This procedure was first successfully used in the early 1990s, and was developed for couples with severe male factor infertility or couples who have had failure to fertilize in a previous in vitro attempt. ICSI overcomes many of the barriers to fertilization and allows couples with little hope of achieving pregnancy to develop fertilized embryos. ICSI allows couples to use the partner’s sperm in cases where donor sperm would have been the only option in the past, and ICSI is needed whenever sperm is obtained by surgical retrieval, such as after unreversed vasectomy.
The IVF procedure is exactly the same as for conventional IVF as far as the stimulation phase, egg retrieval and subsequent culture after fertilization . However, the big difference comes when it is time for the insemination procedure.
In the majority of cases we will have made the decision as to whether the insemination should be carried out with ICSI or conventional IVF well before the day of the egg retrieval. In some cases we will leave the final decision until the day of the egg retrieval, to see which procedure appears most appropriate according to sperm quality. It is always possible that previously normal samples may look decidedly worse on the day of the retrieval and we may opt to carry out ICSI when we would otherwise have done IVF. There is also the chance that given an appropriate sperm sample and enough eggs we will proceed with conventional IVF for some of the eggs and do ICSI for the rest.
During a conventional insemination cycle all of the eggs are inseminated by adding a prepared number of sperm to the dish that they are cultured in. In the case of ICSI it is first necessary to prepare the eggs for the insemination and then check them for maturity.
When the eggs are retrieved (or in fact ovulated during a natural cycle) they are surrounded by a collection of cells called cumulus cells. These cells are an important factor in the ability of the sperm to be able to fertilize the egg, so the cumulus cells are left surrounding the eggs in a conventional insemination. However, these cells do need to be removed prior to an ICSI insemination for a number of reasons. The first reason is to allow direct visualization of the egg to make sure that the egg is mature enough to be injected, to position the egg to try and avoid potential damage, and to see the sperm get deposited inside the egg. It also allows the egg to be held in place while the injection is carried out to make sure that the injection is successful, and removes the potential risk of introducing the cumulus cells into the egg during the injection.
A diagram of what happens during an ISCI procedure
The cumulus cells are removed from the egg about 3-4 hours after the egg retrieval has been carried out and then they are placed back into the incubator until it is time to perform the insemination. The injection itself is done using a high power microscope and a pair of micromanipulators, which allow very fine control of the injection tools using joysticks – very much like video game controllers. The injection tools consist of a glass holding pipette, which has a smooth rounded opening and using gentle suction will hold the egg in place, and then an injection pipette. The injection pipette is a very fine glass needle that is used to locate, immobilize and then pick up a single sperm. The pipette is then used to pierce the outer layer of the egg (zona) and then enter the cytoplasm, which is the main part of the egg. There is a very flexible membrane all the way around the outside of the cytoplasm, so it is important to make sure that this has been ruptured, and then the sperm can be deposited into the egg.
There is a potential for the egg to be damaged during the injection procedure, but the chance of that happening is very low, somewhere in the low single digits. ICSI is also not a guarantee that fertilization will take place even though the sperm has been deposited directly into the egg itself. The ICSI fertilization rates are generally comparable to those seen from conventional IVF and in the majority of cases when there are severe sperm issues, the rates are a lot higher than would have been expected without ICSI.
Other than the risk of physical damage to the eggs by carrying out ICSI, there have been some reports that show an increase in birth defects following ICSI. While the real reasons for this are not fully known, there have been a number of published papers that have indicated that this increase in birth defects is more likely to be connected to the sperm that is used to create the embryo rather than the ICSI procedure itself. The reason stated for this is due to the fact that the male factor diagnosis has a possible genetic link, which in turn is passed onto the child. The birth defects observed are surgically correctable, such as hypospadias. Some rare genetic disorders – imprinting disorders – may be slightly more common after ICSI, such as Angelman’s syndrome and Beckwith-Wiedemann syndrome. These are extremely rare disorders, each affecting less than one child in 10,000. Most IVF clinics never see a case of these disorders, and large-scale studies are needed to determine if these disorders are truly linked to IVF or ICSI procedures or are more common due to infertility itself.
Learn more about ICSI at ORH
The ICSI procedure has allowed countless couples to conceive. Couples that would be unable to conceive through a regular IVF insemination, due to severe male factor or other reasons, the ability to have a child of their very own. We are proud to offer ICSI, when appropriate, to our patients. To learn more about the ICSI procedure and what it could mean for you please contact us.
