1, sperm duct obstruction: such as congenital deficiency of the vas deferens such as atresia and other malformations, surgical ligation of the vas deferens, chronic inflammation of the sperm duct and its surrounding tissues moon tumor, etc. 2, retrograde ejaculation: such as the bladder neck has been operated or damaged or post-operative epileptic scar contracture so that the urethra deformity; bilateral lumbar sympathectomy or rectal cancer after abdominal perineal surgery; diabetes-induced pubic nerve damage; hypertrophy of the seminiferous cyst, as well as severe urethral stricture; certain drugs such as adrenaline blockers body blood flat, grasping b spray acting knotamine can cause changes in the function of the sympathetic nerves that innervate the bladder jump.