What is embryo cryopreservation?
Embryo cryopreservation or embryo freezing is the process of freezing and storing the embryos produced, from fresh cycle IVF treatment, for future use. It is the most effective technique for fertility preservation in women and is often included in part of IVF programmes to ensure the future use of unused embryos. Often fertility treatments, such as IVF, ICSI and egg donation, generate surplus healthy embryos. In around 50% of cases these embryos are of good enough quality to be frozen and stored for future use. Embryo freezing, therefore, offers greater flexibility to couples in their family planning and can be used effectively to reduce the number of multiple births. If after family building, there are unwanted and remaining embryos they can be optionally donated to other infertile couples.
Embryo freezing maximises the use of embryos produced from a fresh cycle and increases the chances to conceive from the same batch of embryos. The use of frozen-thawed embryos is much less invasive procedure for the woman than undergoing a fresh IVF cycle.
How does cryopreservation work?
The process involves oocyte retrieval from the woman and subsequent in vitro fertilization with her partner’s or donor sperm. The embryos are then exposed to cryoprotectants and are carefully cooled under controlled conditions and then stored, immersed in liquid nitrogen, at very low temperatures (-196ºC) for long-term storage. When they are desired for use, the embryos are thawed and arrangements are made for implantation.
Once frozen, embryos can be stored in this way for many years before being thawed and used in treatment. Pregnancies have been reported from frozen-thawed embryos stored for more than 30 years (see our blog – ‘Healthy twins born from 30 year old frozen embryos’). The risk of birth defects is not increased as a result of embryo freezing.
Vitrification is the most common method used for the embryo freezing, widely considered as the best method for this purpose including and the egg freezing. At Life Clinic, paying attention to every detail that can contribute to success, we are only using the best freezing kits (the Kitazato kit) on the market. Kitazato is recognized as one of the pioneering brands in driving and improving vitrification.
Further reading on embryo cryopreservation
For a more in-depth review of Embryo Cryopreservation and its implications in fertility medicine, please refer to the following journal articles.
Yen and Jaffe’s Reproductive Endocrinology (2019)
Embryo cryopreservation involves many of the steps of in vitro fertilization, including stimulation of multiple follicles with FSH, prevention of premature LH surges with a GnRH analogue, triggering of the process of ovulation, retrieval of oocytes, fertilization with sperm, and cryopreservation of embryos.
From: Yen and Jaffe’s Reproductive Endocrinology (8th ed.), 2019
The Future of Cryopreservation in Assisted Reproductive Technologies (2020)
In this journal article some of the latest advances, strategies, and practices in ART cycles are reviewed using elective cryopreservation of embryos, cryopreservation of oocytes, and whether these developments are likely to bring improvement to IVF outcomes.
Bosch, E., De Vos, M., Humaidan, P., Front. Endocrinol., 20 Feb 2020
Cryopreservation of Gametes and Embryos and Their Molecular Changes (2021)
This is a recent article that outlines cryopreservation as an ART technique. It then delves deeper into the individual procedures and methods involved including vitrification techniques and effects of cryopreservation in embryos.
Estudillo et al., International Journal of Molecular Sciences, 2021, 22(19), 10864
