To investigate the effectiveness of modified mechanical percussion for eliminating upper urinary tract stone fragments after extracorporeal shock wave lithotripsy.

We assigned patients aged 18-60 years with upper urinary tract calculi to the modified mechanical percussion (trial) or observation (control) group. Kidney-ureter-bladder radiography and ultrasound were used for diagnostic evaluation. The primary outcome was the stone-expulsion rate (SER) at 6 hours. The first stone-expulsion time, the SER at 3, 12, and 24 hours, the stone-free rate, additional interventions, and adverse events (AEs) were recorded.

A total of 120 patients underwent randomization: 60 for each group. The mean first stone-expulsion time in the trial and control groups was 6.75 and 13.58 hours, respectively (P = .001). The SERs at 3, 6, and 12 hours in the trial group were 51.8%, 75.4%, and 76.8%, respectively, which were higher than the control group (all P <.05). Among patients who expelled fragments within 6 hours, the stone-free rates were improved at 1 week (P = .002) and at 2 weeks (P = .000). Patients needed fewer additional interventions in the trial group (P = .035). AEs occurred in 42.9% (24 of 56) and 67.9% (38 of 56) of the patients in the trial and control groups, respectively (P = .008). Age, gender, stone size and location, and SER at 24 hours did not differ significantly among the groups.

Modified mechanical percussion significantly improved SERs and accelerated stone passage after shock wave lithotripsy, resulting in a stone-free status with a lower risk of AEs and reduced need for additional interventions.