What are the causes of male infertility?

Patient's question:

Causes of male infertility

Doctor's answer:

(1) Azoospermia or Oligozoospermia
When the sperm density in semen is lower than 0.2×10? /ml, the chances of conception for the female decrease, leading to infertility. This type of infertility can be classified as permanent or temporary. The former is seen in cases of congenital testicular developmental disorders or severe lesions in the testes or seminal vesicles. The latter is often caused by excessive sexual activity leading to a temporary decline in sperm production, usually resulting in a decrease in sperm count rather than complete absence of sperm.
(2) Poor Sperm Quality
If the semen contains a high proportion of non-viable or dead sperm (exceeding 20%), or if the sperm motility is poor or the percentage of abnormal sperm exceeds 30%, it often leads to infertility.
(3) Abnormal Physicochemical Characteristics of Semen
Normal semen quickly coagulates into a gel-like state after ejaculation and then fully liquefies within 15–30 minutes. If the semen does not coagulate after ejaculation or does not fully liquefy, it may indicate lesions in the seminal vesicles or prostate. Bacterial or viral infections of the reproductive tract can also alter the composition of semen, leading to infertility.