Updated: Jul 15, 2018
There are two ways that an egg may be fertilized in the laboratory: IVF and ICSI. In traditional IVF, 50,000 or more swimming sperm are placed next to the egg in a laboratory dish. Fertilization occurs spontaneously when one of the sperm enters into the cytoplasm of the egg. In the ICSI process, a tiny needle, called a micropipette, is used to inject a single sperm into the center of the egg. Fertilization achieved through ICSI can be up to 80-90% whereas through IVF it is aound 50 -60 %. With either traditional IVF or ICSI, once fertilization occurs, the fertilized egg (now called an embryo) grows in a laboratory for 2 to 5 days before it is transferred to the woman’s uterus (womb).