The purpose of ICSI (Microinjection of the spermatozoon in the ovum) is to facilitate fertilization by reducing or eliminating the obstacles that the sperm find in their attempt to penetrate the egg and succeed in fertilizing it. It consists of the direct microinjection of a spermatozoa inside the oocyte. It is performed in the laboratory by the embryologist, who uses micro-manipulators to drill the cell membrane of the oocyte and introduce the selected sperm into the interior. This technique is reserved for cases in which IVF fertilization is predicted to fail and has contributed to the resolution of many cases of severe male infertility.