Intracytoplasmic sperm injection (ICSI) is an in vitro fertilization procedure in which a single sperm is injected directly into an egg. The reasons for using ICSI are related to the absence of sperm in the ejaculate (azoospermia), sperm present in low concentrations (oligospermia), poor sperm motility (asthenospermia), poor sperm morphology (teratospermia), if the sperm is obtained by surgical methods, with binding problems and penetration of the sperm into the egg, if the amount of frozen sperm is limited, if there has been preimplantation genetic diagnosis (PGD), which is used to screen embryos for a certain genetic disorder. A small amount of washed sperm is placed in a cup in a thick viscous medium containing polyvinylpyrrolidone. Then the most normal-looking spermatozoa are selected. Semen is sucked up by the tail of the needle and is ready for injection. The ovum is placed under a microscope and moved using micromanipulation devices. A thin, hollow glass needle is inserted into the interior of the oocyte and loaded with a single sperm. After the procedure, the oocyte will be placed in a cell culture and checked for signs of fertilization the next day.