Male infertility is a multidisciplinary discipline with its own characteristics, which focuses on the study of infertility and infertility in couples where the male partner is the main cause. The definition of infertility (WHO): Infertility is defined as the inability of a woman to conceive after more than one year of normal sexual function without the use of contraception. Epidemiology and etiology Approximately 25% of couples fail to conceive within 1 year of marriage, of which 15% will seek treatment and less than 5% will reluctantly accept the inability to have children. Infertility affects both men and women, with the male partner accounting for approximately 50% of the causes of infertility. If there is only a single factor, the more fertile partner can compensate for the less fertile partner, but in most cases, both partners have a problem. If both partners have decreased fertility, this usually results in the inability to have children. The causes of reduced male fertility are congenital and acquired genitourinary tract malformations, reproductive tract infections, elevated scrotal temperature (varicocele), endocrine disorders, genetic defects and immune factors. However, no cause can be found in up to 60-75% of patients (idiopathic male infertility), who have no relevant medical history, normal physical and endocrine examinations, and semen analysis showing oligospermia, weak spermatozoa and teratozoospermia. Often, these abnormalities occur together and are referred to as oligozoospermia and teratozoospermia (OAT). The main causes of male infertility are summarized in Table 1. Table 1 Etiology statistics of 7057 male infertility cases Sexual dysfunction 1.7% Genitourinary tract infections 6.6% Congenital malformations 2.1% Acquired diseases 2.6% Varicocele 12.3% Endocrine disorders 0.6% Immune factors 3.1% Other abnormalities 3.0% Idiopathic semen abnormalities (OAT syndrome) or unknown causes 75.1% Unexplained male infertility may be caused by A variety of factors, such as chronic stress, environmental factors causing endocrine disruption, reactive oxygen elements and genetic defects. The main prognostic factors affecting infertility are: the duration of infertility; whether it is primary or secondary; the results of semen analysis; the age and fertility of the female partner. When no contraception is used and the inability to have children exceeds 4 years, the monthly pregnancy rate is only about 1.5%. Currently, women in many Western countries do not consider having children until after they have completed their education and started working, yet women’s fertility at age 35 is only about 50% of that at age 25, dropping to 25% at age 38, and may drop further to less than 5% beyond age 40. In assisted reproduction, the age of the woman is the most important factor affecting the success rate. When classifying infertility, both partners should be examined at the same time; it is important to know the duration of infertility, previous fertility history and the age of the female partner to accurately assess infertile couples; the fertility of the female partner must be taken into account when diagnosing and treating male infertility, as it may determine the final outcome; urologic male specialists should examine all infertile male patients for urogenital abnormalities to clarify The diagnosis must be made before starting appropriate treatment (drugs, surgery or assisted reproductive technology). When semen analysis suggests abnormalities (Table 2), a detailed male examination is necessary. This is because the results of semen analysis remain a prerequisite for making appropriate treatment, especially when complete standardized laboratory tests are required. For this reason, the World Health Organization (WHO) published the Laboratory Manual of Human Semen and Sperm-Cervical Mucus Interaction (4th edition). Table 2 Normal semen standards (WHO 1999) Volume ≥2.0 ml PH 7.0-8.0 Sperm density ≥20 × 106/ml Total sperm count ≥40 × 106/one ejaculation Viability 60 min after ejaculation, grade A (fast forward-moving sperm) ≥25% A+B (forward-moving sperm) ≥50% Sperm morphology ≥14% of normal morphology under strict criteria # Sperm viability ≥50% of sperm survived Leukocytes