Cryopreservation (called also cryoconservation) is a special procedure in which cells and tissue can be stored for long periods to be used later. These are frozen and stored in liquid nitrogen at -196° Celsius. Cryopreservation is a common method used in fertility treatment. Several different materials can be frozen: unfertilised eggs, embryos, sperm, testicular tissue and ovarian tissue.
The quality and quantity of a woman’s egg supply rapidly begins to deteriorate after age 35. The frozen, unfertilised eggs are a valuable egg store which can be used to conceive children in the future. American Hospital Tirana’s elective fertility preservation program assists women who wish to freeze eggs in order to have children later in life. Many of our patients have had successful pregnancies resulting from frozen eggs.
When cryopreservation of eggs is indicated? Women may opt for egg elective freezing for the following reasons:
- A history of early menopause in her family
- Cancer – As we know, cancer diagnosis and therapy (surgical, chimiotherapy and radiotherapy) can have a detrimental effect on the ovaries. It is a fact also, that the success of cancer therapy is increasing continuously. In these patient, freezing the eggs before starting the cancer therapy is an option to preserve their fertility and to have childrens after the cancer therapy is finished.
- Any condition which may result in premature ovarian failure or the removal of your ovaries (severe endometriosis, recurrent ovarian cysts etc)
- Social egg freezing: Some young women may want a child, but they may not be able to or want to become pregnant at their current stage of life for personal reasons. It may be, for example, that her own career does not allow for this or that she has not yet found the right partner. In Albania, these women are able to have their eggs frozen for a later date.
Cryopreservation of eggs … How it works?
The fertility preservation process begins with a consultation with a physician from our IVF team. We’ll discuss your needs, the processes involved, and any questions you may have. In addition, we’ll conduct blood tests and a pelvic ultrasound to assess the number of eggs in your ovaries (ovarian reserve).
To help safely stimulate your ovaries to produce more mature eggs than they would in a natural cycle, you’ll take fertility medication. The right time for retrieval varies across patients, and will be assessed by your physician. Usually the stimulation it takes 8 – 12 days. The retrieved eggs are then frozen using a vitrification (fast freezing) process. If your wish is to freeze embryos (eggs already fertilized with sperm), the eggs are fertilized after retrieval.
In a typical IVF or ICSI treatment cycle, the woman’s ovaries are stimulated to produce many eggs. Following fertilisation and embryo culture, the best embryos are selected for embryo transfer. For about 50% of couples, there will also be good embryos which are surplus to those required for embryo transfer. These embryos can be frozen at this point for future use.
Embryo freezing (cryopreservation) is a method of preserving the viability of embryos by carefully cooling them to very low temperatures (-196oC). This is carried out in the laboratory using specialised freezing equipment and the embryos can then be safely stored in liquid nitrogen for extended periods. The chosen cryopreservation technique used by our lab is vitrification.
What are the benefits of embryo freezing?
The main benefit of embryo freezing is the option to have frozen embryos thawed and transferred to the woman’s uterus in the future without having to undergo stimulation of the ovaries or egg retrieval. It is also possible that there may be enough frozen embryos for more than one subsequent cycle.
Embryo freezing is also used for fertility preservation for a married woman who gets diagnosed with cancer. Before starting the cancer therapy she may have an in vitro fertilization cycle and freeze all the embryos. After the cancer therapy is finished she may continue with the transfer of the frozen / thawed embryos.
What does a frozen embryo transfer cycle actually involve?
Frozen embryo transfer cycles are relatively simple. In some cases, the woman’s natural cycle will be monitored by ultrasound to assess the development of the lining of the uterus and to determine the timing of ovulation and hence embryo transfer. In other cases, depending on the woman’s history a more hormonally controlled cycle may be warranted. The decision regarding the most appropriate treatment will be made in consultation with the clinician.
Are there any disadvantages to embryo freezing?
Approximately 70% of the embryos that are frozen will survive the thawing process. This does however vary between patients and it is possible that none of a couple’s embryos will survive the freezing and thawing process.
How successful are cycles involving the transfer of frozen / thawed embryos?
Overall, frozen embryos have a slightly lower chance of implanting than fresh embryos. This is mainly because in general the best embryos in a group will already have been transferred on the fresh embryo transfer.
Storing sperm prior to an IVF, egg donor or IUI cycle ensures the availability of sperm should the male partner have difficulty producing a sample on the day of egg retrieval or should the male not be available to produce a fresh sample due to other medical reasons.
Some men discover they have diseases or must undergo treatment or surgery that will cause permanent sterilization or genetic damage. As cancer detection and treatment techniques improve, more cancer conditions are being detected at younger ages in men, with better and longer survival rates. Therefore, more men in their fertile years are now considering this option.
Good candidates include:
- In cases of low sperm counts where multiple semen collections may be necessary for use in a single insemination.
- To preserve semen for deferred inseminations when an intimate partner is temporarily absent.
- Prior to assisted reproductive technologies such as In Vitro Fertilization; to secure a good quality semen specimen for the future procedure.
- Prior to vasectomy, but still desire to keep a possible option open for future roles.
- Single woman may choose donor to achieve a pregnancy. The semen is quarantined for a period of time while the donor is screened for infectious diseases.
The situations when cryopreservation is useful are:
- As part of artificial or assisted fertilisation. Here the surplus good embryos are frozen, and the couple can use them in the future.
- Before treating severe illnesses. In some serious diseases, there is a very high risk of becoming infertile due to the treatment of the disease. This can be the case, for example, in the treatment of cancer by chemotherapy, radiotherapy or surgery. After a thorough medical consultation and assessment of the risk, those who want to have children can take precautions to prepare for a loss of fertility and have their sperm or testicular tissue or their eggs or ovarian tissue cryopreserved before the treatment.
- In social freezing. Some young women may want a child, but they may not be able to or want to become pregnant at their current stage of life for personal reasons. It may be, for example, that her own career does not allow for this or that she has not yet found the right partner. In Albania, these women are able to have their eggs frozen for a later date.