Intracytoplasmic Sperm Injection (ICSI)

Intracytoplasmic Sperm Injection (ICSI)

What is intracytoplasmic sperm injection?

Intracytoplasmic sperm injection is a micromanipulation technique used in the process of in vitro fertilisation (IVF). It involves injecting a single sperm into the centre of a mature oocyte under a microscope (i.e., injecting the sperm through the egg’s shell so that the sperm does not need to penetrate the shell in order to fertilise the egg).

The injected ovum is them monitored in the lab for signs of fertilisation. The injection of sperm directly into the centre of ovum bypasses a number of events in the fertilisation process, which are highly dependent on the ability of the sperm to travel to the site of an egg, and then recognise, bind to, penetrate and fertilise that egg. This technique is therefore used to treat male factor infertility related to the quality and quantity of sperm.

The natural fertilisation of an egg by sperm is highly dependent on the motility of sperm. In men with low sperm count or morphologically abnormal sperm, the number of sperm which have the ability to travel to and fertilise an egg is reduced. Because of this, many men with a low sperm count or morphologically abnormal sperm are infertile.

Traditional IVF techniques have also been highly dependent on sperm motility. For example, the most popular technique for IVF is known as the ‘swim up’ in which sperm and eggs are placed in a culture which mimics conditions inside the uterus and the sperm then recognise and bind to the eggs as they swim around. Historically this meant that IVF was not a particularly effective treatment for male factor infertility related to semen quality. The development of intracytoplasmic sperm injection techniques have revolutionised the treatment of male factor infertility. They have a high rate of success for treating men with low sperm counts or morphologically abnormal sperm.

In summary

Intracytoplasmic sperm injectionIntracytoplasmic sperm injection is an intricate procedure, performed under a microscope by a highly skilled medical professional. The procedure itself is relatively simple (in comparison to other micromanipulation techniques) however before the actual sperm injection can be performed, spermatozoon and oocytes must be retrieved and specially prepared so that they are ready for the injection process.

A single viable sperm and oocyte are then selected for injection. Microscopic instruments (a holding pipette and an injecting pipette) are used to pick up the sperm and inject it into the centre of the ovum. The pipette is then removed and the injected ovum placed in a growth culture medium, where, if the procedure has been successful, fertilisation will occur, usually 16-20 hours following the injection.

Successfully fertilised embryos will then be implanted into a woman’s uterus,or cryopreserved for future use.

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