Real-World Global Outcomes of RIRS in Anomalous Kidneys: A High Volume International Multicenter Study

Objectives

To analyse the trends and outcomes of RIRS (retrograde intrarenal surgery) for treatment of urolithiasis in anomalous kidneys in a large international multicentre series.

Methods

We designed a multicentric retrospective study. Nineteen high-volume centres worldwide were included. Pre-, peri- and postoperative data were collected, and a subgroup analysis was performed according to a renal anomaly.

Results

We analysed 414 procedures: 119 (28.7%) were horseshoe kidneys, 102 (24.6%) pelvic ectopic kidneys, 69 (16.7%) malrotated kidneys and 50 (12.1%) diverticular calculus. The average size (SD) of the stone was 13.9 (±6) millimetres and 193 (46.6%) patients had a pre-operative stent. In 249 cases (60.1%) a disposable scope was used. A UAS (ureteral access sheath) was used in 373 (90%) patients. A Holmium laser was used in 391 (94.4%) patients. The average (SD) operating time was 65.3 (±24.2) minutes. Hematuria, caliceal perforation and difficulty in stone localisation were mostly seen in diverticular stones and difficulty in UAS placement and lithotripsy in the cases of renal malrotation. The overall complication rate was 12%. The global stone-free rate (SFR) was 79.2%. Residual fragments (RF) were significantly lesser in the pre-stented group (p<0.05). Diverticular calculi were the group with more RF and needed ancillary procedures (p<0.05).

Conclusion

RIRS in patients with anomalous kidneys is safe and effective with a high single-stage SFR and low complication rate. There is a trend towards using smaller and disposable scopes and smaller UAS. Diverticular stones can still be challenging with higher rates of intraoperative hematuria, caliceal perforation and RF.