Use of the ureteral access sheath during ureteroscopy: A systematic review and meta-analysis

Could radiological parameters help to predict the failure of ureteral access sheath placement

To identify the radiological parameters which may help to predict the success of ureteral access sheath (UAS) placement during retrograde intrarenal surgery (RIRS).The study included 49 patients in whom failure ureteral access sheath placement in RIRS and 49 control group patients who were successfully placement between January 2023 and December 2023. The age, gender, body mass index (BMI), non-contrast computed tomography (NCCT), and kidney ureter bladder (KUB) radiographs were compared between the two groups. Measurements of the anteroposterior (ap) diameter of the pelvic inlet, anteroposterior diameter of the pelvic outlet, interspinous distance diameter were taken from non-contrast computed tomography (NCCT), while pelvic anteroposterior diameter and pelvic lateral diameter were measured from kidney ureter bladder (KUB) radiography. There were no significant differences between the groups in age, gender, body mass index, ap pelvic inlet diameter, ap pelvic outlet, and interspinous distance diameter. However, a statistically significant difference was found between the pelvic ap diameter and pelvic lateral diameter values measured on the KUB radiography. The values for pelvic ap diameter and pelvic lateral diameter measured in the KUB radiographs can be used to predict the likelihood of UAS passage during RIRC procedures. However, further studies with larger patient groups are needed to establish a cut-off value.

Preoperative α1-Blockers Impact on Outcomes of Patients Undergoing Ureteroscopy with Ureteral Access Sheaths: A Systematic Review and Meta-Analysis

Introduction: The use of a ureteral access sheath (UAS) during ureteroscopy (URS) has been associated with the risk for ureteral injuries. Preoperative administration of α1-blockers presents a potential mitigator of such lesions by inducing ureteral relaxation, which may also contribute to improving other surgical outcomes. Methods: A comprehensive literature search was conducted across MEDLINE, Embase, and Cochrane databases for studies comparing preoperative α1-blockers administration vs its non-use in adult patients without pre-stenting undergoing URS. Binary outcomes were evaluated using risk ratios (RRs) and odds ratios (ORs) with 95% confidence intervals (CIs). Heterogeneity was measured with the Cochran's Q test, I2 statistics, and prediction intervals (PIs). A DerSimonian and Laird random-effects model was utilized for all outcomes. Results: Eleven studies encompassing 1074 patients undergoing URS were included, of whom 522 (48.60%) received α1-blockers before the procedure. Preoperative α1-blockers were associated with a reduction in significant ureteral injuries (RR 0.30; 95% CI 0.17-0.53; I2 = 6%; PI 0.10-0.88) and an increase in mean successful UAS insertion (OR 2.14; 95% CI 1.08-4.23; I2 = 23%; PI 0.51-8.93). In patients undergoing exclusively ureteroscopy lithotripsy (URSL), the medications also reduced total complications (RR 0.62; 95% CI 0.46-0.84; I2 = 0%) and complications graded Clavien-Dindo III or higher (RR 0.16; 95% CI 0.04-0.69; I2 = 0%), but no significant difference between groups was found in the stone-free rate (RR 1.10; 95% CI 0.86-1.40; I2 = 91%; PI 0.47-2.59). Conclusion: Preoperative α1-blockers were linked to a decrease in significant ureteral injuries with UAS use and fewer complications during URSL procedures. However, their impact on the successful insertion of a UAS remains uncertain. Consideration of administering preoperative α1-blockers in non-stented adult patients undergoing URS with UAS is advisable.

Evaluation of the effect of 9.5/11.5-fr ureteral access sheath use on acute kidney injury with the myo-inositol oxygenase biomarker in patients undergoing retrograde intrarenal surgery: a prospective, randomized, and controlled study

INTRODUCTION

We aimed to investigate whether a low intrarenal pressure provided by ureteral access sheath (UAS) use had a positive effect on the prevention of acute kidney injury through the evaluation of the myo-inositol oxygenase (MIOX).

MATERIAL AND METHODS

The patients were divided into two groups according to whether a 9.5/11.5-Fr UAS was used during retrograde intrarenal surgery (RIRS): UAS group and non-UAS group. RIRS was performed under gravity irrigation and manual pumping was not used. For the measurement of MIOX, 5 cc blood samples were taken from the patients preoperatively and four hours postoperatively.

RESULTS

Operation time and hospital stay were significantly longer in the UAS group. The mean preoperative and postoperative MIOX values were 0.77 ± 0.36 ng/ml and 0.74 ± 0.38 ng/ml, respectively, in the UAS group, and 0.74 ± 0.31 ng/ml and 0.83 ± 0.40 ng/ml, respectively, in the non-UAS group. The mean MIOX change was -0.29 ± 0.36 in the UAS group and 0.08 ± 0.44 in the non-UAS group, indicating no significant difference between the groups.

CONCLUSION

Even if UAS is not used, significant acute kidney injury is not observed under gravity irrigation and therefore, if we avoid manual pumping, the intrarenal pressure remains low, thus potentially rendering the use of 9,5/11,5-Fr UAS unnecessary.

Surgical Force: Initial Study and Clinical Implications in the Assessment of Ureteral Access Sheath Induced Injury

Purpose: Ureteral access sheaths (UAS) pose the risk of severe ureteral injury. Our prior studies revealed forces ≤6 Newtons (N) prevent ureteral injury. Accordingly, we sought to define the force urologists and residents in training typically use when placing a UAS. Materials and Methods: Among urologists and urology residents attending two annual urological conferences in 2022, 121 individuals were recruited for the study. Participants inserted 12F, 14F, and 16F UAS into a male genitourinary model containing a concealed force sensor; they also provided demographic information. Analysis was completed using t-tests and Chi-square tests to identify group differences when passing a 16F sheath UAS. Participant traits associated with surpassing or remaining below a minimal force threshold were also explored through polychotomous logistic regression. Results: Participant force distributions were as follows: ≤4N (29%), >6N (45%), and >8N (32%). More years of practice were significantly associated with exerting >6N relative to forces between 4N and 6N; results for >8N relative to 4N and 8N were similar. Compared to high-volume ureteroscopists (those performing >20 ureteroscopies/month), physicians performing ≤20 ureteroscopies/month were significantly less likely to exert forces ≤4N (p = 0.017 and p = 0.041). Of those surpassing 6N and 8N, 15% and 18%, respectively, were high-volume ureteroscopists. Conclusions: Despite years of practice or volume of monthly ureteroscopic cases performed, most urologists failed to pass 16F access sheaths within the ideal range of 4N to 6N (74% of participants) or within a predefined safe range of 4N to 8N (61% of participants).

Effect of bladder emptying status on the ureteral access sheath insertion resistance and following ureteral injury in RIRS: a prospective randomized controlled trial in academic hospital

PURPOSE

To evaluate the effect of bladder emptying status on the ureteral access sheath (UAS) insertion resistance and following ureteral injury.

METHODS

Eighty patients were enrolled and randomly divided into bladder emptying group and control group before UAS placement. A digital force gauge (Imada Z2-50N) was used to measure the resistance during the UAS insertion. The ureteral injury was evaluated and graded with Post-Ureteroscopic Lesion Scale (PULS) system at the end of procedure. The mean resistance, maximum resistance in different ureteral segments, and ureteral injury were compared between the two groups.

RESULTS

The mean resistance (3.12 ± 0.49 vs. 4.28 ± 0.52 N, P < 0.001), maximum resistance in the whole procedure (5.17 ± 0.72 vs. 6.39 ± 0.96 N, P < 0.001) and distal ureter (3.07 ± 0.75 vs. 6.18 ± 1.17 N, P < 0.001) in the bladder emptying group were significantly lower when compared to the control group. In subgroup analysis, the similar result was also noted in patients with BMI ≥ 25 when compared to patients with BMI < 25, while there was no significant difference between men and women, age ≥ 50 years versus age < 50 years. The incidence of PULS 1-2 ureteral injury in the bladder emptying group was lower than the control group (35% vs. 55%, P = 0.045). The ureteral injury in distal ureteral was less frequently noted in bladder emptying group than the control group (22.5% vs. 55%, P = 0.006); however, there was no significant difference in middle and upper ureter (P > 0.05).

CONCLUSION

Emptying the bladder before UAS insertion can effectively reduce the UAS insertion resistance and the risk of distal ureteral injury in RIRS.

Effect of ureteric access sheath on outcomes of retrograde intrarenal surgery for renal stone disease: a randomized controlled trial

BACKGROUND

The need of ureteric access sheath (UAS) in retrograde intrarenal surgery (RIRS) has been controversial for gaining high success in terms of stone free rate (SFR), reducing operative times and complications. There has been lack of high level of evidence in the literature on this topic.

MATERIALS AND METHODS

This prospective randomized controlled trial (RCT) was conducted in the Department of Urology, PGIMER, Chandigarh from July 2019 to Dec 2021. The effect of UAS on the outcome of RIRS (SFR, operative time and complications) for renal stone disease was assessed. Ninety patients were randomized into two groups: 41 patients in Group 1 (RIRS with UAS) and 40 patients in Group 2(RIRS without UAS) were finally analyzed after exclusion. All the patients underwent preoperative double J stent placement at least 10 days prior to the definitive procedure. Operative time was recorded and postoperative pain was assessed by visual analogue scale(VAS) at 6 and 24 h postoperatively. Complications and emergency visits were recorded up to one month post procedure. SFR was assessed at 1 month using noncontrast CT KUB. Success was defined as absence of any residual fragment more than 3 mm in maximum diameter.

RESULTS

Demographic parameters (age, body mass index, and comorbidities) and preoperative parameters (stone burden, proportion of recurrent stone formers and proportion of patients with inferior calyceal stones) were comparable between the two groups. Operative times (45.49 vs 48.38 min; p - 0.484) and VAS scores at 6 and 24 h post-op (p - 0.577) were also comparable between Group 1 and Group 2. SFR was comparable in Group 1 and Group 2 (78.05% vs 80%, p - 0.829). Postoperative complications were higher in the UAS group, but not statistically significant (4.88% vs 0%; p - 0.157).

CONCLUSION

The use of UAS during RIRS is not associated with improved SFR. RIRS can be performed safely without the use of UAS and without increasing postoperative complications.

The Role of 12/14F Ureteral Access Sheath in Flexible Ureteroscopy for Moderate Nephrolithiasis

INTRODUCTION

The aim was a retrospective analysis of 12/14F ureteral access sheath (UAS) usage on perioperative outcomes in patients with moderate nephrolithiasis (MN). MN was defined as a maximum of two unilateral kidney stones with a maximum stone diameter of 6-10 mm.

MATERIAL AND METHODS

We conducted a monocentric retrospective univariate and multivariate analysis of flexible ureteroscopies (fURS) performed for MN between 01/2014 and 12/2018.

RESULTS

A total of 402 fURS were performed in patients with urolithiasis; 112 MN cases underwent further analysis. UAS was successfully applied in 33 MN cases [33/112 (29.46%)]. UAS was inserted regardless of the maximum kidney stone diameter and the presence of multiple kidney stones (p > 0.05). Univariate analysis revealed a prolonged median operation time (UAS: 94 min, non-UAS: 74 min, p = 0.04) and median fluoroscopy time (UAS: 75 s, non-UAS: 57.5 s, p = 0.04) in the UAS cohort. These differences were not confirmed on multivariate logistic regression.UAS was not associated with better stone-free rates in either the univariate or multivariate analysis (UAS: 26/33, non-UAS: 61/79, p = 1.0) nor with the occurrence of Clavien-Dindo ≥2 complications (UAS: 3/33, non-UAS: 9/79, p = 0.98) or median length of hospital stay (UAS: 2 days, non-UAS: 2 days, p = 0.169).

CONCLUSION

We identified no statistical benefits from the usage of 12/14F UAS for MN. As no relevant UAS-associated complications were documented, both strategies (with and without UAS) are feasible.

International Alliance of Urolithiasis guideline on retrograde intrarenal surgery

OBJECTIVES

To set out the second in a series of guidelines on the treatment of urolithiasis by the International Alliance of Urolithiasis that concerns retrograde intrarenal surgery (RIRS), with the aim of providing a clinical framework for urologists performing RIRS.

MATERIALS AND METHODS

After a comprehensive search of RIRS-related literature published between 1 January 1964 and 1 October 2021 from the PubMed database, systematic review and assessment were performed to inform a series of recommendations, which were graded using modified GRADE methodology. Additionally, quality of evidence was classified using a modification of the Oxford Centre for Evidence-Based Medicine Levels of Evidence system. Finally, related comments were provided.

RESULTS

A total of 36 recommendations were developed and graded that covered the following topics: indications and contraindications; preoperative imaging; preoperative ureteric stenting; preoperative medications; peri-operative antibiotics; management of antithrombotic therapy; anaesthesia; patient positioning; equipment; lithotripsy; exit strategy; and complications.

CONCLUSION

The series of recommendations regarding RIRS, along with the related commentary and supporting documentation, offered here should help provide safe and effective performance of RIRS.

Comparison of retrograde intrarenal stone surgery with and without a ureteral access sheath using kidney injury molecule-1 (KIM-1) levels: a prospective randomized study

The objective is to compare patients who underwent retrograde intrarenal surgery with and without a ureteral access sheath (UAS) using kidney injury molecule-1 (KIM-1) levels. We also examined the difference in kidney damage between standard and dual lumen UAS. Sixty patients diagnosed with kidney stones and scheduled for RIRS were randomized into three groups: RIRS without UAS (Group 1), 11Fr/13Fr Boston scientific Navigator™ UAS (Group 2), and 11Fr/13Fr dual lumen ClearPetra™ UAS (Group 3). Data were prospectively collected in consecutive patients. Urine KIM-1/Cr levels were measured preoperatively, at postoperative 4 h, and on a postoperative day 14. Stone size, location, number, pre- and postoperative stent use, operation time, stone-free rate (SFR), post-ureteroscopic lesion scale (PULS) grade, hospitalization duration, and complications were recorded. There was no significant difference in demographical parameters and preoperative KIM-1/Cr levels among the groups. Postoperative 4th-hour urine KIM-1/Cr levels were higher in patients without UAS than patients with UAS (1.86, 0.67, 0.63 Groups 1, 2, 3, respectively). In comparing group 1 with groups 2 and 3 separately, Group 1 had a statistically significantly higher value than both groups (p = 0.002, p = 0.001, respectively). According to UAS type, there was no significant difference between groups 2 and 3. The use of UAS during RIRS has been shown to reduce kidney injury in the evaluation with KIM-1. Different UAS types on kidney injury and which one can protect the kidneys more during the procedure; will be elucidated by prospective randomized studies involving larger patient groups and UAS types.

Ureteral Access Sheaths and Its Use in the Future: A Comprehensive Update Based on a Literature Review

Ureteral access sheaths (UASs) are part of urologist’s armamentarium when performing retrograde intrarenal surgery (RIRS). Recently, the world of RIRS has changed dramatically with the development of three game-changers: thulium fiber laser (TFL), smaller size single use digital flexible ureterosopes and intraoperative intrarenal pressure (IRP) measurement devices. We aimed to clarify the impact of UASs on IRP, complications and SFRs and put its indications in perspective of these three major technological improvements. A systematic review of the literature using the Medline, Scopus and Web of Science databases was performed by two authors and relevant studies were selected according to PRISMA guidelines. Recent studies showed that using a UAS lowers IRP and intrarenal temperature by increasing irrigation outflow during RIRS. Data on the impact of a UAS on SFRs, postoperative pain, risk of infectious complications, risk of ureteral strictures and risk of bladder recurrence of urothelial carcinoma after diagnostic RIRS were inconclusive. Prestenting for at least one week resulted in ureteral enlargement, while the influence of pre-operative administration of alpha-blockers was unclear. Since TFL, smaller single use digital ureteroscopes and devices with integrated pressure-measuring and aspiration technology seemed to increase SFRs and decrease pressure and temperature related complications, indications on the use of a UAS may decrease in the near future.

Advances in Ureteroscopy: New technologies and current innovations in the era of Tailored Endourological Stone Treatment (TEST)

Ureteroscopy has undergone many advances in recent decades. As a result, it is able to treat an increasing range of patient groups including special populations such as pregnancy, anomalous kidneys and extremes of age. Such advances include Holmium laser, high-power systems and pulse modulation. Thulium fibre laser is a more recent introduction to clinical practice. Ureteroscopes have also been improved alongside vision and optics. This article provides an up-to-date guide to these topics as well as disposable scopes, pressure control and developments in operating planning and patient aftercare. These advances allow for a custom strategy to be applied to the individual patient in what we describe using a new term: Tailored endourological stone treatment (TEST).

Level of evidence: 5

Comparison of retrograde intrarenal stone surgery with and without a ureteral access sheath using kidney injury molecule-1 (KIM-1) levels: a prospective randomized study

The objective is to compare patients who underwent retrograde intrarenal surgery with and without a ureteral access sheath (UAS) using kidney injury molecule-1 (KIM-1) levels. We also examined the difference in kidney damage between standard and dual lumen UAS. Sixty patients diagnosed with kidney stones and scheduled for RIRS were randomized into three groups: RIRS without UAS (Group 1), 11Fr/13Fr Boston scientific Navigator™ UAS (Group 2), and 11Fr/13Fr dual lumen ClearPetra™ UAS (Group 3). Data were prospectively collected in consecutive patients. Urine KIM-1/Cr levels were measured preoperatively, at postoperative 4 h, and on a postoperative day 14. Stone size, location, number, pre- and postoperative stent use, operation time, stone-free rate (SFR), post-ureteroscopic lesion scale (PULS) grade, hospitalization duration, and complications were recorded. There was no significant difference in demographical parameters and preoperative KIM-1/Cr levels among the groups. Postoperative 4th-hour urine KIM-1/Cr levels were higher in patients without UAS than patients with UAS (1.86, 0.67, 0.63 Groups 1, 2, 3, respectively). In comparing group 1 with groups 2 and 3 separately, Group 1 had a statistically significantly higher value than both groups (p = 0.002, p = 0.001, respectively). According to UAS type, there was no significant difference between groups 2 and 3. The use of UAS during RIRS has been shown to reduce kidney injury in the evaluation with KIM-1. Different UAS types on kidney injury and which one can protect the kidneys more during the procedure; will be elucidated by prospective randomized studies involving larger patient groups and UAS types.

The dilemma of 12/14F ureteral access sheath (UAS) usage: a case control study

BACKGROUND

The insertion of a ureteral access sheath (UAS) is a frequent procedure during flexible ureteroscopy (fURS) to facilitate kidney stone treatment. The aim of this study was to investigate the influence of 12/14 French (F) UAS on fURS outcomes.

METHODS

We performed a retrospective monocentric analysis of fURS procedures conducted at the Department of Urology (University Hospital Schleswig-Holstein, Lübeck, Germany) for kidney stone treatment via lithotripsy or basket stone retrieval between September 2013 and June 2017. Uni- and multivariate analyses were done with the help of RStudio (Version 1.0.136) software.

RESULTS

In total, 283 consecutive fURS were analyzed. UAS was applied in 98 cases (34.63%). The insertion of UAS was preferred in cases with multiple kidney stones and larger median maximal stone diameter (p < 0.05). UAS usage correlated with elevated radiation exposure in seconds (94 vs. 61; p < 0.0001), prolonged operation time in minutes (99 vs. 66, p < 0.0001), length of hospital stay over 48 h (LOS, 22.49% vs. 10.81%; p = 0.015), more frequent postoperative systemic inflammatory response syndrome (SIRS, 13.27% vs. 4.32%; p = 0.013) and lower postoperative stone-free rates (60.20% vs. 78.92%; p = 0.0013). Moreover, we conducted uni- and multivariate subgroup analysis for cases with multiple kidney stones (≥ 2) and comparable stone burden; UAS was inserted in 48.3% of these cases (71/147). On multivariate logistic regression, UAS insertion was statistically associated with prolonged operation time in minutes (101 vs. 77; p = 0.004). No statistical differences regarding radiation exposure, stone-free rates, postoperative SIRS rates or LOS were noted between UAS and non-UAS patients with multiple kidney stones of similar size (p > 0.05).

CONCLUSIONS

12/14F UAS does not seem to improve overall outcomes in fURS for kidney stones. In patients with multiple kidney stones it may be associated with elevated operation time without a clear benefit in terms of improved stone-free status or reduced perioperative complication rate. Further prospective randomized studies to specify the indications for UAS usage are urgently needed.

Role of pre-operative ureteral stent on outcomes of retrograde intra-renal surgery (RIRS): systematic review and meta-analysis of 3831 patients and comparison of Asian and non-Asian cohorts

PURPOSE

To evaluate the outcomes of pre-stented (PS) versus non-pre-stented (NPS) patients who have undergone retrograde intrarenal surgery (RIRS) for renal calculi with subgroup analysis of Asian and non-Asian cohorts.

METHODS

Protocol is registered in PROSPERO, CRD42021261123. Eligible studies identified from four electronic databases. Meta-analysis was done to enumerate the outcomes of RIRS in between PS and NPS. Secondary sub-analysis was done to look for differences in outcomes in Asian and non-Asian cohorts.

RESULTS

Fourteen studies involving 3831 patients (4 prospective, 10 retrospective studies) were included. PS patients experienced higher success rates of ureteral access sheath (UAS) insertion than NPS (RR 1.09, 95% CI 1.05-1.13, p < 0.00001). PS patients had lower risk of ureteral injuries from UAS placement (RR 0.69, 95% CI 0.50-0.96, p = 0.03). No significant differences in intra- and postoperative complications between two groups were found. Stone-free rate (SFR) outcomes for residual fragment (RF) cut-off of < 1 mm and < 4 mm favoured the PS patients (RR 1.10, 95% CI 1.04-1.17, p = 0.002 for < 4 mm, RR1.10, 95% CI 1.02-1.19, p = 0.02 for < 1 mm). In the subgroup analysis, PS Asian patients had similar SFR as NPS patients for SFR(< 4 mm) but non-Asian population showed better outcomes in the PS patients for SFR(< 4 mm) (RR 1.31, 95% CI 1.13-1.52, p = 0.0005).

CONCLUSIONS

This meta-analysis suggests that pre-stenting results in a higher success for UAS placement, minimising intraoperative ureteric injury, with higher overall SFR for any RF cut-off in PS cohorts. In non-Asian cohort, significant differences occurred at SFR < 4 mm but not for SFR < 1 mm. No difference was seen in our Asian cohort for any SFR cut-off in both PS and NPS patients.

The Life and Death of Percutaneous Stone Removal: "Looking Back-Looking Forward"

Although percutaneous nephrolithotomy (PCNL) is less morbid than open surgery, it still carries risks of significant complications as well as injury to the renal parenchyma. Flexible ureteroscopic stone removal, although causes no appreciable damage to the renal parenchyma, has limitations, most notably, a lower stone-free rate than PCNL. Advances in our knowledge regarding ureteral physiology combined with technical developments applied to ureteral access sheath deployment and size may well propel retrograde intrarenal surgery to the forefront of kidney stone removal, regardless of stone size or location.

Impact of Preoperative Stenting on the Outcome of Flexible Ureterorenoscopy for Upper Urinary Tract Urolithiasis: A Systematic Review and Meta-Analysis

PURPOSE

This study aimed to investigate the effect of preoperative stenting (POS) on the perioperative outcomes of flexible ureterorenoscopy (fURS).

MATERIALS AND METHODS

A systematic review and meta-analysis was conducted based on the PRISMA statement. From the initially retrieved 609 reports, we excluded the ineligible studies at 2 stages. We only included studies that contained fURS patients with and without POS in the same report. Data of patients who underwent semirigid ureteroscope only were excluded from the analysis. The Newcastle-Ottawa Scale (NOS) system was applied for risk of bias assessment.

RESULTS

A total of 20 studies including 5,852 patients were involved. 48.5% of the patients had preoperative stent. Stone-free rate was significantly higher with prestenting; odds ratio (OR) was 1.98 (95% CI: 1.51-2.58) (Z = 5.02; p = 0.00001). It also displayed tendency toward lower complications; OR was 0.74 (95% CI: 0.52-1.05) (Z = 1.67; p = 0.09). POS significantly increased the use of ureteral access sheath; OR was 1.49 (95% CI: 1.05-2.13) (Z = 2.22; p = 0.03). Risk of bias assessment showed 13 and 7 studies with low and moderate risk, respectively.

CONCLUSIONS

POS clearly improves the stone-free rates after fURS. It might reduce the complications, especially ureteral injury. These findings might help solve the current debate and can be useful for urologists during patient counselling for a proper decision-making.

Examining the Impact of Different Properties of Ureteral Access Sheaths in Reducing Insertion Force during Retrograde Intrarenal Surgery: An In Vitro Study

BACKGROUND AND PURPOSE

This study aimed to evaluate the characteristics of ureteral access sheaths (UASs) that can reduce the insertion force while accessing the upper urinary tract.

MATERIALS AND METHODS

Six different types of 12/14-Fr UASs were used. We evaluated the properties of UASs such as the diameter of the outer sheath, length of the inner dilator tip exposed from the outer sheath, sheath flexibility (assessed in terms of bending force of the tip or base), flexibility ratio (i.e., bending force value of tip-to-base ratio), and frictional force of the outer sheath surface. We measured the force required for inserting the UAS into an artificial ureteral model and examined the correlation between the relevant characteristics and insertion force for each UAS.

RESULTS

Overall, a lower tip-to-base flexibility ratio (r = 0.66) and a lower frictional force (r = 0.50) were inversely correlated with insertion force. The force of insertion into the bifurcation was associated with the flexibility of the base (r = -0.64), flexibility ratio (r = 0.79), and frictional force (r = 0.66). Moreover, a shorter dilator tip (r = 0.52), lower flexibility ratio (r = 0.52), and lower frictional force (r = 0.50) were correlated with a lower insertion force at the proximal ureter.

CONCLUSION

A UAS with a rigid base and flexible tip parts, a smoother surface, and a shorter dilator tip would be preferable for reducing the insertion force. These findings may be crucial for selecting or developing an ideal UAS that can decrease the risk of ureteral injury.

Does ureteral access sheath affect the outcomes of retrograde intrarenal surgery: a prospective study

OBJECTIVES

To evaluate whether or not using a ureteral access sheath (UAS) affects the perioperative outcomes after retrograde intrarenal surgery (RIRS) performed in patients with renal stones.

MATERIAL AND METHODS

An observational study was carried out using data of 60 patients who underwent RIRS with the diagnosis of renal stones <2 cm between February 2017 and November 2017 at our institution. The data of the 60 patients were registered prospectively during the study period. Patients were divided into two groups based on whether a UAS was used (Group 1-30 patients) or not (Group 2-30 patients) during RIRS. Perioperative outcomes and complications were collected and analyzed.

RESULTS

The stone burdens of the patients in Group 1 and in Group 2 were 76.59 mm² and 62.19 mm², respectively (p = .160). There was no statistically significant difference in SFR (p = 1.000), complication rates (p = .418), and operation time (p = .411) between both groups, except for the fact that postoperative pain intensity levels using the VAS were slightly higher in Group 2 (4.13 ± 2.37 vs. 5.33 ± 1.89, p = .064).

CONCLUSIONS

In the present study, we showed that similar success and acceptable complication rates can be achieved without using UAS compared to using UAS during RIRS. However, using UAS may provide an advantage in reducing postoperative pain after RIRS.

Understanding Ureteral Access Sheath Use Within a Statewide Collaborative and Its Effect on Surgical and Clinical Outcomes

Introduction: Ureteral access sheaths (UASs) are frequently used during ureteroscopy (URS), but their use is not without potential risk. We investigated patterns of UAS use and associated outcomes across practices in Michigan within a quality improvement collaborative. Methods: The Michigan Urological Surgery Improvement Collaborative (MUSIC) Reducing Operative Complications from Kidney Stones (ROCKS) initiative maintains a web-based, prospective clinical registry of patients undergoing URS for urinary stone disease (USD). We analyzed all patients undergoing primary URS for renal and ureteral stones from June 2016 to July 2018 in the ROCKS registry. We determined rates of UAS usage across practices and associated outcomes, including 30-day emergency department (ED) visits and hospitalization, as well as stone-free rates. Using multivariate logistical regression, we determined the predictors of UAS use as well as outcomes, including stone-free rates, ED visits, and hospitalizations, associated with UAS use. Results: Of the 5316 URS procedures identified, UASs were used in 1969 (37.7%) cases. Stones were significantly larger and more likely to be located in the kidney in cases with UAS use. UAS use during URS varied greatly across practices (1.9%-96%, p < 0.05). After adjusting for clinical and surgical risk factors, UAS use significantly increased the odds of postoperative ED visits (odds ratio [OR] = 1.50, 95% confidence interval [CI] 1.17-1.93, p < 0.05) and hospitalization (OR = 1.77, 95% CI 1.22-2.56, p < 0.05) as well as decreased the odds of being stone free (OR = 0.75, 95% CI 0.57-0.99, p < 0.05). Conclusions: In the current study, UAS use during URS for USD was not associated with an increased likelihood of being stone free; moreover, it increased the odds of a postoperative ED visit and or hospitalization. Our findings demonstrate that UAS use is not without risk and should be employed judiciously.

Massive retroperitoneal hematoma as an acute complication of retrograde intrarenal surgery: A case report

BACKGROUND

Retrograde intrarenal surgery (RIRS) has been proven to be a safe and effective treatment modality in large-scale quantitative studies. However, although its safety profile has been established, it also has a potential risk of life-threatening complications. We here describe our experience with a patient who developed a huge periureteral hematoma after RIRS with holmium laser lithotripsy.

CASE SUMMARY

A 73-year-old woman visited our center with a complaint of gross hematuria. An enhanced computed tomography (CT) scan revealed a 1.5-cm left renal pelvis stone with hydronephrosis. The patient underwent RIRS. During the surgery, a 12/14-Fr ureteral access sheath was applied and a 6-Fr ureteral catheter was indwelled thereafter. On postoperative day 1, she experienced aggravated left flank pain and left lower-quadrant tenderness without rebound tenderness. A follow-up CT scan was taken, which revealed a huge hematoma in the periureteral space, not in the perirenal space, with suspicious contrast medium extravasation. Immediate angiography was performed; however, it showed no evidence of active bleeding. She was conservatively managed with hydration and antibiotic and nonsteroidal anti-inflammatory drug therapy, and was discharged on postoperative day 7. However, she visited our outpatient department with recurrent left flank pain at 5 d from discharge. Ultrasonography confirmed that the double J-stent was intact. To rule out stent malfunction, the stent was changed. Decreased size of the hematoma was observed in the imaging studies, and conservative management for candiduria was performed for 1 wk.

CONCLUSION

Although RIRS is an effective and safe procedure for the management of renal stones, clinicians should be aware of its potential complications.

Advanced ureteroscopic techniques for the management of kidney stones

PURPOSE OF REVIEW

Recent years witnessed significant changes in the endourological management of renal tones because of the development of new, more advanced instruments. Retrograde intrarenal surgery (RIRS) has gained particular advantage from such technological progress and now tends to be considered the gold standard treatment for uncomplicated less than 20 mm renal stones. Using a step-by-step approach, this review aims to highlight current achievements but also unsolved problems in RIRS.

RECENT FINDINGS

Several technical details of RIRS, including preoperative stenting, use of ureteral access sheets, lithotripsy method, and renal drainage, remain open to discussion and linked to surgeon's preference. Moreover, there is a wide range of variation in efficacy and safety data, with major complications being episodic but often under-reported.

SUMMARY

RIRS has gained increased popularity among the urological community. This is certainly because of the continuous technological advancements, which have continuously improved the RIRS performance but also to the perception of ease and safety of this procedure when compared with the other available treatment modalities, particularly percutaneous nephrolitotomy. Indeed, the reported advances in RIRS technique have significantly improved the outcomes of this procedure but care should be taken not to underestimate its potential challenges.

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.

Characterization of intracalyceal pressure during ureteroscopy

PURPOSE

To provide the first report of measuring intracalyceal pressures during ureteroscopy (URS).

METHODS

A prospective single-center clinical study using a cardiac pressure guidewire to measure intracalyceal pressure during flexible URS was performed. Eight patients (45 calyces) undergoing URS for nephrolithiasis were included. A Verrata^® pressure guide wire was passed through the working channel of a dual lumen flexible ureteroscope and into the calyces while irrigation was maintained at 150 mmHg. Pressure was measured in the renal pelvis, upper pole, interpolar, and lower pole calyces both with and without a ureteral access sheath (UAS). The pressure in each location with and without a UAS was compared. The correlation between calyceal pressure and infundibular dimensions (width, length) was determined.

RESULTS

Intracalyceal pressure was significantly lower in each region when a UAS was used. Compared to patients with a 12/14Fr UAS, those with a 14/16Fr UAS had significantly lower pressure in the interpolar (25.3 ± 13.1 vs. 44.0 ± 27.5 mmHg, p = 0.03) and lower pole (16.2 ± 3.5 vs. 49.2 ± 40.3 mmHg, p = 0.004) calyces. Interpolar calyceal pressure in the presence of a UAS was significantly higher than the renal pelvis pressure (RPP) (30.8 ± 19.6 vs. 17.9 ± 11.0 mmHg, p = 0.004).

CONCLUSIONS

During flexible URS, RPP strongly correlates with, but does not uniformly represent, the intracalyceal pressure. With a 14/16Fr UAS and an inflow pressure of 150 mmHg, RPP and intracalyceal pressure never exceed the threshold for renal backflow.

Impact of ureteral access sheath on renal stone treatment: prospective comparative non-randomised outcomes over a 7-year period

PURPOSE

To compare the outcomes (stone free rate and complications) of renal stone treatment with and without the use of ureteral access sheath (UAS). The worldwide use of UAS has risen over the last decade; however, questions still remain on the safety and outcomes with its use. We wanted to look at the role of UAS for treatment of consecutive renal stones over a 7-year period.

METHODS

The outcomes of flexible ureteroscopy and stone treatment (FURS) for renal stones with and without the use of UAS was prospectively compared from March 2012 to July 2018. Patients were divided into two groups: group-1 where UAS was used for stone treatment and group-2 where a UAS was not used. Data were collected prospectively on consecutive patients for demographics, stone size, location and number, pre and post-operative stent usage, operative time duration, stone free rate (SFR), length of stay and complications.

RESULTS

During the study period, 338 patients underwent FURS for renal stones, of which a UAS was used for 203 (60%) patients. The mean age of patients was 56 years (range 2-89 years) with a male:female ratio of 204:134. The mean cumulative stone size and the mean number of stones was 16.5 ± 10.8 mm and 11.37 ± 8.08 mm (P < 0.001), and 2.17 ± 1.99 and 1.66 ± 1.50 (P = 0.009) for groups 1 and 2 respectively. The pre and post-operative stent insertion rates were similar in the two groups. The procedural time was longer in group-1 (54.8 ± 25.8 min) compared to group-2 (41.3 ± 22.2 min) (P < 0.001). The SFR for group-1 (88%) was slightly lower than group-2 (94%) although this was not statistically significant (P = 0.07). There were no intra-operative complications in either of the groups. Post-operative complications were seen in eight patients in group-1 (7 Clavien I/II and 1 Clavien IVa) and two patients in group-2 (Clavien I) (P = 0.19).

CONCLUSION

The use of UAS for renal stones is safe with no intra-operative complications noted in our series. Good stone-free rates were obtained for large and multiple renal stones with a small risk of minor complications post-operatively.

Predictors of emergency department attendance following ureterorenoscopy for urolithiasis

BACKGROUND

We sought to determine the rate of emergency department (ED) attendance for complications after ureterorenoscopy (URS) for stone disease and to identify risk factors for ED attendance after URS.

METHODS

An analysis of all patients undergoing URS over 12 months at a single institution was performed. Patient demographics, preoperative and intraoperative variables associated with postoperative complications and subsequent ED attendance were collected. Logistic regression analyses were performed to determine predictors of URS complications presenting to ED.

RESULTS

In total, 202 ureteroscopies were performed on 142 patients for urolithiasis. The mean age was 50.73 ± 13.93 and 66% were male. The incidence of re-presentation to ED was 14.8% (n = 30). Patients presented with postoperative pain (n = 10; 4.95%), pyrexia (n = 9; 4.46%), urinary tract infection (UTI) (n = 7, 3.47%), haematuria (n = 3, 1.49%) and urosepsis (n = 1; 0.5%). Significant risk factors for ED attendance included preoperative stent dwell time > 30 days (P = 0.004), recently treated positive preoperative urine culture (P < 0.0001), stone size ≥ 13 mm (P = 0.043), stone location mid-ureter (P = 0.036) and female gender (P = 0.005). The following factors did not predict ED attendance, stent omission, access sheath utilization and operation duration.

CONCLUSION

Risk factors for ED attendance after URS include prolonged pre-stent dwell time, stone size ≥ 13 mm, treatment for a positive preoperative urine culture, mid-ureteric stone location and female gender. Urologists should be aware of these findings to decrease the risk of emergency re-presentation after elective URS surgery.

Impact of case volume per year on flexible Ureteroscopy practice: an internet based survey

Background

To report current worldwide variation in techniques and clinical practice of flexible ureteroscopy (FURS) among endourologists of different case volumes per year.

Methods

Two invitations to complete an internet survey were emailed to Endourological Society members. Some of survey questions asked about indications of using FURS for renal and upper ureteral stones. Others were concerned with clinical practice of FURS (such as preoperative stenting, use of ureteral access sheath (UAS) and safety guidewire, technique of Laser lithotripsy and fragment retrieval, and post-FURS stenting. Responders were distributed into two groups; high-volume (> 100 cases/year) and low-volume surgeons (< 100 cases/year) and data were compared between both groups.

Results

Responses were received from 146 endourologists all over the world (62 high-volume and 84 low-volume). FURS for intrarenal stone > 20 mm was used by 61% of high-volume surgeons compared with 28.6% for low-volume (P < 0.001). Semirigid URS was used for upper ureteric stones in 68% among high-volume group and 82% in low-volume group (P = 0.044). UAS was used by 62% in low-volume group and 69% in high volume group (P = 0.516). Laser stone dusting was preferred by 63% in low-volume group versus 45% by high-volume (P = 0.031). More responders in low-volume group preferred to leave the stent for 6 weeks (P = 0.042).

Conclusions

The use of FURS for treating upper tract calculi has expanded by high volume endourologists to include large renal stones > 20 mm. Low-volume surgeons prefer to use semi-rigid URS for treatment of upper ureteral stones, to apply Laser stone dusting and maintain ureteral stents for longer periods.

Practice patterns of ureteral access sheath during ureteroscopy for nephrolithiasis: a survey among endourologists worldwide

Background

The use of ureteral access sheath (UAS) during ureteroscopy is controversial. We aimed to explore practice patterns of UAS during ureteroscopy for nephrolithiasis among endourologists worldwide.

Methods

A 15-question survey was designed using the SurveyMonkey® platform. The questions covered the background and professional experience of the potential respondents, indications for UAS insertion, UAS caliber and possible complications associated with its use.

The questions were anonymously tabulated in order to determine practice patterns of UAS during ureteroscopy for nephrolithiasis among endourologists.

The survey was then distributed via e-mail to all the Endourological Society members.

Results

216 members responded. 99.53% of the respondents practice as endourologists, 63.4% are fellowship trained and 74.4% are at least 6 years post-fellow. 73.2% practice in an academic facility. 77.3% perform at least 100 ureteroscopies annually. 46 and 76% routinely use UAS for the treatment of ureteral and kidney stones, respectively. In both cases, the 12/14 access sheath is the most common. 42% use UAS in primary ureteroscopy. 90.3% believe that a double J stent insertion is not mandatory prior to UAS insertion. 79.1% think the use of UAS does not increase postoperative complications rate, and if the latter does encounter, then most likely it is either a ureteral stricture (93.2%) or pain (48%).

Conclusions

UAS is commonly used by highly skilled endourologists during ureteroscopy. 12/14 UAS is mostly used. Ureteral stricture and post-operative pain are proposed as possible complications following UAS introduction, however pre-stenting is not mandatory as overall low complication rate is expected.

Outcomes of retrograde intrarenal surgery compared with ultra-mini percutaneous nephrolithotomy in the management of renal calculi

Introduction

To evaluate the outcomes of retrograde intrarenal surgery (RIRS) and ultra-mini percutaneous nephrolithotomy (umPCNL) in the management of renal calculi.

Material and methods

Between March 2015 and January 2018, a total of 44 patients were treated with umPCNL. The outcomes of these patients were compared with 75 patients who underwent RIRS for renal calculi during the same time period.

Results

Median stone size was 9 mm in the umPCNL group and 7 mm in the RIRS group. Stone-free rates after a single procedure were achieved in 85% of patients for the RIRS group and 98% for the umPCNL group. 16% of RIRS patients were left with a ureteric stent, whilst 7% of patients (n = 5) needed a second RIRS. One patient in the umPCNL group was left with a percutaneous nephrostomy; all other patients were left totally tubeless. The mean operative time was 66 minutes in the RIRS group and 55 minutes in the umPCNL group (p = 0.04). The minor complication rates for the RIRS and umPCNL groups were 17% and 15%, respectively. One patient in the RIRS group required postoperative nephrostomy insertion; there were no major complications in the umPCNL group. The median length of stay was 0 days in the RIRS group and 1 day in the umPCNL group.

Conclusions

The overall study showed that umPCNL has low complication rates and good stone-free rates, with a lower requirement for ancilliary procedures. UmPCNL is an acceptable alternative in selected patients with small- to moderate-sized renal calculi.

Updates in endourological management of urolithiasis

Urinary stone disease, or urolithiasis, is a very common disease with increasing prevalence and incidence. With the advancement of endoscopic techniques, the treatment outcomes of ureteroscopy (or transureteral lithotripsy) and percutaneous nephrolithotomy are continuously improving. In recent years, there have been many new developments in the field, including new endoscopy design, more effective auxiliary tools, improvement in treatment protocols, introduction of robotic technology, combining both ureteroscopy and percutaneous nephrolithotomy (endoscopic combined intrarenal surgery or transureteral lithotripsy-assisted percutaneous nephrolithotomy), improvement in laser technology, and so on. All these new inputs will further improve the treatment efficacy and safety of the procedures, thus benefiting our patients. In the present review, we briefly go through the main steps of ureteroscopy and percutaneous nephrolithotomy, with a concise description and application of these new advances.

Comparison of suctioning and traditional ureteral access sheath during flexible ureteroscopy in the treatment of renal stones

PURPOSE

To compare the efficiency and safety of suctioning ureteral access sheath (UAS) and traditional UAS during flexible ureteroscopy (FURS) for treatment of renal stones.

METHODS

Between January 2015 and December 2017, 165 patients who had renal stones successfully underwent FURS with suctioning UAS created by connecting a channel on the tail of the suctioning UAS to a vacuum device. The outcomes of these patients were compared with those of 165 patients undergoing FURS with traditional UAS using a 1:1 scenario matched-pair analysis. The matching parameters were age, gender and stone burden.

RESULTS

The baseline characteristics were homogeneous between the two groups. The suctioning UAS group had significantly higher SFR one day postoperatively (82.4% vs. 71.5%; P = 0.02), but SFR 1 month postoperatively was comparable in the two groups (P = 0.13). The incidence of overall complications was significantly higher in the traditional UAS group (24.8% vs 11.5%; P < 0.001). Regarding individual complications, the traditional UAS group was associated with a significantly higher incidence of fever (13.9% vs 5.5%; P = 0.009) and urosepsis requiring only additional antibiotics (6.7% vs 1.8%; P = 0.029). No significant difference was noted in the incidence of septic shock, hematuria, steinstrasse or ureteral stricture. The suctioning UAS group had significantly shorter operative time (49.7 + 16.3 min vs. 57.0 ± 14.0 min; P < 0.001).

CONCLUSIONS

Compared to traditional UAS during FURS for treating renal stones, suctioning UAS had the advantages of higher SFR 1 day postoperatively, a lower incidence of infectious complications and a shorter operative time. Further well-designed studies are required to confirm the results.

Prevention and management of urosepsis triggered by ureteroscopy

Urosepsis is a potentially life-threatening phenomenon that may occur after an ureteroscopic procedure. With the increasingly widespread adoption of ureteroscopy, there is a concern that the rates of urosepsis may increase. This review examines the current work being undertaken to minimize postprocedure infections both in the field of device development and in clinical care. Guidelines for the diagnosis and management of urosepsis will be discussed.