Endourology and Stones Improved Durability of Flex-Xc Digital Flexible Ureteroscope: How Long Can You Expect It to Last? Razvan Multescu, Bogdan Geavlete, Dragos Georgescu, and Petrisor Geavlete OBJECTIVE MATERIALS AND METHODS
RESULTS
CONCLUSION
To retrospectively analyze a significant number of flexible ureterorenoscopic procedures performed with the Storz Flex-Xc model to evaluate its durability. Between May 2012 and May 2013, all the flexible ureteroscopic procedures performed with 3 Storz Flex-Xc flexible ureteroscopes were analyzed. Relocation of the lower pole stones was performed in all cases when possible. In the second and third series, the access sheath was retracted together with the flexible ureteroscope, thus preventing the damages, which its distal part may inflict on the flexed endoscope. A total of 406 procedures were performed on 372 patients: first endoscope used on 96 procedures (90 patients), second one on 151 procedures (139 patients), and third one on 159 procedures (143 patients). Ureteral access sheath was used in 71.4% of the cases. The first endoscope was used for 67.1 hours, the second for 107.7 hours, and the third one for 107.2 hours. Major repairs were needed after significant damages of the outer coating (first endoscope) and severe deterioration of the deflecting mechanism (second and third endoscopes). The digital Storz Flex-Xc seems to be a durable model of flexible ureteroscope. The use of ureteral access sheath and avoidance of overstressing the deflection mechanism by relocating lower pole stones seem to offer substantial advantages in prolonging the lifespan of these expensive instruments. UROLOGY -: -e-, 2014. 2014 Elsevier Inc.
F
lexible ureteroscopy is probably one of the most important additions in modern endourology. During the last decades, the initial very fragile and difficult to maneuver endoscopes were the subject of numerous innovations and technological developments, becoming very useful diagnostic and therapeutic instruments in upper urinary tract pathology. The improved durability, substantial miniaturization, and the introduction of digital endoscopes were the main goals while aiming to increase the efficacy of this type of procedures. Nowadays, flexible ureteroscopy is a routinely used method in many centers. However, despite the recent achievements, there is still room for further improvements of these instruments and of the respective techniques. In this regard, increasing the lifespan of an expensive endoscope is a worthwhile purpose. The aim of our study was to retrospectively analyze the flexible ureterorenoscopies performed with the Storz Flex-Xc digital flexible device and to evaluate its durability and possible ways to prolong its lifespan. Financial Disclosure: The authors declare that they have no relevant financial interests. From the Department of Urology, Saint John Clinical Emergency Hospital, Bucharest, Romania Reprint requests: Razvan Multescu, M.D., Ph.D., Department of Urology, Saint John Emergency Clinical Hospital, Vitan-Barzesti 13, Sector 4, 042122 Bucharest, Romania. E-mail: [email protected] Submitted: August 25, 2013, accepted (with revisions): January 18, 2014
ª 2014 Elsevier Inc. All Rights Reserved
MATERIALS AND METHODS Between May 2012 and May 2013, all the flexible ureteroscopic procedures performed with 3 new Storz Flex-Xc digital flexible ureteroscopes were analyzed. The 3 endoscopes were used consecutively, each being new when its usage period started. The flexible ureteroscopic approach was performed by a single expert urologist (G.P.), with more than 1000 flexible ureteroscopies performed in the past and previous experience with this particular endoscope model. It was applied for diagnostic purposes, treatment of upper urinary tract urothelial tumors, or urolithiasis. All procedures were performed in a standardized manner starting with the passing of a Teflon-coated guide wire in the collecting system and the ureteral dilation when necessary. This last maneuver was applied mostly in relation with ureteral access sheath use and was performed using progressive size ureteral dilators or the access sheath itself. The endoscope insertion was simple, on the guide wire, for the diagnostic procedures and small calculi, whereas in cases of tumor formations and larger urolithiasis, it was preceded by the indwelling of a 12/14F or 10/12F Flexor Cook ureteral access sheaths. The relocation of stones situated in the lower pole was performed in all cases in which it was possible. The only procedural difference between the series was that in the second and the third one, the access sheath was retracted together with the endoscope, thus preventing the damages, which its distal part may inflict on the flexible ureteroscope. In that regard, precautions were taken to keep the entire deflectable tip of the 0090-4295/14/$36.00 http://dx.doi.org/10.1016/j.urology.2014.01.021
1
Table 1. Intraoperative characteristics of the 3 studied groups Studied Parameter Number of procedures Diagnostic procedures Mean operative time for diagnostic procedures Treatment procedures Mean operative time for treatment procedures Mean lower pole time for treatment procedures Deflection loss (up/down)
Group I
Group II
Group III
96 8 8 88 45 8 32.8/54.1%
151 24 10 127 49 12 34.5/56.7%*
159 25 11 134 48 14 33.3/58.5%*
* Before the last ureteroscopy (during the last intervention deflection was completely lost).
endoscope outside the distal part of the access sheath when extraction was performed. After the procedure, the endoscope was washed, cleaned, and stored with the flexible segment straight, in the case provided by the manufacturer. The sterilization method applied was complete immersion in and flushing of the working channel with Cidex.
RESULTS In a interval of 13 months, a total of 406 procedures were performed on 372 patients: 96 procedures on 90 patients using the first flexible ureteroscope, 151 procedures on 139 patients using the second one, and 159 on 143 patients using the third one (Table 1). The procedures were performed for diagnostic purposes in 57 cases (8 in the first series, 24 in the second, and 25 in the third one), upper urinary tract urothelial tumors treatment in 5 cases (1 in the first series, 2 in the second and third ones), and urolithiasis in 344 cases (87 in the first series, 125 in the second, and 132 in the third one). The ureteral access sheath was used in 68.2% of the first group, in 74.8% of the second one, and in 70.4% of the third. Eleven percent of the patients were already prestented when the flexible ureteroscopic approach was attempted. Owing to difficulties to ascend the ureteral access sheath, a supplementary 8% of the cases were also prestented, and the procedure was postponed for 7 days. Lithotripsy with a Dornier Medilas H20 Holmium: YAG laser (Dornier MedTech, Wessling, Germany) with a 270-mm fiber was applied in 90.7% of the lithiasis cases (312 cases, 83 cases with the first ureteroscope, 118 cases with the second one, and 111 with the third one). The mean number of pulses was 6945, whereas the mean energy used was 5490 J. The tipples baskets were used in 79.4% of the lithiasis cases (273 cases) to relocate stones and/or extract fragments resulted from intracorporeal lithotripsy. Lower pole stones were encountered in 31.4% of urolithiasis cases (108 patients, 32 treated with the first ureteroscope, 39 with the second one, and 37 with the third one), relocation before lithotripsy being performed in 77.1% of them (81 patients, 23 treated with the first endoscope, 28 with the second one, and 30 with the third one). In the rest of the cases, laser lithotripsy in situ in the lower calyx was performed, at least until extractable stone fragments were achieved. The first endoscope was used for 67.1 hours (mean procedural time of 8 minutes for diagnostic ones and 2
45 minutes for therapeutic ones), whereas the second one lasted for 107.7 hours (mean procedural time of 10 minutes for diagnostic ones and 49 minutes for therapeutic ones), and the third one for 107.2 hours (mean procedural time of 11 minutes for diagnostic ones and 48 minutes for therapeutic ones). The first flexible ureteroscope required major repairs after significant damages of the outer coating, at the distal end, in the region of the deflectable tip. The wearing of a short segment at the distal part of the outer coating (Fig. 1) was observed during postoperative processing of the endoscope after the 72nd procedure and aggravated progressively during the following interventions. A careful analysis identified the site of the damage as the point of significantly traumatic contact between the flexible ureteroscope and the distal margin of the ureteral access sheath during endoscope retraction. After the 96th procedure, a complete section of the outing coating was recorded. Owing to this incident, during the use of the second and third flexible ureteroscopes, a decision to retract en bloc the endoscope and the ureteral access sheath has been taken. The second and third ones registered a severe deterioration of the deflecting mechanism. Interestingly, although the number of interventions and total operating time was higher in the second and third groups, deflection loss of the 3 endoscopes was similar until deflection capabilities of the second and third ureteroscopes were completely lost.
COMMENT The aim of our study was to analyze the durability of Storz Flex-Xc digital flexible ureteroscope and possible ways to prolong its lifespan, in the circumstances of also applying the previously learned lessons, both from our experience and published literature. The increased fragility was a problem linked from the very beginning with the flexible ureteroscopes. Pietrow et al1 reported in 4 models of Olympus flexible ureteroscopes an average number of 27.5 procedures per instrument (range, 19-34). That was a significant improvement from the first models of such endoscopes, which required repair after an average number of 6-15 uses, however, still remaining insufficient for such an expensive endoscope. Owing to the technological advances, the newer fiberoptic flexible ureteroscopes demonstrated a superior UROLOGY
-
(-), 2014
Figure 1. Position and aspect of the perforation of the outer coating. (Color version available online.)
durability. In addition, these models seemed to be associated with a higher success rate by comparison with their predecessors, the general advice being to switch to these latest generation devices.2 In this regard, Traxer et al3 published a report in which the Storz Flex-Xc was used for 50 procedures with an average operating time of 95 minutes. It is important to mention that the endoscope required a repair after a laser perforation of the working channel, which is an intraoperative accident independent of the number and duration of the previous interventions. Another study using the same endoscope reported 113 and 102 procedures, respectively, the most common causes of damage being represented by the deflection mechanism impairment, inner sheath damage, and fiberoptic bundle breaks.4 Both these studies used Cidex chemical sterilization of the endoscopes, similar to our own experience. However, a comparative evaluation of different cleaning and sterilization methods seems to demonstrate no influence of the technique and/or number of personnel involved in the maintenance of the flexible ureteroscope over durability and function of these instruments.5 The introduction of digital flexible ureteroscopes removed the fiberoptic bundle breakage from the list of possible repair motives. For this reason and also because of the continuous technological development, they offered the perspective of an increased durability together with an undisputed significantly improved visibility and image quality.6,7 Using the URF-Vo digital model from Olympus, Traxer et al reported a number of 60 uses, during which the maximal deflection decreased from 275 to 217 .8 Regarding the suspected intermanufacturers variability, a study of 4 older models emphasized a similar durability.9 However, larger prospective studies are needed to document any potential significant differences between the newer digital flexible ureteroscopes. Our series recorded a still unsurpassed number of procedures before major repairs (at least in the published UROLOGY
-
(-), 2014
literature). Although the mean operating time for therapeutic interventions was somewhat reduced by comparison with the study by Delfidio et al4 and significantly lower by comparison with the study by Traxer et al,3 our total procedural time in the second and third groups is significantly higher than in both of them. This was achieved under the circumstances of very attentive manipulation both by the urologist during the endourologic interventions and the operating room personnel during cleaning, sterilization, and storage maneuvers. We also applied lessons learned from our previous experience and published articles, such as avoiding an increased lower pole time by relocating the stone. Another significant parameter in improving the durability of flexible ureteroscopes was related to the use of ureteral access sheaths. It was advocated that their use increases the instruments’ lifespan by reducing the resistance during insertion and consequently the stress at the tip of the instrument.3 Using this device, the speed of instrument degradation (loss of maximal loss, deformation of the working segment, and so forth) may be decreased. For this reason and also to simplify the stone fragment extraction, we chose to frequently use the ureteral access sheath. Another advantage is that it maintains a low pressure in the collecting system, useful both during the procedures for urolithiasis or tumors.4 In the present series, the access sheath was used more frequently than in the previously cited studies: Delfidio et al reported the use of such instruments in 25% of the cases and Traxer et al in 58% of the cases by comparison with 72% in our therapeutic cases.3,4 However, our preference for the use of this device is not an isolated exception. Another study of Miernik et al10 describing a standardized flexible ureteroscopic technique reports its use in 71% of the cases. The potential reticence concerning the routine use of ureteral access sheaths is related to the increase in costs and intraoperative morbidity, combined with the potential to generate ureteral strictures because of the ischemic effect.11 In this regard, we consider that a significantly prolonged lifespan of a very expensive flexible ureteroscope positively balances the increased cost of a procedure in which such a sheath is used. The potential morbidity associated with access sheath insertion is a reality. The article of Traxer and Thomas12 assessing such problems reported a 46.5% complication rate, of which 13.3% being severe ones involving smooth muscle layers. The predictors of ureteral injuries were male sex, older age, and, the most significant one, absent previous ureteral stenting. In our study, no supplementary significant complications were related to the access sheath insertion. However, while trying to avoid such issues in our series, when difficulties were encountered during this process, the procedure was stopped, the patient was stented, and the flexible ureteroscopic approach was tempted again after 1 week. Regarding the development of ureteral strictures because of ureteral trauma or ischemic suffering, although theoretically possible, this risk was never consistently proven.13 3
The observation that the reason for major repairs in the first ureteroscope was constituted by the deterioration of the outer cover near the tip led to the hypothesis that such damages may be related to the mechanical contact between the distal end of the access sheath and the slightly deflected endoscope. Consequently, in the second and third groups, the ureteroscope was extracted en block with the access sheath. In the respective series, no such damages of the outer sheath were recorded, and this may be the reason for a significantly prolonged lifespan (or to avoid the risk of a potential accident that may abruptly interrupt the utilization period).
CONCLUSION The digital flexible ureteroscope Storz Flex-Xc proved increased durability, being used during a high number of procedures until needing any major repairs. Wearing of the outer coating during multiple procedures seems to be a previously unreported cause of ureteroscope damage. Thus we advise retracting the endoscope en bloc with the ureteral access sheath to prevent such deterioration. The significantly large number of ureteroscopies performed with each of this endoscopes is probably the cumulative effect of a much sturdier endoscope but also applying the previously learned lessons aiming to maximize the lifespan of these expensive instruments: correct and careful manipulation, cleaning or storage, use of ureteral access sheath, and avoidance of overstressing the deflection mechanism. Although there are still some problems to be solved, flexible ureteroscopes evolved during the last decades to become reliable endourologic instruments, effective in upper urinary tract diagnosis and treatment.
4
References 1. Pietrow PK, Auge BK, Delvecchio FC, et al. Techniques to maximize flexible ureteroscope longevity. Urology. 2002;60:784-788. 2. Wendth-Nordahl G, Mut T, Krombach P, et al. Do new generation ureterorenoscopes offer a higher treatment success than their predecesors? Urol Res. 2011;39:185-188. 3. Traxer O, Dubosq F, Jamali K, et al. New-generation flexible ureterorenoscopes are more durable than previous ones. Urology. 2006; 68:276-281. 4. Defidio L, De Dominicis M, Di Gianfrancesco L, et al. Improving flexible ureterorenoscope durability up to 100 procedures. J Endourol. 2012;26:1329-1334. 5. McDougall EM, Alberts G, Deal KJ, et al. Does the cleaning technique influence the durability of the
RESULTS
CONCLUSION
To retrospectively analyze a significant number of flexible ureterorenoscopic procedures performed with the Storz Flex-Xc model to evaluate its durability. Between May 2012 and May 2013, all the flexible ureteroscopic procedures performed with 3 Storz Flex-Xc flexible ureteroscopes were analyzed. Relocation of the lower pole stones was performed in all cases when possible. In the second and third series, the access sheath was retracted together with the flexible ureteroscope, thus preventing the damages, which its distal part may inflict on the flexed endoscope. A total of 406 procedures were performed on 372 patients: first endoscope used on 96 procedures (90 patients), second one on 151 procedures (139 patients), and third one on 159 procedures (143 patients). Ureteral access sheath was used in 71.4% of the cases. The first endoscope was used for 67.1 hours, the second for 107.7 hours, and the third one for 107.2 hours. Major repairs were needed after significant damages of the outer coating (first endoscope) and severe deterioration of the deflecting mechanism (second and third endoscopes). The digital Storz Flex-Xc seems to be a durable model of flexible ureteroscope. The use of ureteral access sheath and avoidance of overstressing the deflection mechanism by relocating lower pole stones seem to offer substantial advantages in prolonging the lifespan of these expensive instruments. UROLOGY -: -e-, 2014. 2014 Elsevier Inc.
F
lexible ureteroscopy is probably one of the most important additions in modern endourology. During the last decades, the initial very fragile and difficult to maneuver endoscopes were the subject of numerous innovations and technological developments, becoming very useful diagnostic and therapeutic instruments in upper urinary tract pathology. The improved durability, substantial miniaturization, and the introduction of digital endoscopes were the main goals while aiming to increase the efficacy of this type of procedures. Nowadays, flexible ureteroscopy is a routinely used method in many centers. However, despite the recent achievements, there is still room for further improvements of these instruments and of the respective techniques. In this regard, increasing the lifespan of an expensive endoscope is a worthwhile purpose. The aim of our study was to retrospectively analyze the flexible ureterorenoscopies performed with the Storz Flex-Xc digital flexible device and to evaluate its durability and possible ways to prolong its lifespan. Financial Disclosure: The authors declare that they have no relevant financial interests. From the Department of Urology, Saint John Clinical Emergency Hospital, Bucharest, Romania Reprint requests: Razvan Multescu, M.D., Ph.D., Department of Urology, Saint John Emergency Clinical Hospital, Vitan-Barzesti 13, Sector 4, 042122 Bucharest, Romania. E-mail: [email protected] Submitted: August 25, 2013, accepted (with revisions): January 18, 2014
ª 2014 Elsevier Inc. All Rights Reserved
MATERIALS AND METHODS Between May 2012 and May 2013, all the flexible ureteroscopic procedures performed with 3 new Storz Flex-Xc digital flexible ureteroscopes were analyzed. The 3 endoscopes were used consecutively, each being new when its usage period started. The flexible ureteroscopic approach was performed by a single expert urologist (G.P.), with more than 1000 flexible ureteroscopies performed in the past and previous experience with this particular endoscope model. It was applied for diagnostic purposes, treatment of upper urinary tract urothelial tumors, or urolithiasis. All procedures were performed in a standardized manner starting with the passing of a Teflon-coated guide wire in the collecting system and the ureteral dilation when necessary. This last maneuver was applied mostly in relation with ureteral access sheath use and was performed using progressive size ureteral dilators or the access sheath itself. The endoscope insertion was simple, on the guide wire, for the diagnostic procedures and small calculi, whereas in cases of tumor formations and larger urolithiasis, it was preceded by the indwelling of a 12/14F or 10/12F Flexor Cook ureteral access sheaths. The relocation of stones situated in the lower pole was performed in all cases in which it was possible. The only procedural difference between the series was that in the second and the third one, the access sheath was retracted together with the endoscope, thus preventing the damages, which its distal part may inflict on the flexible ureteroscope. In that regard, precautions were taken to keep the entire deflectable tip of the 0090-4295/14/$36.00 http://dx.doi.org/10.1016/j.urology.2014.01.021
1
Table 1. Intraoperative characteristics of the 3 studied groups Studied Parameter Number of procedures Diagnostic procedures Mean operative time for diagnostic procedures Treatment procedures Mean operative time for treatment procedures Mean lower pole time for treatment procedures Deflection loss (up/down)
Group I
Group II
Group III
96 8 8 88 45 8 32.8/54.1%
151 24 10 127 49 12 34.5/56.7%*
159 25 11 134 48 14 33.3/58.5%*
* Before the last ureteroscopy (during the last intervention deflection was completely lost).
endoscope outside the distal part of the access sheath when extraction was performed. After the procedure, the endoscope was washed, cleaned, and stored with the flexible segment straight, in the case provided by the manufacturer. The sterilization method applied was complete immersion in and flushing of the working channel with Cidex.
RESULTS In a interval of 13 months, a total of 406 procedures were performed on 372 patients: 96 procedures on 90 patients using the first flexible ureteroscope, 151 procedures on 139 patients using the second one, and 159 on 143 patients using the third one (Table 1). The procedures were performed for diagnostic purposes in 57 cases (8 in the first series, 24 in the second, and 25 in the third one), upper urinary tract urothelial tumors treatment in 5 cases (1 in the first series, 2 in the second and third ones), and urolithiasis in 344 cases (87 in the first series, 125 in the second, and 132 in the third one). The ureteral access sheath was used in 68.2% of the first group, in 74.8% of the second one, and in 70.4% of the third. Eleven percent of the patients were already prestented when the flexible ureteroscopic approach was attempted. Owing to difficulties to ascend the ureteral access sheath, a supplementary 8% of the cases were also prestented, and the procedure was postponed for 7 days. Lithotripsy with a Dornier Medilas H20 Holmium: YAG laser (Dornier MedTech, Wessling, Germany) with a 270-mm fiber was applied in 90.7% of the lithiasis cases (312 cases, 83 cases with the first ureteroscope, 118 cases with the second one, and 111 with the third one). The mean number of pulses was 6945, whereas the mean energy used was 5490 J. The tipples baskets were used in 79.4% of the lithiasis cases (273 cases) to relocate stones and/or extract fragments resulted from intracorporeal lithotripsy. Lower pole stones were encountered in 31.4% of urolithiasis cases (108 patients, 32 treated with the first ureteroscope, 39 with the second one, and 37 with the third one), relocation before lithotripsy being performed in 77.1% of them (81 patients, 23 treated with the first endoscope, 28 with the second one, and 30 with the third one). In the rest of the cases, laser lithotripsy in situ in the lower calyx was performed, at least until extractable stone fragments were achieved. The first endoscope was used for 67.1 hours (mean procedural time of 8 minutes for diagnostic ones and 2
45 minutes for therapeutic ones), whereas the second one lasted for 107.7 hours (mean procedural time of 10 minutes for diagnostic ones and 49 minutes for therapeutic ones), and the third one for 107.2 hours (mean procedural time of 11 minutes for diagnostic ones and 48 minutes for therapeutic ones). The first flexible ureteroscope required major repairs after significant damages of the outer coating, at the distal end, in the region of the deflectable tip. The wearing of a short segment at the distal part of the outer coating (Fig. 1) was observed during postoperative processing of the endoscope after the 72nd procedure and aggravated progressively during the following interventions. A careful analysis identified the site of the damage as the point of significantly traumatic contact between the flexible ureteroscope and the distal margin of the ureteral access sheath during endoscope retraction. After the 96th procedure, a complete section of the outing coating was recorded. Owing to this incident, during the use of the second and third flexible ureteroscopes, a decision to retract en bloc the endoscope and the ureteral access sheath has been taken. The second and third ones registered a severe deterioration of the deflecting mechanism. Interestingly, although the number of interventions and total operating time was higher in the second and third groups, deflection loss of the 3 endoscopes was similar until deflection capabilities of the second and third ureteroscopes were completely lost.
COMMENT The aim of our study was to analyze the durability of Storz Flex-Xc digital flexible ureteroscope and possible ways to prolong its lifespan, in the circumstances of also applying the previously learned lessons, both from our experience and published literature. The increased fragility was a problem linked from the very beginning with the flexible ureteroscopes. Pietrow et al1 reported in 4 models of Olympus flexible ureteroscopes an average number of 27.5 procedures per instrument (range, 19-34). That was a significant improvement from the first models of such endoscopes, which required repair after an average number of 6-15 uses, however, still remaining insufficient for such an expensive endoscope. Owing to the technological advances, the newer fiberoptic flexible ureteroscopes demonstrated a superior UROLOGY
-
(-), 2014
Figure 1. Position and aspect of the perforation of the outer coating. (Color version available online.)
durability. In addition, these models seemed to be associated with a higher success rate by comparison with their predecessors, the general advice being to switch to these latest generation devices.2 In this regard, Traxer et al3 published a report in which the Storz Flex-Xc was used for 50 procedures with an average operating time of 95 minutes. It is important to mention that the endoscope required a repair after a laser perforation of the working channel, which is an intraoperative accident independent of the number and duration of the previous interventions. Another study using the same endoscope reported 113 and 102 procedures, respectively, the most common causes of damage being represented by the deflection mechanism impairment, inner sheath damage, and fiberoptic bundle breaks.4 Both these studies used Cidex chemical sterilization of the endoscopes, similar to our own experience. However, a comparative evaluation of different cleaning and sterilization methods seems to demonstrate no influence of the technique and/or number of personnel involved in the maintenance of the flexible ureteroscope over durability and function of these instruments.5 The introduction of digital flexible ureteroscopes removed the fiberoptic bundle breakage from the list of possible repair motives. For this reason and also because of the continuous technological development, they offered the perspective of an increased durability together with an undisputed significantly improved visibility and image quality.6,7 Using the URF-Vo digital model from Olympus, Traxer et al reported a number of 60 uses, during which the maximal deflection decreased from 275 to 217 .8 Regarding the suspected intermanufacturers variability, a study of 4 older models emphasized a similar durability.9 However, larger prospective studies are needed to document any potential significant differences between the newer digital flexible ureteroscopes. Our series recorded a still unsurpassed number of procedures before major repairs (at least in the published UROLOGY
-
(-), 2014
literature). Although the mean operating time for therapeutic interventions was somewhat reduced by comparison with the study by Delfidio et al4 and significantly lower by comparison with the study by Traxer et al,3 our total procedural time in the second and third groups is significantly higher than in both of them. This was achieved under the circumstances of very attentive manipulation both by the urologist during the endourologic interventions and the operating room personnel during cleaning, sterilization, and storage maneuvers. We also applied lessons learned from our previous experience and published articles, such as avoiding an increased lower pole time by relocating the stone. Another significant parameter in improving the durability of flexible ureteroscopes was related to the use of ureteral access sheaths. It was advocated that their use increases the instruments’ lifespan by reducing the resistance during insertion and consequently the stress at the tip of the instrument.3 Using this device, the speed of instrument degradation (loss of maximal loss, deformation of the working segment, and so forth) may be decreased. For this reason and also to simplify the stone fragment extraction, we chose to frequently use the ureteral access sheath. Another advantage is that it maintains a low pressure in the collecting system, useful both during the procedures for urolithiasis or tumors.4 In the present series, the access sheath was used more frequently than in the previously cited studies: Delfidio et al reported the use of such instruments in 25% of the cases and Traxer et al in 58% of the cases by comparison with 72% in our therapeutic cases.3,4 However, our preference for the use of this device is not an isolated exception. Another study of Miernik et al10 describing a standardized flexible ureteroscopic technique reports its use in 71% of the cases. The potential reticence concerning the routine use of ureteral access sheaths is related to the increase in costs and intraoperative morbidity, combined with the potential to generate ureteral strictures because of the ischemic effect.11 In this regard, we consider that a significantly prolonged lifespan of a very expensive flexible ureteroscope positively balances the increased cost of a procedure in which such a sheath is used. The potential morbidity associated with access sheath insertion is a reality. The article of Traxer and Thomas12 assessing such problems reported a 46.5% complication rate, of which 13.3% being severe ones involving smooth muscle layers. The predictors of ureteral injuries were male sex, older age, and, the most significant one, absent previous ureteral stenting. In our study, no supplementary significant complications were related to the access sheath insertion. However, while trying to avoid such issues in our series, when difficulties were encountered during this process, the procedure was stopped, the patient was stented, and the flexible ureteroscopic approach was tempted again after 1 week. Regarding the development of ureteral strictures because of ureteral trauma or ischemic suffering, although theoretically possible, this risk was never consistently proven.13 3
The observation that the reason for major repairs in the first ureteroscope was constituted by the deterioration of the outer cover near the tip led to the hypothesis that such damages may be related to the mechanical contact between the distal end of the access sheath and the slightly deflected endoscope. Consequently, in the second and third groups, the ureteroscope was extracted en block with the access sheath. In the respective series, no such damages of the outer sheath were recorded, and this may be the reason for a significantly prolonged lifespan (or to avoid the risk of a potential accident that may abruptly interrupt the utilization period).
CONCLUSION The digital flexible ureteroscope Storz Flex-Xc proved increased durability, being used during a high number of procedures until needing any major repairs. Wearing of the outer coating during multiple procedures seems to be a previously unreported cause of ureteroscope damage. Thus we advise retracting the endoscope en bloc with the ureteral access sheath to prevent such deterioration. The significantly large number of ureteroscopies performed with each of this endoscopes is probably the cumulative effect of a much sturdier endoscope but also applying the previously learned lessons aiming to maximize the lifespan of these expensive instruments: correct and careful manipulation, cleaning or storage, use of ureteral access sheath, and avoidance of overstressing the deflection mechanism. Although there are still some problems to be solved, flexible ureteroscopes evolved during the last decades to become reliable endourologic instruments, effective in upper urinary tract diagnosis and treatment.
4
References 1. Pietrow PK, Auge BK, Delvecchio FC, et al. Techniques to maximize flexible ureteroscope longevity. Urology. 2002;60:784-788. 2. Wendth-Nordahl G, Mut T, Krombach P, et al. Do new generation ureterorenoscopes offer a higher treatment success than their predecesors? Urol Res. 2011;39:185-188. 3. Traxer O, Dubosq F, Jamali K, et al. New-generation flexible ureterorenoscopes are more durable than previous ones. Urology. 2006; 68:276-281. 4. Defidio L, De Dominicis M, Di Gianfrancesco L, et al. Improving flexible ureterorenoscope durability up to 100 procedures. J Endourol. 2012;26:1329-1334. 5. McDougall EM, Alberts G, Deal KJ, et al. Does the cleaning technique influence the durability of the
