Purpose: To assess the 30-day stone-free rate and peri-operative outcomes of flexible ureteroscopy (FURS) with flexible and navigable suction ureteral access sheaths (FANS) in adults undergoing same-sitting bilateral retrograde intrarenal surgery (SSB-RIRS). Methods: Prospectively data of 115 adult patients with bilateral kidney stone disease undergoing SSB-RIRS across 14 global centers between July 2023 and March 2024 were analyzed. Patient demographics, stone characteristics and operative outcomes were recorded. A low-dose non contrast CT scan was performed at 30 days to assess the stone-free rate and clinical outcomes. Results: Overall bilateral zero residual fragment(ZRF) was 42.6%; unilateral ZRF was 75.7%. Only two patients were noted to have residual fragments > 4 mm. 1.7% experienced Traxer-Thomas grade 1 ureteric injury which was managed with a ureteral stent for four weeks. No pelvicalyceal injury occured. Postoperative mean loin pain score was 1.7 ± 1.0. None had sepsis nor required blood transfusion. 4.3% required readmission within 30 days of surgery. Multivariate analysis indicated longer total operation time correlated with lower odds of achieving a 100% bilateral stone-free (ZRF) (OR 0.978, 95%CI = 0.959–0.994, p = 0.013). Conclusion: To our knowledge, this is the first multicenter study demonstrating the use of FANS in SSB-RIRS can achieve bilateral ZRF with low complication and re-intervention rates. However, prolonged surgical time may negatively impact outcomes. The indications of bilateral renal stones management with FURS can be expanded in appropriate chosen patients.

Background: The novel pulsed thulium:yttrium–aluminum–garnet (p-Tm:YAG) laser was recently introduced. Current studies present promising p-Tm:YAG ablation efficiency, although all are based on non-human stone models or with unknown stone composition. The present study aimed to evaluate p-Tm:YAG ablation efficiency for stone dust from human urinary stones of known compositions. Methods: Calcium oxalate monohydrate (COM) and uric acid (UA) stones were subjected to lithotripsy in vitro using a p-Tm:YAG laser generator (Thulio®, Dornier MedTech GmbH, Germany). 200 J was applied at 0.1 J × 100 Hz, 0.4 J × 25 Hz or 2.0 J × 5 Hz (average 10W). Ablated stone dust mass was calculated from weight difference between pre-lithotripsy stone and post-lithotripsy fragments > 250 µm. Estimated ablated volume was calculated using prior known stone densities (COM: 2.04 mg/mm³, UA: 1.55 mg/mm³). Results: Mean ablation mass efficiency was 0.04, 0.06, 0.07 mg/J (COM) and 0.04, 0.05, 0.06 mg/J (UA) for each laser setting, respectively. This translated to 0.021, 0.029, 0.034 mm³/J (COM) and 0.026, 0.030, 0.039 mm³/J (UA). Mean energy consumption was 26, 18, 17 J/mg (COM) and 32, 23, 17 J/mg (UA). This translated to 53, 37, 34 J/mm³ (COM) and 50, 36, 26 J/mm³ (UA). There were no statistically significant differences for laser settings or stone types (all p > 0.05). Conclusion: To our knowledge, this is the first study showing ablation efficiency of the p-Tm:YAG laser for stone dust from human urinary stones of known compositions. The p-Tm:YAG seems to ablate COM and UA equally well, with no statistically significant differences between differing laser settings.