Laser Doppler flowmetric determination of ureteral blood flow after ureteral access sheath placement

To Dust or Not To Dust: a Systematic Review of Ureteroscopic Laser Lithotripsy Techniques

PURPOSE OF REVIEW

This review discusses factors affecting outcomes during ureteroscopy (URS) with laser lithotripsy (LL), explores specific clinical challenges to the efficacy of URS LL, and reviews the available literature comparing the dusting and basketing approaches to URS LL.

RECENT FINDINGS

Data show high stone-free rates with URS LL in all locations of the urinary tract and with all stone types and sizes. Recent data comparing LL with dusting versus basketing suggest higher rates of residual fragments with dusting but less utilization of ureteral access sheaths and potentially shorter operative times. Differences in postoperative complications, re-intervention rates, and other outcome parameters are not yet clear. Interpretation of published data is problematic due to variability in laser settings, follow-up intervals, and definitions for what constitutes stone-free status. URS has overtaken shock wave lithotripsy in the last decade as the most commonly utilized surgical approach for treating urolithiasis. Two primary strategies have emerged as the most common techniques for performing LL: dusting and basketing. There is a relative paucity of data examining the difference in these techniques as it pertains to peri-operative outcomes and overall success. We attempt to synthesize this data into evidence-based and experience-based recommendations.

Histopathological correlations to ureteral lesions visualized during ureteroscopy

Purpose

To correlate ureteral lesions visualized during ureteroscopy with histopathological findings.

Materials and methods

Ureteral access sheaths (UAS) sized 13/15 Fr. were inserted bilaterally in 22 laboratory pigs. During retraction of the UAS with a semirigid ureteroscope inside, ureteral lesions were evaluated and registered using the Post-ureteroscopic lesion scale (PULS). Ureters were excised in vivo between the uretero–pelvic junction and the uretero–vesical junction. Embedded in paraffin, 4-µm thick sections were step sectioned at 250–300 µm intervals and haematoxylin and eosin (HE) stained. Histopathological scoring of ureteral wall lesions was subsequently performed according to PULS.

Results

In 72.1% of ureters, the highest histopathological score was at least 1 grade higher than the highest endoscopic PULS score. For 12 (27.9%) lesions, the difference was 2 scores higher, and for 1 (2.3%), it was 3 scores higher. The histopathological PULS grade was higher than the endoscopical PULS grade at all minimum, quartile, and maximum scores. There was a significant difference in the distribution of highest lesional scores between the endoscopic and histopathological PULS (p = 0.002). The calculated mean of the highest scores was 1.49 for endoscopic PULS and 2.51 for histopathological PULS (p < 0.0001).

Conclusion

Histopathological evaluation of ureteral wall lesions after UAS placement revealed a significantly higher degree of severity than observed endoscopically. Thus, endoscopy underestimated the histopathological extent of the lesion in the majority of cases.

Ureteral Access Sheath Influence on the Ureteral Wall Evaluated by Cyclooxygenase-2 and Tumor Necrosis Factor-α in a Porcine Model

Objective: To examine the effect of ureteral access sheath (UAS) on the expression of the pro-inflammatory mediators cyclooxygenase-2 (COX-2) and tumor necrosis factor-α (TNF-α) in the ureteral wall.

Material and Methods: In 22 pigs an UAS was inserted and removed after 2 minutes on one side and 2 hours on the contralateral side. Postoperatively ureters were excised in vivo, and tissue samples from the distal (2 minutes/2 hours) and proximal ureter (2 minutes/2 hours) were snap-frozen before quantitative polymerase chain reaction analysis of COX-2 and TNF-α. Five unmanipulated ureteral units from other pigs served as the control group.

Results: Compared to controls COX-2 mRNA was significantly upregulated in all UAS treated ureteral groups. Similarly, TNF-α mRNA was upregulated in all groups except the 2-minute proximal ureteral group. Both COX-2 and TNF-α expression were significantly higher in the distal than in the proximal ureter in the UAS treated ureters. After UAS insertion for 2 minutes, expression levels in the distal ureter were increased 6.5- and 8-fold for COX-2 and TNF-α, respectively; and after 2 hours of UAS placement COX-2 and TNF-α mRNA expression levels were increased 9- and 9.5-fold, respectively.

Conclusion: The pro-inflammatory mediators COX-2 and TNF-α were significantly upregulated in the ureteral wall by the influence of UAS. These findings may have implications for postoperative pain, drainage, and complications.

Aftermath of Grade 3 Ureteral Injury from Passage of a Ureteral Access Sheath: Disaster or Deliverance?

Background: The ureteral access sheath (UAS) has revolutionized the management of urinary pathology in the upper tract by providing rapid repeatable access to the upper urinary tract. However, in many practices, it remains a controversial tool in endourology given concerns of possible ureteral injury and presumed long-term sequela from those injuries. This case suggests that these concerns may be more hypothetical than real.

Case Presentation: A 32-year-old female with a history of recurrent nephrolithiasis presented with left-sided symptomatic renal colic. She was found to have bilateral nephrolithiasis plus a left 6 × 5 mm proximal ureteral stone with associated moderate hydroureteronephrosis. The patient failed a trial of passage and as such was taken to the operating room for an elective ureteroscopy (URS) during which she sustained a Grade 3 ureteral splitting injury, measuring ∼2–3 cm, to the distal ureter from passage of the 16F UAS. At the end of the procedure a 7/10F endopyelotomy stent was placed. On follow-up URS at 6 weeks, there was no visual evidence of ureteral injury. A Lasix renal scan obtained 8 weeks after stent removal showed no evidence of obstruction.

Conclusion: High-grade ureteral injuries sustained from UAS passage are rare. However, when injuries of this nature occur, the concern over long-term damage to the ureter may well be overstated.

The surgical experience influences the safety of retrograde intrarenal surgery for kidney stones: a propensity score analysis

The aim of this study is to evaluate if surgical experience could influence the outcomes of retrograde intrarenal surgery (RIRS) in terms of stone clearance and complication rate. Patients from five institutions were included in this study. Patients were divided into two groups. Group 1: patients treated by three surgeons in the early phase of learning curve (surgical experience <100 procedures); Group 2: cases operated by two surgeons with great endourological experience (>400 procedures). Patients and stone characteristics, outcome and complications were analyzed. Multivariable regression model was used. Differences between groups were estimated using propensity scores to adjust for the bias inherent to the different characteristics. 381 RIRS were analyzed (Group 1: 150 RIRS; Group 2: 231 RIRS). Clinical data and stone parameters were comparable. The SFR was 70 % in Group 1 and 77.9 % in Group 2 (p = 0.082). Operative time was significantly shorter in the Group 2 (76.3 vs. 53.1 min, p = 0.001). The overall complication rate was significantly lower in Group 2 (20.7 vs. 8.7, p = 0.001). At unadjusted analysis, a non-significant difference was found between centers on SFR (OR 1.51 95 % CI 0.95-2.41). Conversely, a significant difference was found on overall complications (OR 0.36 95 %CI 0.20-0.67) with lower overall complication in Group 2. This study shows that surgeon experience influences the outcomes of RIRS mainly in terms of safety. Further studies will be needed to assess the exact number of procedures necessary to obtain a plateau in the rate of complications and success.

Benefits and risks of ureteral access sheaths for retrograde renal access

PURPOSE OF REVIEW

Ureteral access sheath (UAS) became increasingly popular worldwide. However, the safety of its routine use remains controversial. The aim of the current revision is to provide a systematic review on the benefits and disadvantages of the UAS.

RECENT FINDINGS

A systematic review was performed following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses criteria. Two reviewers independently searched the literature, finally identifying 20 articles valuable for this review. The use of UAS demonstrated several advantages to facilitate retrograde intrarenal access, lower intrarenal pressure, protect the ureter, protect the scope, and expedite stone extraction. Despite this, there is also some evidence that UAS use may be associated with acute ureteral injury and long-term complications, apparently related to maneuvers for UAS insertion and mucosal or deeper layers of injury and ischemia. Furthermore, there are still pending questions on the possible increase in stone-free rates, and decrease in operative time and costs.

SUMMARY

Although the use of UAS is associated with some risk and limiting factors, it appears from this systematic review that its use is common and safe for the retrograde intrarenal access. Therefore, UAS is highly recommended for the treatment of upper tract disease by means of retrograde intrarenal surgery.

Outcomes of flexible ureteroscopy and laser fragmentation for treatment of large renal stones with and without the use of ureteral access sheaths: Results from a university hospital with a review of literature

OBJECTIVE

The aim of this study was to analyse prospective data on flexible ureteroscopy and laser fragmentation (FURSL) of large stones (> 2 cm) to assess whether a ureteral access sheath (UAS) is necessary for the treatment of large renal stones.

MATERIALS AND METHODS

Between March 2012 and October 2014, 43 patients with large stones underwent FURSL. Data were collected on a prospective database for patient demographics, stone characteristics and outcomes of FURSL with and without a UAS.

RESULTS

There were 27 men and 16 women with a mean age of 54 years (range 7-84 years). The cumulative stone diameter was 2.92 cm (range 2-5 cm), with an overall stone-free rate (SFR) of 83.7%. A total of 68 procedures was needed (average 1.58 procedures/patient). The overall complication rate was 8.8% (n = 6); these were Clavien class II complications associated with urinary tract infections treated with additional antibiotics. UAS was not used in 28 procedures (41.2%). Comparing outcomes in those who had a UAS versus those who did not, there were no statistical differences in SFR, complication rate or average number of procedures per patients.

CONCLUSION

Use of a UAS does not make any difference to the SFR or complication rate for FURSL in large stones (> 2 cm) and may not be routinely needed in all cases.

CUA Guideline: Management of ureteral calculi

The focus of this guideline is the management of ureteral stones. Specifically, the topics covered include: conservative management, medical expulsive therapy, active intervention with either shockwave lithotripsy (SWL) or ureteroscopy (URS), factors affecting SWL treatment success, optimizing success, and special considerations (e.g., pregnancy, urinary diversion). By performing extensive literature reviews for each topic evaluated, we have generated an evidence-based consensus on the management of ureteral stones. The objective of this guideline is to help standardize the treatment of ureteral stones to optimize treatment outcomes.

Use of ureteral access sheaths in ureteroscopy

The ureteral access sheath (UAS) facilitates the use of flexible ureteroscopy, enabling improved minimally invasive management of complex upper urinary tract diseases. The UAS, which comes in a variety of diameters and lengths, is passed in a retrograde fashion, aided by a hydrophilic coating and other features designed to confer smooth passage into the ureter with sufficient resistance to kinking and buckling. Use of a UAS has the advantage of enabling repeated passage of the ureteroscope while minimizing damage to the ureter, thus improving the flow of irrigation fluid and visualization within the urethra with reductions in operative times, which improves both the effectiveness of the surgery and reduces the costs. Placement of the UAS carries an increased risk of ureteral wall ischaemia and injury to the mucosal or muscular layers of the ureter, and a theoretically increased risk of ureteral strictures. A ureteral stent is typically placed after ureteroscopy with a UAS. Endourologists have found several additional practical uses of a UAS, such as the percutaneous treatment of patients with ureteral stones, and solutions to other endourological challenges.

Intraoperative Evaluation of Ureteral Access Sheath-Related Injuries Using Post-Ureteroscopic Lesion Scale

OBJECTIVE

In the present study, intraoperative ureteral injuries inflicted during retrograde intrarenal surgery (RIRS) with ureteral access sheath (UAS) use were evaluated using the Post- Ureteroscopic Lesion Scale (PULS).

MATERIALS AND METHODS

Patients in whom a UAS was used during RIRS and for whom ureter images were video recorded during the procedure were included in the study. PULS grading was performed after UAS removal, and video sequences of all patients were viewed by a junior resident, a senior resident, and four experienced urologists and assessed according to the PULS. Ureteral lesions in distal, middle, proximal, and multiple locations were evaluated and compared according to the PULS scale. The inter-rater reliability of PULS grading among various urologists was also evaluated.

RESULTS

The evaluation comprised 101 patients. In 77 patients, 9.5/11.5 French UAS devices were used, and in 24 patients, 12/14 French UAS devices were used. The stone-free rate, clinical insignificant residual fragments, and final stone-free rate were 41.6%, 53.5%, and 98%, respectively. In 58.4% of the patients, no lesions were present according to PULS grading. No lesions of Grade 3 and above were found; however, there were lesions of Grade 1 and 2 in 38.6% and 2.9% of the patients, respectively. Injuries were found in the proximal ureter only and distal ureter only in 45.23% and 40.47% of the patients, respectively. Multiple injuries occurred in 5.94% of the patients (in 3.96% in the proximal and distal ureter, in 0.99% in the mid- and distal ureter, and in 0,99% in the proximal, mid-, and distal ureter). In the grading performed according to the PULS classification, there was a high accuracy among the residents and specialists.

CONCLUSIONS

The assessment of UAS-induced injuries using standardized intraoperative methods will help to evaluate the procedure more objectively and will guide the postoperative follow-up of patients.

Intrarenal pressure and irrigation flow with commonly used ureteric access sheaths and instruments

INTRODUCTION

Flexible ureterorenoscopy is becoming a first-line treatment for many intrarenal stones. Ureteric access sheaths are commonly used to aid access, stone removal and reduce intrarenal pressure. We evaluated the effects of two commonly used access sheaths on irrigation flow and intrarenal pressure during flexible ureterorenoscopy. We measured the effect of scope instrumentation on flow and pressure.

MATERIAL AND METHODS

We utilized a 10/12F and 12/14F, 35 cm Re-Trace™ access sheath with a FlexX2 scope in a cadaveric porcine kidney. We evaluated the effect of four Nitinol baskets (1.3F, 1.5F, 1.9F, 2.2F), three different 200 µm laser fibres and a hand-held pump. Measurements of irrigation flow and intrarenal pressure were recorded and compared between the different sized access sheaths.

RESULTS

Flow rates varied widely between access sheaths. Without instrumentation, mean flow was 17 mls/min (10/12F access sheath), versus 33 mls/min (12/14F sheath) (p <0.0001). Increasing basket size produced a gradual reduction in flow and pressure in both access sheaths. Reassuringly, pressures were low overall (<40 cm H2O). Pressures were significantly reduced when using the larger 12/14F sheath, with and without all instrumentations (p <0.0001). Hand-held pump devices have a marked effect on flow and pressure in both sheaths; with pressures rising up to 121 cm H2O with a 10/12F sheath, versus 29 cm H2O (12/14F) (p <0.0001).

CONCLUSIONS

A 12/14F access sheath offered significantly improved irrigation whilst maintaining significantly lower intrarenal pressure, when compared to a 10/12F access sheath in a cadaveric porcine model. Scope instrumentation affects irrigation flow and pressure in both sized sheaths. Furthermore, there should be caution with hand-held pump devices, especially with smaller sized sheaths, as intrarenal pressure can be very high.

Implementation of Ultramini Percutaneous Nephrolithotomy for Treatment of 2-3 cm Kidney Stones: A Preliminary Report

BACKGROUND AND PURPOSE

Miniatured percutaneous nephrolithotomy (PCNL) techniques such as micro-PCNL (microperc) and ultramini-PCNL (UMP) are usually indicated for renal stones <2 cm. We present our preliminary report of treating patients with 2 to 3 cm renal stones using UMP in a semisupine combined lithotomy position associated with a retrograde ureteral access sheath (UAS).

METHODS

From April 2013 to January 2014, we implemented 13F UMP for 22 patients with renal stones that were 2 to 3 cm with the patient positioned in a 45-degree semisupine combined lithotomy position. A retrograde 9.5/11.5F UAS was placed for maintaining low intrarenal pressure and debris drainage. Flexible ureteroscopy was used for stones inaccessible through the primary percutaneous tract in two patients. A 200-μ holmium laser was used for stone disintegration. Intrapelvic pressure was measured using an open end 5F ureteral catheter inserted through the UAS.

RESULTS

All 22 cases were completed successfully. The mean preoperative stone size was 26.6 ± 4.7 mm (range 21-32 mm), mean operative time was 85.7 ± 18.0 minutes (range 47-112 min), and mean hemoglobin drop was 1.2 ± 0.3 g/dL (range 0.5-2.2 g/dL). Intrapelvic pressure during the surgical procedure ranged 5 to 10 cm H2O. The mean hospital stay was 3.1 ± 1.8 days (range 2-5 d). Complete stone clearance was 18/22 (81.8%) with solo UMP and 20/22 (90.9%) when associated with retrograde intrarenal surgery (RIRS). No major intra- or postoperative complications occurred.

CONCLUSION

Implementation of UMP for the treatment of patients with renal stones 2-3 cm is feasible and safe. The procedure is less invasive and has a faster recovery period. Intraoperative retrograde UAS decreases intrarenal pressure, facilitates removal of stone fragments, and also allows simultaneous RIRS for stones in an inaccessible calix.

Ureteral length in live donor kidney transplantation; Does size matter?

The aim of this study was to evaluate the role of ureteral length on urological complications. Data were retrospective collected from the INEX-trial database, a RCT to compare the intravesical to the extravesical ureteroneocystostomy. Ureteral length was measured in 198 recipients and used to divide recipients into three categories based on interquartile ranges: short (≤8.5 cm), medium (8.6-10.9 cm) and long ureters (≥11 cm). Urological complications were defined as the number of percutaneous nephrostomy placements (PCN). Fifty recipients fell into the short, 98 into the medium and 50 recipients into the long ureter category. Median follow-up was 26 (range 2-45) months. There was no significant difference in number of PCN placements between the categories. There were 9 (18%) PCN placements in the short ureter category, 21 (20%) in medium ureter category and 10 (21%) in the long ureter category, P = 0.886. Risk factor analysis for gender, arterial multiplicity and type of ureteroneocystostomy showed no differences in PCN placements between the three ureteral length categories. We conclude that ureteral length alone does not seem to influence the number of urological complications.

The new concept of ureteral access sheath with guidewire disengagement: One wire does it all

PURPOSE

To prospectively evaluate the new Flexor©Parallel™ Rapid Release™ (Cook(®), Bloomington, IN, USA) access sheath (UAS) which allows the use of a single wire to serve as both safety and working guide.

MATERIALS AND METHODS

Between June and September 2014, adult patients from five European centers who underwent flexible ureteroscopy (fURS) for therapeutic and diagnostic purposes were included. The 12/14Fr Flexor©Parallel™ UAS was evaluated. Data were collected and examined by both univariate and multivariate analyses. The UAS material and usage characteristics were rated per case by the surgeons on a scale from very bad to very good.

RESULTS

In total, 134 UASs were used in 67 male and 67 female patients. Fifty percent of ureters (67 patients) were pre-stented. Ninety percent of the procedures were therapeutic. The overall successful insertion rate was 94 %. Pre-stenting status was the only independent factor for a successful access sheath insertion: 98.5 % of the pre-stented patients had a successful UAS placement vs. 82 % of non-pre-stented (p = 0.001, C.I. 95 %: 1.2). Evaluation of the material and radiopacity was considered very good in over 90 % of cases. Release of the guidewire, hydrophilic coating, gliding of the endoscope and repeatability were considered very good in over 80 %. There were two (1.4 %) UAS malfunctions and one submucosal lesion reported.

CONCLUSIONS

The use of the Flexor©Parallel™ Rapid Release™ (Cook(®), Bloomington, IN, USA) with usage of a single guidewire in a prospective multicentric scenario was clinically applicable in the majority of cases. Pre-stenting increased the chance of a successful insertion from 82 to 98.5 %.

Intraluminal pressure profiles during flexible ureterorenoscopy

Background

Irrigation and instrumentation during ureterorenoscopic procedures may cause increased pressure in the renal pelvis (PP) with potential harmful adverse effects. In order to assess the pressure increases during ureterorenoscopy, we measured the intraluminal renal pelvic pressure during retrograde intrarenal stone surgery (RIRS).

Methods

Twelve patients admitted for RIRS were included. Irrigation rate was standardized to 8 ml/min. A ureteral catheter was retrogradely placed in the renal pelvis for PP measurements. PP was measured one time per second during insertion of the Storz Flex-X2 ureteroscope and during stone treatment.

Results

Baseline PP was mean 10(±4.0) mmHg. During simple ureterorenoscopy, PP was mean 35(±10) mmHg. During stone management the average PP was 54(±18) mmHg and pelvic pressure peaks up to 328 mmHg occurred. In a 5-min standardized period of simple ureterorenoscopy, 83 pressure peaks >50 mmHg were measured in average per patient (range 2–238). Forced irrigation with a 20 ml syringe resulted in pressure peaks up to 288 mmHg.

Conclusion

Very high pelvic pressures are obtained during flexible ureterorenoscopy. Taking into consideration that the threshold for pyelovenous backflow is around 30 mmHg, it is concerning that PPs >300 mmHg are not uncommon during these procedures. Methods to monitor and lower the PP during ureterorenoscopy, therefore, are considered of importance.

Differences in renal stone treatment and outcomes for patients treated either with or without the support of a ureteral access sheath: The Clinical Research Office of the Endourological Society Ureteroscopy Global Study

PURPOSE

To describe the differences in the treatment and the outcomes of renal stones treated with flexible ureteroscopy (URS) either with or without the support of a ureteral access sheath (UAS).

METHODS

The Clinical Research Office of the Endourological Society URS Global Study involved the collection of prospective data from consecutive patients treated with URS at centers around the world over a 1-year period. Baseline characteristics, stone location, treatment details, postoperative outcomes and complications were recorded. Inverse-probability-weighted regression adjustment (IPWRA) analyses were conducted on outcome from patients treated with or without the use of a UAS to determine the impact on stone-free rates (SFRs).

RESULTS

Of 2239 patients treated with flexible URS, 1494 (67 %) patients were treated with the use of a UAS and 745 (33 %) without a UAS. The IPWRA analyses conducted on 1827 patients with complete data and based on treatment and outcome models showed that if URS procedures were performed without the use of an UAS, the average stone-free rate would be 0.504 compared with 0.753 with a UAS. This average treatment effect of 0.248 was not significant (P = 0.604). Using IPWRA analysis on only the treated population in the estimations revealed no significant difference between using and not using a UAS (31 %; ATET: 0.311; P = 0.523).

CONCLUSIONS

The study showed no difference in SFR when a UAS was used or not. Whereas UAS did not increase the risk of ureteral damage or bleeding, postoperative infectious complications were reduced.

Simultaneous retrograde intrarenal surgery for ipsilateral asymptomatic renal stones in patients with ureteroscopic symptomatic ureteral stone removal

Background

Ipsilateral asymptomatic renal stone associated with symptomatic ureteral stone is not a rare event, and the recommended treatment policy was not declared clearly. This study was conducted to compare the outcomes of simultaneous retrograde intrarenal surgery (RIRS) and ureteroscopy to ureteroscopy alone for this clinical event.

Methods

415 patients with symptomatic ureteral stone and ipsilateral asymptomatic renal stones were reviewed to obtain two match groups, who were treating with simultaneous modality (group A, N = 72), or ureteroscopy alone (group B, N = 72). Matching criteria were ureteral and renal stone side, duration and location, the presence of pre-stented. Perioperative and postoperative characteristics were compared between the two groups.

Results

Mean stone burdens were similar between group A and B. Mean operative duration for group A and B were 72.4 ± 21.3 and 36.4 ± 10.2 min, respectively (P < 0.001). Mean hospital duration was 6.4 ± 2.9 and 5.3 ± 2.1 days in group A and B, respectively (P = 0.521). Ureteral SFR was 100% in each group. Renal SFR for RIRS was 86.1%. Complication rates in group A were higher (22.2% vs 13.9%), but the differences were not statistically significant (P = 0.358). In group A, complications were significantly less in pre-stented patients (3/25 vs 5/11, P = 0.04). Auxiliary treatment rate was significant higher in group B (69.4% vs 5.6%, P < 0.001) during follow-up (mean >18 months).

Conclusions

Simultaneous RIRS for ipsilateral asymptomatic renal stones in patients with ureteroscopic symptomatic ureteral stone removal can be performed safely and effectively. It promises a high SFR with lower auxiliary treatment rate, and does not lengthen hospital duration and increase complications.

Percutaneous nephrolithotomy and ureteroscopy in children: evolutions

The increasing incidence of pediatric stone disease has coincided with significant advances in technology and equipment, resulting in drastic improvements in management. Miniaturization of both ureteroscopes and percutaneous nephrolithotomy (PCNL) equipment has facilitated access to the entirety of the urinary tract and has made ureteroscopy a first-line therapy option along with shock-wave lithotripsy for kidney and ureteral stones. Advances in PCNL have decreased patient morbidity while preserving stone clearance rates. In this review, the advances in operative approach for ureteroscopy and PCNL in children and its applicability to current surgical management of pediatric stone disease are discussed.

The use of a ureteral access sheath does not improve stone-free rate after ureteroscopy for upper urinary tract stones

PURPOSE

To evaluate the impact of a ureteral access sheath (UAS) on stone-free (SF) rate after flexible ureteroscopy for upper urinary tract stones.

MATERIALS AND METHODS

We retrospectively reviewed 280 patients who underwent flexible ureteroscopy (URS) for upper urinary tract stone between 2009 and 2012. Patients were divided into two groups based on whether a UAS was used (n = 157) or not (n = 123). SF rate was evaluated at one and three months after surgery by abdominal imaging. Quantitative and qualitative variables were compared with Student's t test and χ2 test, respectively. A logistic regression model was used to determine the predictive factors of SF status.

RESULTS

Stone size was similar in both groups (15.1 vs. 13.7 mm, p = 0.21). SF rates at one and 3 months were comparable in UAS and non-UAS groups (76 vs. 78% and 86 vs. 87%, p = 0.88 and 0.89, respectively). Complication rates were similar in both groups (12.7 vs. 12.1%, p = 0.78). In multivariable analysis, stone size was the only predictive factor of SF rate (p = 0.016).

CONCLUSION

The routine use of a UAS did not improve SF rate in patients undergoing flexible URS for upper urinary tract calculi.

Controversies in ureteroscopy: Wire, basket, and sheath

In the last one to two decades, flexible ureteroscopy has rapidly expanded its role in the treatment of urologic stone disease. With the frequent and expanded use of flexible ureteroscopy, other ancillary instruments were developed in order to ease and facilitate this technique, such as ureteral access sheaths (UAS) and a variety of wires and baskets. These developments, along with improved surgeon ureteroscopic competence, have often brought into question the need to implement the “traditional technique” of flexible ureteroscopy. In this review, we discuss a brief history of flexible ureteroscopy, its expanded indications, and the controversy surrounding the use of UAS, wires, and baskets.

Retrograde intrarenal surgery for the treatment of renal stones in patients with a solitary kidney

OBJECTIVE

To evaluate the efficacy and safety of retrograde intrarenal surgery (RIRS) in the treatment of renal stones in patients with a solitary kidney.

MATERIALS AND METHODS

From December 2008 to March 2012, 24 patients with a solitary kidney who were treated with RIRS for renal stones were included in the study. All patients were preoperatively evaluated with urine culture, serum biochemistry, urinary ultrasonography, noncontrast computed tomography or intravenous urography, or both. The procedure was considered as successful in patients with complete stone disappearance or fragments <4 mm on computed tomography. Preoperative, operative, and postoperative data of the patients were retrospectively analyzed. The mean serum creatinine levels before and after the procedures were compared using a paired sample t-test.

RESULTS

The study included 24 patients with a mean age of 44.41 ± 12.15 years (range, 24-70). The mean stone size was 19.83 ± 5.90 mm (range, 10-35). The mean operative time was 55.83 ± 10.90 minutes (range, 40-75). The success rates were 83.3% and 95.8% after the first and second procedures, respectively. A pigtail stent was placed in all patients. The mean serum creatinine levels before the procedures and at 2 weeks after removal of the pigtail stents were 1.54 ± 0.55 mg/dL (range, 0.7-2.8) and 1.56 ± 0.50 mg/dL (range, 0.9-2.6), respectively (P = .92). Minor complications, classified as Clavien I or II, occurred in 4 patients (16.6%). No major complications (Clavien III-V) occurred in the study group.

CONCLUSION

RIRS is an effective and safe procedure that can be used to manage renal stones in patients with a solitary kidney.

Prospective evaluation and classification of ureteral wall injuries resulting from insertion of a ureteral access sheath during retrograde intrarenal surgery

PURPOSE

The safety of using a ureteral access sheath during retrograde intrarenal surgery remains controversial. Using a novel classification, we prospectively evaluated the incidence and severity of ureteral access sheath driven ureteral wall injury after flexible ureteroscopy for retrograde intrarenal surgery.

MATERIALS AND METHODS

Data on a total of 359 consecutive patients who underwent retrograde intrarenal surgery for kidney stone were prospectively collected at 2 academic centers. We propose what is to our knowledge a novel endoscopic classification of iatrogenic ureteral wall injury. Ureteral injuries after retrograde intrarenal surgery were assessed visually with a digital flexible ureterorenoscope. The primary outcome measure was the incidence and nature of ureteral injuries. We sought factors predisposing to such injuries.

RESULTS

Ureteral wall injury was found in 167 patients (46.5%). Severe injury involving the smooth muscle layers was observed in 48 patients (13.3%). Males vs females (p = 0.024) and older vs younger patients (p = 0.018) were at higher risk for severe ureteral access sheath related ureteral injury. The most significant predictor of severe injury was absent ureteral Double-J® stenting before retrograde intrarenal surgery (p <0.0001). Pre-stenting vs no pre-stenting decreased the risk of severe injury by sevenfold. Body mass index, a history of diabetes mellitus, vascular disease or abdominopelvic radiation therapy and operative time were not associated with severe ureteral injury.

CONCLUSIONS

Ureteral access sheath use for retrograde intrarenal surgery should involve systematic visual assessment of the entire ureter to recognize severe ureteral injury. The incidence of severe ureteral injury is largely decreased by preoperative Double-J stenting.

Comparison of a novel radially dilating balloon ureteral access sheath to a conventional sheath in the porcine model

PURPOSE

Traditional ureteral access sheaths rely on tapered dilators and the Dotter principle of axial force to gain access into the ureter. We compared the performance of a novel balloon expandable ureteral access sheath using radial dilatation with that of a conventional ureteral access sheath.

MATERIALS AND METHODS

Ten farm pigs underwent randomized placement of the novel sheath in 1 ureter and a conventional ureteral access sheath in the contralateral ureter followed by videotaped ureteroscopy. Acute study end points included maximum and mean force of sheath insertion and removal, saline flow rate and subjective urothelial damage following sheath insertion/inflation. Additionally, blinded reviewers rated urothelial damage on digitally recorded video following sheath removal. Chronic data included gross and histological ureteral analysis at 30 days.

RESULTS

The novel ureteral access sheath inserted with less maximum force (0.36 vs 1.48 pounds, p <0.001) and less average force (0.11 vs 0.49 pounds, p = 0.001). The flow rate during 5 minutes was higher in the new sheath (90.0 vs 80.6 cc per minute, p <0.05). Withdrawal forces were not statistically different between the sheaths. The novel sheath also had a lower subjective trauma scale rating (4.2 vs 6.1, p <0.05). Eight blinded reviewers determined that the novel ureteral access sheath resulted in less total urothelial tear length (1.3 vs 2.7 cm, p = 0.03) and less visible ureteral damage in all animals except 1 (p = 0.04).

CONCLUSIONS

The novel balloon expandable ureteral access sheath had easier insertion and a better flow rate, and caused less urothelial trauma in this porcine model. This ureteral access sheath offers a promising new option for ureteral access. A randomized clinical trial is in progress to assess the benefits of this new ureteral access sheath.

Expanding use of ureteral access sheath for stones larger than access sheath's internal diameter

The internal diameter of the ureteral access sheath limits the size of stones that can be removed during flexible ureteroscopy. We describe a technique that allows removal of larger stones, which are entrapped and removed en bloc with the access sheath. This new technique was shown to be efficient and safe.

Safety And Efficacy of Ureteral Access Sheaths

The ureteral access sheath (UAS) was introduced as a means of passing a flexible ureteroscope. Although the device was initially lauded for its ability to facilitate ureteroscopic access, passage was difficult and risked ureteral injury, and the UAS fell out of favor until the development of a new generation of devices that was easier to insert. The UAS should be advanced under fluoroscopy over a stiff guidewire, and the surgeon should ensure copious hydration of all inner and outer surfaces. Use of the UAS is purported to improve irrigant flow and visibility. The UAS can induce transient ureteral ischemia and promote an acute inflammatory response, but it also prevents potentially harmful elevations in intrarenal pressure. Unequivocal data are not yet available to suggest that UAS use during ureteroscopy protects or harms the upper urinary tract. The UAS also has the potential to improve stone-free rates by allowing passive egress or active retrieval of fragments. A large prospective study is needed to unequivocally determine if UAS use is superior in terms of stone-free rates. Cost studies reported to favor UAS use, although a formal cost-effectiveness analysis has not been performed. Further study is needed before routine use of the UAS can be recommended.

Is there a role for small-diameter ureteral access sheaths? Impact on irrigant flow and intrapelvic pressures

OBJECTIVES

To evaluate irrigant flows and intrapelvic pressures with small-diameter access sheaths. Ureteral access sheaths improve irrigant flow and decrease intrarenal pelvic pressures during flexible ureteroscopy. However, no comparisons of individual sheaths have been conducted. Previous studies have demonstrated more favorable results with the 12F sheath than with the 10F sheath.

METHODS

Ureteral access sheaths were tested ex vivo in porcine kidneys. An 18F angiocatheter was placed in the renal pelvis and connected to a Hewlett Packard Gauss Pressure transducer. Irrigant was maintained at 100 mm Hg pressure. Irrigant flow and intrapelvic pressures were measured with three flexible ureteroscopes at baseline and using each of four 10F sheaths, with the sheaths positioned in the middle ureter and the ureteroscopes positioned in the renal pelvis. The pressure at which irrigant efflux through the sheath occurred and the rate of irrigant efflux through the access sheath were measured.

RESULTS

Intrapelvic pressures measured greater than 40 mm Hg, and irrigant flows remained at less than 15 mL/min when the Olympus URF-P3 and Storz 11274AAU flexible ureteroscopes were tested with all four sheaths. The intrapelvic pressures, irrigant inflow, and irrigant efflux with the Wolf 7325.172 (7.5F) flexible ureteroscope were optimized in combination with the Cook Peelaway 10F and Applied Access 10F sheaths.

CONCLUSIONS

Small ureteral access sheaths should be used only with the Wolf 7325.172 flexible ureteroscope. The Cook Peelaway (10F) and Applied Access (10F) sheaths offered the greatest increase in irrigant flow and decrease in intrapelvic pressures.

Ureteral access strategies: pro-access sheath

Routine use of the ureteral access sheath during flexible ureteroscopic procedures provides consistent, reliable, and unencumbered access to the upper tracts. The ureteral access sheath can be reliably and easily deployed if used properly and requires no special training. As such, it can be easily adopted into current urologic practice. Not only does the access sheath facilitate rapid, repeated, and atraumatic access to the upper tracts, but it also avoids back-loading over a superstiff guidewire, which may incur costly damage to the ureteroscope. The access sheath reduces overall costs and decreases operative times. Furthermore, application of a ureteral access sheath reduces the frustration associated with complex and some routine ureteroscopic procedures by optimizing irrigant flow to improve the surgeon's endoscopic vision while minimizing the intrarenal pressures that the kidney must tolerate. There is no evidence that the access sheath results in clinically significant ureteral ischemia, and extensive clinical use of the access sheath for long procedures has not resulted in increased stricture formation. Finally, the ureteral access sheath is useful for other procedures, such as PCNL, by improving visualization and minimizing the requirement for multiple percutaneous access sites. Winston Churchill said it best: "Give us the tools and we will finish the job." Industry has provided urologists with the tools in the form of advanced flexible ureteroscopes, the holmium laser, nitinol baskets, and the ureteral access sheath. Now it is up to urologists to finish the job.

The argument against the routine use of ureteral access sheaths

The current authors' experience with thousands of ureteroscopic procedures has led them to believe that ureteral access sheaths are seldom necessary. No study to date has accurately determined an advantage of using these sheaths for routine ureteroscopy. The current authors have outlined their alternative methods that eliminate the reported advantages of the sheaths. Their philosophy of stone treatment uses laser lithotripsy for small stone burdens and SWL or PNL for larger stone burdens and eliminates the need for prolonged ureteroscopic procedures. Several disadvantages of access sheaths are evident. When this information is taken into account, the routine use of a ureteral access sheath becomes unnecessary. It is only in unusual cases that ureteral access sheaths are of any utility.

Assessment of stricture formation with the ureteral access sheath

OBJECTIVES

To analyze the long-term incidence of ureteral stricture formation in a series of patients in whom a new-generation ureteral access sheath was used. A new generation of ureteral access sheaths has been developed to facilitate ureteroscopic procedures. However, some have questioned their safety and whether the device might cause significant ureteral trauma.

METHODS

Between September 1999 and July 2001, 150 consecutive ureteroscopic procedures with adjunctive use of an access sheath were performed. A retrospective chart review to April 2002 was done. Of the 150 patients, 130 underwent ureteroscopy for ureteral stones. Patients who underwent endoureterotomy or treatment of transitional cell carcinoma were excluded from this analysis. Sixty-two patients had follow-up greater than 3 months and were included in the analysis. Overall, 71 ureteroscopic procedures were performed, with 9 patients undergoing multiple procedures. Ninety-two percent of the patients had pathologic findings above the iliac vessels. The average patient age was 45.3 years (range 17 to 76), and 70% and 30% of the patients were male and female, respectively. The mean clinical follow-up was 332 days (range 95 to 821), and follow-up imaging was performed within 3 months after ureteroscopy in all patients.

RESULTS

The 10/12F access sheath was used in 8 ureteroscopic procedures (11.2%), the 12/14F access sheath in 56 (78.9%), and the 14/16F access sheath in 7 (9.8%). One stricture was identified on follow-up imaging of 71 procedures performed, for an incidence of 1.4%. The patient developed the stricture at the ureteropelvic junction after multiple ureteroscopic procedures to manage recurrent struvite calculi. The access sheath did not appear to be a contributing factor.

CONCLUSIONS

The results of our series indicate that the ureteral access sheath is safe and beneficial for routine use to facilitate flexible ureteroscopy. However, awareness of the potential ischemic effects with the use of unnecessarily large sheaths for long periods in patients at risk of ischemic injury should be considered. We advocate the routine use of the device for most flexible ureteroscopic procedures proximal to the iliac vessels.