How does intracytoplasmic sperm injection help when sperm cannot fertilize an egg?

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Diagram showing the female reproductive system with labeled ovaries, fallopian tubes, uterus, and vagina, alongside hormone pathways and the process from ovulation to fertilization and early embryo development. — infertility Major structures and hormones involved in the initiation of pregnancy. Also seen, at right, is the development of an egg cell (ovum) from follicle to embryo.

Intracytoplasmic sperm injection (ICSI) is a specialized medical procedure designed to assist couples when a male partner has very low sperm counts or sperm that are otherwise unable to fertilize an egg naturally.

In this process, a single sperm is selected and injected directly into the cytoplasm—the material surrounding the nucleus—of an egg that has been retrieved for in vitro fertilization (IVF). By bypassing the natural barriers that typically prevent fertilization, this technique allows for successful conception even when sperm motility or quality is compromised. Once the eggs are successfully fertilized, they are placed into the woman’s uterus to facilitate pregnancy.1