Influence of Pelvicaliceal Anatomy on Stone Clearance After Flexible Ureteroscopy and Holmium Laser Lithotripsy for Large Renal Stones

Purpose: This study was performed to evaluate the impact of pelvicaliceal anatomy on stone clearance in patients with remnant fragments in the lower pole after flexible ureteroscopy and holmium laser lithotripsy (fURSL) for renal stones >15mm. Patients and Methods: This retrospective study included 67 patients with radiopaque residual fragments (>2mm) in the lower pole after fURSL for large renal stones (>15mm). The preoperative infundibular length (IL), infundibular width (IW), infundibulopelvic angle (IPA), and caliceal pelvic height (CPH) were measured using intravenous urography. Multivariate analysis was performed to determine whether any of these measurements affected stone clearance. Results: Of the 67 patients, 55 (82.1%) were stone free (SF) 3 months after fURSL. The anatomic factors significantly favorable for an SF status were a short IL, broad IW, wide IPA, and low CPH. On multivariate analysis, the IPA had a significant influence on an SF status after fURSL (p=0.010). An IPA <30 degrees was a negative risk factor (p=0.019). Postoperative complications occurred in nine patients (13.4%), including Clavien grade I complications in two patients (2.9%), grade II in six patients (8.9%), and grade IIIa in one patient (1.8%). Almost all complications were minor. Conclusions: An IPA <30 degrees is the only negative risk factor for stone clearance after fURSL for large renal stones according to our multivariate analysis. Additional studies are required to further evaluate the characteristics of the pelvicaliceal anatomy influencing stone clearance.