The Patient's Guide to Embryology

IVF vs ICSI – Which is more successful?

There are many pros and cons to each technique, but the choice between IVF and ICSI could mean the difference between success and failure.

What is the difference between IVF and ICSI?

IVF (in vitro fertilization) and ICSI (intracytoplasmic sperm injection) are both methods of fertilization. There are many pros and cons to each technique, but the choice between IVF and ICSI could mean the difference between success and failure. So what is the difference between IVF and ICSI? Is the choice up to you? What are the difference in success rates? Are both techniques equally as safe?

The main difference between IVF and ICSI lies in the way that the sperm fertilizes the egg. In IVF, the sperm and egg are placed in a culture dish and allowed to fertilize naturally without any interference. In ICSI, a single sperm is injected directly into the egg using a microneedle.

IVF is a more natural method of insemination since it aims to mimic what would happen in the body in a natural pregnancy. The fastest sperm will find the egg first, it binds to the outer shell of the egg and squirms inside to fertilize it. For ICSI insemination, the embryologist will choose a sperm that looks healthy and inject it directly into the egg, bypassing the natural selection and egg-sperm binding processes.

IVF vs ICSI – Which is right for me?

When should traditional IVF be recommended?

  • Normal sperm parameters
  • Women with tubal or ovulatory causes of infertility
  • Unexplained infertility

When should ICSI be recommended?

  • Low sperm concentration
  • Low sperm motility
  • Low sperm morphology
  • High sperm DNA fragmentation
  • High sperm clumping
  • High number of antisperm-antibodies
  • Previous failed fertilization with traditional IVF
  • Frozen eggs or IVM eggs
  • Required for some add-on treatments such as AOA and PGT-A

IVF vs ICSI – Which is more successful?

IVF is the traditional method of insemination which has been used since the first IVF baby was born and the same technique is still used today. This is because it is effective and non-invasive. However, some people opt for ICSI and many clinics only use ICSI to inseminate eggs. This is because ICSI is consistent and reliable.

Both methods of insemination have similar overall fertilization rates at around 70% and no difference in the chance of getting pregnant, but many clinics opt to use ICSI when it isn’t necessarily required because it gives more control than traditional IVF.

Traditional IVF has a slightly higher rate of total fertilization failure compared to ICSI because there is a risk that the sperm won’t be able to bind to the egg, whereas ICSI bypasses egg-sperm binding by injecting directly inside the egg. Traditional IVF also has a higher rate of abnormal fertilization because there is a risk that more than one sperm can enter the egg. On the other hand, there are also some additional risks of ICSI. Firstly, injecting the egg is an invasive procedure and there is around 5% chance that the egg will be damaged and usually it cannot recover from this damage. ICSI patients may also have a slightly lower number of mature eggs because the they have less time to complete maturation than in traditional IVF.

Is ICSI safe?

It is important to remember that creating embryos in a laboratory is a complex and delicate process and while the result can be life-changing, the interventions can also have unintended consequences and potential risks. Ultimately, the goal of IVF is to help individuals and couples start a family, but it’s important to remember the gravity of creating life outside the body and to approach the process with caution and care. It is still unknown whether there are any long-term effects to the health of lab-conceived babies so it is important to aim for a minimal intervention approach wherever possible. Since ICSI is only recommended for certain cases (see above), traditional IVF insemination should be used where possible to avoid additional unnecessary handling and manipulation of the eggs and the sperm.

In short, ICSI seems to be a safe procedure based on the data gathered so far, but it will still take many more years before this can be confirmed.

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