Obstructive azoospermia is a condition in which sperm cannot be discharged due to obstruction of the sperm pathway. If the obstruction is in the distal part of the epididymis, the stage can be recanalized by microsurgical means, that is, the unobstructed parts of the vas deferens and epididymis can be microscopically connected so that the sperm can be discharged after the new channel is established. However, if the obstruction is at the proximal end, such as ejaculatory duct obstruction, the possibility of surgical recanalization is relatively small and the success rate is low. The site of obstruction must be clearly identified before the appropriate treatment can be selected. To clarify this diagnosis, a biochemical analysis of seminal plasma is required, and examination of the accessory gonadal material in seminal plasma can often reveal the site of obstruction.