Outcomes of more than 1 000 percutaneous nephrolithotomies and validation of Guy's stone score.

Objective: To present the experience with percutaneous nephrolithotomy (PCNL) at a high-volume Brazilian centre and to evaluate Guy's stone score (GSS) as a predictor of success and complications in PCNL. Patients and

Methods: We prospectively evaluated patients who underwent PCNL between June 2011 and October 2016. Indications for PCNL included renal stones >2 cm in size and stones <2 cm in size in which first-line techniques had failed. All patients underwent a complete preoperative evaluation, including non-contrast-enhanced abdominal computed tomography (CT). Stone complexity was assessed using GSS. Success was defined as the absence of fragments >2 mm on CT on postoperative day 1. Complications were classified according to the Clavien grade.

Results: A total of 1 066 PCNLs were performed on 891 patients. In all, 20.2% were classified as GSS1, 27.4% as GSS2, 35.0% as GSS3, and 17.4% as GSS4. The mean operating time was 108.44 min, and the mean fluoroscopy time was 13.57 min. The overall immediate success rate based on postoperative day 1 CT was 43.8%. Complications occurred in 14.9% of cases, and the mean length of hospital stay was 54.55 h. Stratifying patients according to GSS, success rate was inversely proportional to the calculus complexity: GSS1: 87.9%; GSS2: 62.1%; GSS3: 44.0%; and GSS4: 24.3% (P < 0.001). Higher GSS categories were significantly correlated with the number of puncture tracts (P < 0.001), operating time (P < 0.001), fluoroscopy time (P < 0.001), blood transfusion rate (P < 0.001), complications (P < 0.001) and length of stay (P < 0.001).

Conclusion: In a high-volume centre, PCNL was a reliable surgical technique, with low morbidity and short hospital stay. GSS was confirmed to be a very useful tool for predicting the outcomes of PCNL, and its use should be encouraged.