Egg Freezing

Key points of egg freezing

  • Women who do not have the right male companion or childbearing plan in the short term because of personal reasons can choose egg-freezing as an oocyte preservation method.
  • Female cancer patients can also use egg freezing as a method to preserve fertility against damage from cancer treatment.
  • The egg-freezing process often uses in vitro fertilization (IVF) technology, which requires two to three weeks to complete.
  • Learn more about the process below.

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1. Physical examination

Before freezing eggs, women are required to do a physical examination to check whether they are suitable for this procedure. Typically, physical examination items mainly include ultrasound and blood tests. The ultrasound scans the endometrium and the ovaries’ condition and checks if other health problems exist, such as uterine myoma. Meanwhile, primary blood tests include Sex Hormone Complete Test, tests for different infectious diseases (e.g., syphilis, AIDS, hepatitis B), and Anti-Mullerian Hormone (AMH) test.

PS: AMH is an anti-mullerian hormone, which reflects women’s ovarian reserve function to some extent. Besides, it is an important indicator to evaluate women’s ovarian function at present.

2. Controlled ovarian stimulation

Controlled Ovarian Stimulation (COS) refers to a process in which ovulation stimulating needles are injected starting from the second or third day of menstruation to produce more mature oocytes. A larger quantity and more superior quality of oocytes retrieved during this process will make more advantages in the subsequent oocyte retrieval and freezing. During the COS process, the doctor will take the ultrasound examination to monitor the growth of the follicles in real-time. Until the time is ripe, the doctor will arrange to retrieve oocytes.

3. Oocyte retrieval

Oocyte retrieval is a surgical process using the Transvaginal Ultrasound-Guided Oocyte Retrieval (TVOR) surgical method. It uses a thin and long needle to enter the vagina and directly reach the ovary, followed by oocyte retrieval under an ultrasound probe’s guidance. Although oocyte retrieval is a surgical operation, its process is not that scary as you imagined. It usually takes about 15 – 20 minutes. This operation is generally carried out under anesthesia, which guarantees a painless effect according to the current medical levels, making little difference compared with routine minimally invasive surgery.

4. Egg freezing

Now, most of the oocyte cryopreservation technology applies the vitrification freezing method. Unlike the slow freezing method commonly used previously, the vitrification freezing method utilizes a cryoprotectant before freezing eggs. It requires the eggs placed into liquid nitrogen at a temperature of -196°C for dormancy. By doing this, it can significantly reduce the formation rate of ice crystals in the freezing process. As a result, the eggs are protected from this way. At the same time, the survival rate of the eggs will be greatly increased after thawing. When the oocytes are needed to be used, subsequent operations should be followed, from taken-out and thawing of frozen oocytes to in vitro fertilization through culturing.

Complete procedures from egg-freezing to pregnancy are as follows: injecting hormones in vitro to stimulate the growth of follicles in the ovaries → retrieving oocytes one by one by TVOR → osmotic dehydration with cryoprotectant → vitrification freezing method → preserved in liquid nitrogen for several years → taken-out of the frozen oocytes → thawing and recovery of the oocytes → in vitro fertilization → in vitro culture → embryo transfer → implantation.