Intra-Cytoplasmic Sperm Injection (ICSI)


ICSI refers to a process in which an embryologist will select a single sperm to be injected directly into an egg in order to fertilise the egg.

In comparison, in conventional IVF, fertilisation occurs in a dish by placing many near an egg.
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Before ICSI became a routine technique in the 1990s, men with sperm problems had very little chance of fathering their own children. These days, improved investigations and diagnostic procedures, including tests to assess the genetic integrity of sperm, provide us with a more accurate picture of sperm quality and help clinicians determine the optimal treatment strategy. In fact, the development of new surgical sperm retrieval techniques can help men with no sperm in the ejaculate (a condition referred to as azoospermia) to father their own children, provided that a small number of viable sperm can be retrieved from the testes or surrounding tissue.

Once the eggs have been injected by ICSI, the eggs are incubated overnight, as per conventional IVF, after which the embryologist checks for evidence of fertilisation.

When may ICSI be beneficial?

  • When there are too few sperm for conventional IVF (sperm concentration less than 10 million/ml)
  • When the sperm does not move very well (sperm motility less than 30%)
  • When there are high levels of abnormal sperm (more than 95% abnormal forms)
  • When there are high levels of antisperm antibodies (indicated by positive MAR test results of >90%)
  • When the sperm has been surgically retrieved
  • When the eggs have been frozen
  • When there has been failed fertilisation or poor fertilisation (<20%) in a previous IVF attempt

Is ICSI safe?

ICSI is an invasive technique and so patients are understandably concerned about abnormalities that may result in a child conceived through this procedure. Research indicates ICSI does not cause birth defects in children conceived with the technique. However, the data show an increased incidence rate of birth defects in children following IVF or ICSI, compared to natural conception. This increase is believed to be caused by factors underlying the parents’ infertility. Hence you should be aware of the concerns that the underlying causes of your infertility may be passed on to any children conceived by IVF or ICSI.

Being an invasive technique, eggs may occasionally be damaged by the ICSI technique. This happens in less than 5% of eggs and damaged eggs are never used in further treatment.

Hence, patients with particular causes of infertility may be advised to have further investigations prior to undergoing IVF or ICSI treatment. For example, men with very low sperm count are at higher risk of having deletions in their Y chromosome. We will advise such men to have a genetic test to assess how intact their Y chromosome is prior to ICSI. Similarly, men with no sperm in the ejaculate are more likely to have absence of the vas deferens (this is the tube which transports sperm from the testis to the base of the penis). Such men are more likely to carry a cystic fibrosis gene mutation. It is advisable for such men to undergo a screening test for cystic fibrosis (which is a blood test) before undergoing fertility treatment.

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