Objective: To review the efficacy of retrograde intrarenal surgery for treatment of renal calculi performed in Siriraj Hospital.
Material and Method: Retrospectively reviewed of 111 RIRS that been performed in Siriraj Hospital between June 2012 and
November 2015. Residual stone was assessed at 1 month post-operatively by plain films (KUB) or urinary tract ultrasonography
(US). Success rate of the procedure was defined as the stone-free status or presence of residual fragments less than 3 mm.
Results: From 111 patients, average stone size was 11.8+0.6 mm. There were 73 patients whom previously been treated with
other modalities.Stone free was accomplished in 90 patients (81.1%) with only 4 patients with residual stone that needed
retreatment (3.6%). Stone burden and stone numbers showed significant influence on the success rate. Average operative time was 62.3+2.4 minutes. The mean hospitalization was 3.0+0.3 days. Sepsis was found in 6 patients, which successfully treated with intravenous antibiotic with no mortality. During the study, we used total 5 flexible ureterorenoscopes. We noticed that each scope could be used in approximately 22.2 cases (15-33) before requiring equipment maintenance.
Conclusion: RIRS is a minimally invasive treatment for renal calculi with a high success rate and low morbidity.

Keywords: Retrograde intrarenal surgery, RIRS, Renal calculi, Renal stone