In vitro fertilization is a form of treatment applied to women who cannot conceive with classical methods. It is based on the principle of transferring embryos, which are formed as a result of combining male (sperm) and female (egg) progeny cells under laboratory conditions, to the uterus. Fertilization performed under laboratory conditions is achieved spontaneously (in vitro fertilization) or by human intervention, by injecting a single sperm into a single egg (microinjection).

In vitro fertilization started to be applied to women who had permanent damage to their tubes as a result of infection or surgical procedure, and after a short time, it started to be used in the treatment of other causes that lead to infertility. Today, successful results are obtained with in vitro fertilization methods in endometriosis, unexplained infertility cases and male infertility.

Microinjection, which has been applied especially in recent years, is described as a revolution in the treatment of men who have sperm in their testicles, even though the sperm count is very low and even there is no sperm in their semen.