Factors Affecting Safety and Efficacy of PCNL in Lower Calyceal Stones

Abstract
Background: The management of lower calyceal stones is still one of today's topics in endourology. Percutaneous nephrolithotomy (PCNL) is found to be a highly effective procedure in treatment of lower pole calculi. However, many factors are affecting the stone free rate and complication rate.
Aim of the Study: The aim of this study was to evaluate the factors that affect the safety and efficacy of PCNL in lower calyceal stones more than 2cm.
Patients and Methods: Forty eight patients with lower pole calculi more than 2 cm underwent percutaneous nephro-lithotomy. Preoperative, operative and postoperative data were reported. Multivariate analyses as well as univariate analyses were used to investigate the effects of different variables on residual stones and blood transfusion rate. These factors include age, sex, laterality, body mass index, history of ipsilateral open renal surgery, operative time, lower pole parenchymal thickness, presence of hydronephrosis, stone burden and stone density.
Results: Unvariate analysis determined that stone burden (p<0.001), stone count (p<0.02), lower pole parenchymal thickness (p<0.03), presence of hydronephrosis (p<0.001) and operative time (p<0.04) were statistically significant with the stone free rate. Multivariate analysis revealed that, presence of hydronephrosis (odds ratio [OR]: 0.365, 95% confidence interval [CI]: 0.104-0.652, p=0.034), lower pole parenchymal thickness (OR: 0.347, 95% CI: 0.241-0.874, p=0.04), the operative time (OR: 0.587, 95% CI: 0.149-0.857, p=0.032), stone count (OR: 0.647, 95% CI: 0.205-0.874, p=0.028) and stone burden (OR: 0.428, 95% CI: 0.169-0.985, p=0.021) were significant independent factors influence stone residual. Univariate analysis determined that stone burden (p<0.001), body mass index (p<0.015), history of ipsilateral open renal surgery (p<0.017), lower pole parenchymal thickness (p<0.001) and operative time (p<0.015) correlated with blood transfusion rate. Multivariate analysis revealed that stone burden (OR: 0.628, 95% CI: 0.149-0.852, p=0.014), operative time (OR: 0.452, 95% CI: 0.125-0.856, p=0.002), lower pole parenchymal thickness (OR: 0.365, 95% CI: 0.014-0.836, p=0.002), body mass index (OR: 0.589, 95% CI: 0.159-0.744, p=0.038) and history of ipsilateral surgery (OR: 0.635, 95% CI: 0.258- 0.825, p=0.017) were significant independent factors influence blood transfusion rate.
Conclusion: PCNL is a safe and effective procedure for lower calyceal stones more than 2cm. The stone free rate in the study was affected mainly by the stone burden and the operative time, the stone count, the degree of hydronephrosis and the lower pole parenchymal thickness were also involved. The blood transfusion rate was also affected by the stone burden, the operative time, the BMI, history of ipsilateral open renal surgery and the lower pole parenchymal thickness.