Rojo EG, Teoh JYC, Castellani D, et al. - For treating urolithiasis in anomalous kidneys, retrograde intrarenal surgery (RIRS) affords a safe and effective choice. In such cases, RIRS provides a high single-stage stone-free rate (SFR) and low complication rate.

• A multicentric retrospective study of 414 procedures (RIRS) (cases included horseshoe, pelvic ectopic, and malrotated kidneys, diverticular calculus).

• Average size (SD) of the stone was 13.9 (±6) millimetres, and average (SD) operating time was 65.3 (±24.2) minutes.

• Overall complication rate and global SFR was 12% and 79.2%, respectively.

• The pre-stented group had significantly lesser residual fragments (RF).

• A trend towards using smaller and disposable scopes and smaller ureteral access sheath was observed.

• Higher rates of intraoperative hematuria, caliceal perforation and RF were seen in the diverticular stone group.