INTRACYTOPLASMIC SPERM INJECTION (ICSI)
What is ICSI?
ICSI is a micromanipulation technique performed by an embryologist using very precise instruments and a specialized microscope. A single sperm is selected, isolated and drawn into a micropipette. It is then injected directly through the outer layers of the egg into its core (the cytoplasm). The micropipette is quickly withdrawn and the egg is allowed to fertilize and divide.
In contrast to standard IVF techniques, which rely on the ability of the sperm to bind to and penetrate the egg's membrane, ICSI eliminates the need for sperm binding and only requires that there be as many live (but not necessarily motile) sperm present as there are mature eggs. Using a sophisticated microscope with state of the art optics, each oocyte is stripped of its surrounding cumulus cells and held in place with a glass micropipette (the "holding" pipette). The embryologist then takes a second, smaller pipette (the "ICSI" pipette) and draws up one sperm from the processed semen sample. The ICSI pipette containing the sperm then pierces the outer zona pellucida and oocyte membrane and, with the aid of fine mechanical controls, the sperm is deposited near the middle of the oocyte. The ICSI pipette is then removed from the oocyte.
Who is a candidate for ICSI?
Most couples undergoing ICSI suffer from male infertility that involves severely depressed sperm count, morphology and/or motility, although there may be other contributing factors as well. A standard semen analysis done as part of the couple's infertility work-up will usually reveal any potential problems with the sperm so that the embryologist knows what to anticipate on the day of the oocyte retrieval. Some men who were previously considered to be completely sterile (azoospermic) actually have some mature sperm and, since only a few are necessary to perform IVF with ICSI, they are candidates for ICSI. In the most severe forms of male infertility, where there are no sperm at all in the ejaculate, ICSI can sometimes be done successfully with sperm retrieved from the ejaculatory ducts or testicle MESA or TESA. On occasion, as when previous IVF cycles have resulted in poor fertilization, ICSI is recommended despite the lack of a clearly identified male problem.
Once fertilization has occurred by ICSI, the outcome of the IVF procedure is not significantly different from conventional IVF. That is, the success rate then depends on other factors relating to the couple's fertility, such as the female partner's age and embryo quality. Pregnancy outcome after ICSI is comparable to that after standard IVF.