Intracytoplasmic sperm injection (ICSI)

How ICSI differs from standard IVF

In standard IVF, prepared sperm and eggs are placed together and fertilisation happens on its own. In ICSI, an embryologist injects one sperm directly into each mature egg. As the HFEA explains, this maximises the chance of fertilisation by bypassing the barriers a sperm would normally have to cross. Every other stage — stimulation, egg collection, embryo transfer — is the same as IVF.

When it is used

ICSI is mainly used for male-factor infertility. The HFEA lists reasons including a very low sperm count, poor sperm movement or shape, surgically collected sperm, and previous cycles with no or very low fertilisation.

When it is not recommended

Both the HFEA and ASRM are clear that there is currently no good evidence that ICSI improves the chance of a baby when infertility is not related to sperm. Using it routinely in that situation adds cost without a proven benefit. Ask your clinic why ICSI is being recommended for your situation specifically.

Things to consider

Because ICSI is carried out as part of an IVF cycle, the risks of IVF also apply. There is also a small chance that eggs are damaged during the process, and a slightly higher rate of some problems has been reported in children born after ICSI — though it is uncertain whether this relates to the technique or to the underlying infertility.