 Patients enrolled were confirmed the presence of CBD stones using magnetic resonance cholangiopancreatography. Patients with large bile duct stones were randomly assigned to ESTLBDENBD group and ESTLBD group. A descriptive analysis will be performed on primary endpoint, containing frequency of number and percentage of patients. A two proportion equality test will be conducted to explore whether incidence rates are different. Descriptive statistics including number N, mean, median, standard deviation, minimum and maximum, will be produced for all continuous variables. Frequency tables of number N and percentage of subjects will be produced for all categorical variables. 