The PolyDiagnost PolyScope
Comparing Single-Use and Reusable Flexible Scopes
The LithoVue and other similar scopes offer a nearly 1:1 exchange for a reusable scope in the domains of optics, flexibility, and other performance characteristics. Dale et al.  performed a series of benchtop comparisons of the LithoVue to fiberoptic and digital reusable scopes. They demonstrated that the LithoVue offers superior deflection of up to 276′ with an empty working channel and maintains superior maximal deflection with a 200 nm laser fiber or 1.9fr basket in the channel relative to the reusable scopes. Optical resolution was on par with the digital scope, the Storz Flex-Xc (Karl Storz, Germany), and superior to the fiberoptic scope, the Wolf Cobra (Richard Wolf, Germany). Additionally, LithoVue maintained higher irrigant flow via the working channel with instruments in place. Similar benchtop studies comparing the LithoVue to other single-use scopes as well as both fiberoptic and digital reusable scopes have confirmed parity between devices with a few exceptions [21, 22]. Dragos et al.  examined the tip deflection characteristics of a number of fiberoptic and digital reusable scopes as well as the LithoVue. They demonstrated that the relatively longer inflexible tip housing the camera chip found on all digital scopes, LithoVue included, limits the ability to enter an acutely angled calyx when compared to a fiberoptic scope. Additionally, in another report, Dragos et al.  demonstrated that stiff instruments such as PTFE wires or biopsy forceps have a greater impact on loss of maximal deflection in single-use scopes relative to reusable scopes.
Clinically, the LithoVue has been evaluated relative to reusable ureterscopes in many reports. Usawachintachit et al.  performed a case-control study to compare the LithoVue to the Olympus URF-P6 fiberoptic reusable scope. They demonstrate that in clinical use, the single-use scope had a 4.4% failure rate versus 7% for the reusable scope. Interestingly, they also found that the single-use scope saved about 10 min of OR time and was associated with fewer perioperative complications. They postulated the time difference observed may be due to simplified setup of the single-use scope (LithoVue requires plugging in a single cable versus the individual light cord and camera for the fiberoptic reusable scope). The reduced complications are not as easily explained; however, none of the differences in complications were secondary to infectious etiology, nor were they serious complications (all Clavien grade 1 or 2 regardless of scope used). Such significant differences in OR time and postoperative complications have not been reproduced in subsequent studies comparing single-use to reusable ureteroscopes.
Mager et al.  performed a prospective cohort study to compare the LithoVue to both a fiberoptic reusable scope and digital reusable scope. They report no difference between any of the scopes in terms of case success (ability to reach the target anatomy), perioperative complications, OR time, or radiography exposure time.
Given the disposable nature of single-use scopes, there have been concerns raised by urologists regarding sufficient durability to complete a prolonged or difficult case. In the above-referenced study , of the 68 cases completed with LithoVue, only one scope failure was reported. This failure occurred early in the case and was deemed to be due to a faulty scope which was replaced at no cost. Additionally, Doizi et al.  examined the maximal deflection of LithoVue at the start and completion of 40 consecutive cases with no significant difference found between the time points.
Some concerns about single-use scope durability may arise from the feel of these scopes in the surgeon’s hands. Single-use scopes are far lighter than reusable scopes, which may create the feel of a poorly made device. However, rather than be a detriment, this may actually be an advantage. Proietti et al.  assessed the weight of a number of clinically available flexible ureteroscopes including digital and fiberoptic as well as single-use (LithoVue). The single-use scope was by far the lightest of the scopes at 277.5 g. On the other end of the spectrum, the Olympus URF-V2 digital reusable scope weighs in at 942 g. The relative weight of the ureteroscope may not seem important, but as demonstrated by Ludwig et al. , significantly more muscle work is required to complete a standard flexible ureteroscopy training task when using a heavier scope. Single-use scopes may thus allow less surgeon fatigue during longer cases or after multiple cases, which may improve efficiency in the OR. Such claims have been studied with other fatigue reducing surgical equipment, most notably the surgical robot [28, 29]. Although they used time as a measure of surgeon fatigue, Seklehner et al.  demonstrated a correlation between time in the OR and worsened stone-free rates. Such studies suggest the economic implications of using single-use scopes may go well beyond device acquisition and maintenance cost.
At the time of this writing, single-use scopes similar to the LithoVue such as the Pusen PU3022 have undergone limited published trials. Marchini et al.  performed in vitro comparison of the LithoVue and Pusen scopes and noted differences in resolution, irrigation flow rates, deflection loss with an instrument in the working channel, etc. Many of these differences were statistically significant, but relatively subtle as they were similar to the variation seen between different manufacturers of reusable scopes and their clinical significance is unclear. Clinically, Salvadó  reported on the Pusen scope in 11 cases and found no performance deficits.
The modern operating room creates an enormous amount of waste. This translates not only into cost to the healthcare system but potentially cost to the environment. One concern with single-use scopes is the exacerbation of this problem by adding yet another item to the waste bin at the completion of a case. At the time of writing, only one study has attempted to illuminate this issue with regard to single-use scopes. Davis et al.  examined the carbon footprint of a single-use scope (LithoVue) and a digital reusable scope (Olympus URF-V2) . The solid waste produced and energy consumption required for the manufacture, repair, sterilization , and ultimate disposal of each scope was estimated and this converted to the equivalent mass of CO2 produced. The authors used data from their own institution, including an average of 16 cases before the reusable scope required repair and 180 total cases before final disposal. They reported an average of 4.43 kg of CO2 produced per case for a single-use scope and 4.47 kg of CO2 produced for the reusable scope. Thus, it appears the potential environmental impact of single-use scopes is comparable to reusable scopes when measured by carbon footprint.
Performance issues aside, the logic of a single-use ureteroscope hinges upon its cost. Single-use ureteroscopes are a fraction of the price of a new reusable scope, but they remain relatively expensive as a line item for every case as a disposable instrument. Nonetheless, they eliminate the significant and uncertain repair costs associated with reusable scopes, offer the urologist a scope with consistency, like new performance in nearly every case, and remove the possibility of delayed or canceled cases due to sterilization or breakage issues.
Unfortunately, determining the economic impact of using a single-use ureteroscope is not a simple task. Negotiated prices for all ureteroscope-related services from initial scope acquisition to repair costs are variable and often confidential. At the time of this writing, the most commonly published price for the LithoVue is $1500 USD , and this is the price point upon which nearly all cost analysis studies have been based.
Note that the majority of centers that have performed cost analyses are academic training centers. As previously discussed, the number of cases a reusable flexible scope can be used before needing repair may be dependent on who is using the scope. Thus, cost analysis of single-use scopes differ significantly at centers not involved in training residents.
Martin et al.  performed a cost-benefit analysis comparing the LithoVue to a digital flexible ureteroscope (Storz Flex-XC, Karl Storz, Germany). They examined 160 cases completed with the reusable scope and compared the actual cost of these procedures to the projected costs of using a single-use scope for every case assuming a fixed cost for the LithoVue of $1500 USD per scope. They did not include the purchase price of the reusable scopes in their analysis, so this analysis may not be applicable to centers looking to establish or upgrade an existing fleet of ureteroscopes. They report the cases completed with reusable scopes cost on average $848 USD. At that price point, the authors concluded that if a center is performing 99 or more ureteroscopies per year, the reusable scopes were the more economical option.
A similar analysis by Mager et al.  reported the “breakpoint” for single-use scopes to be between 61 and 118 cases per year.
Taguchi et al.  performed a micro-costing analysis of cases completed with a fiberoptic reusable ureteoscope (Olympus URV-P6) and cases completed with the LithoVue . Their analysis assigned a price to every step of every procedure including steps such as disposal of the single-use scopes. One week of consecutive cases performed with each scope were analyzed. They report the average cost for the reusable scope cases was $2799 USD and for the single-use scope cases was $2852 USD. Note this study reported relatively high reusable scope repair cost at $957 USD per case and despite being performed at the same center as the Usawachintachit et al. study , found no significant OR time advantage to using the single-use scope.
Providing a slightly different angle, Tosoian et al.  reported that at their high volume academic center, they would remain profitable so long as average repair costs for their reusable scopes remained under $1199 USD per case.
Selective Use of Single-Use Scopes
Ozimek et al.  performed a cost analysis comparing a mix of cases completed with fiberoptic and digital reusable scopes to projected costs with a LithoVue. Similar to Martin et al. , they report that scope-related costs would have nearly doubled if they switched to single-use scopes for all cases. However, in examining their cases, they noted the majority of scope repairs were required following cases in which access to a lower pole calyx with an infundibulo-pelvic angle of <50° was required. The authors point out that if a single-use scope were used in these cases, the cost savings to their institution would have been enormous. They postulated that not only would repair costs have been decreased but total case number would have increased as case delays and cancelations would have been avoided, increasing overall revenue.
This report suggests that for high and potentially even moderate volume centers, selective use of single-use scopes may offer a major economic advantage. In addition to lower pole stones, other high-risk cases for scope damage have been identified including antegrade ureteroscopy and attempted ureteroscopic treatment of stones over 2 cm . Additionally, Keller et al.  suggested that certain maneuvers to improve ureteroscope deflection can create enormous stress on the instrument and should only be employed with a single-use scope. For example, forced tip deflection, which is performed by forcing the scope to flex prior to the flexible tip fully exiting the access sheath, will decrease the deflection diameter of the scope by 66%. This allows entry into very steeply angled calyces but creates 4x more torque on the scope than regular full flexion.
Molina et al.  reported their results of selective use of the LithoVue at their center. They used a single-use scope in any case where the greatest stone diameter was over 15 mm or the stone was of any size requiring lithotripsy for treatment but located in a lower pole calyx and could not be easily relocated to an upper or middle calyx for lithotripsy. Over 15 months, they performed 228 ureteroscopies, 17 with a single-use scope per their selection criteria. They report a cost savings of over $52,000 USD relative to the prior 228 cases performed at their center. This translates to about $229 USD of savings per case.
Scope damage during difficult cases is not only a problem from an economic standpoint. Huynh et al.  reported on two cases of reusable ureteroscopes becoming entrapped in patients during surgery. One was able to be removed with endoscopic maneuvers, the other required open surgical extraction. Analysis of scope use in the second case revealed the scope had been used over 80 times for more than 2000 h of service. Accordioning of the distal bending rubber on the ureteroscopes was felt to be the initiating event in each case. Similar findings are echoed in a report examining the most common indications for repair of reusable scopes  as well as a review of mechanisms related to intraoperative ureteral avulsion injuries . Certainly single-use scopes are not immune to structural failure; however, these data suggest the most dangerous failures are likely unique to reusable scopes used during multiple prior cases.
Despite much evidence suggesting single-use scopes are nearly equal to reusable flexible ureteroscopes in benchtop and clinical testing and recent work demonstrating there may be an economic advantage to using a single-use scope in selected cases, there persists a sentiment among urologists that reusable scopes are superior. Certainly, what differences exist between the two categories of scopes are subtle and difficult to objectively measure. For example, the authors have noted the LithoVue has a tendency to “white out” the center of the image, especially during laser activation. This phenomenon is not as pronounced in reusable digital scopes and will likely improve with advancing technology. In fact, the authors have noted improvement in this area with interval software improvements to the monitor’s image processing software. Additionally, the currently clinically available single-use ureteroscopes all have larger tip and shaft diameters than most fiberoptic reusable scopes [20, 23, 24], potentially limiting their ability to gain access via a narrow ureter. Nonetheless, the most difficult cases that put ureteroscopes under the greatest strain and thus have the most potential for single-use scopes to assert an economic advantage are often the cases most urologists would choose to use their most high-performing scope.
As flexible ureteroscopes continue to evolve, single-use scopes may overcome this performance barrier. Digital imaging technology will continue to improve and become smaller and cheaper, allowing more maneuverable, higher definition scopes. New single-use scopes from multiple suppliers will enter the market, drive down proves, and/or improve on scope performance. It is likely that current reusable scope manufacturers will either join the single-use market or innovate ways to decrease repair costs. Fortunately, these changes will likely increase the availability of flexible ureteroscopy around the world by reducing the costs to low volume centers without access to repair or reprocessing facilities. If we look to the evolution of laser fibers, baskets, and many other endoscopic tools as examples, a near future with a completely disposable endourologic tool chest is not hard to imagine.