ICSI (Intra Cytoplasmic Sperm Injection)
ICSI is a technique whereby a single sperm is injected directly into an egg to aid the creation of an embryo.
The initial stimulation and monitoring of the patient is the same as in IVF, and the drugs used are also the same.
IVF and ICSI differ only in the technique with which the fertilisation of the egg is achieved in the laboratory. The experience of the couple while undergoing super-ovulation, egg collection, embryo transfer, and subsequent luteal phase support and pregnancy testing are all exactly conventional IVF.
The first step of ICSI is denudation of the oocytes which means that the eggs are treated with an enzyme to remove the surroundings cells. The eggs are then examined under the microscope and the mature eggs are identified, and selected for ICSI. Meanwhile the sperm is prepared and placed into medium to slow them down, after which they are selected for microinjection. A single sperm is aspirated into a fine glass needle and is then injected directly into the egg. After injection the eggs are returned to the incubator for culture. In contrast to IVF, ICSI bypasses the natural processes, which lead to the entry of the sperm into the egg.
Fertilization, if it has taken place, can be observed about 18 hours after injection. In general about 15% of eggs are expected to be damaged by the microinjection procedure. The fertilized eggs are observed for 48 to 72 hours and then the embryos are replaced in the uterine cavity using a small embryo replacement catheter.
After the transfer, you need to take progesterone pessaries or injections. Two weeks following replacement, a pregnancy test is done to confirm implantation. The pregnancy rate with ICSI is similar to the pregnancy rate with standard IVF.
Chances of success:
The success rate for ICSI has increased rapidly in the last few years, a live birth rate of 22 % per embryo transfer. However your chances of success will very much depend on your own individual circumstances.
Risks of ICSI:
Whilst there are only a few serious doubts about the chance of genetic disorders due to the ICSI technique itself, it is possible that genetic disorders which led to low sperm counts or reduced motility in the father's sperm may be passed on to a son.
When the male infertility has been acquired due to infection (such as mumps), or injury, or due to operation (such as previous vasectomy), or due to the presence of anti-sperm antibodies there is no reason to believe that the infertility is likely to be passed on to the next generation.
However, the tests presently available are not absolutely perfect, and will only detect about 80% of such abnormalities.
There is some evidence that babies conceived as a consequence of ICSI may have an increased risk of a chromosomal abnormality. Many such abnormalities may be relatively minor and be of relatively little consequence.
Evidence present till date:
Sperm with structural defects
Studies have shown that sperm, which appear structurally abnormal, have a higher incidence of chromosomal abnormalities. Abnormal sperm and/or eggs may result in failure to fertilize, failure to implant recurrent reproductive loss or abnormalities in the offspring.
Chromosome abnormalities in the infertile male population
1. Overall, there is a 10 fold increase in chromosomal abnormalities in infertile male (approx. 5%) compared with the general population (<0.4%).
2. Results from several studies show that infertile males with normal semen parameters are less likely to have chromosomal abnormalities compared to those with abnormal semen parameters.
3. Between 4 and 5% of oligozoospermic individuals (low sperm counts) have chromosomal abnormalities, the majority of which are autosomal defects.
4. Between 13 and 14% of non-obstructive azoospermic individuals (no sperm in semen) have chromosomal abnormalities, the majority of which are sex chromosome anomalies, particularly trisomies such as Klinefelter's.
5. 5-10% of azoospermic men selected for ICSI have absent vas deferens. The majority of these cases are associated with mutations in the cystic fibrosis (CF) gene. Men with this condition appear to be compound heterozygotes for the CF mutations, and are therefore at an increased risk of passing cystic fibrosis on to their offspring.
6. Another chromosomal abnormality clearly associated with male infertility is microdeletions on the Y chromosome. These deletions have been found in approximately 6% of males with sperm counts of less than 5 million per ml, and in approximately 8 % of men with complete absence of sperm in their semen. These same deletions will probably be passed on directly to the sons of these individuals.
7. Chromosomal profiles of individuals are determined from blood cell analysis and represent the overall chromosome constitution of that individual (karyotyping). While the blood karyotype of infertile males with below normal semen parameters may appear perfectly normal, research has shown that there is an increased frequency of chromosomal abnormalities in their sperm.
Birth defects
Clearly more research is required to determine the long-term effects of the ICSI procedure, since it is still a new technique, the oldest child being born in 1992. While there are clearly enhanced risks using ICSI as a form of treatment, it is emphasized that the odds overall appear very much in favor of this technique being highly successful.
So far, assessment of children conceived in this way (and there have been some thousands conceived in this way now) is reassuring, and suggests that the incidence of congenial abnormalities may not be any greater than the normal incidence in the general population. However, such children remain relatively few in number, and are, at present, no more than a few years old. Although to date the children so conceived appear reassuringly normal, it is impossible at this stage to be certain that genetic problems may not be found at a later stage in life.
Which couples should consider ICSI?
The indications for ICSI are far too many and vary from case to case. However some of the common indications are as follows:
- Male factor infertility
- No sperm in the ejaculate but seen in the testes
- Failed fertilization during previous IVF cycle
- Elderly women, as the availability of eggs will be scarce
Is ICSI possible in men who have no sperm in the ejaculate?
If the absence of sperm in the ejaculate is due to an obstruction or absence of the tube carrying sperm from the testicle it may be that sperm production within the testicle continues, and it may then be possible to aspirate these sperm directly from the testicle or from the adjoining collecting duct called the epididymis.
In this situation, sperm may be collected in one of 3 ways: By percutaneous epididymal sperm aspiration (PESA) or by Micro-surgical aspiration of the sperm from the testicle or epididymis (MESA) or a procedure involving testicular biopsy (TESA/TESE). These procedures are an additional procedure over and above that of ICSI. It is, at this instant, unlikely to be certain what the success rate will be following such procedures, but they probably work just or almost as well as other cases involving ICSI.
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