33-39% of the stone surgeries are repeated within 120 days and 12-59% of the patients with residual stones will return for additional care within 5 years. This RCT evaluated the role of ultrasonic propulsion of stones on stone related outcomes in patients with <5mm sized residual stones 4 weeks after surgery. 82 patients were randomized in 1:1 fashion to either observation vs ultrasonic propulsion of the stone. The intervention group underwent ultrasound to locate the stone after which 25milisecond 350kHz sound pulses at a max intensity of 200W/cm2 were delivered to the stone for upto 3 sec by the therapy transducer which was attached to the ultrasonic head. Any movement of the stone was seen in real time and the dislodged stones were retargeted. Total treatment exposure was limited to 5 min. The patients were positioned in lateral decubitus with head down and the transducer was placed under the ribs to allow easy stone passage and a maximum of 4 sessions were allowed. The primary outcome of the study was relapse defined as urgent/ unscheduled symptomatic visit to ED, subsequent surgery for the stone or growth of the stone and the pre-specified follow up period was 5 years. After the follow-up period, the treatment group had 52% longer time to relapse (1530 days vs 1009 days) and had 70% lower risk of relapse (19.45% vs 50%). 60% of the patients visually observed stone passage within 3 weeks of the treatment in the intervention group. None of the patients had moderate or serious adverse events but mild adverse events were reported in 45% of the patients, the most common of which was discomfort / pain during the procedure in 38% of the patients.