ICSI stands for intracytoplasmic sperm injection. ICSI may be used as part of an IVF treatment In normal IVF, many sperm are placed together with an egg, in hopes that one of the sperm will enter and fertilize the egg. With ICSI, the embryologist takes a single sperm and injects it directly into an egg. For this a specialized ICSI machine is used. Success rate is more in ICSI in certain indications.