Utility of the Guy’s Stone Score in predicting different aspects of percutaneous nephrolithotomy
Objective: To evaluate Guy’s scoring system (GSS) as a grading system for complexity of kidney stone before percutaneous nephrolithotomy (PCNL) as a predictor for different items of outcome.
Patients and methods: Between July 2014 till July 2015, 100 patients with renal stone (s) and candidates for prone PCNL were evaluated and graded by GSS preoperatively. All intraoperative and postoperative data and complications using modified Clavien system were recorded, collected and statistically analyzed in relation to different grades of GSS to evaluate its predictive ability to different items of outcome.
Results: Mean age of the patients was 47.38 ± 14.6 years. The patients were distributed in different grades of GSS with no statistically significant difference as mean age, sex, and mean BMI of the patients, stone side and previous renal surgery. There was high statistically significant difference in mean operative time, rate of blood transfusion, and mean number of renal punctures between different Guy’s scores, with all of them showed the highest values at GS IV. There was significant correlation between increase in the grade of GS and the need for re-PCNL and auxiliary procedures. The final stone free rate (SFR) was 93% and complication rate was 27% with significant increase in the immediate success rate, SFR, and complication rate with advancement of the grade of GSS.
Conclusion: GSS has a positive correlation with SFR, re-treatment rate, need for auxiliary procedure, and rate of complication.