Impact Ureteral Sheath Design During Ureteroscopy

The purpose of this study is to assess whether one of two ureteral access sheaths is safer for patients undergoing ureteroscopy. Both sheaths are FDA approved devices and commercially available. The investigators will compare the ability of sheaths to access the kidney through the ureter and will compare damage done to the ureter after completion of the procedure. Access sheaths are standard of care for this procedure; this study seeks to optimize outcomes for patients.

Patients undergoing ureteroscopy who do not have ureteral stents in place and who have not had an ipsilateral procedure within 90 days will be recruited and consented.

The purpose of this study is to compare two ureteral access sheaths in how the sheaths damage the ureter during flexible ureteroscopy.

Condition Intervention Kidney Stones Nephrolithiasis Urolithiasis Device: Cook Flexor or Boston Scientific Navigator HD

Study Type: Interventional Study Design: Intervention Model: Two group randomized assignment Masking: Single blind Primary Purpose: Treatment

Primary Outcome Measures:

• Successful placement of sheath (yes or no).

Secondary Outcome Measures:

* Subjective rating of damage to ureter. At the completion of the procedure, video of the intraluminal ureter is recorded as the sheath is withdrawn. Videos are analyzed by two blinded staff endourologists to score ureteral injury on a standard 5-point scale (0 to 4); reference Traxer and Thomas.
* Ease of placement of each sheath. Surgeons will be asked to subjectively rate the ease of placement on a standardized scale from 0 to 4, 4 being easiest which will be rated by the surgeon who inserted the sheath immediately after placement.

Arms Assigned Interventions Device: Cook Flexor and Boston Scientific Navigator HD Device: Cook Flexor or Boston Scientific Navigator HD Patients will be assigned to one of two ureteral access sheaths. If the first sheath is failed to be placed, the backup sheath will be attempted.

Standard ureteroscopy will take place. The intervention takes place before the ureteral access sheath is placed. The patient will be randomized to one of the two sheaths. The randomized 12/14Fr sheath will be attempted. If placed successfully, the rest of the operation continues as planned. If the initial sheath is unable to be placed, a second backup sheath (opposite brand) will be used, also in size 12/14Fr. The surgeon will be asked to rate the ease of placement of the sheath on a standardized scale. If these sheaths fail, it is the surgeon's discretion to continue with the smaller sheath, continue without sheath or place stents and attempt the procedure at a later date. The operation is then continued in standard fashion. Once the ureteroscopy is completed, before the scope and access sheath are removed, video recording of the ureter will be conducted as the ureteroscopy and sheath are removed.

Videos will be analyzed by blinded urologists who will rate the extent of ureteral damage on a standardized scale of 0 to 4 according to the study published by Traxer et al. 2013. Intra-operative data includes total time of initial sheath insertion (in seconds), total time sheath is in place (minutes) from placement to removal, and use of laser. Differences in operative time, ease of placement, ability to maintain access, and ease of instrument passage are also evaluated between devices, as well as success rates, and device failure rates and post-operative complications. Means are compared using a t-test and proportions are compared using a chi-squared test. An intention to treat model is used for statistical analysis. When video ratings differ between surgeons, the higher rating of damage will be used. Inter-rater reliability is assessed with Cohen's kappa coefficient.

After the study, subjects will not be contacted. The investigators will collect data from participants' medical records including information of whether participants develop complications or return for a subsequent procedure as well as size and location of kidney stones prior to the surgery.

Eligibility Criteria:
Inclusion Criteria:

* Patients planned for ureteroscopy
* Current CT scan within 90-days before the operation
* Able to give informed consent
* Ages 18 years and older

Exclusion Criteria:

* Inability to give informed consent
* Age less than 18 years
* Pregnant
* Stones in the ureter
* Having previous ipsilateral ureteral or renal surgery within 90 days
* Having stents placed in ipsilateral ureter within 90 days