: A retrospective chart review was conducted of cases that underwent ureteroscopy for nephroureterolithiasis across 2 high volume institutions between January 2012 and September 2016. Patient demographics, cumulative stone size, operative time, use of ureteral access sheath, laser lithotripsy, basket extraction, preoperative ureteral stent and postoperative ureteral stent placement were extracted from the electronic medical record. Findings of followup renal ultrasound, kidney-ureter-bladder x-ray and/or computerized tomography at approximately 8 weeks after surgery were recorded. RESULTS: A total of 1,332 ureteroscopies were performed with 1,060 cases (79.6%) returning for routine upper tract imaging after ureteroscopy. Postoperative hydronephrosis was noted following 127 cases (12.0%). Factors predicting presence of hydronephrosis after ureteroscopy include lower body mass index (p=0.0016), greater cumulative stone size (p=0.0003), increased operative time (p <0.0001), preoperative ureteral stent (OR 1.49, p=0.0299) and postoperative ureteral stent placement (OR 6.43, p=0.0031). Postoperative hydronephrosis was not associated with use of ureteral access sheath, age, laser lithotripsy or basket extraction. CONCLUSIONS: Use of ureteral access sheath did not have a significant impact on development of postoperative hydronephrosis, suggesting ureteral access sheath is safe for use during ureteroscopy. Ureteral strictures remain rare following ureteroscopy, seen in only 1.0% of our cohort. With an observed prevalence of hydronephrosis of 12.0% on followup imaging at 8 weeks, routine upper tract imaging after ureteroscopy remains a valuable prognostic tool.