By fertility experts from Spain.
The secret life of an embryo seems like a fascinating topic. Embryologists are the ones who know them better than anyone else. They play a very important role in the whole IVF process, working at the crossroads of science and patient care. In this webinar, Theoni Pastroma [Clinical Senior Embryologist at Gennima IVF] explains some of the secrets of the embryology lab and answers attendees’ questions.
According to Theoni Pastroma, the embryology profession involves a wide range of complex responsibilities. A person suited for the job should have many necessary qualities, the most important of which are technical skills (to perform all the lab procedures – both the least and the most complicated ones) and scientific knowledge (to design and choose the best treatments). An embryologist is also responsible for the quality control of equipment and materials used as well as following and complying with the laws and regulations in force. In addition to higher education and experience, each embryologist should be good at judgement and decision making and – very often – at working under pressure and time constraints. Last but not least, they should constantly focus on professional development and training new skills, including social ones, such as exemplary communication with doctors, nurses and patients.
Despite all the embryologists’ skills, it is very important to understand that embryology cannot repair embryos. It can however nurture them and help them achieve their maximum potential. Theoni Pastroma explains that the maximum potential of an embryo can be achieved through a series of steps. It all starts with the careful planning of individualised treatment.
In order to achieve the best IVF treatment results, embryologists collaborate with doctors, nurses, midwives, andrologists, urologists and geneticists. They review couples’ medical history, especially previous IVF attempts, in order to decide what are the best fertilisation techniques to be used in a given case.
The next step is ensuring a safe environment which is crucial to developing embryo culture. For instance, the embryology lab is filtered with specialised filtering systems that reduce potential toxic components in the air. Temperature and humidity in the lab are also controlled by air conditioning systems and working surfaces are heated in order to avoid exposing the embryos to extreme temperature changes. All this leads to creating a “stress-free” environment for the embryo at the time when it is handled and nurtured outside the womb. Apart from taking care of the environment, embryologists also make sure that embryos get all the nutrients they need to develop. Embryos are grown in special culture dishes that are set up with appropriate culture media for every step of embryo development.
Once a safe environment and materials are ensured, the work in the lab begins. Theoni Pastroma reminds us that it is carried out according to strict protocols that are reviewed regularly for potential improvements. It is important to mention here that all these protocols are developed with safety in mind in order to avoid any possible damage to gametes and embryos. Besides, safety in the lab includes labelling and witnessing.
Most of the work done by embryologists takes place in specific time points in order to match the timing of oocyte maturity and embryo development. Additionally, new technologies help embryologists take care of embryos in even a better way. For example, time-lapse incubators such as the EmbryoScope+ allows observing embryos at all times in an undisturbed environment without taking them out throughout the whole course of culture. Using advanced technologies to analyse the time-lapse videos helps embryologists select the best embryos for transfer and freezing. It has been proved that there are clinical benefits of using time-lapse culture and evaluation, such as improved implantation and ongoing pregnancy rate as well as reduced early pregnancy loss.
Moreover, there are also technologies that allow looking after embryos even when embryologists are not in the lab. These include monitoring systems equipped with sensors and alarms, electricity generators and even an emergency evacuation plan for cryopreserved material in case of natural disaster.
As Theoni Pastroma sums up, embryologists look after embryos in all sorts of ways. Through their work, they are able to import unique quality to the whole process of IVF treatment.
It depends on day on the day that we would do the biopsy. If it is a day 3 embryo, we tend to avoid grade 3 and grade 4 embryo. We mainly try to biopsy grade 1 and grade 2 embryos unless the patient doesn’t have any of those. So then we might try to do a biopsy to a day 3 and grade 3 embryo as well. Now, if it is a day 5 biopsy, it is very important to have a full expanded blastocyst with quite a lot of cells, so then we are able to remove some of the cells. So if it is a blastocyst that is graded C or D of the inner cell mass and trophectoderm, then we would probably not try to biopsy that.
You would have to check that the next day the eggs have actually matured in cultures and they are at the metaphase 2 stage which is the right stage to be injected. And as soon as you’ve seen that, you should inject them. In general, it is better to do it quicker than leave it for later as there is a specific time frame when the eggs maintain their fertilising ability.
Yes, it is possible with the new technology. Now we’re now using time-lapse incubators, like the EmbryoScope +. it is possible to have a look at the embryos. There is an application and the patients can download it on their phones. They can actually have access to their embryos. It’s important to note that they can only see their own embryos and nobody else’s. Also, when we do the embryo transfer, we tend to give the little video of the embryos developing to the patients before they go home. So the answer is: yes, you can see them.
Well, this is a new thing for everybody. It is still developing and it is not widely used in clinical practice yet. Eventually, it will make our life a little bit easier in the lab. Artificial Intelligence means the software that will be trained on the basis of the embryologists’ knowledge to grade the embryos. I think in the future it will be a very useful tool for the embryologists to choose the best embryos. Hopefully, it will improve pregnancy rates.
In our lab, we usually freeze embryos on day 5. We don’t usually freeze embryos on day 6. There are studies that have showed that if embryos are slower in their development, there might be problems with their chromosomes. But a lot of labs do day 6 freezing. Certainly, I would expect embryos to be more advanced on day 6 than 1AA and 2AB. They’re a bit slow for day 6. Now, a 2AA and 3AA embryo on day 5 is acceptable. It depends on the time of the day. If this is in the morning, then it is fine because you have to remember it all starts with the time the insemination has taken place. So if you look at them very early in the morning, they might still not be expanded enough. And then if you leave you for a few more hours until midday, then the expansion might be right for you to be able to freeze them.
5BC means that the embryo has already started to get out of its outer shell which is a zona. The first letter of the grading refers to the inner cell mass. This the part of the embryo that gives the baby and C is the grade or the trophectoderm which is the outer cells that will give the placenta if a pregnancy takes place. Studies have shown that the grade of the trophectoderm, which is a C in this case, is more important than B so definitely a 5 BC embryo has the chance to give a pregnancy. It should be transferred if there is nothing better. A 6BC means that the embryo has been completely removed from the zona and it’s now completely out. This is a part of the natural development, we need them to shed this outer cell so they can implant to the uterus. In general, I would say embryos that keep developing should be replaced unless they have stopped developing. Only then we would cancel an embryo transfer.
We would cancel an embryo transfer only if an embryo doesn’t develop at all. We definitely need to be able to see cells and we definitely need to be able to count enough cells. Sometimes while embryos develop and the cells are dividing, they get very fragmented. If an embryo is very fragmented, that means it’s probably grade 4 and then we will probably suggest not to put it back. But if you can count enough cells, although there are fragments there, and if there is no choice of a better quality embryo, we would suggest to transfer it.
There are different opinions on that. The process is very big so different processes need different time to master. There are no official training programs in many countries around the world. One of the official programs takes place in the UK. According to the Association of Clinical Embryologists in the UK, the basic training takes from 3 to 4 years. Then an extra training is required for every extra skill that an embryologist acquires. So in order to be able to work on their own in the lab and doing the standard procedures like egg collection, sperm preparation, selecting embryos for embryo transfer, etc., they need to work in the lab for at least two years under the supervision of more experienced colleagues. And then they do need to have extra ICSI training and biopsy training and they should continue their development in order to be fit to do all these processes.
We can’t keep the information about the experience of the embryology team. Actually you can see all the embryology team on our website and you can see what training they’ve had, their education and different processes that they’re taking part in. But you couldn’t choose who is taking care of your embryos. The way the work is carried out in the lab means that a whole team is involved in the treatment of every couple. So it’s like a rotor every day. One embryologist will be looking after the egg collections, someone else will be preparing sperm samples, some of us will be doing the ICSIs on that day. It is not that one person starts with the egg collection and finishes at embryo transfer because the workflow wouldn’t be easy in this way. It’s not efficient to work like that. So you don’t get to choose your embryologist but you’re welcome to meet them and speak to them during the treatment.
I agree that air quality is very important. We maintain the same same conditions both in the operating room and in the lab. Surely the eggs are not exposed to the air as much when in the operating room because they only stay in there for like a few seconds. In fact, they’re not really exposed to air in the operating room because they go straight from the ovary into the tube the follicular fluid is collected in. Then this tube is opened in the lab. So they’re not really exposed to the air in the operating room as much. But if someone can have the same conditions in the operating room as in the lab, then I think that would be ideal.
Most clinics around the world don’t have an EmbryoScope yet. If I remember correctly, about 20% of treatments around the world have and use the EmbryoScope+ at the moment. A classical method has worked for years and it does still work. It doesn’t reduce the quality of the embryos. Embryos have got their own dynamics. The way they’re looked after can help them maximize their potential. The difference between the classical method and the time-lapse incubator is that you have to take the embryos out of the incubator in order to check them. That means you expose them to the lab air. So what you need to do is to make sure all your working services are heated and the air quality is good. You have to be quick when you’re doing all these procedures in order to return them back into a safe environment of the incubator and hopefully, they’ll be fine. We are using a combination of both the classical method and the time-lapse incubator. They are safe to use and have been used for years and most clinics still use them. So if used properly, they shouldn’t reduce your chances of success.
The number of embryos we thaw depends on the number of embryos we want to transfer. It also depends on the stages at which the embryos have been frozen. For example, in our clinic sometimes we freeze embryos on day 1 which is the pronuclear stage. In this case, we recommend more than one embryo to be thawed out because you don’t know exactly the way they’re going to develop. If someone has more embryos, we suggest that more of them are thawed and cultured so we can choose the best out of them. But if they’re frozen at the blastocyst stage, then it depends on how many we need to transfer. If we’re only transferring one, then one embryo is enough to thaw out. Then we check it again the next morning to see if it has survived during the night and extra expanded and then we can transfer it. In case this embryo doesn’t make it through the night and the patient has another one, there’s enough time to thaw another embryo in the morning and transfer the other one that will be better.
Actually it’s not just watching the embryo. Because the embryo staying in the time-lapse incubator at all times, their environment remains stable and that means there is no stress and they’re happier. We don’t disturb them and that gives them a chance to develop. By collecting all these images and by analysing the videos we have the chance to examine characteristics of the embryos that we couldn’t do before when we were just taking snapshots of their quality. That gives more information about the way they’re developing. The studies have shown it’s not only the stage of the embryo that is important but it’s also the rate at which the embryo reaches the stage. The time between the different cell divisions is also very important. Yes, there have been studies that have reported an increase in pregnancy rates as high as 10%. That is correct.
It depends on the patient and the couple and what they feel that they should do. Some people might be very interested in watching exactly how the embryos are developing and someone else may feel that this is very stressful for them or very emotional. At the moment we don’t offer this option to the patients in our clinic. I think sometimes having too much information might actually be a bit confusing and very stressful for patients. I think it’s important to know how to judge the value of the information you get. For embryologists, cell divisions and timings have meaning because this is what we do every day. But it may be very stressful for a patient to watch the embryos because they don’t actually know what they’re doing. So I guess it depends on the couple and it’s a personal perspective of every patient.
Actually it depends on the rest of the parameters of the sperm as well. If you have five million sperm swimming and only 2% of them are normal, then the absolute number of normal sperm is still quite a lot. So by looking at the sample, you will probably be able to find some sperm of normal morphology to use for your ICSI. Overall, if the quality of the sperm is very low, the fertilisation rate with ICSI is not as good as it would be if the sample was better.
The truth is that once the embryo put back to the womb, there is not a lot that you can do. What we usually recommend is maybe to be a bit more relaxed for two or three days. You may even stay at home, but not in bed – just try to avoid things that stress you out. But there is not one particular thing that you can do specifically to help your embryo implant apart from being very careful with the medication that you need to take until your pregnancy test.
Sometimes we do combine fresh and frozen embryos. For example, if someone has got one frozen embryo in storage and then they go through a second cycle and they end up with one more embryo, it is possible to combine the two and put the two back during the same embryo transfer. It’s not always the one or the other, at least not in Greece. Maybe in some other countries, there are regulations that suggest it should be one or the other. But that is probably just for monitoring purposes of the success rates after different techniques.
The companies that are transferring embryos and sperm between clinics or countries are usually certified companies and they have the appropriate training to carry biological material. If the sperm or the embryos or the eggs are transferred in the right containers and all the regulations are followed, then that shouldn’t influence the quality of the gametes and embryos. They should be absolutely safe to arrive at their destination.
If you combine fresh and frozen, that doesn’t make your chances better because your embryos will do what they’re supposed to do. But if you’re asking whether the fresh are better than the frozen or the other way around, then I’d say: these days the results of frozen embryo transfers are comparable to fresh embryo transfers. These days the freezing techniques, mainly vitrification, have very much improved from what they used to be in the previous years. Therefore, the results of frozen embryo transfers are comparable to fresh embryos transfers.
If the frozen embryo survives the freezing and thawing process and it continues to develop, it should do exactly the same what it would do if it was transferred as a fresh embryo. So if everything goes well with freezing and thawing, the success rate should be similar.