Factors affecting stone clearance in Percutaneous Nephrolithotomy

Abstract

Introduction: Percutaneous nephrolithotomy (PCNL) is the treatment of choice for large and complex renal stones. It is of paramount importance to deliver the maximum clearance with minimal morbidity. There are different anatomical, stone-related and patient-related factors affecting the stone-free rate. This study is conducted to delineate the factors predicting stone clearance in PCNL.

Methods: A prospectively maintained database of 114 cases, who underwent PCNL between January to October 2016 in Tribhuvan University Teaching Hospital, was analysed. Age, gender, body mass index, surgical and medical history, renal anomalies, American Society of Anesthesiologists score, tract size, type of tract dilatation, fluoroscopy time, stone density, stone location and burden, skin to stone distance, presence of hydronephrosis, and duration of surgery were correlated with the stone clearance. Stone clearance was evaluated with either X-ray or ultrasound of the kidneys, ureters and bladder up to three months of PCNL.

Result: Stone clearance rate was 85.96%. Stone burden(p<0.001), stone location(p=0.03), number of calyces involved by stone(p<0.001) and presence of hydronephrosis(p=0.005) were statistically different between stone-free and stone-residue group. Multifactorial analysis showed that stone burden, location and no. of calyces involved by stone were the only factors effecting stone free rate. Area under curve for the stone burden was 0.842 (p<0.001).

Conclusion: Stone burden, location and number of calyces involved by the stone are the principal factors determining the stone clearance in PCNL.