Fertilisation of the egg (ovum) outside the body. The fertilised ovum is then incubated until the blastocyst stage develops, when it is implanted into the UTERUS. IVF is used when a woman has blocked FALLOPIAN TUBES or when the sperm and ovum are unable to fuse in the reproductive tract. Hormone treatment results in the potential mother's producing several mature ova, some of which are removed from the ovary using a LAPAROSCOPE and fertilised with her partner's semen. (See ASSISTED CONCEPTION.)