Cryopreservation of Embryos
If you were offered in vitro fertilization as an infertility treatment method, you will most likely be prescribed hormonal therapy. Healthy ovaries generally show good reaction to ovulation stimulation, producing numerous good quality follicles. A time will come when your doctor will conduct a centesis and hand the eggs over to an embryologist, who will then conduct further work on artificial insemination, which may result in the conception of a new life, or even several lives.
In Russia it is customary to transfer a maximum of 2-3 good quality embryos inside the uterine cavity during an IVF procedure. Usually, the specialists offer the patient to leave the remaining embryos (10-15, or maybe even more) for cryopreservation. This is a paid service, however, if one attempt is unsuccessful, the other embryos can be used for a second attempt.
Historical Facts
Australia, 1983. The first recorded birth by a woman who was implanted with embryos that underwent cryopreservation. 2 years later, an English couple had a normal birth following a pregnancy that occurred after the transfer of a blastocyst that had also undergone the process of freezing-thawing.
Method Popularity
This method is used universally. There are countries that have decidedly negative attitude toward it. Germans, for example, have only allowed this type of treatment at the pronucleus stage, or the initial stage of fertilization.
What Can Be Frozen
Doctors at medical centers subject oocytes, sperm, and embryos that can be at any stage of development to this procedure. In addition, ovarian tissue can also be frozen.
Every infertility treatment center uses its own methods. This factor, as well as the particular issues that exist in certain countries, influence the choice of embryos that can be subjected to cryopreservation:
- fertilized eggs;
- 4, 8-cell embryos;
- blastocysts.
The section titled "Road from Zygote to Blastocyst" and the websites of various clinics can show you photos of embryos at different stages of development.
Only fresh good quality embryos that have been left over after the transfer of the necessary number of embryos into a woman's uterus are subjected to this procedure.
For sperm this method is used in the following instances:
- if a man has cancer, to secure some supply of sperm prior to the start of chemotherapy. This sperm can later be used during an IVF procedure;
- if a partner is having trouble giving sperm at the proper time. This situation usually arises with out-of-town patients;
- sperm donorship;
- a man's decision to postpone fatherhood. Given that there has been a noticeable decline in male fertility in recent years, this decision might become more and more popular.
Oocyte freezing is practical, for example, if there are contraindications for ovarian stimulation or it is impossible to conduct IVF during a certain period.
Oocytes do not endure freezing well, since they are very fragile. Oocyte can easily be damaged during the process of freezing and thawing. For that reason, the chances of egg fertilization and successful outcome of fertilization, insemination decrease to 3-4%, when cryopreserved oocytes are used.
Tissues are frozen when a female patient is suffering from cancer. They are subsequently used by transplant surgeons. The freezing-thawing process destroys about 7% of the follicles. There aren't any precise data with regard to pregnancies that occurred after tissue transfer. There are data that show that endocrine function is restored in roughly 9-36.
Technology
Cryopreservation is characterized by the use liquid nitrogen. Its temperature is about 196 degrees, and it allows to slow down cellular activity.
Medical centers choose various containers to store frozen embryos, for instance, cryoloops, cryovials, or simple straws. Every container contains a maximum of 2-3 frozen embryos. The procedure takes a long time - 2-4 hours.
The cryopreservation process typically utilizes special substances – cryoprotectants: sucrose, glycerol, propylene glycol, DMSO. The ingredients prevent the formation of ice crystals inside the cells that could injure the embryo. This occurs because intracellular water leaves the cells; the only way to prevent it is to ensure the presence of cryoprotectants in the environment where human cells are placed.
The content of 40% or more helps speed up the freezing process. The embryos become glass-like, ice crystals are absent. There are certain inconveniences in this method. Thawed embryos must be rinsed in ice-cold water. Yet with all the negatives, the difficulties, this technology is the one that's considered the most promising.
Cryoprotocol: Variations
The uterus needs to be prepared prior to the transferring thawed embryos. This process is called cryoprotocol. Ovarian stimulation and centesis are eliminated. There are two possibilities of transfer time for cryo-embryos – the programmed and the natural cycle.
Natural Cycle
This version is used when a female patient maintains normal ovulation. Injections of hormonal agents are eliminated. Certain doctors believe that endometrium will then be better prepared for embryo transfer.
Preparations for transfer begin on day 7-10 of the cycle; that is when a woman is scheduled for a visit with a clinic's doctor. The specialists begin monitoring, carefully examining the results of blood work and ultrasound. Subsequently it becomes clear how soon ovulation will take place. Then doctors make the decision to thaw the embryos in order to conduct the transfer.
Programmed Cycle
This version is used when regular cycle is absent or there is endometrial pathology. Programmed cycle of the endometrium is a method of transfer preparation. A woman is prescribed progesterone, estrogens, though without pituitary blocking; occasionally preparations are used whose purpose is to block the pituitary.
Every type of protocol has about equal chances of success. Fertility specialist and embryologist decide how many embryos to transfer. The decision is taken based on several factors: the quality of embryos, the patient's age, the particulars of the cryopreservation.
Cryoprotocol has advantages over other procedures; it requires fewer financial expenditures. It also gives the ability to choose the time, which is particularly valued by out-of-town women and patients who attend the procedures while having to work.
Effectiveness (Odds)
According to statistics, pregnancy occurs half as often following cryoprotocol. The freezing method is very popular, however, since this procedure is cheaper than the regular IVF protocol.
There are two reasons for lower success rate with the use of cryoprotocol:
1) Embryos that are left for freezing are of lower quality; the best ones were used earlier (in the fresh cycle).
2) This method affects the quality of embryos; the process of thawing is sometimes accompanied by significant losses.
From Personal Experience (excerpt):
"..My embryos were frozen several times. There were instances when 11 of the transferred embryos were cryopreserved, and only two were "alive" after thawing. I was very upset, I was hoping that my embryos could be used for several IVF protocols.."
Embryos can be frozen at different stages of development. The effectiveness of those transfers will differ as well. Experts believe that a well thawed blastocyst survives implantation better than others. Ask the doctor, who will be performing your IVF, to give you statistical information, so you could compare the effectiveness of transferring 4-8 cell embryos and a blastocyst. It is quite possible that a particular infertility treatment center was able to achieve good success, which would encourage you.
From Personal Experience (excerpt):
"...I had to undergo numerous IVF attempts: fresh, cryo. Every time I asked the doctors where my IVF was performed, how good my chances were. They quoted me these numbers: thawed embryo transfer – 10-12 % ( a maximum of 16-18% at the best medical centers), 30-35% - for the use of fresh embryos (40-45% - at the best medical centers)..."
This twofold difference between fresh and cryoprotocols continues to linger. There is an increase in effectiveness of fresh cycles (up to 40-45%), cryoprotocols (up to 20-25%). The reason for the rise in effectiveness of the latter is the mastering of blastocyst freezing by the specialists.
You can read true stories of success, which you can find in the section "Our Victories". Problems and nuances of cryoprotocol are covered in the section "Cryo"; the "IVF Clinics" section contains various topics as well.
Stories of success can instill faith, confidence, give hope. If you wish to tell something to others, to share your emotional trials, feelings, experience, please write to us!
Storage Life
Properly frozen embryos have very long storage life – up to several decades. Storage containers are periodically subjected to regular checkups, whose goal is to make sure that the system is operating as it's supposed to, that there are no damages to the containers, that the normal levels of liquid nitrogen are maintained.
To Store or Not to Store?
In vitro fertilization helps an ever--growing number of couples to get children. Quite often spouses are hesitant to try the IVF procedure again after a failed attempt, to use the remaining embryos. These days very few wish to become a large family. The spouses will have to decide soon whether or not to use the frozen embryos. Maybe they will wish to have another child in a couple of years. These types of doubts preclude making a hasty decision; it is better to continue paying for cryopreservation services.
If, however, you have decided that you will not be conceiving again: one or two children that you have now are enough, you should opt out of storage.
There are several ways of doing it:
- destruction;
- transfer of embryos to a childless couple (donorship);
- scientific research.
You should not ignore the clinic's demand to make any kind of decision, to pay for their services. The degree of client responsibility is stipulated in the contract; that's why you should read it carefully to protect yourself against any undesirable consequences.
There are no unequivocal opinions regarding the husband's, wife's use of embryos that were created during marriage, after the death of one of the spouses, after a divorce.
American and British legislations, for example, forbid their use without the consent of the second spouse.
Personal: Faith Evolution
"...The first attempts were made at the time when these services were not widespread, and the clinics that conducted these procedures were just beginning to emerge. It was hard to believe in success achieved with the use of cryo-embryos. There were five of them, and yet everything turned out well.
When I found this medical center for the first time – it was a while ago – I was surprised that you could freeze the cells. There were very few clinics like that back then, few could get the necessary equipment. If you looked at the Guide to clinics, you probably saw the entry "availability of cryo-equipment". It is a very important factor that needs to be taken into account when choosing a medical center, especially when many follicles are produced.
A clinic has this equipment but does not provide patients with a guarantee of higher effectiveness. This fact goes to show that specialists in that clinic follow the achievements in the area and the experience of Western doctors.
10-15 years ago, many people doubted whether they should trust such technologies. There was fear of what would be done to the unborn children, a lack of faith in the success of such an endeavor. An unsuccessful procedure ignored a list of truly unsuccessful attempts.
Nowadays, the situation has completely changed. Now, if we are talking about five unsuccessful attempts, it means there might be cryoprotocols among them. Then the advice for the patients will be completely different than with 5 protocols that were all fresh.
The effectiveness of technologies began growing rapidly after the year 2000. Forums began featuring numerous messages about successful results. Patients began looking first and foremost at the embryologists' expertise. In a short while, the most important thing for a woman will be the body – the most precious technology there is, because it is precisely the body that is capable of reproducing numerous precious cells, which will then grow into beautiful embryos.
These technologies give many infertile families a chance to have a child – after the first, second or third attempt.
An unsuccessful attempt hurts. You should focus on the positive, there is still a chance – cryo-transfer. You come again, you wait and hope. There are all these precious embryos, who are waiting for a chance in their life-saving straws. Who knows, maybe success is right there, right around the corner!
If you already succeeded and are currently changing diapers for a long-awaited IVF baby, who knows, in six months, a year, two years, you might decide to have a second or third child. Many who come to the Probirka website become infected with the desire to have many-many babies. Frozen embryos would be quite useful in those cases.
Cryopreservation became successful, fears and doubts have gone away. I am happy that reproductive medicine is making giant leaps forward. I am very grateful to the specialists at infertility treatment clinic. Any programmes in our country conform to European levels, and their effectiveness allows us to hope only for the best!
