FLEXIBLE URETEROSCOPES: A SINGLE CENTER EVALUATION OF THE DURABILITY AND FUNCTION OF THE NEW ENDOSCOPES SMALLER THAN 9Fr:

How to evaluate a flexible ureterorenoscope? Systematic mapping of existing evaluation methods

Objectives

The objective of this study was to identify, map and review scope‐related and user‐related parameters used to evaluate the quality of flexible ureterorenoscopes. Thereby identifying key items and variability in grading systems.

Methods

A literature search of four databases (MEDLINE [Ovid], EMBASE [Ovid], Web of Science, Google scholar and the Cochrane Library) was performed according to the Preferred Reporting Items for Systematic Reviews and Meta‐Analyses guidelines encompassing articles published up to August 2020. A total of 2386 articles were screened.

Results

A total of 48 articles were included in this systematic scoping review. All studies had a prospective design. Five key items in the assessment of flexible ureterorenoscopy were distinguished: ‘Manoeuvrability’ (87.5%), ‘Optics’ (64.6%), ‘Irrigation’ (56.3%), ‘Handling’ (39.6%) and ‘Durability’ (35.4%). After regrouping, every key item could be divided into specific subcategories. However, the quality assessment showed a wide variation in denomination, method of measurement, circumstances of measurement, tools used during measurements, number of measurements performed, number of observers, and units of outcomes.

Conclusion

The research field regarding quality assessment of ureterorenoscopes is heterogeneous. In this systematic scoping review we identified five key parameters: Manoeuvrability, Optics, Irrigation, Handling and Durability, used to grade flexible ureterorenoscopes. However, within these categories we found a wide variety in terms of method of measurements. A standardised, uniform grading tool is required to assess and compare the quality of flexible ureterorenoscopes in the future.

Minimally invasive urology - Pearls, pitfalls and experience in the Caribbean

The Caribbean is made up of several independent nations and the availability of urology and more specifically endourology services varies widely between them. In this article we explore the history and current state of endourology in the English speaking Caribbean as well as the challenges faced within the region many of which are shared by the different territories.

Update on flexible ureteroscopy

OBJECTIVE

An update on ureteroscopy with focus on current technology and newer instrumentation is presented.

METHODS

A literature search through Medline-indexed journals as well as personal comments are included in this review. Topics such as new semirigid and flexible ureteroscopes, lasers, ureteral access sheats, wires and stone extraction devices are outlined.

RESULTS

Thanks to the continuous advances of technology and miniaturization of instruments, ureteroscopy is an ever-expanding field. A clear outline of the available instruments and techniques with reference to published results catches the status of this dynamic field.

CONCLUSIONS

Urologists are faced with a host of new products related to ureteroscopy every year. This review serves to identify the most useful and proven advances in the field and helps in selecting the equipment needed for a successful minimally invasive approach to upper urinary tract pathologies.

Evaluation of the mechanisms of damage to flexible ureteroscopes and suggestions for ureteroscope preservation

AIM

To investigate the causes and costs of flexible ureteroscope damage, and to develop recommendations to limit damage.

METHODS

The authors analysed repair figures and possible causes of damage to 35 instruments sent for repair to a leading UK supplier over a 1-year period, and calculated cost figures for maintenance of the instruments as opposed to repair and replacement costs.

RESULTS

All damages were handling-induced and therefore did not fall under the manufacturer's warranty: 28 % were damaged by misfiring of the laser inside the instrument; 72 %, mainly crushing and stripping of the ureteroscope shaft tube, were likely to have occurred during out-of-surgery handling, washing and disinfection. Seventeen (4 %) instruments were not repaired and consequently taken out of service due to the extensive costs involved. Eighteen (51 %) ureteroscopes were repaired at an average cost of 10 833 USD.

CONCLUSION

Damages to flexible ureteroscopes bear considerable costs. Most damages occur during handling between surgical procedures. Thorough adherence to handling procedures, and courses for theater staff and surgeons on handling flexible instruments may help to reduce these damages and prove a cost-saving investment. The authors provide a list of recommended procedural measures that may help to prevent such damages.

Semirigid ureteroscopy of the proximal ureter can be aided by external lower-abdominal pressure

BACKGROUND AND PURPOSE

Smaller semirigid ureteroscopes with large working channels and excellent optics are widely available. Ureteroscopic treatment of upper-ureteral stones has become increasingly popular, although flexible ureteroscopy is more frequently the method of choice. Access to the upper ureter with a semirigid ureteroscope (SR-URS) can be challenging and hazardous, especially when negotiating the iliac vessels. We sought to determine whether lower-abdominal pressure (LAP) facilitated SR-URS access to the upper ureter for safe laser lithotripsy.

PATIENTS AND METHODS

Thirty-two consecutive patients who underwent ureteroscopic management of upper- ureteral stones were evaluated. Twenty-four (75%) were male; seventeen (53%) had a right-sided stone. The mean largest stone diameter was 10.2 +/- 4.6 mm. These 32 patients were compared with a matched cohort of patients who underwent SR-URS procedures without the use of LAP.

RESULTS

Access to the upper ureter was possible in 30 patients (94%). The LAP was helpful in 18 patients (56%): it facilitated passage of the SR-URS in 16 patients (50%) and laser fiber placement in 11 cases (34%). Access to the upper ureter was possible in all women. The mean operative time was 54 minutes in the LAP group and 75 minutes in the matched cohort without LAP (P = 0.026). There were no significant deformities of the SR-URS and no complications.

CONCLUSIONS

Contrary to popular practice, the upper ureter can be accessed safely and efficiently with a 7.5F SR-URS in nearly all patients. Lower-abdominal pressure can be helpful to negotiate passage of the endoscope over the iliac vessels or to place the laser fiber on stones.

Ureteric access with flexible ureteroscopes: effect of the size of the ureteroscope

OBJECTIVE

To determine the optimum size of a flexible ureteroscope (FU) to minimize the need for ureteric dilatation.

MATERIALS AND METHODS

FUs from several different manufacturers and with different shaft diameters were used for ureteroscopy in adults. An initial attempt was made to pass one of the larger diameter FUs; if this was unsuccessful, the smaller 7.5 F FU was used. The results were reviewed retrospectively.

RESULTS

Flexible ureteroscopy was used in 115 consecutive patients at two different institutions. The ability to pass the FUs with no formal dilatation was directly related to the FU diameter. The rate of failing to pass with no formal dilatation was 37% for the 9.0 F, 8.5% for the 8.6 F, 5% for the 8.4 F and 0.9% for the 7.4 F ureteroscope.

CONCLUSION

Although other factors influence the overall effectiveness of the FU, the ability to pass FUs is directly related to their outer diameter. When only the ease of introduction is considered, the ideal ureteroscope outer diameter is 7.4 F.

Renal Stone Disease: The Urological Perspective

Percutaneous nephrolithotomy, extracorporeal lithotripsy and ureteroscopy have changed the face of urolithiasis. Open surgery is becoming extremely rare today. Nevertheless, the cooperation between nephrologist and urologist remains essential and is the only way to prevent recurrence.

Physical properties of flexible ureteroscopes: implications for clinical practice

BACKGROUND AND PURPOSE

Physical characteristics may be important in the performance of a flexible ureteroscope. This study evaluated the strength of the shaft and deflection mechanism of several instruments.

MATERIALS AND METHODS

Sequential loads were placed along the axis of downward deflection to measure the stiffness of the shaft and strength of deflection. Bending pressure was defined as the force required to deflect the tip of the ureteroscope 15 degrees from baseline. Buckling pressure was defined as the force that resulted in catastrophic bending (>90 degrees) of the shaft of the ureteroscope. Strength of deflection was defined as the force that resulted in loss of 10 degrees of active deflection.

RESULTS

Bending pressures were lower for the Olympus URF-P3 (6.4 g) and Wolf 7325.172 (6.0 g) ureteroscopes. Similarly, buckling pressures were lower for these two ureteroscopes (9.0 g and 11.6 g, respectively). The Wolf and Storz flexible ureteroscopes had stronger deflection mechanisms than the Olympus URF-P3 and the ACMI DUR-8.

CONCLUSIONS

This study demonstrates significant differences in ureteroscope strength. Higher buckling pressures may facilitate advancement of a ureteroscope over a guidewire but may impede secondary deflection. Lower bending pressures may facilitate passive intrarenal manipulation. Strength of deflection may impact the ability to maintain deflection with an instrument in the working channel.

Exaggerated primary endoscope deflection: initial clinical experience with prototype flexible ureteroscopes

OBJECTIVE

To increase the clinical usefulness of the actively deflectable flexible ureteroscope by making sequential changes in design and then using these prototypes clinically; and to develop a clinical series using the optimum prototype and contrast it with an extensive database of patients treated with the traditional flexible ureteroscope.

METHODS

A series of prototypic flexible ureteroscopes was developed and used clinically. The active deflection of the prototype ureteroscope was evaluated with and with no accessories in the working channel, and compared with a standard 7.5 F ureteroscope. Clinical data were then accrued and compared with a previously published database.

RESULTS

The progression of prototypes led to a final version which incorporated > 300 degrees primary active deflection, shaft miniaturization (8.4 F) and an increase in endoscope shaft stiffness. The prototype flexible ureteroscope had significantly greater active deflection than the standard ureteroscope, especially when working channel accessories were used. In all, 115 endoscopic procedures were carried out, the indications for which included endoscopic lithotripsy for distal calculi (51), treatment of upper tract urothelial carcinoma (27), diagnostic endoscopy (26) and retrograde endopyelotomy (three). No guidewire was required to place the flexible ureteroscope into the upper urinary tract in 27% of patients. Active intramural dilatation for access was only required in 3% of the procedures. All lower pole calyces were accessed with this instrument.

CONCLUSIONS

Adding exaggerated deflection is a timely advance in flexible ureteropyeloscopy. This and the other changes in design facilitated complex retrograde endoscopic procedures and increased the therapeutic potential of the instrument.

Are new-generation flexible ureteroscopes better than their predecessors?

OBJECTIVE

To compare two newly designed flexible ureteroscopes with their respective predecessors, to determine whether design advances have overcome the limitation of tip deflection, which may interfere with diagnosis and treatment of lower pole renal pathology.

MATERIALS AND METHODS

Two new-generation flexible ureteroscopes, the DUR-8 Elite (ACMI, Southborough, MA, USA) and 11278AU (Karl Storz Endoscopy, Culver City, CA, USA) were compared with their previous models, the ACMI DUR-8 and the Storz 11274AAU. Active tip deflection and irrigation flow rates with and without various endoscopic tools were assessed. Specifications, purchase prices and repair costs were obtained from each manufacturer. The field of view and screen image size of each ureteroscope were also compared.

RESULTS

The ACMI DUR-8 Elite and the Storz 11278AU had improvements of 79 degrees and 144 degrees, respectively, from their respective older models. Although the tip deflection of all ureteroscopes was compromised by inserting different endoscopic tools, these new instruments were less affected. With a 3 F basket inside the working channel, the ACMI DUR-8 Elite and the Storz 11278AU had only 0.7% and 2.8% loss of upward tip deflection, compared with their older models, at 9.6% and 5.0%, respectively. However, the flow rates of these new instruments were decreased.

CONCLUSION

The new flexible ureteroscopes have significantly better active tip deflection than previous models, both with and without endoscopic instrumentation inserted. However, improved flexibility is at the expense of decreased flow rates and higher purchase costs.

Transurethral ureterorenolithotripsy using new automated irrigation/suction system controlling pressure and flow compared with standard irrigation: a randomized pilot study

PURPOSE

To compare in a random fashion an automated irrigation/suction pump system with the standard pressurized technique during transurethral ureterorenolithotripsy.

PATIENTS AND METHODS

Between July 2001 and December 2001, 47 patients were prospectively included. Prior to randomization, rigid instruments were allocated to 25 patients (group R) and flexible instruments to 22 patients (group F) according to stone location. The groups R and F were then randomized separately, and the pressurized technique was employed in groups R1 and F1, while the automated system was employed in groups R2 and F2. Operative time, amount of liquid consumed, and stone-free rate at the end of the procedure were analyzed.

RESULTS

For the entire series, ureteroscopy time using the automated system (mean 42 +/- 17[SD] minutes; range 15-90 minutes) was 35% less than with the pressurized technique (mean 65 +/- 25 minutes; range 20-135 minutes) (P = 0.04 Wilcoxon score). The stone-free rate was significantly higher in groups R2 + F2 (92%) than in groups R1 + F1 (69%) (P = 0.048).

CONCLUSION

With the ENDO FMS UROLOGY system, there was a significant reduction in the mean ureteroscopy time: 32% less with the rigid instrument and 53% less with the flexible instrument. This seems to be attributable to a wider working space and highly improved visibility. The integrated suction at constant flow allows efficient evacuation of stone fragments while limiting cavity pressure. These results, obtained on 47 patients, should be confirmed by larger randomized studies.