Intracytoplasmic Sperm Injection (ICSI)
What is Intracytoplasmic Sperm Injection (ICSI)?
Intracytoplasmic Sperm Injection (ICSI) is a procedure in which sperm are directly injected into the egg. This procedure is used primarily when men have poor semen characteristics. ICSI is usually offered to couples who have had poor or no fertilisation during standard IVF, or when fertilisation is thought to be less likely to occur with routine IVF. ICSI can be seen as one of the major break throughs in treatment of male infertility since only a few normal sperm are needed for conception. Men who were previously seen as completely sterile now have an excellent chance to have their own child.
ICSI was first used in 1992 and offers an alternative to donor sperm for those who have severe male infertility which includes:
- Poor sperm morphology (abnormally shaped sperm)
- Poor sperm motility (slow moving sperm)
- A low sperm count
- An obstruction which prevents sperm release (such as vasectomy)
- Antisperm antibodies (antibodies produced by the man’s body which may inhibit sperm function)
- Vasectomy reversals resulting in very low sperm counts or poor quality sperm production
In standard in vitro fertilisation (IVF), between 50,000 and 100,000 sperm are placed in the same dish as a single egg, and sperm are allowed to naturally fertilise the egg. In the event that no abnormalities in the sperm exist, normal fertilisation is often confirmed the next morning. However, in cases of male factor infertility where significant abnormalities in the count, motility, and/or shape of the sperm exist, IVF results in very poor fertilisation rates, often resulting in no fertilised eggs and thus no embryos for transfer. Since ICSI involves the injection of only a single sperm into each egg, even the most severe of male factor abnormalities can be overcome.
Using a high magnification microscope, a single sperm in injected into the centre of a mature egg using a very fine glass needle many times smaller than a human hair. The early stages of ICSI treatment are the same as for conventional IVF. The female partner takes fertility drugs to stimulate her ovaries so that several eggs can be collected. Then the semen sample is prepared in the lab to isolate as many healthy moving sperm as possible. The sperm are washed and prepared for fertilisation. Each egg is injected with a sperm cell such that several embryos will be available for transfer and storage. The injected eggs are placed in an incubator and are checked the next day for signs of fertilisation. We then choose the embryos most likely to grow into a healthy baby for transfer.
Approximately 30% to 40% of all infertility is due to a male factor. ICSI has revolutionised the treatment of male infertility with a rate of fertilisation around 70%. While ICSI does not absolutely guarantee fertilisation, the rate of complete failed fertilisation is very low and is most common in cases with limited egg supply. To date, tens of thousands of children have been born around the world as the result of ICSI.
The difference between IVF and ICSI
Ovarian stimulation and egg retrieval in ICSI and IVF are exactly the same. The only difference between the two is the way the egg is fertilised. IVF allows the sperm to penetrate the egg of its own accord. However in an ICSI cycle each suitable mature egg is injected with a single prepared sperm cell. This is done under a microscope by qualified technicians using very fine tools (known as micromanipulation). If the egg is fertilised the embryo is inserted into the uterus in the same way as for IVF.