Intrauterine (intracytoplasmic sperm injection) is a laboratory technique in which an embryologist selects a single sperm cell and injects it directly into a mature egg using a high-resolution microscope and specialised micromanipulation equipment.

Unlike conventional IVF, in which eggs and sperm are placed together and fertilisation is allowed to occur in the laboratory, ICSI is a highly targeted process: a selected sperm cell is injected directly into each mature egg.

The method is particularly useful when sperm count, motility or morphology makes conventional fertilisation unlikely. Even when semen parameters are satisfactory, careful assessment of sperm morphology and motility under high-powered microscopy supports the selection process.

ICSI is mainly recommended in cases of severe male-factor infertility or when there is evidence that conventional IVF may not achieve satisfactory fertilisation.

ICSI may be recommended in situations including:

• Oligozoospermia, when the sperm count is very low.
• Asthenozoospermia, when sperm motility is reduced.
• Teratozoospermia, when a high proportion of sperm have abnormal morphology.
• Severe male-factor infertility, when natural fertilisation or conventional IVF is unlikely to succeed.
• Azoospermia, including cases in which sperm is retrieved surgically from the epididymis or testis.
• Obstruction of the male reproductive tract, when no sperm are present in the ejaculate but sperm can be retrieved surgically.
• High levels of antisperm antibodies, which may affect the sperm’s ability to fertilise the egg.
• Previous fertilisation failure during an IVF cycle.
• A low or zero fertilisation rate in a previous IVF cycle.
• Increased sperm DNA fragmentation, when this is considered clinically relevant by the fertility specialist and embryologist as part of the overall assessment.

ICSI should not be selected automatically, but only after a comprehensive assessment of the couple. In some cases it is the most appropriate option; in others it may be combined with additional techniques or a different treatment strategy.

ICSI offers important benefits, particularly when the semen sample shows severe abnormalities.

Its principal advantage is that only a very small number of sperm cells is required. Even when very few sperm cells are available—for example, following surgical sperm retrieval—ICSI may make fertilisation possible.

The technique also allows the laboratory to select sperm with favourable motility and morphology, improving the chance of fertilisation when conventional IVF may not be sufficient.

ICSI is therefore a valuable option for couples affected by severe male-factor infertility, previous fertilisation failure or the need to use surgically retrieved sperm.

Success Rates with ICSI

ICSI success rates depend on many factors and are not the same for every couple.

Under appropriate conditions, ICSI can achieve fertilisation in approximately 65% to 75% of mature eggs. However, the fertilisation rate is not the same as the clinical pregnancy or live-birth rate.

The final outcome of a cycle depends on factors including:

• the woman’s age;
• egg quality;
• careful preparation before egg retrieval to maximise the number of mature eggs;
• the number of eggs that can reasonably be collected for the individual woman, which affects the overall statistical chance of success;
• sperm quality;
• the response to ovarian stimulation;
• embryo quality;
• the condition of the uterus and endometrium;
• planning, experience and care during embryo transfer;
• the history of previous treatment attempts;
• the cause of infertility.

Every couple should therefore receive individualised information. Responsible medical care is not based on general promises, but on a realistic assessment of the circumstances of each case.

ICSI and Male Infertility

ICSI is one of the most important advances in the treatment of male infertility. When sperm count, motility or morphology is severely impaired, it may make fertilisation possible when it would otherwise be extremely difficult.

ICSI is also particularly important in cases of azoospermia, when no sperm are present in the ejaculate but sperm can be retrieved surgically from the testis or epididymis. It allows even a very small number of retrieved sperm cells to be used.

Successful treatment requires close collaboration between the fertility specialist, urologist or andrologist, and the embryology laboratory. Planning must be especially careful when only a limited number of sperm cells is available or when sperm has been obtained surgically.