Presented by: Marie Chicaud MD
Service d'urologie, CHU Limoges

Introduction

Kidney Stone Calculator (KSC) is a free software that estimates the duration of endocorporeal laser lithotripsy (ELL) during flexible ureteroscopy (fURS), based on the stone volume. This tool has been previously clinically evaluated with Holmium:YAG (Ho:YAG). We aimed to evaluate the clinical performances of KSC with  Thulium Fiber Laser (TFL) and to compare these results with those obtained with Ho:YAG.

Materials

This prospective multicenter clinical study included patients with kidney and ureter stones treated by fURS with ELL and preoperative non-contrast computed tomography(NCCT), in 4 centers, between January 2020 and April 2023. Demographic, urolithiasis and peri-operative data were prospectively collected. The correlations between estimated and effective ELL durations overall then according to the laser source(LS) were calculated. Univariate and multivariate analyzes on the pre-(volume, location, stone density, presence of anatomical anomaly) and per-operative (laser adjustment, operator level, relocation, use of a basket) criteria were then carried out according to the LS.

Results

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A total of 89 patients were included (Ho:YAG; TFL). The groups were comparable except for presence of urolithiasis pathology, anatomical abnormalities, kidney stones location and previous surgical urolithiasis history (Table 1). A significant correlation (r=+0.89) between estimated and effective ELL durations was found overall(p<0.001), and within the two groups (TFL: r=+0.95, p<0.001; Ho :YAG=r=+0.81,p<0.001). Mean efficiency and ablation rates were 18.22 and 15.68J/mm3 and 0.71 and 0.53mm3/s for TFL and Ho:YAG, respectively (Table 2). In multivariate analysis, the difference between estimated and effective ELL durations was influenced by preoperative criteria (volume>2000mm3 for Ho:YAG, volumes (500-750mm3) and calicial diverticula for TFL) and on operative criteria (fragmentation setting (p>0.001) and use of a basket (p=0.05) for Ho:YAG, no factor found for TFL).

Conclusion

Kidney Stone Calculator is a reliable tool for ELL estimation for both TFL and Ho:YAG. Various criteria, which differ depending on the LS, can lead to underestimating the effective duration of ELL (volume>2000mm3, use of a basket, fragmentation setting for Ho:YAG and volumes (500-750mm3) and calicial diverticula for TFL).

Funding

None

Lead Authors

Stessy Kutchukian, MD
Service d'urologie, CHU Poitiers

Francois Audenet, MD,PHD
Service d’Urologie, Assistance-Publique Hôpitaux de Paris, Hôpital Européen George Pompidou

Laurent Berthe, PHD
PIMM, UMR 8006 CNRS-Arts et Métiers ParisTech

Laurent Yonneau, MD
Service d'urologie, Hôpital Foch

Thierry Lebret, MD PHD
Service d’Urologie, Hôpital Foch

Marc-Olivier Timsit, MD PHD
Service d’Urologie, Assistance-Publique Hôpitaux de Paris, Hôpital Européen George Pompidou

Arnaud Méjean, MD PHD
Service d’Urologie, Assistance-Publique Hôpitaux de Paris, Hôpital Européen George Pompidou

Catalina Solano, MD
Service d'urologie, APHP, Hôpital Tenon

Luigi Candela, MD
Division of experimental oncology/unit of Urology, URI, IRCCS Ospedale San Raffaele, Milan, Italy; Vital-Salute San Raffaele University

Steeve Doizi, MD PHD
Service d'urologie, APHP, Hôpital Tenon

Co-Authors

Frédéric Panthier, MD, Mec
Service d'urologie, APHP, Hôpital Tenon

Aurélien Descazeaud, MD PHD
Service d'Urologie, CHU de Limoges

Olivier Traxer, MD
Service d'urologie, APHP, Hôpital Tenon