Value of Computed Tomography for Predicting the Outcome After Percutaneous Nephrolithotomy

INTRODUCTION Computerized tomography of the urinary tract (CT-UT) has been established as the diagnostic procedure of choice for urinary stones. This study aimed to evaluate its role in predicting the outcome of percutaneous nephrolithotomy (PCNL) in terms of stone free rate and residual fragments. METHOD This prospective cohort study was conducted on 34 patients in the Urology Department of Theodor Bilharz Research Institute from January 2013 to March 2014. The patients who had large and/or multiple renal stones, including staghorn stones, in 19 renal units scheduled for PCNL were included in this study. All had a pre-operative CT-UT to determine the stones' characteristics and renal anatomy. CT-UT, together with a kidney-Ureter-Bladder (KUB) film, was taken on the first post-operative day. The data were analyzed by SPSS version 17 using independent-samples t-test and the chi-squared test. RESULTS CT-UT showed a statistical significant sensitivity in detecting residual fragments over standard KUB, yet this significance was lost when corrected to significant residual. Stone size and density were independent factors for the presence of residual stones. CONCLUSION CT-UT post PCNL was sensitive to detect residual fragments, yet it showed no superiority over standard KUB in detecting significant residual.