Tarih:Feb 7, 2017 Yazar:Ender Yalcinkaya Kalyan
Today I would like to write this essay as an answer to the questions regarding oocyte (egg) freezing. Oocyte freezing has become a practice that is highly demanded in recent years. Most of the women who admitted to us with an intention for oocyte freezing are the women who are planning to have marriage at older ages but are anxious about the diminished ovarian reserve. Besides, there are also some women who have to undergo chemotherapy at younger ages and thus want to freeze their eggs before the treatment for future use. Of course, although they are less in number, some women want to freeze their oocytes at younger ages without any health reason; but we can not help them since elective gamete freezing is not legally allowed in our country. It is necessary to say that women can also freeze their eggs under specific conditions as mentioned above in Turkey. They should also have a report from authorized hospitals indicating that they have a diminished ovarian reserve and they should give this report to the clinic in which they plan to freeze their oocytes.
The improvement of vitrification techniques marked an era in oocyte freezing. Previously, survival rates of the oocytes after freezing-thawing were considerably low. However, in recent years, we as embryologists can offer oocyte freezing to the patient comfortably with the improvement in vitrification and special oocyte freezing protocols. Today, survival rates of post-thaw oocytes have reached up to almost 85-90%. Although it still remains lower compared to the embryos, it is far higher compared to the previous rates of 50-60% and thus, promising.
While oocyte freezing can be performed for a limited group of women in our country due to the legal restrictions, younger and more number of oocytes can be frozen in the countries that allow oocyte donation legally. This can be considered as oocyte banking. Today in the same countries, sperm banks are commonly used but there are exposed to very stringent auditing systems. It is necessary to keep this in mind!
The women who started an oocyte freezing program are given ovary-stimulating gonadotrophins as in IVF treatment. All oocytes are collected and only the oocytes at mature stage are frozen. In other words, all the oocytes collected can not have achieved complete maturation. The patients should be informed about this condition at the beginning of treatment.
There is another thing I would like to underline about oocyte freezing. As we choose good quality embryos for freezing purposes depending on the better survival rates, the same rule should apply to the oocytes. In other words, I can say that it should be kept in mind that oocyte quality is gradually decreasing by the age of 35; and especially the women above 40 years old should be informed about the possible lower survival rates of the oocytes, post-thaw fertilization and pregnancy rates in detail; informed consent should be taken from the patient under these information and treatment should be started later on. Sometimes we meet some patients who are married but want to conceive a child at a later time, and apply us for oocyte freezing. If they plan to have a later pregnancy, orientating patient towards embryo freezing instead of oocyte freezing can be a better approach.
You can contact me for further questions. Take care.