(a) The flexible ureteroscope has been inserted in the sheath, but its deflection mechanism remains inside it. The deflection is significantly limited, and the mechanism of deflection is under tension and could be easily damaged. (b) The deflection mechanism is out of the access sheath. The scope can deflect efficiently. Notice the radiopaque ring at the site that the deflecting distal part of the flexible ureteroscope scope is connected to the shaft of the scope. This site should always be outside the sheath in order to prevent damage to the deflection mechanism
Most modern accessories are made of nitinol, which resists kinking and causes minimal loss of deflection. Crucial factors to avoid complications and damage to the scope include carefully selecting extraction devices, using a safety guide wire, maintaining good visualization all the time, avoiding forceful or blind manipulation, and introducing the device while the scope is straight .
Processing, Cleaning, and Sterilization of Flexible Ureteroscopes
A main cause of damage outside the patient is the cleaning technique. Some available cleaning techniques do not ensure instrument viability and appropriate sterilization. Thus, the method of cleaning should be based on the manufacturer’s guidelines . Patient safety and optimal clearing of the instrument should be ensured by documenting and monitoring the cleaning process and sterilization. A study by McDougall et al. investigated if cleaning techniques and personal errors could affect ureteroscope failure, showing that when the processing and handling of the scopes was done by the surgeons and endourology support staff, the durability of the scopes was not affected . Another study compared handling of the scope by endourology staff with handling by the central processing unit. Results showed that when the endourology staff handled the ureteroscopes, the average number of uses was 28.1 before any repair. The number of uses before repair was only 10.8 when the scopes were handled by the central unit . Thus, the staff should be aware of the fragility of the ureteroscope and make every effort to prevent the onset of corrosion, pitting, and rusting .
Prior to each use, every new, repaired, and refurbished ureteroscope should be checked, cleaned, and sterilized by following the methods recommended by the manufacturer . Precleaning is necessary to remove any debris and to make the scope safe for handling. Flushing of working channels with enzymatic detergent or water and removing all visible soil from the interior and exterior of the scope are also recommended .
After every use, the scope should immediately be immersed in warm water. Prior to manual cleaning, a leak test should be done. To ensure that internal channels are intact and to avoid any damage to the scope, the instrument should be sent back to the manufacturer for repair if a leak is detected [30, 31]. If no leak is found, the scope should be disassembled and cleaned of all protein material using the recommended enzymatic detergent to facilitate a biocidal process [30–32]. After visual inspection and cleaning, a high-level disinfection or sterilization should be performed according to the manufacturer instructions and healthcare organization regulations . Care must be taken to rinse the ureteroscope and flush the channels to remove any traces of disinfectant solution . Adherence to strict protocols and documentation and monitoring of the process are crucial to avoid any infectious outbreaks, damage to the scope, and compromise of staff safety.
The quality of water used for the processing has a great influence on the proper function and durability of the ureteroscope. A hard layer (lime deposits, scale) might form on the ureteroscope depending on water hardness and temperature and can sometimes be very difficult to dissolve. Cleaning solutions relying on tap water—even when using deionized water—will leave mineral residues on ureteroscopes that will not wash off completely. These factors can negatively affect the instrument’s proper function. The quality of the rinsing water for final disinfection and cleaning should be free of pathogenic microorganisms. When an instrument is rinsed in tap water, recontamination can occur .
Routine sterilization is recommended for initial and subsequent sterilization of all instruments. Before sterilization, the ureteroscope must be fully cleaned, with all visible organic material, blood, and cleaning solution completely removed . Instruments may be sterilized in ethylene oxide (EtO), steam, STERRAD® sterilization systems, or STERIS® Amsco V-PRO® sterilization systems. Sterilization is highly recommended for “critical” instruments to be used for hysteroscopy, neuroendoscopy, laparoscopy, or arthroscopy. High-level disinfection is recommended for “semi-critical” instruments which come into contact only with intact mucous membranes or non-intact skin .
Flexible ureteroscopy (fURS) has evolved to be the most used modality for surgical treatment of renal stones over the past 15 years . Despite technological advances, the durability of flexible ureteroscopes is still a major concern. Due to limited durability and the relatively high cost of repair, the multiuse (reusable) ureteroscope continues to be a significant financial obstacle to initiating flexible ureteroscopy programs worldwide. Moreover, the maintenance, processing, and sterilization of flexible ureteroscopes lead to significant costs.
Flexible ureteroscope repair has been clearly stated in the literature as a significant cost parameter in several studies [37, 38]. Knudsen et al. showed that 46–59% of the cost of a flexible ureteroscopy program results from ureteroscope repairs . Landman et al. evaluated flexible ureteroscopes from different manufacturers and calculated the overall costs associated with the use of each of the ureteroscopes for 25, 50, 75, and 100 cases during the 1st year (while under warranty) and with subsequent use. They concluded that 70% of the major ureteroscope repairs may result from operator-induced damage . When the newer digital scopes were evaluated, the investigators observed an average of 12 uses before the need to repair the digital scopes . In an attempt to address costly issues with durability and need for repairs, the single-use disposable ureteroscope was introduced; these scopes have to withstand only one case and do not require any repair or maintenance.
The LithoVue (Boston Scientific, Marlborough, MA) was the first disposable ureteroscope introduced on the market. The scope was shown to be comparable to conventional scopes in terms of visibility and manipulation in a cadaveric study . Usawachintachit et al. reported the clinical outcomes between two randomized groups of patients undergoing flexible ureteroscopy for upper urinary tract pathology. The first group underwent surgery utilizing LithoVue, and the second group used reusable fiber-optic flexible ureteroscopes. LithoVue was related to an average 15.5-min reduction in operating room time and a 12.6% reduction in complications. Instrument failures were similar between LithoVue and the reusable flexible ureteroscopes . Similar results showing the efficacy of single-use flexible ureteroscopes , including scopes other than LithoVue, have been published and suggest that the single-use flexible ureteroscopes could be a promising alternative to reusable flexible ureteroscopes without compromising the clinical outcome of fURS . Nonetheless, the purchase cost of these scopes remains high and represents a limiting factor for their acceptance. However, recent economic studies calculating the cost of purchase, repair, maintenance, and sterilization showed that the single-use scopes could be considered more cost-effective in specific clinical settings [42, 43].
The clinical use of flexible ureteroscopes requires training of and care by surgeons as well as support personnel related to the maintenance, cleaning, storage, and sterilization of these instruments. The repair costs of these instruments are high and may represent a significant financial burden. The use of single-use flexible ureteroscopes may be cost-effective in some clinical settings by avoiding the need for maintenance and repair.