AUA 2022: Ureteroscopic Thulium Laser Lithotripsy Augmented with a Novel Reverse Thermal Hydrogel in an In-Vivo Porcine Model

( The Engineering and Urology Society included a poster session featuring work from Douglas Schneider and colleagues presented results of their study assessing thulium laser lithotripsy augmented with a novel reverse thermal hydrogel (Hydrogel) developed by UroGen Pharma in an in-vivo porcine model. Hydrogel is a liquid at room temperature but becomes significantly more viscous at body temperature, transforming into a semisolid gel. This was hypothesized to help address the persistent challenge of small residual stone fragments following ureteroscopic laser lithotripsy.


A. Stone implanted in calyx prior to instillation of Hydrogel
B. Stone implanted in calyx after instillation of Hydrogel

Canine calcium oxalate stones were implanted into four randomized in-vivo porcine kidneys via pyelotomy, and a percutaneous temperature probe was placed into the calyx with stone. In the experimental kidneys with Hydrogel, superpulse thulium laser lithotripsy was performed with the addition of 5cc of Hydrogel instilled prior to lithotripsy using a 5Fr molded ureteral catheter. In the control kidneys without Hydrogel, laser lithotripsy was performed in the standard fashion. After dusting, remaining visible fragments were basketed and a ureteroscopic brush was used to entrap any residual dust or small fragments. Kidneys were then harvested, bivalved, and washed to obtain remaining fragments, which were then dried, sieved, and weighed to determine stone clearance rates.

Hydrogel was found to facilitate greater stone clearance. 99.3% of stone mass was successfully cleared from kidneys where lithotripsy was augmented with Hydrogel, compared to 92.2% of stone mass cleared from control kidneys. Control kidneys also reached a higher peak temperature, 55°C without Hydrogel, compared to 36°C with Hydrogel:



Mr. Schneider concluded by emphasizing that:

  • Hydrogel effectively augmented ureteroscopic laser lithotripsy and stone removal, resulting in a stone clearance of 99.3%
  • During thulium laser lithotripsy, Hydrogel exhibited thermoprotective properties, preventing the high intra-calyceal pressures seen in control kidneys


Presented by: Douglas Schneider, Medical Student, University of California, Irvine, Department of Urology

Written by: Douglas Schneider, University of California, Irvine, during the Annual Urology Association Conference (AUA) 2022 in New Orleans, Louisiana, May 13-16, 2022

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