Flexible Ureterorenoscopy Versus Shockwave Lithotripsy for Kidney Stones ≤2 cm: A Randomized Controlled Trial

No clear recommendations are available on whether retrograde intrarenal surgery (RIRS) via flexible ureterorenoscopy or shockwave lithotripsy (SWL) should be preferred for kidney stones ≤2 cm, except for lower-pole stones.To compare outcomes between RIRS and SWL.This was a single-center randomized controlled trial from March 2015 to May 2018. Patients with a single 6-20-mm kidney stone were enrolled (NCT02645058).Patients were randomized to RIRS or SWL.The primary endpoint was the single-procedure stone-free rate (SFR) at 1 mo. Two levels of success were set: fragments ≤4 mm (SFR-4) and no residual fragments (SFR-0). Secondary endpoints were the SFR at 6 mo and 1 yr and rates of complications and further treatments.A total of 138 patients underwent treatment (70 RIRS vs 68 SWL). In comparison to SWL, RIRS SFR results were higher at 1 mo (SFR-4 70.0% vs 45.6%; p = 0.004; SFR-0 50.0% vs 26.5%; p = 0.004) and 6 mo (SFR-4 79.7% vs 63.6%; p = 0.038; SFR-0 59.4% vs 40.9%; p = 0.032). There was no difference in SFR measures between the groups at 1 yr (SFR-4 p = 0.322; SFR-0 p = 0.392). Overall complications were comparable (p = 0.207), but the complication rate for stones >10 mm was higher for the SWL group (p = 0.021). The need for further treatment was comparable (p = 0.368). In terms of patient satisfaction, 86.8% and 77.1% of patients would choose SWL and RIRS again, respectively (p = 0.24).RIRS achieved better SFRs in comparison to SWL at 1 and 6 mo, but not at 1 yr. The RIRS complication rate was lower for stones >10 mm. SWL remains a viable alternative, especially for 6-10-mm stones, providing comparable results to RIRS in the long term.We compared outcomes for the treatment of kidney stones ≤2 cm with two techniques: flexible ureteroscopy, in which a flexible telescope is passed through the urethra and bladder to reach the ureter between the bladder and kidney; and shockwave lithotripsy, in which shockwaves are applied to the skin over the location of the kidney stone. Ureteroscopy achieved better stone-free results at 1 and 6 months, but not at 1 year.