There are two basic methods of fertilization, simple IVF (IVF) and the cytoplasmic sperm injection (ICSI). 

The choice of method depends primarily on the quality of sperm.

IVF:

IVF: Conventional IVF is applied when all semen parameters are normal. Ovaries after an egg collection are incubated at 37 ° C and 5% carbon dioxide for 2-4 hours, then a specific number of spermatozoa is placed in each culture dish. In the simple method of IVF, any particular intervention is not performed. The spermatozoa erode the outer cells of the egg and one of them penetrates and impregnates.

ICSI:

ICSI: The ICSI mainly applied for the treatment of male infertility, i.e. in cases of oligospermia, asthenospermia, teratozoospermias). In the process of ICSI, an embryologist selects morphological sperm and, smoothly, with a needle mikrogonomopoiisis places the sperm into the oocyte cytoplasm. In some cases, a woman produces very small number of eggs. As a result, we choose the method of ICSI for fertilization in order to achieve the highest possible number of embryos for embryo transfer.