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What is the artificial oocyte activation?

6 fertility expert(s) answered this question

Answer from: Andrew Thomson, FRCPath

Embryologist, Consultant Clinical Embryologist & Laboratory Manager
Centre for Reproduction and Gynaecology Wales (CRGW)

Artificial oocyte activation has been around since about 2012 legally in the UK. Belgium is the hotbed and have great processes, they get really really good results using it and it’s used for patients who have either complete failure of fertilization using ICSI or in some cases those who have repeated cycles of low fertilization with ICSI and when I say low – less than 20 – 25% and in a normal fertilization mechanism, what you will see is, there’s what’s called calcium oscillations and that helps the fertilization that’s a sign of fertilization and those calcium oscillations trigger a whole mechanism of things associated with fertilization. What you see is with artificial egg activation is there’s just one massive dose of calcium and that helps the fertilization aspect after a ICSI cycle. The theory is that the sperm that haven’t previously fertilized the eggs have absence of a special protein called PLC zeta which is being shown in my opinion quite definitively to be the protein responsible for triggering fertilization and certainly those men that lack PLC zeta need to have artificial egg activation. Artificial egg activation won’t always help everyone with reduced fertilization. What you should really be doing is testing for those PLC zeta levels in the first place – if they’re normal, egg activation won’t help but if they’re very very low or not there at all, then egg activation will help. The problem is getting somewhere to test the PLC zeta levels in the first place because not that many places do it. It’s normally in a research setting but it’s just one of those things because of that, people tend to jump straight to it without the proper diagnostic tests.

Answer from: Yacoub Khalaf, Professor

Gynaecologist, Professor of Reproductive Medicine and Surgery at King’s College

This is using a particular chemical the sperm is dodgy. Dodgy means that it does not have the cap that surrounds the head of the sperm that releases certain chemicals to aid with this process. If that is diagnosed on scientific ground, adding some chemical that usually includes some calcium or its derivative or some other material can be helpful. However, doing it as a routine will be just a bad investment and a bad way of applying something that only benefits a very very very small minority of patients where the man’s sperm can’t be trusted to do the job.

Answer from: Alessandra Parrella

Embryologist, Andrologist, Embriologist
IVF-Life Group

When the spermatozoa enter the oocyte, the calcium ion concentration activation takes place in the cytoplasm. This event is known as oocyte activation and allows correct fertilisation. However, sometimes oocytes fail to activate due to absence of calcium ion concentration leading to fertilisation failure after ICSI. To avoid this a modified technique successfully applied to obtain fertilisation. One of the most common is ICSI with calcium ionophore. After ICSI procedure, the injected oocytes are placed for a short time in the medium containing calcium ionophore and subsequently they are placed in normal culture medium where they will stay until Day 5 or Day 6.

Answer from: George Koustas, DR

Embryologist, Director of Embryology and Quality Manager
Agora Clinic

When the sperm enters the egg and sperm begins a process that is called oocyte activation that in terms starts the fertilization process. The sperm does that by increasing the calcium concentration inside of the oocyte which then triggers a series of processes to enable the oocyte to become fertilized. Again, during this time, the oocyte will create a block to stop more sperm coming inside the egg if we perform the IVF. If the oocyte is not activated, the oocyte will not fertilize and therefore will not develop into an embryo.
Studies have shown that a chemical called calcium ionophore may assist in activating the oocyte by increasing the calcium concentration in the oocyte which the oocyte needs for fertilization. Simply oocyte activation is when we place the eggs after ICSI solution for a few minutes that has calcium ionophore to assist the eggs to be fertilized. Then the day after we assess the eggs for signs of fertilization.
Can everyone have this treatment? No. Usually it is recommended for patients that had failed ICSI before meaning no fertilization after ICSI or patients that had very low fertilization after ICSI. It is not recommended for patients that they had fertilization but it was abnormal after ICSI – that could be a group of older patients.

Answer from: Michael Carroll, BSc, PhD, PgCAP, CBiol, FRSB, FIBMS, FHEA, FLS, ANSHCS

Embryologist, Reader (Associate Professor) in Reproductive Science at Manchester Metropolitan University

In order for sperm to fertilize an egg it has to change the concentration of calcium within the egg and this activates the egg and allows it to develop into an embryo so, it moves it from an egg state into the embryo state and when sperm bind to an egg they release a tiny little chemical called PLC-zeta and this PLC-zeta to initiates that to hold that change in calcium within the cytoplasm of the egg. Sometimes, the eggs don’t respond to the sperm or the sperm are deficient in this little chemical, this PLC-zeta, therefore, the clinician or the embryologist would inject the sperm with a chemical that will mimic what the sperm would normally give and that’s called artificial oocyte activation. Normally it’s done alongside ICSI so, it’s done at the same time and the sperm is injected into the egg during that IVF procedure called ICSI. It’s not painful, it occurs within the egg and the sperm. It does come with its risks in that you’re injecting chemicals into the egg but the concentrations are known to be safe for the eggs and there are plenty of babies born through this artificial oocyte activation procedure. It’s only done in cases where there’s continued or repeated failed fertilization and also in cases where it’s confirmed that the sperm are deficient or have mutant PLC-zeta therefore, it’s a wave of allowing that fertilization to take place with the sperm that doesn’t have that chemical.

Answer from: Despina Tzanakaki

Senior Embryologist, Director of IVF and Andrology lab at Aretaieio Hospital

Artificial oocyte activation involves addition of calcium ionophore to culture media where the oocytes are kept in the lab. Calcium ionophores are chemicals that may simulate oocyte activation, a process that is normally triggered when the sperm reaches an egg. Oocyte activation starts the process of embryo development also allowing only one sperm entering the egg. In case that oocyte is not activated, then it will not develop. According to HFEA, artificial oocyte activation is rated amber meaning that there is conflicting evidence from RCTC, so whether it is effective at increasing chances of having a baby for most of fertility patients. Although, there are few studies that support the effectiveness of artificial oocyte activation at improving the fertilization rate in ICSI cycles where egg activation has failed in previous treatment cycles. There is actually not enough evidence that supports the idea, there are also no follow up studies on the safety of this method. Moreover, the artificial oocyte activation could theoritically cause embryo unemploidity which could lead to miscarriage, so considerring possible risks, this treatment should be only offered to selected patients who had had failed fertilisation in previous attempts.

About this question:

What happens during oocyte activation? Who can benefit from the oocyte activation? When it is recommended?

The technique called Artificial oocyte activation (AOA) is used to avoid fertilisation failure. This technique is used in case there was poor or no outcome after fertilisation in previous treatment.

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