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.
Intracytoplasmic Morphological Sperm Injection (IMSI)
IMSI is a modification of the ICSI technique where sperm samples are examined under a microscope that is almost 6000 times more powerful to better assess their "morphology". At a higher power the embryologist can identify tiny defects in the sperm head that would not otherwise be visible with standard ICSI.
Although it is yet to be confirmed to be of benefit for all requiring sperm injection, it is recommended in those with a history of recurrent implantation failures, recurrent ICSI failures or severe teratospermia (abnormal sperm shape).
In essence it is a selection tool, to aid embryologists choose the optimal sperm for ICSI. If the sperm count or motility is already so low that it limits the number of sperm available for ICSI, IMSI may not be a suitable technique for you.