The aim of every IVF treatment is to achieve pregnancy in the quickest and most comfortable way possible for our patients. Therefore, when a treatment begins, the goal is the transfer of one or two top-quality embryos into the uterus of the recipient mother.
In some cases, at the embryo transfer stage, the patient has a large number of good quality embryos available. It is not possible to transfer all of them due to the risk of multiple pregnancies.
These viable embryos that are not used for the transfer are frozen in order to be used at a later date. They can be used if the couple decides to try for another child or if subsequent attempts with fresh embryos fail.
Some important facts relating to embryo freezing:
Embryo freezing is not always carried out in every IVF cycle. In most treatments soft stimulation is used in order to obtain an adequate number of eggs causing minimum discomfort to the patients. In this case, spare embryos are not generated.
Not all embryos are viable for freezing. Although there may be several embryos in the laboratory, the embryologist can see which of them would not survive the freezing and defrosting process. These embryos are not frozen. We only freeze embryos where there is a reasonable possibility of survival after the defrosting process.
Some frozen embryos unfortunately do not survive the defrosting process. This means that even though we start a treatment, it does not necessarily mean that we will eventually have embryos to transfer to the uterus.
Pregnancy rates obtained using frozen embryos are slightly lower than the ones achieved using fresh embryos.
The treatment that the patient needs to undergo in order to carry out a frozen embryo transfer is quick, simple and comfortable. Few injections are required It takes no longer than two weeks and there is no need for frequent monitoring (usually no blood tests are required and normally no more than one ultrasound scan is necessary).
Pregnancies following this treatment proceed normally. The occurrence of complications is no higher than in any other kind of treatment or natural pregnancy. There is no link associated with this treatment to malformations and/or the physical and intellectual development of the child.
Frozen embryos are stored for periods of five years. If the couple decides to end storage, they have four options: use the embryos themselves for a further IVF treatment, donate the embryos to another couple, donate the embryos to scientific research or destroy them.
The embryo is frozen using liquid nitrogen which stops all biological processes. The embryo is in a state of suspended animation and stays in this state until it is needed. The embryo is then slowly thawed out and its biological processes reactivated.
(Embryo cryopreservation) Embryo freezing is a well-established form of assisted conception treatment. The first frozen embryo baby was born in 1984. Embryo cryopreservation allows multiple embryo transfers from a single egg collection and improves the chances of livebirth.
Advantages of embryo cryopreservation.
Allow maximizing the potential for conception for IVF and prevent wastage of viable normal spare embryos. Perhaps this is the most important advantage of cryopreservation.
Approximately 50% of women may have spare embryos available for freezing. In some clinics,the pregnancy and live birth rate with frozen-thawed embryo transfer is as high as those achieved with fresh embryo transfer.
Freezing all embryos for subsequent transfer may be advised for women who are at a high risk of developing severe ovarian hyperstimulation syndrome following ovarian stimulation for in-vitro fertilization (IVF).
When embryo implantation may be compromised in cases such as the presence of endometrial polyps, poor endometrial development, break through bleeding near the time of embryo transfer or illness.
Difficulty encountered at fresh embryo transfer e.g. cervical stenosis (inability to pass through the cervical canal because the cervix is narrowed or scarred, etc).
Cryopreservation of embryos is very important to be incorporated in the egg donation programs. It is not always possible to synchronize the recipient’s cycle with that of the egg donor. In some countries, it is mandatory to freeze all embryos created from donated eggs, quarantined for a period of six months and until the donor have a repeat negative screening tests.
As a result of successful cryopreservation programs, frozen embryos have also become available for donation to infertile couples.
Cryopreservation of Semen Sperm cryopreservation or sperm freezing is a method for men to preserve their sperm and store it in a bank for future use. Many medical treatments, including several cancer therapies, can damage sperm quality, which is why it is advisable to freeze sperm before receiving the medical treatment.
Although there is no information about how long frozen sperm can remain effective, sperm twenty years or older have been used successfully in pregnancies. Sperm freezing allows this sperm to be used in the future in fertility treatments, such as intra uterine insemination (IUI) or in vitro fertilization (IVF).
Sperm Freezing - What to Expect Patients are usually referred to the andrology laboratory for sperm cryopreservation by their doctor. At the first visit patients can ask questions and clarify anything they might want to know about sperm freezing and cryopreservation, such as storing the samples long term and billing, before the sample is collected and the semen storage agreement signed. Additionally, patients are always welcome to call with additional questions or clarifications.
How Cryopreservation Is Performed
After a semen sample has been collected, it is placed on a warming block maintained at 37°C, to liquefy. At this time, the semen sample is mixed in a 1:1 ratio with a freezing medium that allows the sperm to survive the freezing and storage process.
Frozen in Liquid Nitrogen
Semen samples are slowly frozen in liquid nitrogen vapors. Once the samples have been frozen in the liquid nitrogen vapors, they are placed in special containers where they are stored in the liquid nitrogen until they are needed. Each ejaculate can yield from one to six vials. Each vial of a patient’s semen sample is labeled with the patient’s name, the date, and a unique number recorded on the side. This information will be used to catalog the semen sample into the storage facility.
Test Thaw Procedure
The survival rate of sperm after cryopreservation can vary widely. Depending on the