Semen abnormalities Absence of sperm, too few or deformed sperm, low viability, such as congenital testicular development disorders or severe lesions of the testes and vas deferens, which can affect conception. Normal semen condenses into jelly soon after ejaculation and liquefies all over again within the next 15-30 minutes. If semen does not coagulate after ejaculation, or if it liquefies abnormally, it can also cause infertility. Spermatogenic disorders Chromosomal abnormalities, cryptorchidism, congenital orchidrosis or bilateral testicular hypoplasia can cause infertility due to impaired spermatogenesis. Localized testicular lesions, such as testicular tuberculosis, epididymitis, prepubertal mumps complicated by orchitis, varicocele, etc., will affect sperm production ability. Factors affecting the union of sperm and egg The epididymis, vas deferens, ejaculatory ducts, urethra and external genitalia are all necessary pathways for the discharge of semen, and lesions in any of them can affect the union of sperm and egg and cause infertility. For example, congenital penile agenesis, hypospadias, obstruction of the vas deferens, retrograde ejaculation, difficulty in sexual intercourse, etc. Endocrine disorders such as testicular insufficiency, primary or secondary hypogonadism, and hypothyroidism can also cause infertility. Other diseases In addition to the many causes mentioned above, certain systemic diseases, severe malnutrition, frequent exposure to radiation, high temperature work, toxic effects of drugs, long-term use of crude cottonseed oil and the presence of sperm immune antibodies can cause infertility.