What should I choose? Fresh or frozen donor eggs for my next treatment? This topic was discussed by Carolina Alonso, an Embryologist and Egg Donation Program Coordinator and Guillermina Alonso, International Patient Coordinator at URE Centro Gutenberg in Spain.
I would say that right now, there is no difference at all between using fresh and frozen oocytes. With the new technology, called vitrification, the quality of the oocytes – the rates for fresh and frozen oocytes – it will be the same.
There is no difference from a medical point of view. The only difference is with the fresh, we retrieve the oocytes from the ovaries, and four hours later, we inseminate the eggs. With the frozen ones, we retrieve the oocytes, and within two hours we vitrify them, and when the patient comes, we need to defreeze the oocytes, wait for two hours and then inseminate them as well.
When it comes to this question, there is a difference in organizing the treatment itself. We have a shorter waiting time because we don’t have to wait for the egg donor to come, and to do all the blood tests. We just have to take the oocytes from our egg bank and go ahead with the procedure. It reduces stress for the patients, as there is no need for synchronization, so it is much easier.
We guarantee 8 mature oocytes in our egg donation program. The Spanish Fertility Society they also say, the optimum number to have two embryos, there should be 8 mature eggs offered.
It depends on the patient as well though, sometimes we have severe malefactor, and 8 eggs may not be enough, so we need more, or the couple wants to have at least two babies. On the other hand, there will be a woman who is 48 – she might want to have only one baby, we don’t want to freeze more embryos if we know that the couple is not going to use them.
As I said we think that eight is the optimum number of mature oocytes, so with 8 or 9, it should be a good number to try to defreeze.
We have 90% of survival rate, so if we defreeze 8 eggs, we should have 7-8 oocytes to fertilize. We always try to defreeze between 8 to 10 oocytes, to guarantee 8 mature oocytes.
We do have our own bank, but if a patient comes, and we don’t have oocytes in the egg bank with the phenotype they are asking for, we can buy them from a different egg bank.
They always have to have the authorization as a human Egg Bank by the Spanish Society.
No, it’s not possible because in Spain the egg donation is anonymous. It is regulated by law from 2006, which says the egg donation is volunteering, anonymous and altruistic act. So we cannot accept oocytes from a country where the egg donation is non-anonymous.
They have been talking about that. We don’t know what’s going to happen. It can happen at some point. I believe we will have fewer egg donors as it happens in other countries.
The result is going to depend a lot on the clinic, on the training or the techniques they use, and I don’t know from which year they’ve provided those results. The latest results from ESHRE from 2018, also confirmed that no difference was observed, when it comes to the frozen vs fresh. We send our results to the Spanish Fertility Society every year, where they can see all the result from all the clinics which are published on their site.
We always offer the possibility of freezing the sperm in the first visit. It depends on the quality of the sperm. It can be lower quality when we use frozen sperm. We always have to test the sperm, because if f. e. sperm has an infection – it can be treated before, it would be better to use fresh sperm.
If the sperm quality is low and the patient will take some vitamins etc. it is again better to use fresh sperm. When the quality is good, it is a very good option to freeze the sperm. If we have the frozen sperm stored, the couple can come to the clinic for embryo transfer and stay for only one night and leave. If we don’t have frozen sperm, and we have to use fresh, we need the patient to come to the clinic, give a semen sample, and then after 5 days we can do the embryo transfer – they would need to stay at least 1 week. It is also less stressful for the couple, having a frozen sample stored.
I have the results from 2018, and we had 65% of fertilization per transfer with frozen and with fresh oocytes we got at 66%. For donor eggs, cumulative pregnancy success rates (including fresh and frozen embryo transfers) in 2018 the rate is 81%.
Is the recommended freeze time for frozen donor eggs?
Once we retrieve the oocytes, they should be frozen in two hours, not longer.
No, it doesn’t have an expiry date. Many studies say – the quality of the oocytes doesn’t change with time. Once the oocytes are frozen, the quality will remain the same, after ten years or more. It is the same with embryos, they do not deteriorate over time.
If there’s no embryo in the straw, it’s because when you are freezing it, something happens and it is not in the straw from the very beginning.
We always try to freeze separately, one in the straw. We usually transfer on day 5, so we freeze blastocyst, now we always freeze one.
Sometimes we indeed defreeze embryos which were frozen six years ago, and in that time we froze them in the same straw. We defreeze the embryos, and if we just transfer one, we freeze the other one, there’s no difference once again in the results, even with freezing them two times. So if you have two embryos in the same straw, and you want to transfer just one, you don’t have to worry.
We don’t offer any guarantee programs at the clinic. We do cooperate with some companies where they offer such programs, they have very good ethics and standards, so if any patients ask us about such programs, we can always provide the details etc.
We don’t use it at our clinic. It is another media culture. We use another media, we culture the embryos until day-5-6.
It is true, we try to select all our donors, they are all between 18 and 30. We do the gynaecological examination etc. but sometimes that may happen. We always explain that there is never a 100% guarantee. All the patients need to sign consent and are well-informed about this. It has happened a few times, we always talk with the patients and try to find solutions.
Remember, I an embryologist, not a gynaecologist. But I have to say that we never had a successful pregnancy with own eggs in a 46-year-old woman. With egg donation, it is a high pregnancy rate, at 80%. I would say it is your best chance of pregnancy. I cannot say you have
zero chances with your own eggs, but it would be very difficult to get pregnant.
Yes, we do use time-lapse incubators, and we always offer them to all our patients. We
always say you have more tools to select the embryo for embryo transfer. Time-lapse incubators have a camera, which takes pictures of the embryos, every 15 minutes, so you have much more information on the embryo. Once you have to select the embryo, and you do single embryo transfer with one blastocyst. That helps to select the best embryo with the highest potential of pregnancy.