Intracytoplasmic Sperm Injection (ICSI) is a specialized form of In Vitro Fertilization (IVF) that is used for the treatment of severe cases of male-factor infertility. ICSI involves the injection of a single sperm directly into a mature egg. ICSI is an excellent method to fertilize the egg in the IVF lab, after the eggs have been retrieved from the female.
IVF with ICSI involves the use of specialized micromanipulation tools and equipment and inverted microscopes that enable embryologists to select and pick up individual sperm in a specially designed ICSI needle. The needle is then carefully advanced through the outer shell of the egg and the egg membrane – and the sperm is injected into the inner part (cytoplasm) of the egg. This usually results in normal fertilization in about 75-85% of eggs injected with sperm. The eggs are then checked daily for successful fertilization.
So who should be treated with ICSI?
There really is no “standard” when discussing ICSI, in regards to which cases or couples should have the ICSI procedure and for those who shouldn’t. Many clinics and physicians will suggest or use ICSI for sever male factor infertility, and some may choose to use ICSI on every case. Unfortunately the large majority of IVF clinics are somewhere in the middle of these extremes.
Although the mindset of ICSI has changed over time, ICSI is being performed more (as a percentage of total cases) than were done 10-12 years ago. As more advancements in medicine continue to prove well and profitable, our thinking will continue to progress as well.
Most common reasons for ICSI:
- Severe male factor infertility for couples who do not want donor sperm insemination.
- Sperm concentrations of less than 15-20 million per milliliter
- Low sperm motility, less than 35%
- Very poor sperm morphology (subjective- specific cutoff value is debatable)
- Previous IVF with no fertilization or a very low rate of fertilization (low percentage of mature eggs that were normally fertilized).
- Low yield of eggs at egg retrieval. ICSI being used to try to get a higher percentage of eggs fertilized that with conventional insemination of the eggs (mixing eggs and sperm together).
Fertilization and Pregnancy rates
Many Fertility programs will see a success rate of about 70-85% of eggs injected using ICSI becoming fertilized. This is referred to as the fertilization rate, not to be confused with pregnancy success rate.
Pregnancy success rates for IVF procedures that use ICSI have in some studies shown to be higher than for those doing regular IVF and choose not to utilize ICSI. This is due to many of the IVF cases needing ICSI, the female is usually young and fertile, therefore, having good egg quantities and good quality eggs, as compared to other women that are doing IVF for other reasons. It seems that the average egg and quality is better in ICSI cases as well as for male factor cases. This is because there is less likely a problem with the eggs in comparison to cases dealing with unexplained infertility. There are some unexplained cases that have reduced egg quantity or quality, which can lower the chances for a successful IVF outcome.
The success rates for IVF with ICSI vary according to the specifics for each individual case, the ICSI technique used, the skill level of the person performing the procedure, and the overall quality of the laboratory, the quality of the eggs, and the embryo transfer skills of the infertility physician. There are some cases where IVF with ICSI is performed due to “egg factor,” as well as in low ovarian reserve situations. These types of cases occur when there is either a low number of eggs or a poor “quality” of eggs or both. In these types of cases, ICSI fertilization and pregnancy success rates seem to be a lower. This is mainly due to quality of the embryos. Therefore, the quality of the eggs is a crucial factor in determining quality and viability of embryos. So in these some cases, assisted hatching is done on the embryos prior to transfer, in order to maximize chances for pregnancy.