If this process were bilateral , then the problem would originate in the bladder trigone or urethra ( or the prostate around the urethra ) or some process ( such as a large neoplasm ) that could impinge on both ureters 如果病变是双侧的，原因可能是膀胱三角或尿道前列腺部的病变；或是其它能侵犯两侧输尿管的病变（如大的肿瘤块） 。
