for people ages 18-80 (full criteria)
study started
estimated completion
Thomas Chi



Reusable flexible ureteroscopes are widely used to treat various upper urinary tract diseases including urinary stones. However, they require a long turnover time between procedures because of the sterilization process. Moreover, repeated use of a scope ultimately deteriorates its image quality which leads to a high maintenance cost in the long-term. A disposable digital flexible ureteroscope was released in the United States in January 2016, offering an improved image resolution, new scope performance characteristics with every case, and no need for sterilization and repair. Preliminary data from our center has demonstrated that disposable scopes shorten operative time by 25% compared to reusable fiberoptic scope and are associated with a 2/3 reduction in procedural complication rate. Therefore, treatment with disposable scopes may be more effective for patients and facilitate cost management within the hospital. Here, we propose a three-armed, prospective randomized study, comparing treatment outcomes between disposable digital, reusable fiberoptic, and reusable digital flexible ureteroscopes.

Official Title

Randomized Controlled Trial Comparing Disposable to Reusable Flexible Ureteroscope for Treatment of Upper Urinary Tract Stone


This is a single center, prospective, randomized controlled pragmatic clinical trial designed to compare between disposable, reusable fiberoptic, and reusable digital ureteroscopes in upper urinary tract stone treatment efficacy. Three hundred subjects with kidney and/or ureteral stones are planned to recruit for the study. All subjects will be computer sequence-randomized into having their ureteroscopic treatment performed with a disposable (LithoVue™), reusable fiberoptic (URF-P6™), or reusable digital (URF-V2™) flexible ureteroscope. Patient's demographics, physical, laboratory, and image findings will be collected before surgery. These clinical data are already being collected as part of an ongoing registry study. Perioperative timing as well as operator's satisfaction and fatigue and need for a second ureteroscope during the case will be recorded during the treatment course. Other clinical data will be collected at days 7, 30, 90, 180 after surgery. The condition of the used ureteroscopes will be tracked and recorded to confirm the repair rate.

Screening data will be reviewed to determine subject eligibility. Subjects who meet all inclusion criteria and none of the exclusion criteria will be entered into the study.

The following surgical treatment will be used similarly for all three randomized arms and represents standard of case therapy:

Ureteroscopic stone removal Under general anesthesia, the patient is placed in the lithotomy position. All procedures are performed under direct videoscopic and fluoroscopic guidance. Fluoroscopic screening is utilized using a mobile multidirectional C-arm fluoroscopy unit. Initially, a safety guide-wire is placed into the renal pelvis, followed by a ureteral access sheath as needed to maintain low intra-renal pressure and to facilitate the procedures. Using a flexible ureteroscope, renal or ureteral stones are identified and fragmented with a holmium YAG laser. Basket extraction of residual fragments is done until visual complete clearance of stone fragments is achieved.

After ureteroscopy is done and stone clearance is achieved, a ureteral stent is placed at the end of the procedure to drain the kidney for 2-21 days if it is clinically indicated.

The total duration of the study is expected to be one year for subject recruitment and one year and six months for final subject follow-up.


Kidney CalculiUreter Calculiureteroscopyflexible ureteroscoperandomized controlled trialCalculiNephrolithiasisUreteral CalculiUreterolithiasisreusable fiberoptic ureteroscopereusable digital ureteroscopedisposable digital ureteroscope


You can join if…

Open to people ages 18-80

  1. Male or female ≥ 18 years of age at their first clinical visit.
  2. Patients with either unilateral or bilateral upper urinary tract stone of any size and location, treatable by flexible ureteroscopy, diagnosed by preoperative ultrasound, computed tomography or plain radiographic imaging
  3. Patients being able and willing to provide consent.

You CAN'T join if...

  1. Serious illness likely to cause death within the next 5 years, so as to exclude significant metabolic derangements that might lead to adverse surgical outcome.
  2. Pregnancy.
  3. Staged ureteroscopic procedure.
  4. Antegrade flexible ureteroscopy.
  5. Dual procedures (ureteroscopy concurrently performed with other operations).

Lead Scientist


not yet accepting patients
Start Date
Completion Date
University of California, San Francisco
Study Type
Last Updated