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Intracytoplasmic sperm injection (ICSI)

For around half of heterosexual couples who are having problems conceiving, the cause of infertility is sperm-related. ICSI is the most common and successful treatment for male infertility. This page will introduce you to ICSI, who it might be suitable for and what the risks are.

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Who might be recommended to have ICSI?

Your doctor may recommend ICSI if:

  • you have a very low sperm count
  • your sperm are abnormally shaped (poor morphology) or they don’t move normally (poor motility)
  • you’ve had IVF previously and none, or very few of the eggs fertilized.
  • you need sperm to be collected surgically from the testicles or epididymis (a narrow tube inside the scrotum where sperm are stored and matured); for example because you have had a vasectomy, or you have a blockage that prevents sperm reaching the ejaculate, caused by disease, injury, or a genetic condition, or because you have an extremely low sperm count
  • you’re using frozen sperm in your treatment which isn’t of the highest quality, especially if it was stored because your fertility was under threat, or following a surgical sperm retrieval.
  • you’re having embryo testing for a genetic condition, and sperm sticking to the outside of the eggs would interfere with the results.

Is there anyone ICSI isn’t right for?

If you’ve had treatment in the past and poor quality or immature eggs meant the sperm and the egg had trouble fertilising, then ICSI is unlikely to help.

Is it worth having ICSI even if we don’t have male infertility?

For most people who have no evidence of male factor infertility, the chances of getting pregnant are the same whether they have ICSI or not and it will cost more if you’re paying for your own treatment.

Find out more about costs and funding

There are also some concerns around the fact that ICSI may cause developmental defects in children (see risks below) so you may not want to take that risk, however small, unless you really need to.

How successful is one cycle of ICSI?

ICSI itself is very successful at helping the sperm and the egg to fertilise. However, as in IVF there are still many other factors affecting a successful pregnancy, including the age of the woman and whether she has any fertility difficulties herself. Success rates for ICSI tend to be very similar to IVF so we don’t publish separate statistics.

Find out more about IVF success rates on the IVF page.

Visit our research and data page for the latest data on success rates.

Claire and Richard had two unsuccessful cycles of ICSI before deciding to move on from treatment. Read Claire's story.

Couple reading a book together in a field

Claire and Richard had two unsuccessful cycles of ICSI before deciding to move on from treatment.

Read Claire's story

How does ICSI work?

Your treatment will be exactly the same as with IVF. The only difference is that instead of mixing the sperm with the eggs and leaving them to fertilise, a skilled embryologist (embryo specialist) will inject a single sperm into the egg.

This maximises the chance of fertilisation taking place as it bypasses any potential problems the sperm will have in getting inside the egg.

Find out more about IVF

How safe is ICSI?

ICSI carries slightly more risks than some other fertility treatments, including a risk that eggs may be damaged when they’re cleaned and injected with sperm.

It has been suggested that the use of ICSI may also be associated with long-term health issues for the children born. However, we cannot prove this either way until we have more conclusive evidence.

Risks that may be associated with ICSI include:

  • certain genetic and developmental defects in a very small number of children born using this treatment; however, problems that have been linked with ICSI may have been caused by the underlying infertility, rather than the treatment itself
  • the possibility that a boy conceived as a result of ICSI may inherit his father’s, or donor's, infertility (it is too early to know if this is the case, as the oldest boys born from ICSI are still in their teens). However, where there is a clearly defined genetic cause of male infertility, particularly if it is associated with the Y chromosome, it is highly likely that male offspring will inherit their father’s, or donor's, infertility.

If you think this might apply to you, you may want to consider having genetic testing first to avoid the low sperm count being passed onto a male child. You’ll probably want to discuss the full implications of taking these tests with your clinic’s counsellor before going ahead.

There are also all the usual risks that come with IVF treatment.

I’ve had ICSI and it didn’t work – what next?

As with IVF, many experts recommend that you wait for a couple of months after treatment before trying again. This gives you a break from the stress of treatment and a chance for your body to recover. If you want, you can try ICSI again if your doctor thinks you have a reasonable chance of success.

Alternatively, you can think about your options and decide whether to continue treatment or explore other options for having a family, such as using donor sperm or adoption. 

Review date: 15 April 2026