IVF may be used to overcome female infertility in the woman due to problems of the fallopian tube, making fertilisation in vivo difficult. It may also assist in male infertility, where there is defect sperm quality, and in such cases intracytoplasmic sperm injection (ICSI) may be used, where a sperm cell is injected directly into the egg cell. This is used when sperm have difficulty penetrating the egg, and in these cases the partner's or a donor's sperm may be used. ICSI is also used when sperm numbers are very low. ICSI results in success rates equal to those of IVF fertilisation.
For IVF to be successful it may be easier to say that it requires healthy ova, sperm that can fertilise, and a uterus that can maintain a pregnancy. Due to the costs of the procedure, IVF is generally attempted only after less expensive options have failed.
This also avails for egg donation or surrogacy where the woman providing the egg isn't the same who will carry the pregnancy to term. This means that IVF can be used for females who have already gone through menopause. The donated oocyte can be fertilised in a crucible. If the fertilisation is successful, the zygote will be transferred into the uterus, within which it will develop into an embryo.
IVF can also be combined with preimplantation genetic diagnosis (PGD) to rule out presence of genetic disorders. A similar but more general test has been developed called Preimplantation Genetic Haplotyping (PGH).