Male infertility, characterised by reduced semen quality, is largely due to disorders relating to sperm production.
The most common reason for male infertility is when the man has an insufficient number of intact sperm cells with good motility. In some men, the sperm contains too few sperm cells (oligospermia). This condition may be linked to lifestyle factors such as smoking or consuming alcohol on a regular basis. Another cause of the body producing fewer sperm cells may be environmental influences.
If the sperm cells lack sufficient motility to reach the egg cell and fertilise it, this is known as asthenozoospermia. If the sperm cells are additionally malformed (teratozoospermia) or the sperm does not contain any sperm cells at all (azoospermia), fertilisation by natural means is virtually impossible. For men with very limited sperm quality or very low sperm production, in many cases, tissue may be removed from the testicles (testicular biopsy). Sperm cells may then be extracted from it (Testicular Sperm Extraction, TESE) and frozen in order to fertilise two or three selected egg cells later after their removal from the woman using Intracytoplasmic Sperm Injection (ICSI).
Infertility can also be caused by a disruption in sperm transport because the vas deferens is blocked or obstructed or the sperm cannot exit during ejaculation. In some cases, an obstructed vas deferens may be remedied through a surgical procedure. Testicular tissue can also be removed in order to extract sperm cells (TESE) and perform artificial insemination using ICSI. This also applies to men who have undergone sterilisation (vasectomy). If there is no ejaculation at all, for example due to paraplegia, the combination of TESE and ICSI is also an option.