ICSI stands for Intracytoplasmic Sperm Injection, a specialized form of in vitro fertilization (IVF) used primarily for the treatment of severe cases of male infertility.

During ICSI, a single sperm is injected directly into the cytoplasm of an egg using a fine glass needle as opposed to letting the sperm fertilize an egg naturally in the standard IVF process. This procedure increases the chances of fertilization by bypassing the natural barriers that may prevent sperm from fertilizing the egg. After fertilization occurs, the resulting embryo is then transferred to the uterus following the standard IVF process.