Various sperm production disorders may affect a man’s fertility. Sperm production may be reduced or absent, or sperm mobility may be poor. Therefore, it is important to carry out a sperm analysis early on. The disorder may be congenital or temporary. Infections, some medicines, heavy use of alcohol, stress or other temporary factors may have a strong effect on sperm production. Consequently, any abnormal analysis results must be confirmed before further examinations.
Male infertility may also be due to the failure of the testes to descend, which has been corrected too late, since sperm production is only possible at temperatures lower than body temperature. Poor semen quality may also be due to varicocele formation in the testicular vein, a previous disease affecting the genital organs (such as chlamydia) or antisperm antibodies.
When the sperm count falls below 15 million per milliliter, fertility begins to decline. Sometimes there is a complete absence of motile sperm in the semen. If the sperm count is less than 10 million per milliliter, further examinations will be carried out. These include blood samples and an ultrasound examination of the scrotum.
Where necessary, a tissue biopsy will also be taken from the testicle to investigate the cause of the lack of motile sperm. In rare cases, a chromosomal abnormality or Y deletion may be identified as the underlying cause. Several gene regions that regulate sperm production have been found in the Y chromosome; the deletion of these regions is associated with a heavy reduction in sperm production or its total absence. Often the cause of reduced fertility of sperm cannot be found.