Wenying Wang1, Wencheng Lv1, Ye Tian2. 1. Department of Urology, Beijing Friendship Hospital, Capital Medical University, 95 Yong an Road, Xuanwu District, Beijing,100050, China. 2. Department of Urology, Beijing Friendship Hospital, Capital Medical University, 95 Yong an Road, Xuanwu District, Beijing,100050, China. miniaowwy@aliyun.com.