Cryopreservation in assisted reproduction is a technique by which semen, oocyte or embryo samples can be preserved frozen in liquid nitrogen at -196º, without experiencing significant alterations in order to be used successfully in the future.
There are many causes that can lead a patient to want to freeze these samples, and many doubts that may arise around this procedure. That is why we wanted to speak with Dr. Rafaela González, gynecologist and director of the clinic that the IVI group has in Almería, about all these issues.
In which cases is the freezing of samples used?
Both embryos, ovules and semen can be frozen as part of a fertility treatment or for other causes that Dr. González explains:
Embryos
In cases in which the couple resorts to an In Vitro Fertilization, once the egg is fertilized in the laboratory, either by conventional technique or by the ICSI technique, a series of embryos are obtained to transfer to the uterus.
The Good quality embryos that have not been transferred They are vitrified so that the couple can use them in the future.
Ovules
The eggs can freeze for various reasons:
- Medical preservation
"Preservation for medical reasons is carried out in cases where the woman suffers from some disease, such as cancer, for example, that will require aggressive treatment that may endanger your ovarian reserve "- explains Dr. Gonzalez.
And we have already seen some time as today, fortunately, more and more means are available that help women to preserve your fertility before undergoing any medical treatment That may affect you.
- Social preservation
"This option begins to take more and more women who want delay his motherhood but they are aware that age can affect reproductive capacity. So they decide to freeze their ovules with 30 years, for example, and use them ten years later without the passage of time having affected their quality "
A few months ago we echoed the pregnancy of actress Eva Longoria, who at 42 had decided to turn to the eggs she froze long ago to become a mother. The fact is that the current lifestyle we lead, work, or any other personal circumstance can lead women to make this decision.
- Preservation during treatments
"This type of egg preservation occurs in the case of women who are undergoing a fertility treatment but when it is time to implant the embryo, the medical team discovers some cause that will prevent this implantation. At that time you can , or freeze the embryo if it has already been fertilized, or freeze the oocyte until the medical problem has arisen "- Dr. Rafaela González tells us
Cum
As with ovules, semen can be frozen for the same reasons:
Medical preservation In case of illness.
Social preservation
In this case, Dr. González explains that the man does not decide to freeze his semen for the same reasons as the woman, since the age in the case of the man does not interfere to the same extent as the age of the woman.
"We see this type of cryopreservation especially in the case of men who want to undergo a vasectomy, but decide to freeze their semen before if they change their mind in the future"
- Preservation during treatments
The doctor explains that taking into account that the quality of the semen varies constantly, influencing factors such as food or rest, in the case of men with the quality of the semen very altered they can freeze samples as a safety method, in case that frozen sample had better quality than the one extracted at the time of performing the reproduction treatment.
What requirements should the samples have to ensure viability when thawed?
"In the case of embryos left over from a fertility treatment, the only condition to freeze is that they are viable. That is, if they can be transferred fresh, then they can also be frozen "- explains the director of IVI Almeria.
"With regard to ovules, we must bear in mind that they have a maturation process so they can only be frozen if they are in a stage in metaphase 2 "
"And as for the cum, it can be frozen as long as there are sperm with mobility, regardless of the total number. In any case, the patient should be informed of the conditions of his sample so that he knows the percentage of survival that will exist after defrosting "
How long do frozen samples last
Dr. Rafaela González explains that as long as the samples are cryopreserved in the correct conditions and do not suffer any alteration, there is no specific time after which they cease to be viable.
"In fact, not long ago we were aware that in the United States an embryo that had been frozen for over 20 years had been transferreds. The implantation was a success and the pregnancy is developing normally. This shows that well preserved, the samples can last a long time "- he tells us.
How long do the clinics keep the samples?
Before freezing eggs, semen or embryos, the patient receives a document from the clinic explaining the time the center agrees to save your sample, and what is done with it once the conservation period ends.
The doctor explains that each fertility clinic marks its own times, taking into account that there is a common legislation for the conservation of embryos and ovules, and a different one for the conservation of semen. In this case, IVI proceeds as follows:
Embryos
Leftover embryos from an IVF treatment they are cryopreserved for two years, and after this time the couple decides what to do with them, considering the following possible alternatives:
Continue its conservation for longer, renewing it for periods of one year. Dr. González explains that it is usually the option that most couples turn to.
Start a treatment again using those frozen embryos.
If the couple decides not to take care of these embryos, they have two options: or donate them to another couple, provided that the requirements required for this purpose are met, or donate them to research studies.
"It is rare for a couple to choose to donate them to another; it is an option that is not usually considered. Regarding the donation for research studies, it is important to know that currently in our country there are no studies that require the use of this type of biological material "- explains the doctor.
"According to the law, embryos cannot be destroyed until the woman's reproductive age ends, which is 50 years. Therefore, if a couple does not want to take charge and asks for their destruction, our clinic will continue to keep them until such time as that woman has turned 50 ".
What if in that course of time the couple repents and want to recover their frozen embryos to undergo treatment?
"In that case they can recover it without problems paying the years in which the embryo has remained frozen at the clinic's expense."
Ovules
The legislation in the case of the ovules is similar to that of the embryos, so the alternatives that can be raised are the same as just mentioned, except that in IVI the vitrification of oocytes is carried out for five years as part of the treatment , and from there the patient renews it voluntarily and annually.
Cum
As we have commented above, semen conservation is governed by a different law, so after considering the options mentioned above, if the patient does not want to take care of his sample, it can be destroyed, unlike embryos and ovules.
Could it be the case of sample losses?
A few days ago we met the news of a man who had frozen his semen at the Ramón y Cajal Hospital in Madrid, before undergoing cancer treatment, and later, when he wanted to recover it, The hospital confessed to losing its sample.
Before such news we asked Dr. González her opinion on the case, as well as how to proceed from the clinics at the time of get rid of frozen semen samples:
"I cannot offer an opinion on this case because I do not know what could have happened. It is rare that a semen sample is lost"
"Regarding the How to proceed when disposing of semen samples, I will say that although each clinic has its own protocols, they are all governed by a series of common criteria set by the Spanish Fertility Society, so before freezing a sample, the client must sign a consent that will indicate the time it will remain frozen in the clinic "
"In the case of IVI, we are very insistent with patients when the freezing time of their samples ends. And although the client knows in advance how long we will have his frozen semen, and what we will do with the sample if it is not put in Contact us to express your desire to renew the freeze for longer, to use it or to donate it, always We decided to notify you by courtesy before proceeding to the elimination"
"And we do it by all possible means, including by certified mail if necessary, to ensure that, in effect, The customer is aware that the cryopreservation time of his sample is over"
"And if you still don't give us any answer, After one month of the notice, the sample is destroyed. But this is only done in the case of semen because, as I said, it is forbidden to destroy eggs and embryos "
IStock photos
Acknowledgments Dr. Rafaela González, director of the IVI Almería clinic
In Babies and More Infertility, In Vitro Fertilization, Assisted Reproduction, Fertility
