Early clinical outcomes using a 6.3 Fr single use ureteroscope ...

Ureteroscopy has become an increasingly popular and essential procedure in urology, allowing healthcare professionals to diagnose and treat a wide range of urological conditions1. The advent of flexible ureteroscopy (fURS) has revolutionized the field, affording enhanced access and visualization of the upper urinary tract, thereby facilitating minimally invasive interventions for stones, tumors, and other pathologies2.

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While fURS has become the gold standard for managing many kidney stones, the traditional reliance on reusable flexible ureteroscopes has presented several challenges. These devices, often complex and delicate in design, are susceptible to damage and wear with repeated use3. The intricate channels and lenses can accumulate debris and biofilms, necessitating meticulous cleaning and sterilization procedures to ensure patient safety. However, even with rigorous reprocessing protocols, the risk of cross-contamination and the potential for decreased optical performance over time remain concerns4.

Furthermore, the maintenance and repair of reusable flexible ureteroscopes can be costly and time-consuming. The intricate components and specialized tools required for these tasks often necessitate sending the devices to external repair facilities, leading to delays in patient care and increased healthcare expenditures5. These challenges have prompted the exploration of alternative solutions, particularly in resource-limited settings where the financial burden of maintaining reusable ureteroscopes can be substantial6.

In response to the limitations of reusable flexible ureteroscopes, the development of single-use devices has emerged as a promising solution. Single-use flexible ureteroscopes offer several distinct advantages over their reusable counterparts7. First and foremost, they eliminate the risk of cross-contamination, as each device is used only once and then discarded. This is particularly crucial in the context of infectious diseases and antibiotic resistance, where the use of sterile, single-use instruments can significantly reduce the incidence of healthcare-associated infections4. The elimination of maintenance and repair costs can also lead to substantial cost savings over time, making single-use ureteroscopes an attractive option for hospitals and clinics with limited budgets8. Moreover, the consistent performance of single-use devices ensures that each procedure is performed with a pristine instrument, free from the wear and tear that can accumulate with repeated use9.

Looking towards the future, the evolution of flexible ureteroscopes shows no signs of abating. Ongoing research and development efforts are focused on further miniaturization, enhanced imaging capabilities, and the integration of novel technologies such as laser lithotripsy and robotic assistance7. The advent of disposable single-use ureteroscopes has also gained momentum, offering potential advantages in terms of sterility, cost-effectiveness, and operational efficiency8.

According to the manufacturer’s specifications, the 6.3 French (Fr) single-use flexible ureteroscope is designed to offer high-resolution imaging and an ergonomic design intended to enhance navigation and diagnosis of kidney stones. Its small, flexible diameter ensures full kidney access, while the disposable design guarantees sterility, eliminates cross-contamination, and reduces reprocessing costs. Cost-effective and reliable, it streamlines workflows and enhances patient outcomes. However, these attributes require further clinical validation.

This prospective study compared the performance (stone-free rate, operative time, and complication rates) and safety profile of the new 6.3 Fr single-use ureteroscope, representing the latest advancement in miniaturization, with a standard single-use model in the treatment of kidney stones. The study aimed to assess whether the smaller diameter of the new ureteroscope translates into tangible clinical benefits, such as improved stone clearance, shorter procedure times, and reduced complications, ultimately enhancing patient care and outcomes.

This randomized prospective, single-center study was conducted between May and July at “Saint John” Emergency Clinical Hospital, Bucharest, Romania, following approval by the institutional ethics committee. All patients provided informed consent prior to participation. The study was retrospectively registered in the Chinese Clinical Trial Registry (ChiCTR) under the number ChiCTR, on 21/03/.

Forty patients with radiologically confirmed kidney stones, measuring ≤ 2 centimeters (cm) in diameter, were included in this study. Inclusion criteria required patients to have single or multiple kidney stones and to have been pre-stented prior to surgery. Eligible patients also needed to be under 75 years of age and capable of attending the scheduled 1-month follow-up.

Exclusion criteria included oncological patients, patients with ureteral stones, positive urine culture, severe comorbidities, and inability to comply with follow-up requirements.

All patients underwent preoperative evaluation, including non-contrast computed tomography (CT) to assess stone volume, location, and Hounsfield units (HU), as well as urine culture to rule out infection.

All patients received a single intravenous dose of a second-generation cephalosporin antibiotic for prophylaxis prior to surgery. Under general anesthesia, flexible ureteroscopy was performed by a single experienced endourologist using a flexible suction ureteral access sheath (ClearPetra, 10/12 Fr) (Fig. 1). For the ClearPetra 10/12 Fr access sheath, the scope-to-sheath ratio was approximately 63% for the 6.3 Fr ureteroscope and 75% for the 7.5 Fr ureteroscope, ensuring sufficient space for irrigation and stone fragment evacuation. The ureteroscope (Fig. 2) was advanced under fluoroscopic guidance into the ureter and renal collecting system. A 200-micrometer (µm) pulsed Thulium Fiber Laser (TFL) system (Fiber Dust, Quanta System, Italy) was used for lithotripsy, providing precise stone fragmentation with minimal thermal damage (Fig. 3). The same lasing technique and energy settings were applied across both groups, with a standardized pulse energy of 0.2–0.5 J and a frequency of 10–30 Hz, ensuring uniform fragmentation conditions. The ClearPetra sheath facilitated continuous aspiration of larger stone fragments and irrigation fluid, thereby reducing intrarenal pressure fluctuations and improving fragment clearance (Fig. 1). Fragments larger than 2 millimeters (mm) were aspirated through the sheath, while smaller fragments (< 2 mm) were left in situ for spontaneous passage. In cases where residual fragments < 2 mm remained, a double J stent was placed. For patients with residual fragments > 2 mm, the stent was removed at a median of 3 weeks (2–4 weeks) postoperatively, before the 30-day post-op non-contrast CT (NCCT), to ensure an accurate assessment of stone-free status.

All patients underwent a NCCT at 30 days postoperatively to assess the stone-free rate (SFR), which was defined as the absence of residual fragments larger than 2 mm. Patients with residual fragments ≤ 2 mm were classified as clinically insignificant residual fragments.

Patient demographics, stone characteristics (volume, location, HU), operative time, laser time, total energy used, SFR, and complications (classified according to the Clavien-Dindo system) were recorded. Data were analyzed using SPSS 20. Since continuous variables are reported as means with ranges (minimum–maximum values), statistical comparisons were performed using the Student’s t-test, provided normality assumptions were met. Categorical variables were analyzed using the Chi-square test. Statistical significance was set at p < 0.05.

Patients were divided into two groups based on the ureteroscope used:

• Group 1 (n = 20): 6.3 Fr single-use flexible ureteroscope (Hugemed).

• Group 2 (n = 20): 7.5 Fr single-use flexible ureteroscope (Hugemed).

The primary outcome was the comparison of SFR between the two groups. Secondary outcomes included operative time, laser time, total energy used, and complication rates.

This study was conducted in accordance with the Declaration of Helsinki and adhered to local ethical guidelines. All patients provided informed consent before participation.

A total of 40 patients with kidney stones ≤ 2 cm in diameter were enrolled in the study between May and July . The sample size of 20 patients per group was determined based on feasibility and comparable studies evaluating flexible ureteroscopy outcomes. While no formal power analysis was performed, this study serves as a preliminary investigation for future larger-scale research. Patients were divided into two groups based on the ureteroscope used: Group 1 (n = 20) underwent flexible ureteroscopy with a 6.3 Fr single-use flexible ureteroscope (Hugemed), and Group 2 (n = 20) underwent the same procedure with a 7.5 Fr single-use flexible ureteroscope (Hugemed) (Table 1).

The mean age of patients in Group 1 was 52 years, and 49 years in Group 2. The mean stone volume was .5 cubic millimeters (mm3) in Group 1, and mm3 in Group 2. Lower pole stones were present in 75% of cases in Group 1 and 80% in Group 2. Despite the known challenges of lower pole stone clearance, there was no significant difference in stone-free rates (SFRs) between the groups, suggesting that ureteroscope size did not negatively impact lower pole stone clearance in this cohort. The mean number of stones was 1.5 in Group 1, and 1 in Group 2. The mean HU value of the stones was in Group 1, and in Group 2 (Table 1).

The mean operative time was 58 min in Group 1 and 62.5 min in Group 2, reflecting the greater efficiency of the smaller 6.3 Fr ureteroscope when paired with a suction access sheath. The mean total laser energy delivered was 28.620 J (6.3 Fr) and 35.350 J (7.5 Fr) (Table 1). Laser energy efficiency was 0.047 mm3/J (6.3 Fr) and 0.035 mm3/J (7.5 Fr), while laser energy consumption was 20.89 J/mm3 (6.3 Fr) and 28.34 J/mm3 (7.5 Fr).

In Group 1, the stone-free rate (SFR) reached 95%, with one case of Clavien-Dindo grade 1 (self-limiting hematuria) and one case of grade 2 (febrile UTI requiring intravenous antibiotics). In comparison, Group 2 achieved an SFR of 92.9%, with two cases of grade 1 (mild hematuria resolving without intervention) and one case of grade 2 (febrile UTI requiring hospitalization and IV antibiotics). No complications of the third to fifth grade were reported. During the operation, the postoperative ureteral mucosal injury was assessed, and none of the cases exceeded the first grade. The SFR was higher in Group 1 (95%) compared to Group 2 (92.9%) (p = 0.042). This difference may be associated with improved irrigation flow and fragment evacuation, which could be facilitated by the smaller ureteroscope diameter, though further studies are needed to confirm this hypothesis. This design increases the effective working space within the access sheath, enhancing irrigation flow and the passage of stone fragments during the procedure (Table 1).

No statistically significant differences were observed between the two groups for operative time (p = 0.482), laser time (p = 0.239), total energy used (p = 0.426), or complication rates.

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The introduction of the 6.3 Fr single-use flexible ureteroscope represents an advancement in retrograde intrarenal surgery (RIRS). Its smaller diameter may offer advantages in maneuverability and torque control, potentially simplifying procedures. Some studies suggest that smaller-caliber ureteroscopes can reduce the need for auxiliary tools such as guide wires, sheaths, or stents in selected cases, but further research is needed to confirm these benefits in a broader clinical setting.

Our study aimed to evaluate the performance of a new, smaller-diameter (6.3 Fr) single-use flexible ureteroscope compared to a standard 7.5 Fr model in treating kidney stones. The findings indicate that the 6.3 Fr ureteroscope is as effective as the 7.5 Fr model in achieving stone-free rates (SFRs). In this study, lower pole stones were present in 75% of cases in Group 1 and 80% in Group 2. Despite their gravity-dependent positioning, SFRs remained comparable between the groups, suggesting that flexible ureteroscopy with either ureteroscope size was equally effective in managing lower pole stones. This finding supports previous research that highlights irrigation flow, fragment evacuation efficiency, and ureteroscope deflection angle as crucial for addressing lower pole calculi. While infundibulopelvic angle (IPA) wasn’t specifically assessed here, it remains vital for clearing lower calyx stones. Future studies should explore whether the smaller 6.3 Fr ureteroscope with better deflection benefits cases with narrow IPA. These results also back existing literature on using single-use flexible ureteroscopes for achieving high stone-free rates (SFRs) with proper technique and patient selection7. However, further research should explore whether smaller-diameter ureteroscopes provide additional advantages in anatomically complex cases, such as lower pole stones with a narrow infundibulopelvic angle.

In our study, the SFRs achieved with the 6.3 Fr and 7.5 Fr single-use flexible ureteroscopes were 95% and 92.9%, respectively, with a statistically significant difference favoring the 6.3 Fr device (p = 0.042). This difference suggests a potential association between ureteroscope diameter and fragment evacuation efficiency. The improved SFR in the 6.3 Fr group may be related to enhanced irrigation flow and fragment passage, though further studies are needed to confirm these findings. These findings match existing literature, which underscores the effectiveness of flexible ureteroscopy in achieving high SFRs regardless of device size, provided proper technique and patient selection are employed2.

We discovered that the mean operative times were 58 min for the 6.3 Fr ureteroscope and 62.5 min for the 7.5 Fr model. These durations are consistent with findings from Usawachintachit et al., who reported a mean operative time of approximately 60 min using a single-use flexible ureteroscope10.

Interestingly, the laser time was shorter for the 6.3 Fr ureteroscope (30 min versus 33 min), indicating its potential for more efficient stone fragmentation. This observation is consistent with findings from Ali et al. who reported comparable laser times using a single-use digital flexible ureteroscope, highlighting the effectiveness of smaller-diameter devices in optimizing laser application during ureteroscopy11. In addition to shorter laser times, the 6.3 Fr ureteroscope showed a trend toward higher laser energy efficiency (0.047 mm3/J) compared to the 7.5 Fr model (0.035 mm3/J), while also demonstrating lower energy consumption (20.89 J/mm3 vs. 28.34 J/mm3, respectively). These findings align with prior analyses on laser lithotripsy efficiency, as discussed by Kwok et al.12. Furthermore, studies such as Elshazly et al.13 have shown that employing lower energy settings in flexible ureteroscopy contributes to shorter operative times and mitigates thermal injury, underscoring the value of energy-efficient techniques in endourology. While these differences indicate a potential trend toward improved energy use, further research is required to confirm whether they translate into clinically significant benefits such as shorter overall operative times or improved irrigation flow. Its clinical relevance remains uncertain, and larger multi-center studies with real-time procedural assessments are needed to determine whether improved energy efficiency translates into measurable benefits in surgical workflow and patient outcomes.

Regarding safety outcomes, both the 6.3 Fr and 7.5 Fr ureteroscopes exhibited similarly low complication rates, with no significant differences between the groups. The observed complications were minor (Clavien-Dindo grade 1 and 2), consisting of self-limiting hematuria (Grade 1) and febrile urinary tract infections (Grade 2), all of which were managed conservatively. Notably, all febrile UTIs were successfully treated with intravenous antibiotics, with only one case requiring brief hospitalization. No patients experienced severe complications (Grade 3–5), further supporting the safety of both ureteroscope models. These findings align with existing literature, which consistently reports the low risk associated with disposable ureteroscopes across varying sizes14. The comparable complication rates between the two models suggest that reducing ureteroscope diameter does not compromise safety, reinforcing that improvements in device ergonomics and precision effectively mitigate risks, even as ureteroscope diameters decrease15.

The comparison between the 6.3 Fr and 7.5 Fr single-use flexible ureteroscopes using a suction access sheath suggests that the 6.3 Fr device may offer advantages in certain clinical scenarios, particularly in terms of maneuverability and irrigation flow. However, further studies with larger cohorts are needed to confirm these potential benefits. Its smaller diameter provides a larger effective working space within the sheath, improving irrigation flow and facilitating the passage of stone fragments alongside the ureteroscope. This results in more efficient evacuation of fragments during lithotripsy and minimizes clogging risks. These factors explain the slightly higher SFR (95%) and shorter operative time (58 min) observed in the 6.3 Fr group, as more fragments could be cleared intraoperatively without requiring additional extraction efforts. These benefits contribute to higher stone-free rates, shorter operative times, and a more efficient procedure overall. Smaller-diameter ureteroscopes, like the 6.3 Fr model, have been associated with reduced ureteral trauma, improved maneuverability, and enhanced stone clearance efficiency, aligning with findings in existing literature. For example, a study comparing smaller (4.5/6 Fr) and larger (6/7.5 Fr) semi-rigid ureteroscopes highlighted that reduced instrument size leads to shorter operative times and better stone-free rates16. Additionally, the combination of smaller ureteroscope diameters with suction-assisted access sheaths has been shown to optimize fragment evacuation, further improving procedural outcomes17,18. These results underscore the importance of device miniaturization and advanced suction techniques in advancing endourological procedures.

Although not directly evaluated in this study, the 6.3 Fr ureteroscope demonstrates potential advantages in pediatric scenarios due to its smaller diameter. These attributes are particularly beneficial for managing urinary tract conditions in children, as supported by existing literature. This design minimizes ureteral trauma and facilitates effective management of urinary tract conditions with a lower risk of complications19. While this study did not directly evaluate pediatric patients, existing literature highlights the efficacy of smaller-diameter ureteroscopes in this population. For example, Cannon et al. demonstrated a 76% SFR in 21 children with lower pole calculi using a 6 Fr flexible ureteroscope, underscoring the safety and utility of such devices in pediatric care20. These findings suggest that the 6.3 Fr ureteroscope could further enhance outcomes in pediatric urology, warranting dedicated research to confirm its potential in this group.

In select cases, the 6.3 Fr single-use flexible ureteroscope allows for direct ureteral access without the need for a safety guidewire, potentially reducing procedural complexity and minimizing mechanical trauma to the ureter. Prior studies have demonstrated that guidewire-free access may be feasible in patients with a sufficiently dilated ureter or prior stenting, as it allows for direct insertion without increasing the risk of ureteral injury. However, guidewire use remains essential in certain cases, particularly in patients with narrow or non-dilated ureters, to ensure atraumatic access and avoid potential complications. The decision to forgo a guidewire should be made on a case-by-case basis, taking into account patient-specific anatomical factors and surgeon experience. When appropriate, avoiding mechanical irritation from guidewire placement may enhance patient comfort and expedite recovery. Additionally, it streamlines the procedure, cutting costs associated with extra equipment. These advantages are consistent with the findings reported by Hu et al. who emphasized that smaller-diameter ureteroscopes maintain safety and efficacy without increasing complication rates21.

Similarly, using the 6.3 Fr single-use flexible ureteroscope without an access sheath has shown great promise in simplifying procedures and further reducing ureteral trauma. Salvadó et al. demonstrated in a clinical comparison of three single-use flexible ureteroscope models that smaller-diameter devices effectively navigate the urinary tract without requiring a sheath. This approach not only reduces procedural complexity but also enhances patient recovery, broadening the applicability of sheathless techniques in selected cases22.

The use of a 6.3 Fr single-use flexible ureteroscope may reduce the need for routine postoperative ureteral stenting due to its smaller diameter, which minimizes ureteral trauma and postoperative inflammation. Compared to larger ureteroscopes, the 6.3 Fr model exerts less outward pressure on the ureteral wall, reducing the likelihood of mucosal irritation, edema, and subsequent discomfort that often necessitate stenting. Additionally, the reduced instrument size may facilitate improved irrigation dynamics, preventing excessive intrarenal pressure fluctuations that could otherwise contribute to postoperative complications. Previous studies have suggested that smaller-caliber ureteroscopes are associated with a lower risk of postoperative ureteral edema, which is a common reason for stent placement. However, stenting remains necessary in cases with prolonged operative times, ureteral trauma, or concerns about ureteral patency postoperatively. The decision to place a stent should be individualized based on surgical findings and patient-specific factors rather than solely on ureteroscope diameter. In support of this, Usawachintachit et al. compared a single-use flexible ureteroscope with reusable fiber-optic models, finding that the single-use device reliably navigated the urinary tract while omitting the need for postoperative stenting. This stentless technique simplifies procedures, enhances patient comfort, and supports faster recovery, demonstrating its potential for wider adoption in carefully chosen cases10.

Although oncological patients were not directly included in this study, the 6.3 Fr ureteroscope’s no-touch, no-wire, no-stent approach shows promise potential for this group. This technique minimizes trauma to the ureteral mucosa by avoiding direct instrument manipulation, an important consideration in managing ureteral tumors where preserving tissue integrity is crucial. Supporting this concept, Geavlete et al. demonstrated reduced mucosal lesions and favorable outcomes when employing the no-touch technique for renal stones23. While these findings are specific to stone management, they suggest that similar benefits could extend to oncological scenarios, reducing procedural invasiveness and enhancing post-operative recovery24. Future studies focused on this patient population are warranted to confirm these potential applications.

The consistent performance of the 6.3 Fr single-use ureteroscope, demonstrated by comparable SFRs (93.5%) and low complication rates, highlights its reliability in clinical use. While this study did not directly evaluate economic factors, the single-use nature of the device inherently eliminates reprocessing and maintenance costs, supporting broader claims of cost-effectiveness and sterility benefits as cited in prior literature25.

A limitation of this study is its single-center design and relatively small sample size (n = 40), which may limit the generalizability of the findings. Additionally, the exclusion of pediatric and oncological patients restricts the applicability of the results to these populations, and the study did not directly evaluate the economic and sterility benefits often attributed to single-use ureteroscopes. While this study did not include direct intraoperative measurements of IRP or temperature, these remain important considerations for procedural safety in flexible ureteroscopy. Prior research suggests that smaller-caliber ureteroscopes and suction-assisted sheaths may help reduce IRP fluctuations, potentially lowering the risk of postoperative complications26. Future studies should investigate the influence of ureteroscope size and suction-assisted access sheaths on intraoperative radiation exposure (IRP) and thermal safety to enhance procedural outcomes. Larger, more diverse cohorts are necessary for multi-center studies to validate these findings and explore broader clinical applications.

Looking ahead, the 6.3 Fr single-use ureteroscope epitomizes the revolutionary future of RIRS – smaller, better, and more efficient. By enabling surgeons to adopt a fully wireless, stent-free, and minimally invasive approach, this device is poised to transform the field and set a new benchmark in the management of urological conditions.

As technology advances and infection control standards become more rigorous, single-use flexible ureteroscopes are transforming urologic surgery. Hospitals and urologists are increasingly turning to disposable ureteroscopes to reduce cross-contamination risk, eliminate maintenance burdens, and ensure consistent image quality in every case.

Traditionally, reusable ureteroscopes have dominated the endoscopic urology field. However, challenges like high repair costs, complex reprocessing protocols, and the risk of biofilm retention have pushed the medical community to explore more efficient alternatives.

Key Benefits of Single-Use Flexible Ureteroscopes

1. Reduced Risk of Cross-Contamination

One of the most compelling advantages of single-use flexible ureteroscopes is their role in minimizing infection risks. Unlike reusable scopes, which require meticulous cleaning and sterilization between uses, disposable ureteroscopes are discarded after each procedure. This single-patient approach greatly reduces the possibility of pathogen transmission, particularly in high-risk environments.

In clinical studies, reusable scopes have been found to harbor contaminants even after standard reprocessing. By switching to a single-use ureteroscope, hospitals can enhance their infection control protocols and better protect immunocompromised patients.

2. Consistent Performance and Visualization

Another common issue with reusable flexible ureteroscopes is degradation over time. The more often they're used and sterilized, the more their optical clarity and maneuverability decline. In contrast, a single-use ureteroscope offers the same high-resolution image quality and deflection control for every procedure, without any loss in performance.

Ezisurg Medical's Single-Use Digital Flexible Ureteroscope is designed for clarity, agility, and ease of use. With a built-in digital imaging chip and a lightweight ergonomic handle, it enables precise navigation through the urinary tract with minimal effort.

3. No Repair or Reprocessing Costs

Maintaining reusable ureteroscopes is costly and time-consuming. Each scope requires regular inspection, reprocessing labor, and often expensive repairs. Over time, these indirect costs may surpass the initial purchase price of the device itself.

By adopting disposable ureteroscopes, hospitals eliminate the need for repairs, storage, or sterilization equipment. This not only reduces overhead but also simplifies inventory management, especially in outpatient or ambulatory surgical centers.