Modified Access Sheath for Continuous Flow Ureteroscopic Lithotripsy: A Preliminary Report of a Novel Concept and Technique

To improve the safety and efficacy of ureteroscopic lithotripsy for the treatment of ureteral stone, we made a simple modification to the standard ureteral access sheath (mUAS) and developed a novel technique to overcome the deficiencies of the current procedure.We added an oblique suction-evacuation port with pressure regulating mechanism to the UAS to allow active egress of irrigation fluid and stone fragments. A pressure vent was placed on the egress port. Continuous negative pressure aspiration was connected to the egress port, whereas the continuous irrigation was delivered through the endoscope with a pressure pump. Stone fragmentation was performed using a holmium-YAG laser through a semirigid ureteroscope. Tiny stone fragments were evacuated in the space between the sheath and the scope. When larger fragments came into the sheath that were too large to exit between the scope and the sheath, the scope was withdrawn to just proximal to the bifurcation of the oblique port. This opened up an unimpeded egress channel for the larger fragments. We attempted this procedure in 104 consecutive patients.Seventy-four patients had effective insertion of mUAS. Seven patients failed semirigid ureteroscopy despite effective placement of mUAS. Patient with effective semirigid ureteroscopic lithotripsy had 100% immediate stone clearance and no observed stone retropulsion. Patients who failed semirigid ureteroscopy were converted to flexible ureteroscopy. Five patients had completed stone clearance. The overall immediate stone-free rate was 97.3% and 100% at 1-month follow-up. Complications included two fevers and one minor ureteral false passage.Our modification of UAS has reduced stone retropulsion, improved stone clearance, improved visual field, and probably reduced the intraluminal pressure.