Intracytoplasmic sperm injection (ICSI) is a modification of the IVF procedure. Whilst IVF involves the mixing of sperm with eggs under laboratory conditions, ICSI is a more sophisticated technique in that it involves the injection of one sperm into each egg.
ICSI is carried out using a specialised piece of equipment known as a micro-manipulator by embryologists who hold a licence to perform this technique.
Who is ICSI suitable for?
There are 2 main groups of patients who may be helped with ICSI. They are:-
- Those couples where the male partner has a low sperm count, reduced sperm motility, an increase in the number of sperm with an abnormal appearance or where there are anti-sperm antibodies that cause sperm to stick together
- Those couples who have had failed fertilisation at IVF treatment.
ICSI can also be used following surgical sperm recovery techniques, such as PESA or TESE.
What does ICSI involve?
ICSI follows normal IVF procedures up to the point of egg collection and sperm preparation.
With ICSI the eggs are then carefully separated from the surrounding cumulus cells to check their suitability for injection. Eggs must then be injected at the correct stage of maturity and therefore it is usually not possible to inject all the eggs collected. The embryologist will let you know how many eggs are suitable for injection.
The ICSI injection process involves holding a single egg by gentle suction at one end of a microscopic tube and then picking up and injecting a single sperm into the centre of this egg using an even finer glass pipette. The eggs are then left overnight in the incubator for fertilisation to hopefully proceed. The next day the embryologist assesses the eggs for fertilisation. Between 2-5 days after the egg collection and ICSI, the fertilised eggs (embryos) are assessed again for signs of continued division and the best are selected for transfer into the womb. To allow monitoring of this technique, all the embryos replaced must be from either injected eggs (ICSI) or straightforward IVF, the two cannot be mixed. Embryos not used can be frozen for later use providing they are suitable (your embryologist will advise you at the time of transfer).
Unfortunately, although ICSI can greatly improve chances of fertilisation it cannot be guaranteed. Although most patients will have embryos suitable for transfer some couples may be unlucky and all the eggs may fail to fertilise.