Predicting the outcome of mini percutaneous nephrolithotomy using STONE nephrolithometry score—a single-center experience

To predict stone-free and complication rates following mini-percutaneous nephrolithotomy (m-PCNL) using STONE nephrolithometry score, this prospective observational study was conducted in the Department of Surgery, Urology Unit, Patan Hospital. All the patients undergoing m-PCNL were included. The cases were performed in the prone position, a single tract less than 18 French was made, and pneumatic lithotripsy was done. Stone-free rates were assessed with plain X-ray kidney, ureter, and bladder (X-ray KUB) on the first post-operative day or at 15 days follow-up. Complications within 30 days were graded using modified Clavien grading. A total of 106 patients were included in the final analysis. The overall stone-free rate was 83%. Among the individual variables, only staghorn calculus was associated with residual stone (p = 0.007). Patients who were rendered stone-free had statistically significantly lower STONE scores than those with residual stone (p < 0.001). The complication rate was 23%, and the majority were Clavien grade I complications. A higher STONE score had a greater risk of having complications but was not statistically significant (p = 0.11). STONE nephrolithometry score can predict stone complexity pre-operatively and subsequent stone-free status and thus, helps in pre-operative surgical planning and counseling for possible outcomes following m-PCNL.