Intracytoplasmic sperm injection

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Intracytoplasmic Sperm Injection (ICSI): a simple, shorter guide

Intracytoplasmic Sperm Injection, or ICSI, is a type of IVF. In ICSI, one healthy sperm is injected directly into the cytoplasm of an egg. This bypasses the usual steps a sperm must go through to fertilize an egg on its own.

How ICSI differs from standard IVF
- IVF mixes eggs with thousands of sperm, relying on many to fertilize.
- ICSI uses just one sperm per egg, injected straight into the egg.

When is ICSI used
- Male infertility with very few or no sperm in the semen (azoospermia) or when sperm need to be taken from the testicle or epididymis.
- Eggs that are difficult to fertilize with standard IVF or after previous IVF failures.
- It can be used with donor sperm or in other complex cases.

What happens in the procedure
- Eggs are collected from the woman.
- A single sperm is selected and injected into the egg with a tiny needle.
- The egg is checked the next day for fertilization, and healthy embryos are then placed into the uterus.

ROSI: a related method
- Round Spermatid Injection (ROSI) uses round immature sperm when mature sperm aren’t available. It’s less common and has different challenges but can help in certain azoospermia cases.

Sperm selection methods (brief)
- PICSI: selects mature sperm by binding them to hyaluronic acid.
- MACS and IMSI: lab methods to improve selection of viable sperm.
- Piezo-ICSI: uses tiny mechanical pulses to aid injection.

Outcomes and safety
- ICSI is widely used and generally safe and effective for male-factor infertility.
- There is a small risk of passing on genetic issues; results depend on many factors, including age and the quality of eggs and sperm.
- Prenatal screening is used, and interpretations may differ somewhat for pregnancies conceived with ICSI.

A brief history
- The first ICSI pregnancy occurred in 1991, with the first live birth in 1992.