I. Definition of azoospermia Azoospermia is a condition in which no sperm are found in the ejaculated semen after centrifugal sedimentation and microscopic examination for three consecutive times, and the condition of non-ejaculation and retrograde ejaculation needs to be excluded. The disease is currently the biggest problem of male infertility. Classification 1. Non-obstructive azoospermia: interruption of the spermatogenic process or absence of spermatogenic cells due to congenital or acquired factors, manifested by the absence of sperm in the semen. 2. Obstructive azoospermia: The spermatogenic function of the testes is normal, but the sperm produced cannot be excluded from the body due to obstruction of the vas deferens or congenital absence of the vas deferens. (3) Etiology (1) Non-obstructive azoospermia 1. Primary or congenital factors (1) Somatic chromosomal abnormalities: 11, 9%-15% of azoospermia is caused by chromosomal abnormalities, of which Creutzfeldt-Jakob syndrome (47, XXY) is the most common. trisomy 21, trisomy 8, XYY syndrome and Y chromosome microdeletion all present varying degrees of testicular spermatogenic dysfunction. (2) Chromosomal abnormalities in spermatogenic cells: In those with normal karyotype, spermatogenic block at the primary spermatocyte stage due to abnormal first meiosis is common. (3) Cryptorchidism, congenital anorchidism 2, secondary factors (1) chemotherapy: anti-cancer drugs such as alkylating agents and vincristine have an anti-seminogenic mitogenic effect. (2) Radiotherapy: Radiotherapy can cause temporary azoospermia, such as 600-800 rads for 1 time in single irradiation area, which can cause permanent infertility. (3) Nutrition: Vitamin A deficiency and zinc deficiency can prevent spermatogenesis. (4) Heat: Primary spermatocytes are most sensitive to high temperature, long-term sauna, elevated body temperature and long-term high-temperature work can lead to oligospermia or even azoospermia. (5) Endocrine factors: adrenogenital syndrome can inhibit gonadotropin secretion and hyperprolactinemia can lead to a relative shortage of androgens, both of which can cause spermatogenic blockage at the primary spermatocyte stage. (6) Testicular factors: varicocele can involve the function of testicular mesenchymal cells, reducing testosterone production and causing testicular spermatogenic dysfunction. Damage to the testicular arteries can cause changes in the testicular internal environment and affect its spermatogenic function. (7) Environmental factors: environmental pollution, food additives, organic solvents, herbicides and pesticides all have an effect on spermatogenic function. (2) Obstructive azoospermia 1. Congenital factors: congenital absence of vas deferens, seminal vesicles and ejaculatory ducts, congenital epididymal dysplasia or non-connection with testes. 2. Acquired factors (1) Infection: one of the most common secondary factors. Inflammation of testes, epididymis, vas deferens and prostate can cause obstruction from testes to different parts of the ejaculatory duct. (2) Trauma: Cryptorchidism surgery, hernia repair and testicular sheath reversal in early childhood may damage the young vas deferens and cause vas deferens obstruction. (3) Tumors: Tumors of seminal vesicles, seminal cords, epididymis, testes and prostate gland can cause pressure or destruction of the vas deferens and cause azoospermia.