Assisted Oocyte Activation (AOA)

What is Assisted Oocyte Activation

When a sperm fertilises the egg, the sperm does not just deliver the male DNA to the egg, it also delivers specific molecules and components to the egg essential in “activating” the egg. One molecule in particular causes the egg to release its calcium ion stores which in turn initiates the fertilisation and embryo development process. 

AOA or calcium ionphore activation mimics the release of the calcium ions by exposing the egg post ICSI to special media rich in calcium ions that diffuse into the oocyte to “activate” the eggs. 

N.B there are different ways other that calcium ionphore activation to “activate the egg”, such as mechanical and electrical methods, but the chemical method described here is by fat the most common.

Who should consider it 

AOA is typically considered for patients who have experienced repeated ICSI cycle failures due to poor or no fertilization, even when healthy, mature eggs and viable sperm are used. It is used for couples with a specific male factor infertility condition called globozoospermia, where the sperm is morphologically abnormal as it is missing its acrosome (th cap that sits on top of the sperm head) which contains the molecular that activates the egg. It is also recommended for patients when there is suspected oocyte activation deficiency issues such as suspected depleted calcium stores in the egg. More recently, some early data suggests it can also support with embryo quality, so some clinics have started suggesting to some patients for that reason, as well as for patients using surgically retrieved sperm. 

What does the research say? 

The research on AOA has shown that this technique can be beneficial for certain couples, particularly those with a history of failed fertilization during ICSI. Studies have reported varying success rates, with some showing improved fertilization rates and subsequent embryo development after AOA is performed.

One study highlighted that AOA using chemical agents improved fertilization outcomes and embryo quality in couples who previously experienced failed fertilization with standard ICSI procedures¹. Another study noted that while AOA could enhance fertilization rates, it does not guarantee improved clinical pregnancy rates, suggesting that while AOA may overcome initial fertilization barriers, other factors may still impact overall success².

Safety

The safety of AOA is still under investigation, with limited long-term data available. There are concerns that AOA may not fully mimic natural fertilization processes, which could lead to potential risks. Professional guidelines advise against routine use of AOA due to these uncertainties and recommend it only for select cases with a confirmed need.

myfertility’s take on Assisted Oocyte Activation

AOA can be a crucial tool (and even the only tool) to give patients the chance of getting past one of the main milestones of fertility treatment, fertilisation. While we are strong proponents of it, especially for these patients with globozoospermia or those with repeated fertilisation failures, it is important to note that we do not have any long term studies on it’s safety (even though you can argue that for most of fertility treatment). 

When you're going through a challenging and emotional journey like fertility treatment, it can be tempting to try everything available. However, it's crucial to remember that more isn't always better. Over-promises on the benefits of new technologies or "add-ons" might not deliver meaningful results. That’s why we believe that being well-informed about your fertility treatment options can significantly improve your infertility treatment journey.

It's important to consult with a fertility specialist to determine the most appropriate treatment for your specific situation. 

If you want to learn more about the best fertility clinics for you, and which clinics do these treatments, be sure to check out our clinic finder and clinic matcher. We built these tools to help you find and match with IVF clinics and fertility specialists near you, and filter through them all based on their success rates, prices, patient reviews, technologies and support services offered. 

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