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

Comparison of the mechanical, flow, and optical properties of contemporary flexible ureteroscopes

OBJECTIVES

New designs have improved the ability of flexible ureteroscopes to assess the upper urinary tract. However, limitations of tip deflection may interfere with diagnosis and treatment of lower pole renal pathologic features and smaller working channels may impair irrigant flow. Our purpose was to compare the new flexible ureteroscopes with prior models to determine whether engineering advances have overcome these problems.

METHODS

Two newly released flexible ureteroscopes, the ACMI DUR-8 Elite and the Storz 11278AU, were compared with four other ureteroscopes, the ACMI DUR-8, Storz 11274AAU, Olympus URF-P3, and Wolf 9F. Active tip deflection, irrigation flow rates, and intraluminal pressures with and without various endoscopic tools were assessed. The specifications, purchase prices, and repair costs were obtained from the individual manufacturers. Also, the field of view and screen image size of each scope were compared.

RESULTS

The ACMI DUR-8 Elite and Storz 11278AU had improved tip deflection of 79 degrees and 144 degrees, respectively, from previous ureteroscopes. Although the tip deflections of all ureteroscopes were compromised by the insertion of endoscopic tools, new ureteroscopes were less affected. With a 3F basket within the working channel, the ACMI DUR-8 Elite and the Storz 11278AU had a loss of downward deflection of only 0.7% and 2.8% compared with a loss of 9.6% and 5.0% for their older models, respectively. However, the flow rate of these new instruments was decreased.

CONCLUSIONS

The new flexible ureteroscopes have significantly better active tip deflection than previous models, both with and without endoscopic instrumentation inserted. However, improved flexibility comes at the expense of a decreased flow rate.

Open mini-access ureterolithotomy: the treatment of choice for the refractory ureteric stone?

OBJECTIVE

To report the experience in one centre of the efficacy and safety of open mini-access ureterolithotomy (MAU) and to discuss relevant current indications.

PATIENTS AND METHODS

MAU was undertaken in 112 patients (mean age 38 years, range 26-57) between 1991 and 2001; the details and outcomes are reviewed. The mean (range) stone size was 12 (8-22) mm, with 30 stones in the upper, 69 in the mid- and 13 in the lower ureter. In 15 cases the stones were impacted and there were signs of infection in the proximal ureter.

RESULTS

MAU was successful in 111 patients; the one failure was caused by proximal stone migration early in the series. The mean (range) operative duration was 28 (10-44) min and the hospital stay 42 (24-72) h; 33 patients were in hospital for 24 h, 72 for 48 h and seven for 72 h. The blood loss was minimal, at 50 (30-150) mL. The drain was removed after 5 (5-7) days. Patients reported using opioid or nonsteroidal anti-inflammatory analgesia for a mean of 4 (1-7) days after surgery. The mean time to resumption of work was 16 (8-35) days.

CONCLUSIONS

MAU is a safe and reliable minimally invasive procedure; its role is mainly confined to salvage for failed first-line stone treatments but in selected cases, where a poor outcome can be predicted from other methods, it is an excellent first-line treatment.

Evaluation of overall costs of currently available small flexible ureteroscopes

OBJECTIVES

To perform a meta-analysis of the currently available data regarding the durability of flexible ureteroscopes to establish cost estimates for the purchase and use of five currently available, smaller than 9F, ureteroscopes. Healthcare costs have become increasingly germane to the determination of disease management strategies. Improved ureteroscope technology has expanded the role of these instruments. However, the initial purchase costs and high maintenance costs have become problematic with these fragile instruments.

METHODS

Ureteroscope durability data on the Storz 11274AA, Olympus URF-P3, Wolf 7325.172, ACMI AUR-7, and ACMI DUR-8 were collected from three prior studies. Combining the durability data and cost data regarding the initial purchase price and maintenance costs of these instruments, we calculated the overall costs associated with the use of each of the ureteroscopes for 25, 50, 75, and 100 cases during the first year (warranties included) and with subsequent use.

RESULTS

The variability in the costs associated with the use of the currently available smaller than 9F ureteroscopes was significant. The initial instrument purchase price, durability, repair costs, and associated warranties all contributed to large discrepancies in the cost of performing ureteroscopy. In this model, during the first year of ownership, the projected cost of performing 100 ureteroscopic cases varied by a difference of 95% depending on the ureteroscope used.

CONCLUSIONS

Physicians and institutions that perform ureteroscopy should strongly consider the purchase price, durability, repair cost, and associated warranties before the purchase of small flexible ureteroscopes.

Ureteroscopy: effect of technology and technique on clinical practice

PURPOSE

Technical advances in ureteroscopy allow for more aggressive management of upper tract pathology. We evaluate to what extent clinical practice and treatment efficacy have been impacted by improvements in technology and technique.

MATERIALS AND METHODS

In 1998, 176 consecutive patients underwent 182 ureteroscopic procedures at our institution. Retrospective chart review was performed. Factors such as clinical indication, pathology location, type of ureteroscope, procedure duration, procedure success, complication rate and length of stay were evaluated. Data from the 1998 cohort were compared to those obtained from a cohort of patients from 1992. Statistical analysis was performed using chi-square test.

RESULTS

Overall stone extraction rate was 94.4% (1992) vs 88.5% (1998) (p = 0.05). Proximal stones were treated in 13.5% (1998) vs 28.3% (1998) of cases. Distal stone extraction rate was 97.2% (1992) vs 95.1% (1998) (p = 0.43) and proximal stone extraction rate was 76.5% (1992) vs 71.9% (1998) (p = 0.73). Diagnostic inspection success rate was 98.3% (1992) vs 98.3% (1998). Use of flexible ureteroscopy was 11.5% (1992) vs 29.4% (1998). Complication rate was 12% (1992) vs 10.2% (1998) (p = 0.76). Of the cases 76.1% were outpatient in 1998 vs only 50% in 1992.

CONCLUSIONS

Recent advances in ureteroscopic technology permit more aggressive instrumentation of the upper tract as reflected in higher use of flexible ureteroscopy and more frequent attempts to manage proximal ureteral calculi. These advances have not translated into better efficacy of calculus treatment. Furthermore, our data reflect a nationwide trend toward outpatient treatment.

Techniques to maximize flexible ureteroscope longevity

OBJECTIVES

To assess methods to improve the longevity and durability of flexible ureteroscopes by using the ureteral access sheath, 200-microm holmium laser fiber, and nitinol baskets or graspers during routine ureteroscopic procedures. Despite adequate advances in fiberoptics and endoscope design, the decreased size of currently available flexible ureteroscopes makes damage inevitable after repeated use. However, new auxiliary tools may be able to enhance ureteroscope durability.

METHODS

The indications for performing flexible ureteroscopy were proximal ureteral stones (n = 32), renal calculi (n = 59), treatment of upper tract transitional cell carcinoma (n = 3), evaluation of hematuria or filling defect (n = 7), and treatment of ureteral strictures or ureteropelvic junction obstruction (n = 8). Using four new 7.5F flexible ureteroscopes, we prospectively evaluated the number of passes of each ureteroscope until more than 20 optical fibers were broken, more than a 25 degrees loss of deflection in either direction had occurred, or the instrument sustained injury requiring repair by the manufacturer.

RESULTS

One hundred nine flexible ureteroscopic procedures (average 27.5 procedures per instrument; range 19 to 34) were performed with the four new flexible ureteroscopes before being sent for repair. Adjuncts to reduce scope damage during these procedures were the use of the ureteral access sheath (n = 109), nitinol devices allowing lower pole stone retrieval (n = 27), and the 200-microm holmium laser fiber for stone fragmentation, tumor ablation, and incision of ureteropelvic junction/ureteral stenoses (n = 91). The average number of passes until more than 20 optical fibers were broken was 15.3 (range 12 to 20), until more than a 25 degrees loss of deflection occurred was 50.3 (range 42 to 66), or until the scope required repair was 66.7 (range 46 to 82).

CONCLUSIONS

Flexible ureteroscopy will be used increasingly to manage upper urinary tract pathologic findings. Historically, the number of procedures performed before a flexible ureteroscope requires repair averaged 6 to 15. By incorporating the new ureteroscopic accessories, such as nitinol devices, a ureteral access sheath, and the 200-microm holmium laser fiber into common practice, one can reduce the strain on these fragile 7.5F endoscopes, thereby maximizing their longevity.

Assessment of basic endoscopic performance using a virtual reality simulator

BACKGROUND

The objective of this study was to evaluate the effect of supervised training using a state-of-the-art virtual reality (VR) genitourinary endoscopy simulator on the basic endoscopic skills of novice endoscopists.

STUDY DESIGN

We evaluated 21 medical students performing an initial VR case scenario (pretest) requiring rigid cystoscopy, flexible ureteroscopy with laser lithotripsy, and basket retrieval of a proximal ureteral stone. All students were evaluated with objective parameters assessed by the VR simulator and by two experienced evaluators using a global rating scale. Students were then randomized to a control group receiving no further training or a training group, which received five supervised training sessions using the VR simulator. All students were then evaluated again in the same manner using the same case scenario (posttest).

RESULTS

Comparing the results of pre- and posttests, no major differences were demonstrated for any variable in the control group. In the trained group, posttest results revealed statistically significant improvement from baseline in the following parameters: total procedure time (p = 0.002), time to introduce a ureteral guidewire (p = 0.039), self-evaluation (p < 0.001), and evaluator assessment (p < 0.001). Comparing the posttest results of the control and trained arms, we found significantly better posttest scores in the trained group for the following parameters: ability to perform the task (p = 0.035), overall performance (p = 0.004), and total evaluator score (p < or = 0.001).

CONCLUSIONS

Students trained on the VR simulator demonstrated statistically significant improvement on repeat testing, but the control group showed no improvement. Endourologic training using VR simulation facilitates performance of basic endourologic tasks and might translate into better performance in the operating room.

Flexible ureteroscopes: a user's guide

OBJECTIVE

To compare, quantitatively and qualitatively, four small-diameter flexible ureteroscopes.

MATERIALS AND METHODS

Four flexible ureteroscopes from different manufacturers, i.e. the DUR-8 (ACMI, Southborough, MA, USA), Olympus UPF-3 (Keymed, Southend-on-Sea, UK), Storz 11274AA (Karl Storz GmbH, Tuttlingen, Germany) and the Wolf 9 F (Henke Sass Wolf GmbH, Tuttlingen, Germany), were assessed quantitatively by measuring the active tip deflection and irrigation flow rate with laser fibres (200 micro m, 365 micro m), an electrohydraulic lithotripter (1.9 F) and grasping forceps (3 F) in position. They were then assessed subjectively by two endourologists who scored them, using a visual analogue scale (maximum 10), for insertion, deflection mechanism, manoeuvrability, rigidity, image quality and overall satisfaction.

RESULTS

All the endoscopes are < 9 F at the tip, although the length of the smallest diameter (bevelled tip vs section of shaft) was variable. Tip deflection was 87-100% of the manufacturers' specifications and decreased by similar percentages with instruments in the working channel. The irrigation flow rate was comparable for instruments with a 3.6 F working channel (72-88 mL/min with an empty working channel), although much greater for the Wolf, which has a 4 F channel (116 mL/min). Direction and image size were nearly identical, as was the field of view, apart from the Wolf (60 degrees vs 90 degrees ). There was agreement in the user assessment for three instruments, with overall satisfaction scores being Storz (4), ACMI (7.5) and Olympus (8.6), but disagreement in scores for Wolf (1.9 vs 5.3).

CONCLUSIONS

Whilst there were considerable similarities in the objective assessment among the instruments, the user assessment showed qualitative variability. Thus it is important to try the different instruments before selecting one. Additional variables to consider include durability, cost and service/warranty, which vary considerably among instruments.

A 10-year experience of managing ureteric calculi: changing trends towards endourological intervention--is there a role for open surgery?

OBJECTIVES

To study changing practices in the management of ureterolithiasis with the introduction of newer technologies, the efficacy and safety of endourology, extracorporeal shock wave lithotripsy (ESWL) and open surgery, and to determine if any indication remains for open ureterolithotomy in a tertiary endourology unit.

PATIENTS AND METHODS

A 12-year retrospective review (1987-1998) was conducted of all primary ureteric stones treated by ESWL, endoscopy, intracorporeal shock wave lithotripsy (ISWL) administered via ureteroscopy, and open surgery.

RESULTS

In all, 1195 patients were treated for primary ureteric stones, 44% by ESWL, 37% by ureteroscopy and ISWL, and 20% by open surgery. At the 3-month follow-up the stone-free rates for ESWL monotherapy, ureteroscopy and open surgery were 95%, 85% and 97%, giving an efficiency quotient of 73%, 64% and 94%, respectively. The overall complication rate for ESWL was 13%, for ISWL 32% and for open surgery 13%, but the complications of open surgery were often serious and potentially life-threatening.

CONCLUSIONS

With recent advances in endourology the indications for open surgery have decreased considerably, from 26% in 1987-95 to 8% in 1996-98. However, the remaining indications for open ureterolithotomy include failure of less invasive modalities, the presence of medical/anatomical abnormalities, a concomitant open procedure, and the presence of large impacted calculi for which patients prefer to avoid multiple procedures.