UT Health Physicians

Intracytoplasmic sperm injection (ICSI)

The intracytoplasmic sperm injection (ICSI) technique attempts to achieve fertilization by the direct injection of a single sperm into the cytoplasm (interior) of the egg. After retrieval of the eggs, they are freed of surrounding cells by a combination of enzyme treatment and microdissection. Using special micromanipulation equipment, the mature eggs are individually injected with a single sperm. Injected eggs are returned to the laboratory incubator and are treated thereafter as in conventional IVF.

The ICSI technique was developed to treat cases of severe male factor infertility where there is not enough sperm for traditional fertilization to be effective. Candidates for ICSI may include patients with severe reductions in sperm number or motility, regardless of cause and patients with a history of failure of fertilization in conventional in-vitro fertilization (IVF). The ICSI technique may also be used to achieve fertilization using surgically extracted sperm from patients with anatomic or surgical conditions (such as vasectomy) which prevent sperm from entering the ejaculate. In all these cases, donor sperm or ICSI may provide the only options for conception.

The mechanical placement of a sperm into the egg bypasses all the normal processes of sperm-egg interaction that occur naturally as well as in conventional IVF. These processes normally lead to the selection of the single fertilizing sperm based on its ability to pass through the many layers of cells surrounding the egg, to contact and bind to the egg coating (zona), to penetrate this coating, to contact and merge with the egg cell membrane and ultimately to be drawn into the egg where the genetic material in the sperm joins that of the egg. These interactions help assure that a normal sperm is selected by the egg for fertilization. Even when conventional IVF is performed, the egg is exposed to tens of thousands of sperm from which to choose. In sperm injection, it is the laboratory that chooses. We rely on the size, shape, and motility of sperm to choose the ones for injection. While these characteristics are useful, they do not guarantee that the sperm selected for injection is normal.

The potential consequences of injecting a normal appearing sperm that is in fact abnormal include the development of a genetically abnormal embryo. Previous experience suggests that most abnormal conceptions do not implant or develop in the uterus. The incidence of congenital abnormalities (birth defects) following ICSI appears to be no higher than that of the general population. This observation is based on the experience of several thousand babies born worldwide following ICSI. Despite this reassurance, it is prudent to regard ICSI as an experimental technique not without risk since long term follow-up of offspring (regarding, for example, their fertility is unavailable). Recent evidence suggests that some forms of severe male factor infertility are genetic and may be passed on to children through the ICSI procedure. In addition, you should realize that within the normal human population a certain percentage (approximately 4%) of children are born with physical or mental defects, and that the occurrence of such defects is beyond the control of physicians.

Apart from the possible genetic consequences of selecting an abnormal sperm for injection, the physical trauma to the egg resulting from sperm injection can lead to degeneration of the egg, decreased fertilization rate, poor or arrested embryo development following fertilization, and reduced chance of a successful pregnancy outcome.

The benefit of ICSI is that it provides a way to treat extreme cases of male factor infertility which otherwise would remain untreatable. Experience shows that fertilization in vitro requires a minimum number of motile, normal shaped sperm. The chance for fertilization in vitro becomes very low when this minimum number of sperm is not available. Theoretically, only a few sperm are necessary to undertake ICSI. To date, however, the successful outcome of sperm injection is neither predictable nor consistent for all patients. One other option is the use of donor sperm. Use of donor sperm may normalize the success of conventional IVF in couples with severe male factor infertility. In cases where male factor is the only diagnosis, pregnancies with donor sperm can be achieved through timed insemination, a treatment far less expensive and complicated than IVF.

UT Health Fertility Center doctors are also faculty at The University of Texas Health Science Center San Antonio School of Medicine. This allows us to remain one of the most cost-efficient fertility practices in the area. Our staff is happy to answer questions about referrals, itemized diagnostic and treatment costs and billing options. The UT Health Fertility Center participates in a variety of insurance plans. For your convenience, we accept VISA, MasterCard, and Discover.