An epididymectomy is a male sterilization surgery that removes the epididymis, or the tube in the scrotum where the sperm become able to move. An epididymectomy can be done on either one side or both sides of the scrotum. It does not always make the male animal sterile forever, because the tubing can grow back later. It is performed on animals such as bulls. It is sometimes done on human men if the men have pain after vasectomy, a tumor, or a cyst that is difficult to treat.