Egg Freezing

Prior to undergoing the egg-freezing process, women are required to undergo a physical examination to assess their suitability for the procedure. Typically, the physical examination involves ultrasound and blood tests. Ultrasound scans assess the condition of the endometrium and ovaries, checking for the presence of other health issues such as uterine myomas. Simultaneously, primary blood tests encompass a Sex Hormone Complete Test, screenings for various infectious diseases (e.g., syphilis, AIDS, hepatitis B), and an Anti-Mullerian Hormone (AMH) test.

Note: AMH, or anti-Mullerian hormone, is a hormone that reflects women's ovarian reserve function to some extent. It is also a crucial indicator for evaluating a woman's current ovarian function.

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.

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.

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.