Intra-Cytoplasmic Sperm Injection (ICSI)
Intra-Cytoplasmic Sperm Injection (ICSI)
This refers to a technique whereby a single sperm is injected into the egg.
- After the egg collection, the cumulus cells, which surround the egg, are removed. This is called stripping the egg for ICSI.
- A healthy and active sperm is selected and rendered immotile.
- It is then sucked into the tip of a very fine glass needle (tail first) and injected into the egg (head first). The egg is held in place using a pipette. The injection is a delicate procedure and involves the use of a micro-manipulator (an instrument used to carry out ICSI under the microscope).
A small percentage of eggs, roughly 5%, may be damaged by this procedure.
Who will benefit from ICSI?
- When the sperm concentration is less than 10 million per ml.
- When the motility of the sperm is less than 30%.
- When there are a high number of abnormal forms – more than 90%.
- When there are antibodies in the semen as indicated by a significantly positive MAR test result of more than 90%.
- Previous failure of fertilization or a fertilization rate of less than 20% with conventional IVF.
- When sperm is retrieved by PESA/TESA procedure.
IVF+ICSI split combination treatment
Sometimes IVF and ICSI can be combined in the same treatment cycle. Half the number of eggs could be subjected to IVF treatment (inseminated with sperm) and the remaining eggs could be used for ICSI treatment (where sperm is injected into the eggs). This combination will be very useful when the sperm parameters are border-line. For example, if the sperm count is between 10-20 million and the motility is between 30-50%, half IVF and half ICSI can be done. Or, if the male partner has had a borderline sperm count or motility in the past, but on the day of egg collection, the sperm count, motility and preparation are normal then one could consider half IVF and half ICSI. However, for this combined treatment, one should have a minimum of at least 12 eggs. Sometimes this is used in couples with unexplained infertility.
This technique gives the best of both the treatments. If one has ICSI to be on the safe side, then ICSI has to be repeated again, if the treatment is not successful, without knowing whether it is really necessary or not. If on the other hand, one has IVF, there is a risk of failure to fertilise. This means that there are no embryos for transfer and the whole treatment would have been wasted.
ICSI is an invasive technique and so patients are understandably concerned about abnormalities that may result in a child conceived through this procedure.
The risk of having congenital (birth) abnormality following ICSI treatment is the same as for IVF and in the general population. However, the risk of chromosomal anomalies particularly the sex chromosomal anomalies is increased (0.08% versus 0.3%). There is also a risk of transmitting the fertility problem to the offspring.
In view of the increased risk of sex chromosomal abnormalities in ICSI pregnancies, it is advisable to have a blood test to check the chromosomes of both partners. If any anomaly is detected, it will be advisable to seek genetic counselling.
Men with no sperm in the ejaculate may have absence of vas deferens (this is the tube which transports sperm from the testis to the base of the penis). Such men are more likely to carry the cystic fibrosis gene mutation. It is advisable for such men to undergo a screening test for cystic fibrosis (which is a blood test) before embarking on fertility treatment.
- This is the only treatment for couples with very low sperm count or very low motility.
- This gives the couple an opportunity to have a baby with their own gametes.
Success rate for ICSI
The success rate depends on the skill and experience of the person performing the injection procedure, and so varies from place to place. Other factors such as the woman’s age, duration of infertility, quality of the embryos and number of embryos transferred also affect the success rate.
- The fertilization rate with ICSI is 60% to 70% and complete failure of fertilization occurs in less than 5% of cases.
- The clinical pregnancy rate is between 50% and 60%
- The live birth rate is between 40% and 45%.