During the IVF process, we normally use standard insemination — the egg, which sits in a laboratory dish, is exposed to thousands of sperm. The fittest sperm will fertilise the egg and in this sense, the process is ‘natural’.
However, for a sperm to successfully fertilise an egg, it must penetrate the egg’s outer covering. This may prove difficult for a number of reasons, including:
A semen analysis can assess these parameters. Your fertility specialist will then decide, based on your results, if ICSI is necessary. Additionally, we may recommend ICSI if you have previously had poor fertilisation results using standard insemination.
In intracytoplasmic sperm injection, a single sperm is injected directly into the centre of a mature egg. This bypasses the outer covering of the egg, making it easier for fertilisation to occur. However, it does not guarantee successful fertilisation.
Intracytoplasmic sperm injection is done as part of the IVF process. Following egg retrieval and sperm collection (via self-collection or testicular biopsy), the sperm are microscopically assessed for motility, size and shape. Based on this assessment, one sperm is selected.
The selected sperm is gently injected into the centre of a mature egg (we will assess the egg first to ensure it is mature). If fertilisation is successful, the resultant embryo is then grown and transferred into your uterus, like any other embryo.
For ICSI procedures, we use an incredibly powerful microscope that uses polarised light. This leading technology allows us to assess whether an egg is in optimal condition for fertilisation and to identify the best position to inject the sperm into the egg. Additionally, it provides feedback if fertilisation with ICSI is unsuccessful; our scientists can assess whether the egg or the sperm was responsible by assessing a structure called the ‘spindle’. This knowledge assists us in planning our approach to subsequent IVF cycles.
IMSI may be used if the semen analysis suggests abnormal sperm morphology (i.e. abnormal shape). This technique uses a high-powered microscope that magnifies structures over 6000 times, allowing us to visualise the sperm’s head, midpiece and tail. This enables our scientists to better identify abnormally shaped sperm and consequently choose the best sperm for the ICSI procedure.
High levels of sperm DNA fragmentation can prevent the sperm from fertilising the egg. However, we also know that sperm that can bind to a substance called hyaluronic acid have low levels of DNA fragmentation. Consequently, if semen analysis identifies that a man’s sperm has high levels of DNA fragmentation, we can use HA ICSI to help select the best sperm for the ICSI procedure.
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Dr Hugo Fernandes discusses genetic screening options during IVF, including carrier screening and preimplantation genetic screening.Learn more