Intracytoplasmic sperm injection was developed to treat severe male factor infertility. (The procedures for ICSI are the same as for standard IVF, except for the method of insemination.)

After eggs are retrieved, each mature egg is injected with a single sperm. After examination for fertilization, embryos are cultured and transferred to the uterus. Embryos resulting from ICSI can be frozen and stored for return at a later time.