Flexible ureteroscopy update: indications, instrumentation and technical advances

Unfavorable factors in accessing the pelvicalyceal system during retrograde flexible ureteroscopy (fURS)

Flexible ureteroscopy (fURS) is a well-established procedure for treating multiple upper-urinary tract pathologies, particularly renoureteral lithiasis. Endoscopes have undergone significant advancements, including miniaturization, improved optics, and increased maneuverability. In addition, advancements in accessory instruments, such as the performance of laser fibers, guidewires, and extraction probes, have played a significant role in improving the overall performance of flexible ureteroscopy procedures. However, despite these advancements, unique circumstances can make achieving optimum results during flexible ureteroscopy challenging. These include congenital renal anomalies (horseshoe kidneys, ectopic kidneys, rotation anomalies), as well as the unique intrarenal anatomy (infundibulopelvic angle, infundibular length) or the specifications of the endoscope in terms of maneuverability (active and passive deflection). This review explored challenging scenarios during flexible ureteroscopy procedures in the pyelocaliceal system.

Comparison of single-use flexible ureteroscopes with a reusable ureteroscope for the management of paediatric urolithiasis

INTRODUCTION

To compare the efficacy, side effects, and cost-effectiveness between a single-use digital flexible ureteroscope and a reusable flexible ureteroscope in the treatment of paediatric renal stones.

METHODS

This analytic, case-control, monocentric study included all patients undergoing flexible ureterosopies for stone treatment. Between April 2016 and February 2019, a reusable (Flex-X^C®, Karl Storz) flexible ureteroscope was used (control group), whereas a single-use (Uscope®, PUSEN Medical©) flexible ureteroscope was used in all procedures from March 2019 to April 2021. Clinical and procedural outcomes, operative times, complication rates, hospital stay, and costs per procedure were evaluated.

RESULTS

Forty-three cases using a reusable flexible ureteroscope and thirty-nine using a single-use flexible ureteroscope were included in the study. Demographic patient characteristics, stone burden, location and composition, preoperative presence of a double-J stent, procedural outcomes, mean length of postoperative hospital stay, and complications (4.6% versus 5%, p = 0.81) were comparable between the two groups. Median operative duration for stone removal was 93 min (20-170) with reusable versus 81 min (55-107) with the single-use scope (p = 0.18). Scope failure occurred four times with the reusable scope and in no case with the single-use. The total cost per procedure associated with the use of single-use scopes (798 Euros) was lower than a reusable scope (1483.23 Euros).

DISCUSSION

Single-use flexible ureteroscopes were created to bypass the problems incurred when reusable scopes were damaged and therefore not available for use in surgical procedures. Single-use flexible ureteroscopes are always immediately available and ready to be used, even in urgent cases, as they typically do not require maintenance or sterilization. Compared with their reusable counterparts, single-use flexible ureteroscopes have similar digital performance (270°), image quality and we found no difference in the success and complication rates. Cost analysis of a reusable flexible ureteroscope must consider the purchase price, maintenance and repair costs, and decontamination costs (including handling, detergent, bacterial culture, transportation, and storage costs). In contrast, only purchase price is included in cost analysis for single-use flexible ureteroscopes. Our study suggests that single-use flexible ureteroscopes may be associated with lower costs per procedure than their reusable counterparts.

CONCLUSION

Single-use flexible ureteroscopes are an interesting alternative to their reusable counterparts, particularly in terms of material resource management. Cost analyses conducted using a low volume of cases representative of a paediatric urology division favour the use of single-use ureteroscopes.

Image Distortion During Flexible Ureteroscopy: A Laboratory Model Comparing Super Pulsed Thulium Fiber Laser vs High-Power Ho:YAG Laser

Purpose: Digital ureteroscopes employ "chip-on-the-tip" technology that allows for significant improvement in image resolution. However, image distortion often occurs during laser lithotripsy owing to acoustic wave production. We sought to compare image distortion using different laser power settings and distances from the laser fiber tip to the scope for the Super Pulsed Thulium Fiber (SPTF) laser and high-power Holmium:YAG (Ho:YAG) laser. Materials and Methods: Ureteroscopy was simulated using a silicon kidney-ureter-bladder model fitted with a 12F/14F access sheath and the Lithovue™ (Boston Scientific), disposable digital flexible ureteroscope. At defined laser parameters (10, 20, 30 and 40 W, short pulse), a 200-μm laser fiber was slowly retracted toward the tip of the ureteroscope during laser activation. Image distortion was identified, and distance from the laser tip to the scope tip was determined. Data from the two lasers were compared utilizing t-tests. Results: After controlling for frequency, power, and laser mode, utilizing 1.0 J of energy was significantly associated with less feedback than 0.5 J (-0.091 mm, p ≤ 0.05). Increased power was associated with larger feedback distance (0.016 mm, p ≤ 0.05); however, increase in frequency did not have a significant effect (-0.001 mm, p = 0.39). The SPFT laser had significantly less feedback when compared with all Holmium laser modes. Conclusions: Increased total power results in image distortion occurring at greater distances from the tip of the ureteroscope during laser activation. Image distortion occurs further from the ureteroscope with Ho:YAG laser than with SPTF fibers at the same laser settings. In clinical practice, the tip of the laser fiber should be kept further away from the tip of the scope during ureteroscopy as the power increases as well as when utilizing the Ho:YAG system compared with the SPTF laser platform. The SPTF laser may have a better safety profile in terms of potential scope damage.

Sheathless and fluoroscopy-free retrograde intrarenal surgery: An attractive way of renal stone management in high-volume stone centers

Objective

To evaluate the efficacy and safety of sheathless and fluoroscopy-free flexible ureterorenoscopic laser lithotripsy (FURSL) for treating renal stones.

Methods

Between May 2015 and May 2017, 135 patients with renal stones treated with sheathless and fluoroscopy-free FURSL were prospectively evaluated. Our technique involved a semi-rigid ureteroscopic assessment of the ureter, and the guidewire was left in situ to railroad the flexible ureteroscope. A holmium laser was used to fragment and dust the stones; fragments were neither grasped nor collected.

Results

The study population consisted of 135 patients including 85 males (62.96%) and 50 females (37.04%) with a mean age of 40.65 years (range: 3–70 years) were evaluated. The mean stone size was 17.23 mm (range: 8–41 mm). Complete stone-free status was achieved in 122 (90.37%) patients and clinically insignificant residual fragments (CIRF) in two (1.48%), while residual stones were still present in 11 (8.15%) patients. Postoperative complications occurred in 23 (17.4%) cases and were mostly minor, including fever in 17 (12.6%), pyelonephritis in four (3.0%), subcapsular hematoma in one (0.7%) and steinstrasse in one (0.7%). These complications were Clavien I-II, GI in 17 (12.6%) patients, GII in five (3.7%), and Clavien IIIb in one (0.7%). No major complications were observed. Stone size ≥2 cm, operative time ≥30 min, and lasing time ≥20 min were significantly associated with a higher rate of complications and lower stone-free rates upon univariate analysis (p<0.05).

Conclusion

Sheathless and fluoroscopy-free FURSL are effective and safe for renal stone management, especially for stones under 2 cm in diameter. This process is a feasible option for avoiding sheath complications, which can protect surgeons from the negative effects of radiation.

Surgical technique to achieve high durability of flexible ureteroscopes: A single hospital experience

Background

To describe a novel operative technique resulting in extended durability and improved ease of use of current flexible ureteroscopes (FURS). A surgical method employing a modified technique of using an Olympus digital flexible URF-V ureteroscope was developed.

Methods

We retrospectively studied 546 patients who underwent retrograde intrarenal surgery (RIRS) using this modified approach performed by a single surgeon at our hospital, and investigated the outcome and durability of the ureteroscope.

Results

Through the study period, the URF-V ureteroscope required repair five times in total. During factory maintenance, distal working channel damage was noted twice, and outer bending rubber damage was noted once. The most recent two repairs were required due to laser penetration. Despite the damage and repairs, the deflection system was almost entirely intact after high-frequency use. The durability of FURS determines the efficacy of RIRS for renal stones.

Conclusion

In this report, we described our modified upside-down technique for manipulation of FURS under unequal dual deflection in order to preserve the deflection apparatus, which yielded a greatly prolonged durability. Additionally, the use of mimic drive turning decreased the time needed to train urologists.

Let's Get to the Point: Comparing Insertion Characteristics and Scope Damage of Flat-Tip and Ball-Tip Holmium Laser Fibers

INTRODUCTION

A ball-tip holmium laser fiber (TracTip; Boston Scientific) has been developed to theoretically reduce damaging friction forces generated within a ureteroscope working channel. We compared the insertional forces and damage with a ureteroscope inner lining when inserting standard flat-tip and ball-tip laser fibers.

MATERIALS AND METHODS

A standard ureteroscope channel liner was placed in a 3D-printed plastic mold. Molds were created at four angles of deflection (30°, 45°, 90°, and 180°) with a 1 cm radius of curvature. New 200 μm ball-tip (TracTip; Boston Scientific) and 200 μm flat-tip (Flexiva; Boston Scientific) laser fibers were advanced through the liner using a stage controller. A strain gauge was used to measure force required for insertion. Each fiber was passed 600 times at each angle of deflection. The ureteroscope liner was changed every 150 passes. Leak testing was performed every 50 passes or when the insertional force increased significantly to assess damage to the liner.

RESULTS

At all deflection angles, the average insertional force was significantly lower with the ball-tip laser fibers compared with flat-tip laser fibers (p < 0.001). All trials with the ball-tip lasers were completed at each angle without any leaks. Two of four trials using flat-tip fibers at 45° deflection caused liner leaks (at 91 and 114 passes). At 90° deflection, all flat-tip trials caused liner leaks on first pass. The 180° trials could not physically be completed with the flat-tip laser fiber. Within the flat- and ball-tip groups, an increasing amount of force was needed to pass the fiber as the degree of deflection increased (p < 0.001).

CONCLUSIONS

The ball-tip holmium laser fiber can be safely passed through a deflected ureteroscope without causing liner perforation. The standard flat-tip fiber requires greater insertion force at all angles and can cause the ureteroscope liner to leak if it is deflected 45° or more.

Factors associated with postoperative pain after retrograde intrarenal surgery for kidney stones

OBJECTIVE

We aimed to investigate factors related to early postoperative pain after retrograde intrarenal surgery (RIRS).

MATERIAL AND METHODS

A prospective data analysis of 250 patients who underwent RIRS due to kidney stones was performed. Postoperative pain was evaluated in all patients by using visual analogue scale (VAS). Patients with severe pain (VAS score ≥7) were separated and included in Group I (n=46). While patients without pain or with insignificant pain were included in Group II (n=204). The impact of patient-related (age, gender, renal anomalies, shock wave lithotripsy history, preoperative hydronephrosis) stone-related (stone number, side, size, location and opacity) and operation-related (preoperative and postoperative ureteral J-stenting, ureteral injury, postoperative bleeding and fever, stone-free rates, size of access sheath, and sheath indwelling time) factors on early stage postoperative pain (if any) were investigated.

RESULTS

Female gender increased the risk for pain 3.6-fold (p<0.05). One millimeter increase in stone diameter increased the risk for postoperative pain 1.15-fold. Prolonged sheath time was another important factor which increased the risk for pain (p<0.05). Patients with high residual fragments were also prone to early postoperative pain.

CONCLUSION

According to our results, patient-, stone-and operation-related factors associated with postoperative pain after RIRS were female gender, stone size and sheath time.

Robotically assisted ureteroscopy for kidney exploration

Ureteroscopy is a minimally invasive procedure for diagnosis and treatment of a wide range of urinary tract pathologies. It is most commonly performed in the diagnostic work-up of hematuria and the diagnosis and treatment of upper urinary tract malignancies and calculi. Ergonomic and visualization challenges as well as radiation exposure are limitations to conventional ureteroscopy. For example, for diagnostic tumor inspection, the urologist has to maneuver the ureteroscope through each of the 6 to 12 calyces in the kidney under fluoroscopy to ensure complete surveillance. Therefore, we have been developing a robotic system to "power drive" a flexible fiber-optic ureteroscope with 3D tip tracking and pre-operative image overlay. Our goal is to provide the urologist precise control of the ureteroscope tip with less radiation exposure. Our prototype system allows control of the three degrees of freedom of the ureteroscope via brushless motors and a joystick interface. The robot provides a steady platform for controlling the ureteroscope. Furthermore, the robot design facilitates a quick "snap-in" of the ureteroscope, thus allowing the ureteroscope to be mounted midway through the procedure. We have completed the mechanical system and the controlling software and begun evaluation using a kidney phantom. We put MRI-compatible fiducials on the phantom and obtained MR images. We registered these images with the robot using an electromagnetic tracking system and paired-point registration. The system is described and initial evaluation results are given in this paper.

Flexible ureteroscopy: Technological advancements, current indications and outcomes in the treatment of urolithiasis

The last 3 decades have witnessed great improvements in the technology and clinical applications of many minimally invasive procedures in the urological field. Flexible ureteroscopy (fURS) has advanced considerably to become a widely utilized diagnostic and therapeutic tool for multiple upper urinary tract pathologies. The most common indication for fURS is the treatment of upper urinary tract stones with the aid of Holmium:Yttrium Aluminium Garnet (YAG) laser lithotripsy. Advancements in endoscope technologies and operative techniques have lead to a broader application of fURS in the management of urolithiasis to include larger and more complex stones. fURS has proved to be an effective and safe procedure with few contraindications. Continued progression in fURS may increase its clinical applicability and supplant other procedures as the first line treatment option for urolithiasis.

Categorizing intraoperative complications of retrograde intrarenal surgery

PURPOSE

To review our intraoperative complications of retrograde intrarenal surgery (RIRS) for kidney calculi and stratify these complications according to the modified Satava classification system (SCS).

PATIENTS AND METHODS

230 patients (119 males, 111 females) who underwent RIRS because of kidney calculi were analyzed. We documented and stratified the intraoperative complications according to the modified SCS. There are four grades for this classification: grade 1 complications include events without consequences for patients; grade 2a complications include events that could be treated with endoscopic surgery intraoperatively; grade 2b complications include events which were treated with endoscopic treatment in another session, and grade 3 describes the events requiring laparoscopic or open surgery.

RESULTS

Mean age was 39.1 years (range 1-78). The stone-free rate after one session was 81%. Intraoperative complications were recorded in 30.4% of the patients. According to the modified SCS, grade 1 complications were documented in 15.9%, grade 2a complications were documented in 5.6%, and grade 2b complications were documented in 8.9% of the patients. Grade 3 complications were not detected in any of the patients.

CONCLUSION

In our opinion, the modified SCS can facilitate patients to understand the safety of this surgery and can make it easier to compare the results of different institutes and surgeons.

Ureteroscopic treatment of larger renal calculi (>2 cm)

Objectives

To evaluate the current status of ureteroscopic lithotripsy (UL) for treating renal calculi of >2 cm, as advances in flexible ureteroscope design, accessory instrumentation and lithotrites have revolutionised the treatment of urinary calculi. While previously reserved for ureteric and small renal calculi, UL has gained an increasing role in the selective management of larger renal stone burdens.

Methods

We searched the available databases, including PubMed, Google Scholar, and Scopus, for relevant reports in English, and the article bibliographies to identify additional relevant articles. Keywords included ureteroscopy, lithotripsy, renal calculi, and calculi >2 cm. Retrieved articles were reviewed to consider the number of patients, mean stone size, success rates, indications and complications.

Results

In all, nine studies (417 patients) were eligible for inclusion. After one, two or three procedures the mean (range) success rates were 68.2 (23–84)%, 87.1 (79–91)% and 94.4 (90.1–96.7)%, respectively. Overall, the success rate was >90% with a mean of 1.2–2.3 procedures per patient. The overall complication rate was 10.3%, including six (1.4%) intraoperative and 37 (8.9%) postoperative complications, most of which were minor. The most common indications for UL were a failed previous treatment (46%), comorbidities (18.2%), and technical and anatomical factors (12.3%).

Conclusions

UL is safe and effective for treating large renal calculi. While several procedures might be required for total stone clearance, UL should be considered a standard approach in the urologist’s options treating renal calculi of >2 cm.