 4. Data Analysis The summary statistics will be used to describe the data. Mean95 confidence intervals will be reported for continuous variables, and frequencypercentage will be reported for nominal variables. The primary outcome, rate of postoperative sepsis, and the corresponding 95 confidence interval CI will be reported, and compared between the intervention and control groups at the for the postoperative period using a Chi-squared test. Secondary outcomes will include rate of nonseptic bacteruria, stone-free rate, and LOS and will be compared with using Chi-squared tests or t-test as indicated. The patient characteristics and outcomes between those who have one-year follow up records and those who do not will also be investigated. Using 2-sided P values, statistical significance will be set at p0.05. 