The Impact of Ureteral Access Sheath Design on Ease of Placement and Ureteral Wall Injury During Flexible Ureteroscopy
Phase: NA
Conditions: Renal Stone, Nephrolithiasis, Urolithiasis
Sponsor: The Cleveland Clinic

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PROSPECTIVE RANDOMIZED COMPARISON OF 2 URETERAL ACCESS SHEATHS 
DURING FLEXIBLE RETROGRADE URETEROSCOPY 
 
PI: Manoj Monga, MD 
 
 
Introduction 
 
Ureteral access sheaths provide effective and reliable access during flexible ureteroscopy, and have 
demonstrated numerous advantages.  Access sheaths have been shown to optimize success of flexible 
ureteroscopy, decrease operative time and cost, and minimize morbidity [1].  Technological advancements 
in ureteral access sheath design have significantly improved physical properties that have led to reduced 
failure rates and complications, however, the general design of access sheaths has remained similar for 
some time until recently.  New designs, though commercially available, have a paucity of data comparing 
different models.  
 
Background and Significance 
 
After gaining initial ureteral access with a guidewire, access sheaths are typically back-loaded onto the 
safety guidewire through the inner lumen of the dilator, allowing for gradual ureteral dilation and smooth 
access to the upper collecting system. Until the recent development of Re-TraceTM (Coloplast) and Flexor 
ParallelTM (Cook Urological), guidewires would remain within the inner lumen of the access sheath after 
removal of the dilator, requiring additional instruments to pass directly alongside the guidewire as they are 
advanced through the sheath.  These devices have now been designed with a slit on the dilator that guides 
the wire outside of the sheath, leaving the guidewire to remain parallel but exterior to the sheath as the 
dilator is removed.  This design limits the need to place an additional working wire, and provides a clear 
working channel through the lumen of the sheath.  A clear working channel is likely to increase irrigation 
flow for improved visibility, reduce intrarenal pressures, and help minimize interference between delicate 
ureteroscopes, baskets, and guidewires.   
 
A recent prospective study by Doizi et al [2] evaluating the ability of the Re-TraceTM to gain ureteral access 
with the use of a single safety guidewire demonstrated good insertion rates and validated the effectiveness 
of the design, however, no study to date has systematically evaluated the impact of the design on ureteral 
trauma or provided a comparative analysis between commercially available devices incorporating this 
design.   
 
We propose this randomized study to evaluate the effectiveness and safety of current commercially 
approved devices integrating this design (Re-Trace TM and Parallel TM).  
 
Purpose and Objectives 
 
The primary objective of this study will be to evaluate the ability for 2 different ureteral access sheaths to 
obtain and maintain access to the upper collecting system, as well as evaluate ureteral injury using 
standardized 5-point classification system. 
 
Secondary endpoints will include evaluating ease of instrument passage, stone extraction, device 
placement, and radiopacity. 
 
Hypothesis 
 
We hypothesize that the modified designs of Re-Trace and Parallel devices will demonstrate similar safety 
profiles.  
 
 
 
 
Research method 
 

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The proposed study is a prospective randomized controlled trial comparing the safety and efficacy of 
ureteral access sheaths used in flexible ureteroscopy.  
 
Patients scheduled for flexible ureteroscopy will be identified by the investigator at clinic visits or hospital 
admission at Cleveland Clinic. The research coordinator will approach patients to determine the patient’s 
initial interest in research, and if interested, the consent process will be initiated prior to surgery. 
 
In order to be eligible the patient must be a suitable operative candidate for flexible ureteroscopy and have 
an abdominopelvic computed tomography (CT) to delineate pre-operative stone size, with measurements 
captured in greatest axial and coronal dimensions.  Patients who have had prior ipsilateral upper urinary 
tract reconstructive procedures, ureteral stricture, ureteral malignancy, or impacted ureteral stones will be 
excluded. Pregnant subjects will also be excluded.   
 
Ureteroscopic treatment of renal calculi is a standard of care treatment approach, and participating in this 
study will not deviate from standard of care ureteroscopy procedures, however, procedures specific to the 
research will involve being randomized to the use of one of two ureteral access sheaths: 
 
1. Coloplast Re-Trace 
2. Cook Flexor Parallel 
 
Choice of sheath length will be left to the discretion of the surgeon based on body habitus and site of 
pathology, while sheath diameter will be standardized to 12/14F. Smaller diameter sheaths (11/13F, 
10/12F) will be used if significant resistance occurs during advancement, otherwise patients will be 
excluded from the study if unable to gain ureteral access, or if ureteral balloon dilation or semi-rigid 
ureteroscopy is required to gain ureteral access. 
 
If unable to obtain access with the initial sheath the patient is randomized to, the patient will be randomized 
to a backup sheath. If unable to obtain access with backup sheath, then a second backup sheath will be 
used.  If unable to obtain access with any of the three sheaths with diameter 12/14F, an attempt will be 
made with up to three additional sheaths of a similar smaller diameter (11/13F or 10/12F), in a random 
order.  If access has not been obtained after randomization to 6 sheaths, the patient will be considered a 
failure and it will be the surgeon’s discretion to either place a stent and do a staged second look at a later 
time, proceed with ureteroscopy without a sheath, or balloon dilate.  
 
Pre-operative data collection will include age, race, gender, ASA (American Society of Anesthesiologists) 
score (for comorbidity assessment), body mass index (BMI), and disease history, including stone disease, 
prior ureteroscopic procedures, vascular disease, and pelvic radiation.  Disease fields that will be obtained 
include stone size (maximal axial and coronal dimensions), degree of hydronephrosis 
(mild/moderate/severe), and duration of prior ureteral stenting (if applicable).   
 
Intra-operative data will include recording any buckling, kinking, or difficulty in instrument passage that 
occurs.  Surgeons will be asked to subjectively rate the ease of sheath placement, stone extraction through 
sheath (if applicable), and ease of instrument passage on a scale 1 to 4, with 1 being poor and 4 being 
excellent. Ureteroscopic video will be taken for all procedures, and ureteral wall injuries will be evaluated 
after removal of the UAS by a urologist (Olivier Traxer, MD) blinded to the treatment device using the 
classification methodology previously described by Traxer and Thomas [3].  
 
UAS related injuries determined by ureterosopic video will be categorized into five (or 4 per PULS) grades, 
ranging from 0-4, defined by the following characteristics: 
 
Grade 0: No ureteral lesion or only mucosal petechiae  
Grade 1: Mucosal erosion or a mucosal flap without smooth muscle injury 
Grade 2: Damage to the mucosa and smooth muscle but no adventitia, with no retroperitoneal 
tissue visible 
Grade 3: Injury indicating ureteral perforation involving the full thickness of the ureteral wall, 
including the adventitia 
Grade 4: Total ureteral avulsion 

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Location of the primary injury site(s) (lumbar, iliac, pelvic ureter) will also be noted to determine impact on 
development of future pathology including stenosis, fistula or ureteral stone formation.  
 
Perioperative fields will include OR (surgical) time, type of anesthesia, laser fiber size, guidewire 
specifications, need for dual lumen catheter or introducer catheter, settings of lithotripsy (if applicable - 
rate/energy), use of active extraction for fragments (include basket/grasper specifications), any device 
breakage or damage, and intraoperative complications.   
 
All other procedures associated with standard of care for ureteroscopic treatment of stones, including stent 
placement, will be left to the discretion of the investigator.  Postoperative fields will include postoperative 
complications, need for ancillary procedures, development or persistence of hydronephrosis/obstruction, 
and stone-free status at 4 to 6 week postoperative imaging as determined by ultrasound of kidneys, ureters 
and bladder.  
 
Sample Size 
 
A recent prospective study evaluating ureteral damage in 359 patients undergoing ureteroscopy with a 
12/14F diameter sheath found that when using the same 5-point ureteral damage classification system, low 
grade ureteral injury (score of 0-1) occurred in 86.6% (311/359) of patients, and high grade (score of 2-4) 
occurred in 13.3% (48/359) of patients. 
 
Based on this preliminary data, the study is powered to detect whether there is a difference between device 
designs to cause low (0-1) vs. high grade (2-4) ureteral injury.  Using an alpha of 0.05 and beta of 0.80, and 
assuming a difference greater than 20% between groups is considered significant, approximately 49 
patients will be required per arm, for a total of approximately 98 patients.  
 
We are requesting the IRB allow for a total enrollment of 117 patients to account for screen failures 
(inability to gain access, rigid ureteroscopy required, strictures, etc). 
 
 
Recruitment and Consent 
 
Based on current volumes of ureteroscopic procedures, we anticipate approximately 2-3 patients per week 
will be randomized requiring a total of approximately 9-12 months of active enrollment between to reach a 
total of 100 randomized subjects. Patients will be recruited from either office visits or inpatient 
hospitalizations. The study coordinator will consent patients using the uploaded consent form 
accompanying this document. All procedures, devices and protocols are standard of care. There is no 
additional cost to the patient  outside of standard care. The patient’s insurance company will be billed for 
medical costs.  
 
Data Analysis Plan 
 
Data analysis will involve comparisons of ureteral damage between groups related to device design, 
gender, age, BMI, preoperative stenting, prior stone disease, and prior stone procedures. Differences in 
operative time, ease of placement, ability to maintain access, and ease of instrument passage will also 
evaluated between devices, as well as post-operative complications, success rates, and device failure rates. 
The analysis will be completed by the approved researchers in coordination with a CCF biostatistician Jesse 
Schold. Study data will be stored on the RedCap database. Data may also be stored on encrypted CCF 
issued IronKey and encrypted CCF issued computers. Signed consent forms will be stored in a 
compartment with a lock for the duration of the trial. Approved researches on this IRB will have access to 
these data. 
 
Adverse Events and Data Monitoring Committee 
 
The investigator will report any adverse events to the IRB within 10 days of awareness.  A data monitoring 
committee will not be used.  The primary risk to participants will be the loss of confidentiality, which will 

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be maintained by physical and electronic locks.  Any unexpected findings of concern will be communicated 
face-to-face to the patient by the investigator in a clinic visit.  A Data Monitoring Committee will not be 
used for this study as the devices and procedures used are standard care.  
 
Study Costs 
 
 
 
REFERENCES 
 
1. Kourambas, J., Byrne R, Preminger G: Does a ureteral access sheath faciliate ureteroscopy? J Uro 
165:789, 2001. 
 
2. Doizi S, Knoll T, Scoffone CM: First clinical evaluation of a new innovative ureteral access 
sheath  
(Re-Trace): A European Study. World J Urol. May 3, 2013. 
 
3. Traxer O, Thomas A: Prospective evaluation and classification of ureteral wall injuries resulting 
from insertion of a ureteral accesss sheath during retrograde intrarenal surgery. J Urol. 189: 580-
584.