ICSI: Intracytoplasmic Sperm Injection
Advances in IVF Technology with ICSI
Micromanipulation, the handling of egg and sperm by microscopic instruments, is used to improve the chances of fertilization in cases with impaired sperm function. ACRM offers the most advanced micromanipulation technique, called Intracytoplasmic Sperm Injection (ICSI), in which a single sperm is injected directly into the egg using a glass micro-needle. ICSI has revolutionized the treatment of male infertility by overcoming barriers to sperm entry into the egg. Fertilization is possible even in cases with scant sperm or compromised sperm function.
Male Factor Infertility
As much as one third of the infertility cases in the United States may be attributed to a male factor, which may take the form of: 1) a low sperm concentration or "low sperm count"; 2) low sperm motility (few sperm which swim); 3) sperm which are not able to fertilize eggs because they are not functional due to some abnormality in their structure or biochemical make-up (remove this - they do not contain the enzyme, or have enzymes in too low a quantity to allow fertilization); or 5) combinations of some of these factors.
In-vitro fertilization (IVF) has proven to be a very good therapy for most forms of male factor. This is because the motile (swimming) sperm can be collected and concentrated from the husband's semen and placed in direct contact with the egg in a culture environment in the IVF laboratory. Through the increased number of swimming, and presumably functional, sperm around the egg, the chances of fertilization are improved over intercourse or intrauterine insemination.
Male Infertility Treatment
There are cases of male factor infertility, however, which cannot be addressed even through IVF. In these cases, there are so few sperm, or sperm which are completely immotile (not swimming at all), that even if they are placed in culture with the egg, fertilization will not take place. In addition, there are men who only have immature sperm available, and these may not be fully functional.
An ideal approach to these severe forms of male infertility is to directly inject a single sperm cell into the egg. In this way, the sperm cell is relieved of the work of penetrating the several layers which surround, nourish and protect the egg. Also, relatively few sperm are needed since only one sperm cell is required for each egg.
Scientists in Belgium under the direction of Dr. André Van Steirteghem, developed a method of injecting a sperm cell into the egg and called it, appropriately, Intra-Cytoplasmic Sperm Injection (ICSI - pronounced ick-see). This technique allows fertilization in cases that would have been virtually hopeless.
It is essential to recognize, however, that even though the sperm is placed inside the egg by the injection procedure, the fertilization process may not be completed. Fertilization is a complex continuum of sperm and egg interaction, not simply the entry of the sperm into the egg. If this interaction does not ensue following delivery of the sperm into the egg, fertilization failure may still result.
The ICSI Procedure
ICSI is performed using instruments called micromanipulators. These allow the biologist to "handle" the cells under microscopic observation with magnification of 200 to 400 times. The egg is gently held steady using an instrument called a holding pipette. Using a glass micro-needle, a single sperm is aspirated into the tip of the needle and then carefully injected into the egg. The egg can be examined 15 to 18 hours later to determine if fertilization has occurred.
The pregnancy rates achieved through IVF with ICSI is comparable to those observed with IVF without ICSI. In both IVF with and without ICSI, the incidence of pregnancy is dependent upon a number of factors: the woman's age, any infertility factors she may have, the number of embryos transferred to her uterus and uterine receptivity.