What is Intracytoplasmic Sperm Injection (ICSI)?
Intracytoplasmic sperm injection (ICSI) is a modification of the IVF procedure. While IVF involves the mixing of sperm with eggs under laboratory conditions, ICSI is a more sophisticated technique that involves the injection of a single sperm into each mature egg. ICSI is carried out using a specialised piece of equipment known as a ‘micromanipulator’ by embryologists who hold a license to perform this technique.
This is a more sophisticated technique than conventional IVF. Up to the point of egg collection, ICSI and IVF do not differ.
Ovarian stimulation protocol
Daily fertility drugs (hMG or recombinant FSH or recombinant FSH/LH with or without GnRH agonist or antagonist) are necessary to stimulate the ovaries to produce a high number of oocytes (eggs). The recruitment and development of follicles which contain the eggs, is tracked by regular transvaginal ultrasound scans and sometimes blood tests. When at least three follicles are mature (greater than 17mm in diameter) a hormone injection (hCG) is given to ripen the eggs. Egg collection is performed generally under ultrasound guidance and very seldom by laparoscopy 34-36 hours later. The egg collection procedure takes about 20 minutes.
The ovarian stimulation protocol is individualised to maximise the chances of success while reducing the risks, complications and possibly the costs of treatment.
Sometimes it is possible to proceed to egg collection without using any drugs for ovarian stimulation. In most cases only one or two eggs are collected but immature eggs can be matured in vitro before being fertilised. In most cases only one healthy embryo is available for transfer. Usually there are not enough embryos to be stored. Some people argue that using a “natural cycle” the endometrium (lining of the womb) may be more receptive to the implanting embryos.
What does ICSI involve?
This assisted conception technique involves injecting a single sperm directly into the centre (cytoplasm) of an egg. If fertilisation occurs, the resulting embryo can then be transferred to the uterus (womb) using conventional embryo-transfer methods. ICSI is carried out using a piece of equipment known as “micromanipulator”.
In detail, the ICSI injection process involves holding an egg by gentle suction with a microscopic tube and then selecting and injecting a sperm into the centre of this egg using a very thin glass pipette. The eggs are then incubated overnight to allow fertilisation to occur. The next day the embryologist assesses the eggs to check that fertilisation has occured.
Who are the candidates for ICSI?
a) couples whose male partner has severe sperm abnormalities such as a low sperm count, reduced sperm motility, a high number of sperm with an abnormal appearance or where there are antisperm antibodies, that cause sperm to stick together
b) couples who have had failed IVF treatment because of failed fertilization
c) couples whose male partner has no sperm in the ejaculate but sperm can be retrieved surgically from the testes using techniques like percutaneous sperm aspiration (PESA) or testicular sperm extraction (TESE)
d) women who use frozen eggs
Like IVF, the success rate of ICSI measured as live birth rate can be as high as 40% per cycle with fresh embryos and up to 25% with frozen embryos.
Risks and complications of ICSI
The risks associated with egg collection, the risk of ectopic pregnancy and the risk of ovarian hyperstimulation syndrome (OHSS) are the same as IVF. The risk of multiple pregnancy after ICSI is the same as IVF but it has been reported that there is an increased incidence of monozygotic twinning with ICSI. The risk of failed fertilization is lower with ICSI than it is with IVF.
Regarding any genetic risks, it has been reported that the risks of birth defects in children conceived after ICSI may be higher than natural conception. Publishes studies suggest that the increased incidence may be attributed to parental characteristics including the casue of subfertility and chromosomal abnormalities rather than the use of assisted reproductive technology itself. There is a 1.4-2.0 fold increase in the rate of birth defects following assisted conception as compared to natural conception. Children born after ICSI have a higher rate of chromosomal abnormalities either inherited from paternal structural chromosomal abnormalities or de-novo. A proportion of men with severe sperm problems have a genetic basis for this, usually an abnormality of the Y chromosome. This is likely to be inherited by male offspring after ICSI. Children conceived by ICSI appear to have more congenital abnormalities, particularly urogenital defects, which can be surgically corrected. Overall the data in the literature are reassuring for the long-term consequences of children born after IVF/ICSI.
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