Intra Cytoplasmic Sperm Injection (ICSI)

Intracytoplasmic sperm injection (ICSI) is a technique that has been developed to assist fertilisation when sperm quality and/or quantity is particularly poor. The technique involves injecting a single sperm into the centre of each oocyte. The treated oocytes are checked the day after the ICSI procedure to see if fertilisation has occurred.

The magnified image shows a pipette on the left steadying the oocyte in the middle while a small needle which contains a single sperm is being inserted into the middle of the oocyte.

The ICSI procedure was developed in the 1990s by a team at the Brussels Free University Centre for Reproductive Medicine led by Prof. A Van Steirteghen. It is now widely used when semen contains low sperm in low numbers and/or low motility (movement) and/or high abnormal forms (shapes).

Who considers ICSI?

ICSI is used when there are problems with the sperm that would make it impossible to achieve fertilisation with conventional IVF. ICSI may be appropriate in the following cases:

patients with very low sperm numbers/count (oligospermia)
patients with very low motility (asthenozoospermia)
patients with very high numbers of abnormal sperm (teratozoospermia)
when the sperm have been surgically collected (see Treatment Options>Surgical Sperm Collection)
when there is a high level of antibodies in the semen
when there has been previous failure to achieve fertilisation with conventional IVF, or when very few oocytes have fertilised following IVF

In line with medical best practice of least interference necessary, it is advisable for couples to attempt ICSI unless it is absolutely necessary. Therefore ICSI will generally not be carried out unless one of the above criteria is met and the specialist will advise if ICSI is recommended.

Benefits of ICSI

ICSI is only suitable for attempting to achieve fertilisation where the sperm of the male partner are unable to achieve acceptable fertilisation rates using routine IVF. ICSI has been shown to achieve fertilisation rates of about 60% in the unit where it was developed. (Normal sperm will fertilise about 70% of mature oocytes in IVF).

ICSI has resulted in pregnancy rates which are similar to IVF success rates at the Centre where it was developed. These rates depend to a large extent on:

1) the age of the woman,

2) the woman’s infertility status and cause, and

3) the number of embryos replaced.

For the majority of fertility clinics, IVF success rates vary between 21%–35%.

Disadvantages of ICSI

ICSI is another intervention in the fertilisation process and while extensive trials have been completed and the embryologists are experienced, there may yet be unforeseen complications of ICSI.

Not all oocytes collected may be of suitable quality or mature enough to undergo the injection procedure. If very few oocytes are collected, none may be suitable for ICSI. As ICSI is a very delicate procedure, some oocytes may be damaged, and therefore will not be available for transfer.

Whilst there is evidence from the Brussels group that the incidence of abnormalities in foetuses and children resulting from ICSI procedures is no greater than in the normal population, there may indeed be an increased risk of abnormalities using ICSI. We cannot be sure that these risks will be at the same rate as in the general population.

ICSI and genetic abnormalities

(Y-chromosome defects)

Research has shown that there is an association between the defects on the Y chromosome (the chromosome that is responsible for maleness) and male infertility. Thus, a man who has a defect on the Y-chromosome which affects sperm production, is likely to have male offspring who have the same defect and will also suffer from infertility, but will otherwise be normal.

Genes have been identified on the Y-chromosome that are involved in the production of sperm. If these genes are defective or parts of them are missing (deletions), sperm production will be reduced or non-existent. With the development of ICSI, it is now possible to treat men with extremely low sperm counts, or sperm with very low motility (ability to move effectively). Using ICSI in conjunction with surgical methods of retrieving sperm directly from the testis, it is possible to treat men who have only small areas of sperm production within the testis. It is therefore important that we understand the way in which genetic changes can affect male fertility.

Many fertility clinics offer screening for Y-chromosome deletions to male partners of couples who are about to undergo ICSI for low sperm counts (at the discretion of the specialist). A blood sample is taken and sent to a laboratory or fertility clinic that performs the test. At present we do not know the frequency of these defects among ICSI patients but there is a considerable amount of research being done worldwide. It is important to understand that these genetic defects are only a concern for male offspring and, at worst these children will be expected to experience the same fertility problems as their fathers. However, it is important that you are aware if you have such a genetic defect so that you can take this into account when making decisions about your future treatment.

Patients who conceive following ICSI should carefully consider whether to have antenatal screening tests such as amniocentesis. Further advice should be given by the specialist gynaecologist.

All children born from the ICSI technique may be required to be examined by a consultant paediatrician and a follow-up study of all children born may be undertaken. Patients having ICSI using surgically retrieved sperm for non obstructive azoospermia have a significantly increased risk of miscarriage. These miscarriages are the result of an increase in the level of the chromosomal disorder called mosaicism.

ICSI/IVF Treatment Cycle

All women are treated as for all IVF treatments. Men will be required to provide a semen sample on the morning of the oocyte retrieval. However, if the sperm is to be collected surgically, this will have been performed earlier and frozen, or collected on the days prior to, or on the day, of oocyte collection.

Each oocyte is examined to ensure it is suitable for ICSI, and a single sperm is injected into the oocyte. The oocytes are placed in culture and examined the following day to see whether they have fertilised normally. The balance of the procedure is similar to IVF.