Flexible ureterorenoscopy versus miniaturized PNL for solitary renal calculi of 10-30 mm size.

INTRODUCTION: The value of flexible ureterorenoscopy (fURS) and miniaturized PNL (mPNL) for larger renal calculi is under discussion. This non-randomized prospective study aimed to evaluate fURS and mPNL for solitary renal stones of 10-30 mm size.
MATERIALS AND METHODS: fURS was carried out in 21 patients with last generation 7.5F endoscopes. Ureteral access sheaths were used in 19 patients. For mPNL, an 18F modified Amplatz sheath with a 14F nephroscope were used (n = 25). The procedure was performed either tubeless with an antegrade stent or a nephrostomy. Outcome and complications of both procedures were assessed.
RESULTS: Patients' demographics and stone sizes were comparable (18 ± 5 vs. 19 ± 4 mm, P = 0.08). Patients in the fURS group had a higher mean BMI (31 vs. 27, P < 0.05). Total OR time was significantly longer for fURS (106 ± 51 vs. 59 ± 19 min., P < 0.001). More patients were stone-free after one single percutaneous treatment, while 2nd-stage treatments with fURS were common (total procedures 1.04 vs. 1.52, P < 0.001; immediate stone-free rate (SFR) 96% vs. 71.5%, P < 0.001). SFR after 4 weeks was 100% (mPNL) and 85.8% (fURS) (P < 0.01). Minor complications as classified by Clavien I or II occurred in 16 and 23.8%, mPNL and fURS, respectively, P = 0.13). No major complications (Clavien III-V) occured in both groups.
CONCLUSIONS: Our series supports both the concept of either percutaneous or retrograde endoscopic treatment for renal calculi with both modalities offering excellent safety. However, while for fURS, a significantly higher rate of 2nd-stage procedures was necessary, and mPNL led to faster and higher SFR without increasing complication rate.