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ICSI: intra-cytoplasmic sperm injection


What is intra-cytoplasmic sperm injection (ICSI)?

Intra-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.

Who is ICSI for?

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

ICSI may be recommend if:

  • there is 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 due to a vasectomy or extremely low sperm production
  • frozen sperm of optimum quality is used
  • embryo testing is used


What does the treatment typically involve?

Fertility drugs are used to stimulate the ovaries to produce more eggs, as for IVF. The 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 a partner or donor. The rest of the process is also the same as IVF.

A woman is more likely to get pregnant with twins or triplets if more than one embryo is transferred so single embryo transfer (SET) is recommended if it is the best option. The embryologist will examine the sperm under a microscope and decide whether ICSI could increase the chances of fathering a baby.

The next step depends on whether it is possible to provide sperm without a medical procedure:

If this is possible, a fresh sperm sample is produced on the same day as the 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.
  • If stored sperm is used, it will be removed from frozen storage, thawed and prepared for treatment.


A single sperm is then injected into each egg.

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.