Cytoplasmic transfer is where the cytoplasm from a donor egg is injected into an egg with compromised mitochondria. The resulting egg is then fertilised with sperm and implanted in a womb, usually that of the woman who provided the recipient egg and nuclear DNA. Cytoplasmic transfer was created to aid women who experience infertility due to deficient or damaged mitochondria, contained within an egg's cytoplasm.
Repeated failed rounds of IVF can help identify causes of infertility. For example, if sperm and egg quality are normal, then the conception issue may be rooted at the embryonic or implantation level. In other words, if IVF fails to result in pregnancy despite successful fertilization, embryonic development or implantation may be to blame. Still this is a very expensive way to start getting answers.