IVF And ICSI
Intracytoplasmic sperm injection (or ICSI) is a technique developed in 1992 for increasing the chances of successful fertilization and pregnancy resulting from IVF (in-vitro fertilization). ICSI is offered most often to couples whose failure to conceive has been attributed to male factor infertility (if the male partner has a low sperm count, or poor quality sperm that are unable to fertilize an egg). The ICSI procedure is identical to the IVF process until the point at which mature eggs are harvested from the female partner, and are ready to be fertilized in the laboratory.
ICSI Versus IVF
Following pre-IVF treatment with ovulation-inducing drugs, the resulting eggs are removed from the woman's ovaries and prepared for laboratory fertilization. In a conventional IVF procedure, the male partner's sperm cells are then placed in a dish with the eggs, and left for a certain period of time in the hope that they will be able to penetrate and fertilize them. In ICSI, however, this is not left to chance. Instead, a single sperm is inserted into each of the selected eggs, giving each sperm cell a fighting chance of turning its egg into an embryo.
In ICSI, after the mature eggs are harvested, an egg is selected by the embryologist who captures the egg in a special pipette. (At this point, the male partner has already provided a semen sample.) Now the embryologist, using microscopes to view the whole procedure, picks up an individual sperm cell in a very thin, hollow needle, and uses the needle to push the sperm cell through the outer layers of the egg (the "zona") and into the inner area (the "cytoplasm"). The eggs and sperm are then left for 24 hours, by which time it is likely that fertilization will have taken place.
Similarly to the IVF procedure, a certain number of fertilized eggs (now embryos) are transferred back to the woman's uterus, in the hope that at least one will implant and grow into a healthy baby. Just like IVF, ICSI brings with it an increased risk of a multiple pregnancy (twins or triplets), because more than one embryo is inserted into the uterus. For this reason, reputable fertility clinics offering the procedure will put a cap on the number of embryos that can be inserted. The number of embryos permitted will depend on several factors, not least the female partner's age, health, and whether or not previous IVF or ICSI treatments have been successful.
Various studies have placed ICSI fertilization success rates at between 75 and 85%. This doesn't mean, however, that all these women become pregnant, although some studies have found that the ICSI pregnancy rate is higher than that of IVF. One reason for this might be that ICSI is often used to counteract male infertility - therefore the women who receive the treatment may be younger and have healthier reproductive systems than the women generally receiving IVF.
Candidates For ICSI
Currently, ICSI is most often offered to couples in which the male partner has a low concentration of sperm cells in his semen, and/or sperm cells with poor motility (the ability to swim to meet an egg, and to penetrate it), or poor morphology (sperm cells which are abnormally shaped).
ICSI may also be offered to couples for whom IVF has failed in the past, or who have had low egg harvests as part of the IVF process.