Intracytoplasmic Sperm Injection (ICSI)
ICSI, intracytoplasmic sperm injection, makes it possible for men with severe male factor infertility to father genetically related children. Prior to ICSI, many couples with moderate to severe male infertility had little chance of creating a genetically related child and often had to turn to a sperm donor. ICSI may be performed using ejaculate sperm, sperm retrieved by testicular biopsy or sperm retrieved by epididymal aspiration.
With the ICSI procedure, a single sperm is injected directly into each mature egg. This greatly increases the probability of fertilization.
ICSI can’t be performed until the accessory cells that surround the egg are removed. This is done with a gentle enzymatic procedure. Next, the maturity of the egg is determined. ICSI is performed only on eggs that have reached the maturation stage where they have extruded a polar body. Immature eggs are not injected with a sperm because they do not have any chance of fertilizing. If you are having ICSI done, keep in mind that not all the eggs will be mature enough to inject a sperm.
ICSI is done with the egg is held in place by suction with the ‘large-appearing’ pipet seen on the left in the ICSI video. A motile sperm (one that is alive) is chosen to be injected. The sperm is picked up in the very fine pipet seen on the right. The sperm is brought to the very tip of the pipet before injecting the sperm into the egg so that as little extra fluid as possible is injected into the egg. The pipet with the sperm punctures the egg membrane.
Once the pipet is inside the egg, a small amount of the egg’s content (the cytoplasm) is drawn up into the pipet along with the sperm and the sperm is expelled into the egg. This brings the sperm into close contact with the cytoplasm so that there is a good chance of fertilization. The pipet is then with withdrawn from the egg.
ICSI will cause fertilization in about 75% of oocytes. However fertilization varies a great deal between couples.
ICSI appears to pose no significant side effects in children conceived using the ICSI procedure. Early concerns about possible genetic abnormalities have not been substantiated. However, sometimes the egg may be damaged during ICSI, or fertilization may not be successful.
Some researchers and clinicians have expressed concern that physically selecting and inserting sperm using ICSI might lead to male offspring with reduced fertility. In nature, the “strongest” sperm usually reaches the egg first and initiates fertilization, whereas in ICSI, a human selects the sperm cell. This impedes the natural selection process. Males born using ICSI are now reaching reproductive age and any reduction in fertility will be documented in the near future. Most clinicians believe these males will not have reduced fertility.