The EMS Swiss LithoClast® Trilogy for the treatment of large bladder stones: a prospective international multicenter study

The best treatment for large bladder stones remains debated. The options range from open cystolithotomy to minimally invasive endoscopic techniques, including the Mauermayer stone punch and high-power laser cystolitholapaxy, and more recently the EMS Swiss LithoClast ® Trilogy, which combines ultrasonic and ballistic energy with continuous suction in a single probe and is well established in percutaneous nephrolithotomy (PCNL). We report the first prospective international multicenter experience of the Trilogy system for the transurethral treatment of large bladder stones. Consecutive patients undergoing cystolitholapaxy with the Trilogy system were enrolled prospectively at five recruiting centers in five countries between August 2023 and December 2024. Procedures were performed transurethrally through rigid sheaths of 20.8 to 26 Fr. The primary outcome was lithotripsy efficiency (preoperative CT-derived stone volume divided by probe activation time). Secondary outcomes were the stone-free rate, device safety and reliability, intraoperative urothelial trauma, postoperative complications, and surgeon-rated ergonomics and efficiency. Outcomes are reported both by intention to treat, in which patients converted to laser are counted as failures, and per protocol, restricted to procedures completed with the Trilogy system alone. Forty-four patients were enrolled (median age 76 years, range 27 to 88). Forty-three procedures were attempted; one could not proceed because of a urethral stricture. The stone could not be fragmented in two patients (4.7%), both dense calculi (1591 HU and 1280 HU), and both were converted to high-power laser, leaving 41 procedures completed with the Trilogy system alone (35 male, 85.4%). By intention to treat, the stone-free rate was 93.0% (40 of 43 attempted procedures) and 90.9% (40 of 44 patients enrolled); the per-protocol rate was 97.6% (40 of 41). Median total stone volume was 5987 mm 3 (range 1209 to 66,743) and median stone density was 871 HU (range 75 to 1666). Probe activation time was recorded in an analyzable form in 34 of 41 patients (83%), with a median of 20 min and a median lithotripsy efficiency of 351 mm 3 /min (interquartile range 215 to 549); median total operative time was 59 min ( n = 37). Superficial mucosal injury occurred in 15 patients (37%) and detrusor injury in one (2%); there were no perforations. Two probes broke and two handpieces overheated, but the affected procedures were completed; there were no suction failures. Median surgeon ergonomic and efficiency scores were 7 and 8 out of 10. Complications were minor (two urinary tract infections, Clavien–Dindo II); one unrelated death occurred within 30 days. Where length of stay was recorded (31 of 41 patients), the median was 0 days, with 52% discharged on the day of surgery. Across five international centers, the Swiss LithoClast ® Trilogy proved a safe, reliable, and efficient tool for the transurethral treatment of large bladder stones, with high stone-free rates and favorable surgeon feedback. Very dense stones resisted fragmentation in two patients, so extreme stone density remains a technical limitation of the device by comparison with high-power lasers, and the sheath caliber required is large, though similar to that used with laser cystolitholapaxy. Within those limits, and because it is available in centers where PCNL is performed and needs no dedicated laser infrastructure, the Trilogy system is an attractive alternative to high-power lasers, particularly where laser access is limited.