(UroToday.com) At the WCET 2024 conference, Dr. Steffi Kar Kei Yuen from the SH Ho Urology Centre at The Chinese University of Hong Kong presented significant findings from a multi-center study on the stone-free rate (SFR) and complications following flexible ureteroscopy (F-URS) for renal stones using the flexible and navigable suction ureteral access sheath (FANS). This large-scale study, conducted across 25 centers worldwide, represents one of the most extensive prospective analyses in the field, offering critical insights into the efficacy and safety of suction UAS during flexible ureteroscopy.
The study, conducted between August 2023 and January 2024, involved 394 patients who underwent F-URS for renal stones. Participants were selected to exclude those with abnormal renal anatomy or ureteral stones, ensuring the reliability of the results. Each patient underwent preoperative and postoperative CT scans within 30 days to assess outcomes. Dr. Yuen and her team focused on evaluating the stone-free rate (SFR) and associated complications. The SFR was classified using a grading system: Grade A (zero fragments), Grade B (single fragment ≤2 mm), Grade C (single fragment 2.1-4 mm), and Grade D (single or multiple fragments >4 mm). Multivariable logistic regression was applied to identify predictors of achieving a Grade A SFR.
The study reported that 69% of participants were first-time stone formers, and 58% were pre-stented prior to surgery. Among the cases, 61.9% used ClearPetra, 6.3% utilized Innovex, 23.9% employed Elephant, and 7.9% relied on other suction UAS systems. Only 13.2% of cases required repositioning or fragment extraction using traditional basketing techniques. In terms of surgeon feedback, the subjective assessment of FANS revealed a low malfunction rate of 2%, efficient suctioning in 96.7% of cases, access to all parts of the kidney in 86.8% of cases, and a tubeless procedure in 6.9% of cases.
The results demonstrated that 57.4% of patients achieved a complete stone-free status (Grade A), with no residual fragments. Including those with minimal residual fragments (≤2 mm), the overall success rate rose to an impressive 97.2%. Only 2.8% of patients had larger residual fragments, underscoring the high effectiveness of the FANS technique.
The safety profile of F-URS was also highlighted, with minimal complications reported. Only one patient required a blood transfusion, and a small percentage (3.3%) experienced a low-grade fever, with no cases of sepsis. Low-grade ureteral lesions were observed in just 2% of patients, and only 11 patients required a repeat F-URS procedure. A key finding was the identification of predictors for successful outcomes. Larger stone volumes were associated with lower odds of achieving a complete stone-free status, especially for stones measuring over 1500 mm³. Conversely, the use of the Thulium Fiber Laser significantly increased the likelihood of achieving a completely stone-free outcome.
Following the presentation, a Q&A session with both the audience and moderators provided further insights. One of the moderators inquired about the Elephant suction UAS and its differences compared to other systems. Dr. Yuen explained that, unlike the ClearPetra system, which has an open suction ventilation, the Elephant suction UAS features a sliding ventilation mechanism, allowing the surgeon to control the suction as needed. She also noted that the Elephant system exhibited less air leakage, making it more efficient in terms of suctioning. This observation was supported by the disruption noise caused by air leakage, which was noticeably reduced with the Elephant system. Dr. Yuen attributed this efficiency to the thin clear plastic layer surrounding the Elephant suction UAS, which seals and occludes the lumen upon deployment, enhancing its performance.
Another moderator asked for clarification on what Dr. Yuen meant by "efficiency" during her presentation, and whether this was a subjective assessment by the surgeons involved. Dr. Yuen confirmed that this was indeed a subjective assessment, based on a Likert scale completed by the surgeons.
Additionally, an audience member asked Dr. Yuen if she had any tips to offer, given her extensive experience with various suction UAS systems. Dr. Yuen recommended that, depending on the available laser, she prefers to focus on dusting rather than fragmenting the stones, while simultaneously utilizing the suction to maximize effectiveness.
Dr. Yuen emphasized that these findings demonstrate the high efficacy and safety of F-URS using the FANS technique, with a negligible rate of serious adverse events. The study, conducted without external funding, highlights the potential for FANS to become a standard approach in the management of renal stones. These insights provide a solid, data-driven foundation for optimizing patient outcomes in this increasingly utilized procedure.
Presented by: Steffi Kar Kei Yuen, MBBS, FRCSEd, FCSHK, FHKAM, SH Ho Urology Centre, The Chinese University of Hong Kong, Hong Kong, China.
Written by: Seyedamirvala Saadat, Research Specialist at Department of Urology, University of California Irvine, @Val_Saadat on X during the 2024 World Congress of Endourology and Uro-Technology: August 12 -16, 2024, Seoul, South Korea