The traditional IVF approach is to allow this meeting to take place ‘naturally’, albeit in a laboratory dish: the woman’s egg is placed in a special culture medium with a prepared semen sample containing thousands of sperm. The fittest sperm fertilises the egg, mimicking what would normally happen in the woman’s reproductive tract.

As its name suggests, ICSI is far more precise. Rather than leaving the egg and sperm to meet of their own accord in a laboratory dish, this technique allows us to directly inject a single sperm into a woman’s egg – thereby, overcoming any issues that may be getting in the way of a sperm and an egg meeting and coming together naturally. Here, we consider some of the reasons why ICSI may be considered during IVF and what specific fertility problems it can help overcome.

Who is ICSI suitable for?

When a couple is experiencing difficulties getting pregnant, it can be easy to focus solely on the woman’s fertility. However, a male factor contributes to infertility in approximately 40% of couples who fail to conceive.¹ ‘Male factor infertility’ typically involves an alteration in the number, shape and/or movement of the man’s sperm, all of which can affect the sperm’s ability to fertilise an egg the natural way. ICSI is most commonly used to help overcome these types of sperm-related issues.

ICSI may also sometimes be offered if a woman has very few eggs available (e.g. due to age). In this case, ICSI is used to increase the chances of successful fertilisation, thereby lowering the risk that the woman runs out of eggs before she achieves a successful pregnancy through IVF.

ICSI may also be recommended if one or more previous standard IVF cycles were not successful due to failed fertilisation, or if the reason for cycle failure is unclear but a sperm-related issue is suspected despite a normal semen analysis.²

A checklist for fertile sperm

If your doctor suspects male factor infertility could be affecting your chances of pregnancy, they will usually suggest a semen (sperm) analysis. This is the main method used to test male fertility. During the analysis, a number of different factors that could be affecting your ability to conceive naturally are studied, including:

• The volume of semen, which needs to be sufficient to transport sperm into the female reproductive tract
• The sperm concentration and total sperm count, which affect the likelihood that enough sperm will reach the egg in order for one to fertilise it
• The physical shape of the sperm, as abnormally shaped sperm can have difficulty swimming to the egg or penetrating the egg’s outer layer
• The motility of the sperm (i.e. how well it can swim) – if large numbers of sperm in the sample are ‘weak swimmers’, then a natural pregnancy will be more difficult to achieve.

Your specialist might also recommend additional testing for:

• Sperm DNA damage or fragmentation: sperm with damaged or fragmented DNA have a reduced chance of fertilising an egg
• Sperm antibodies, which if present, can attack and impair sperm function.

Depending on your results, your doctor may then order follow-up tests to make sure the results are accurate and/or to see if anything else is preventing the semen from doing its job.

Once the tests are complete, your specialist will discuss your results with you and explain what your options are, including whether ICSI is likely to increase your chances of successful fertilisation and the overall success of your IVF treatment cycle.

Success rates with ICSI

Because of ICSI, many previously infertile men now have a good chance of fertilising eggs with their sperm. With some couples, pregnancy rates as high as 45% have been achieved with ICSI.³ However, rates this high are not always possible because of other factors, including age and egg quality.

The fertilisation of an egg and its subsequent development into a growing embryo is a complicated process, and there are many reasons why IVF may not be successful, even with the assistance of ICSI. To aid our success rates at Newlife IVF, we:

1. Ensure an egg is suitable for fertilisation prior to ICSI: Using polarised light microscopy, we assess a structure inside the eggs called a ‘spindle’. We call this ‘egg spindle visualisation’. This allows us to identify if an egg is at a certain stage of development (called metaphase II) and therefore, in optimal condition for fertilisation via ICSI.
2. Select the healthiest-looking sperm for ICSI: If the genetic information in the sperm has been damaged, or if the sperm is unable to use its DNA correctly, then there is a risk that development of the embryo will fail, even if it has been successfully fertilised via ICSI.⁴ A number of factors can increase this risk, such as smoking and older age.⁵,⁶ It’s not currently possible to know if the sperm we choose for ICSI is completely free of genetic defects. However, by using an advanced imaging system with an extremely high-powered microscope, we are able to study the structure of individual sperm, helping us to select the optimum sperm to inject into an egg. Sometimes, we may also use another technique, called intracytoplasmic morphologically selected sperm injection (IMSI), to help us pick out a healthier sperm based on its shape. A DNA test can also provide us with more details about sperm quality.
3. Assess the best position to inject the sperm into the egg: Our extremely high-powered microscope also allows us to very precisely inject the selected sperm into the egg, such that we avoid an important structure inside the egg called the spindle. Research has shown that injecting eggs away from the spindle results in higher fertilisation rates and better embryo quality.

Still have questions?

If you are concerned about the possibility of male factor infertility or would like more information about the role of ICSI in an IVF treatment cycle, you can make an appointment with one of our fertility specialists by calling Newlife IVF on (03) 8080 8933. You can also book online via our appointments page.

References