What is intra-cytoplasmic sperm injection (ICSI) and how does it work?

ICSI - injecting sperm into an eggIntra-cytoplasmic sperm injection (ICSI) differs from conventional in vitro fertilisation (IVF) in that the embryologist selects a single sperm to be injected directly into an egg, instead of fertilisation taking place in a dish where many sperm are placed near an egg.  

Is ICSI for me?

ICSI enables fertilisation to happen when there are very few sperm available.

Your clinic may recommend ICSI if:

  • you have a very low sperm count
  • other problems with the sperm have been identified, such as poor morphology (abnormal shape) or poor motility (not moving normally)
  • during previous attempts at IVF there was failure of fertilisation or an unexpectedly low fertilisation rate
  • 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, you do not ejaculate sperm, or because you have extremely low sperm production
  • you are using frozen sperm in your treatment which is not of optimum quality
  • you are using embryo testing.

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Computer screen depicting the procedure for ICSI, which is similar to IVFHow does ICSI work?

Before your treatment starts you will need to complete various consent forms and you, and if applicable your partner, may need to have blood tests to screen for HIV, hepatitis B and C and human T cell lymphotropic virus (HTLV) I and II.

Treatment then typically involves the following:

For women

You take fertility drugs to stimulate your ovaries to produce more eggs, as for IVF, and your progress will be monitored through vaginal ultrasound scans and possibly blood tests.

The eggs are then collected using the same procedure as IVF and each egg is injected with a single sperm from your partner or donor. The rest of the process is also the same as IVF.

You are more likely to become pregnant with twins or triplets if more than one embryo is transferred so your clinic will recommend single embryo transfer (SET) if they feel it is the best option for you. An embryologist will examine your sperm under a microscope and decide whether ICSI could increase your chances of fathering a baby.

The next step depends on whether you are able to provide sperm without a medical procedure:

  • If you can, you produce a fresh sperm sample on the same day as your partner’s eggs are collected.


  • Sperm can be collected directly from the epididymis using a type of fine syringe. This is known as ‘percutaneous epididymal sperm aspiration’ or PESA.
  • Sperm can also be retrieved from the testicles, a process known as ‘testicular sperm aspiration’ or TESA.
  • It is also possible to remove tiny quantities of testicular tissue from which sperm can be extracted. This procedure is called ‘testicular sperm extraction’ or TESE. For more information about PESA, TESA and TESE, speak to your doctor.
  • If you have stored sperm, it will be removed from frozen storage, thawed and prepared for treatment.

A single sperm is then injected into each egg. ICSI provides the opportunity for fertilisation to happen, but it is not guaranteed to succeed.

Finally, if fertilisation does take place, the embryos will be cultured in the laboratory for up to six days and then between one and three of the best-quality embryos will be transferred to the womb.

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Zero sperm count

If you have a zero sperm count (other than caused by vasectomy), the chances of retrieving sperm surgically by PESA, TESA or TESE may be very low.

In this situation, you might consider having a surgical retrieval as a ‘dummy run’ and storing any sperm that are obtained. If no sperm are retrieved, you may want to consider donor insemination (DI) or IVF with donor sperm instead.

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Page last updated: 07 January 2015

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