In vitro fertilization (IVF) is a medical procedure in which mature egg cells that have been collected from a woman are fertilized with sperm outside the body and are then inserted into the uterus of the same or a different woman for gestation. IVF is generally considered only after comprehensive infertility testing has been carried out. It commonly is used for women with tubal blockages, men with reduced sperm counts, or couples whose infertility has no identifiable cause.