Egg Freezing

What is Egg Freezing?

Egg freezing is the procedure of freezing and storing the egg cells retrieved from the ovaries of a woman for future use to have children. For this purpose; starting from the 2nd/3rd days of the menstrual cycle, ovulation induction is performed by administering hormone injections for 10-15 days. The growth of egg cells (oocytes) are monitored with ultrasound examination 3-4 times. When the eggs become mature enough, an injection is made for the follicular rupture to occur. Then, egg retrieval is performed under vaginal ultrasonography guidance and under general anesthesia 36 hours later following this injection. The procedure takes approximately 15 minutes. The eggs are freezed by the vitrification method (fast freezing) and they are kept in liquid nitrogen containers until the patient decides to have a baby but for a maximum of only 5 years as per regulations. If the person wishes to extend this period at the end of 5 years, this period can be extended by obtaining permission from the Ministry of Health.

Freezing technology have advanced significantly over the last 50 years. Before used in humans, several techniques are developed and tried first on animals. Successful freezing of reproductive cells was achieved in 1949 by freezing sperms for the first time. In 1972, mice embryos were frozen first and this was followed by the freezing of human embryos. Human eggs (oocytes) could not be frozen for a long time or the trials were unsuccessful. Although the first establishment of pregnancy by using a cryopreserved (frozen) oocyte was reported in 1986, the routine use of cryopreserved oocytes for achieving pregnancy became possible later after a long time.

The major cause of this slow progress is the presence of a high volume of water in the oocyte; which is the largest cell in the body. The cell volume is highly important for the freezing procedure. Because viruses and bacteria are very small in volume, they remain viable after being frozen and subsequently thawed even though they are not processed. However, because the oocyte is a very large, round, and fragile cell; many difficulties are encountered during the freezing process. Water molecules inside the oocytes crystallize and subsequently may cause cell injury. However; because the sperm is a small cell, it can be frozen effectively. Another fact is that; while a man releases millions of sperms with every ejaculation, a female body can produce only 1 or 2 oocytes every 28 days. Starting from puberty, a man can produce sperms throughout his whole life but a woman has the chance of releasing egg cells only during a time span of 15-20 years.

When 50% of embryonal cells lose viability, the remaining cells can survive and maintain the viability of the embryo, establishing pregnancy. However, there is not such a chance for oocyte freezing.

Who Can Have Their Eggs Frozen?

Although the Ministry of Health previously allowed for egg freezing only for patients undergoing serious surgery or cancer treatment; with the new regulation coming into force, all women with low egg reserves or with a risk of early menopause have been offered “the right to freeze their eggs”.

Young women with low egg reserves, either married or single, can have their eggs frozen and choose to become a mother when they wish. The duration of keeping the eggs is 5 years as per regulations. If the person wishes to extend this period at the end of 5 years, this period can be extended by obtaining permission from the Ministry of Health.


Egg cells of women are frozen when one of the conditions listed below is present:

  • Before starting treatment like chemotherapy or radiotherapy; which can damage egg cells, 
  • Before surgery that will cause the loss of fertility (such as the removal of ovaries),
  • In women with a family member with early menopause in the family history or in women with low egg reserves and no pregnancy history. 
  • In women, who will undergo surgery or chemotherapy for cancer treatment, thus, who will lose fertility.

Egg freezing can be performed in the presence of the following conditions, too:

  • When no sperm cells can be obtained from the male spouse on the day of egg retrieval
  • In countries, where egg freezing is forbidden by law
  • In women from several countries around the globe; who wish to become a mother in later ages

How Is Egg Freezing Performed?

Hormone therapy applied in assisted reproduction treatment is also used for the egg freezing procedure. Treatment starts with the start of menstruation. Hormone injections are administered to increase the number of oocytes to be retrieved. The administration of hormone injections and the follow-up process is the same as performed during an assisted reproduction treatment cycle. Similarly; for the egg freezing procedure, oocytes are retrieved via the vaginal route under anesthesia. Oocytes; which are found under microscope in the embryology laboratory, are retrieved and placed into special solutions. Then, they are placed into special devices called incubators. Surrounding cells around oocytes are removed 2 hours later following the retrieval procedure. Also, their quality and degrees of maturation are assessed. Only high-quality and mature oocytes are frozen and they are kept in liquid nitrogen at a temperature of -196ºC for storage. The vitrification (fast freezing) technique has been used in our clinic since 2006 to perform the cryopreservation (freezing) procedure.

The Vitrification Technique

When vitrification method was developed for oocyte cryopreservation, then as a clinic, we started to freeze oocyte as a routine as well. Also, vitrification is known as fast freezing or changing something into a glass-like substance. After the oocyte is passed through a series of solutions at different concentrations; under microscope, a small volume is taken and placed into the carrier labelled with the patient's name and relevant codes. Then, it is immersed into liquid nitrogen at a temperature of -196ºC and placed into the storage container. Each carrier containing the oocytes should be labelled with the Republic of Turkey identification number of each patient.

Egg Freezing Techniques

Previously, oocytes were frozen by the slow freezing technique. In the slow freezing procedure, harvested oocytes were processed and placed in a device and the temperature was reduced gradually at a slow pace. However, all samples were lost when a problem occurred in the device during the slow freezing procedure. In contrast, no instruments are used for the vitrification procedure. With this technique, certainly higher rates of survival, fertilization, and pregnancy  are obtained compared to the “slow freezing technique”.

Recent studies have shown that the outcomes obtained by the use of fresh oocytes and the use of frozen oocytes via vitrification are similar.

The Importance of Laboratory in Egg Freezing

The experience of the embryologist and the used technique is very important in vitrification. Even a smallest error or delay during the freezing process causes the oocyte to lose its viability. The oocyte must be placed into the carrier at a very small volume and the embryologist must complete this process under a microscope in a certain time span. A high volume or a long loading time results in the loss of viability of the oocyte.

The Importance of Egg Freezing

Not the aging of the uterus but of eggs create hurdles on the way of the establishment of pregnancy. The frozen eggs retrieved from a 30-year-old woman will remain at the age of 30 even when the woman turns 40; meaning that the aging of the uterus does not prevent the fertilization process. Eggs must remain young for fertilization to occur. With advancing age and especially after the age of 35 years, the number and quality of follicles decreases accelerating further beyond the age of 40. The woman with a diminishing egg reserve will have a low chance of becoming pregnant either spontaneously or by undergoing treatment. Even if she becomes pregnant, the risk of miscarriage will be high. The earlier the egg freezing process is, the higher will be your chance of becoming pregnant because your "treasure of eggs" will be preserved and it will be possible to use high-quality eggs. Especially, freezing eggs before the age of 35 is important in this sense.

Selection of the Right Center For Egg Freezing 

For a center that provide egg freezing services; a robust technological infrastructure and embryology laboratory facilities, and the presence of an experienced and competent staff are critically important factors.

EUROFERTIL Laboratories, known for their successful implementation and practice of all methods and techniques with proven efficiency in the field of assisted reproduction, have been using the "vitrification method" since 2006 for the egg freezing process. The fast freezing technique further increases the success of egg freezing. Performing the vitrification technique requires competent and experienced staff. Not only the fast and correct freezing of your eggs but also fast and correct thawing depends on the success of laboratories of your preferred center.

The number and quality of eggs obtained in women who are at risk of early menopause or with low ovarian reserve are already at risk, so it is of great importance that experienced embryologists should take part in the freezing and thawing procedures.

How We Make A Difference 

EUROFERTIL IVF Center, which has been serving only in the field of IVF since its establishment, has been successfully applying the cutting-edge technology and techniques in this therapeutic area for years.

EUROFERTIL has an experienced staff and laboratory facilities, where the latest technologies are used for the correct freezing, storage and thawing of eggs.


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