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Intracytoplasmic Sperm Injection (ICSI)

ICSI treatment has allowed couples where there is a significant male factor problem to achieve treatment success similar to those with other causes of subfertility. Prior to its introduction in 1992, these couples would have not achieved fertilization or very low fertilization rates using standard IVF techniques.

Couples prepare for ICSI in the same way as for standard IVF, namely ovarian stimulation and egg collection. A single motile morphologically normal sperm is carefully identified, picked up using a tiny pipette and carefully injected directly into the cytoplasm (centre) of each mature egg. The fertilised embryos are allowed to develop as for standard IVF prior to transfer.

With ICSI, very few sperm are required and this process involves the direct penetration of the sperm into the egg. It is therefore recommended:

  • When the sperm count is very low
  • When the sperm cannot move properly or are in other ways abnormal
  • When sperm has been surgically retrieved directly from either the epididymis (the coiled tubing outside the testicles which store sperm) or testicle itself
  • When there are high levels of antibodies in the semen that can affect fertilisation
  • When there have been previous low fertilization or fertilization failures
  • When there is a high level of sperm DNA damage

As ICSI bypasses the potential benefit of natural selection seen in IVF where thousands of sperm are left to attempt to fertilise an egg in the right conditions, we do not believe that ICSI should be the treatment of choice unless one of the above criteria are met.

Rarely after collection there are no mature eggs available for injection and a small percentage of eggs (<10%) may be damaged by the injection process and will no longer be viable. However, in both of these scenarios intrinsic egg quality is likely to be the main problem rather than the ICSI process itself. Whilst ICSI maximized chances of successful fertilisation in those with severe male factor fertility, there is still a 1-3% risk of couples failing to achieve any fertilized eggs.

What is IMSI?I

Intracytoplasmic morphologically selected sperm injection (IMSI) is a sperm selection method used in intracytoplasmic sperm injection (ICSI). The technique involves using a microscope to view sperm under very high magnification (over x6000). This allows clinics to view detailed images of sperm.

Are there any risks?

IMSI is a non-invasive test performed on a semen sample as an additional step in the ICSI process. The risks associated with the use of ICSI also apply to IMSI; there are no significant additional risks to the patient or embryo.

What's the evidence for IMSI?

There have been several RCTs within the last decade. Systematic reviews suggest that IMSI could be beneficial in specific situations such as previously failed ICSI attempts. The research that has been carried out does not support the use of IMSI over standard ICSI for infertile men. One small study found that IMSI had improved pregnancy outcomes in older women, however this study was carried out with a small number of women and the link, if any, between IMSI and older eggs is not fully understood.

Lister opinion:

This is a modification of the standard ICSI procedure and one of a number of sperm selection techniques that have been suggested to potentially improve outcome. The major difference between IMSI and ICSI is that a higher magnification is used to assess sperm morphology allowing the embryologist to identify tiny defects in the sperm head that would not otherwise be visible with standard ICSI.

Reviews of randomized trials have shown a benefit in pregnancy but not livebirth rates so it cannot be justified in routine practice (Cochrane, 2013).

However, other trials of lower quality have suggested benefit over standard ICSI  in certain groups such as those with previous failed ICSI cycles (Klement et al, 2013 Fertil Steril), significant male fertility (Balaban et al, 2011 RBMO), those undergoing PGS (Figeira et al, 2011) and in the selection of sperm with lower levels of sperm DNA damage (Hammoud et al, 2012 Andrologia).

We therefore use in selected cases such as those above.

The HFEA "traffic light rating" for IMSI is "red", suggesting that there is no good evidence to show that it is effective for routine use.

Read more about the HFEA traffic light system on fertility "add ons". (Link to our PDF)

A fertility "add-on" is an "optional extras that you may be offered on top of your normal fertility treatment, often at an additional cost. They’re typically emerging techniques that may have shown some promising results in initial studies but haven’t necessarily been proven to improve pregnancy or birth rates".

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The Lister Hospital
Chelsea Bridge Road
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