Influence of stone burden and stone configuration on outcomes of percutaneous nephrolithotomy

Abstract

Background: Literature says that the stone burden, the location and the anatomy of collecting systems play a major role in the management of renal stones. To this purpose, the effect of stone burden and stone configuration on stone-free rate, mean operative time, complication rate, and the requirement of the secondary procedures following percutaneous nephrolithotomy (PCNL) procedure were studied. Methods: Twenty-nine patients undergoing percutaneous nephrolithotomy (PCNL) for renal calculi such as calyceal calculi, pelvic calculi, staghorn calculi (both partial and complete staghorn) or any of the combination of above which are radio-opaque were studied. From each patient, intra-operative information concerning access, punctured calyx, operative time, complications if any and their management were recorded. Operative time is calculated from fluoroscopic puncture of target calyx to nephrostomy tube fixation. Complications if any were recorded throughout the follow-ups. Secondary procedures were usually performed at least one month after the initial procedure. The stone surface area (mm 2 ) was calculated by graph-paper tracing and a stone were called a pelvic component-dominant complex stone if the pelvic component was 50% to 100% and the calyceal component between 0 and 50%. Similarly, a stone was called a calyceal component dominant complex stone if calyceal component exceeded 50%. Results: There were 17 males and 12 females. One patient underwent bilateral PCNL. The mean age of the patient was 37.2 years (9-62 years). The mean size of the stone was of 616.6 mm 2 (205- 1370 mm 2 ) There was a statistically significant decrease in stone-free rate as the surface area increased (P <0.05). The mean operative time is 98.8 minutes (60-180 minutes). For the entire study, the stone-free rate of PCNL was 46.7%. The stone-free rate rose to 83.3% with the additional secondary procedure. The complication rate for the entire group was 36.7%. No colon injuries were seen in this study. Patients were discharged home after a median hospital stay of 7 days (5 to 12 days). Conclusions: There is a decrease in the overall stone-free rate, as well as an increase in both the complication rate and the secondary procedure rate, with increasing stone surface area for PCNL. Concerning stone configuration, there is a decrease in the stone free rate, as well as an increase in the operative time with increasing caliceal components in complex renal stones.