Freezing embryos is the only proven method of preserving fertility. The technology of freezing embryos is to store the embryos obtained through in vitro culture technology in a liquid nitrogen environment of minus 196°C for long-term preservation. If treatment fails during this cycle, these embryos can be thawed and transferred during a later natural cycle.
Frozen embryos
Put the embryos and freezing liquid into cryovials, and use two cooling methods: slow (embryos on days 2-3) and fast (blastocysts on days 5-6) to make the embryos static. A method that can be removed and stored in liquid nitrogen at 196 degrees. If there are remaining embryos with good quality, they can be frozen and stored. They will be thawed and implanted into the uterine cavity during natural or artificial cycles in the future, which will increase the chance of pregnancy.
The number of embryos obtained in one superovulation cycle is large and the quality is good. If all embryos cannot be transplanted at once, the excess frozen embryos can be stored. For patients with severe ovarian hyperstimulation syndrome who are not suitable for embryo transplantation during the treatment cycle, frozen embryos can be stored. The embryos will be resuscitated and transplanted in the future natural cycle or artificial cycle. The clinical pregnancy rate of frozen embryo resuscitation was 48.28%, and the clinical pregnancy rate of blastocyst resuscitation was 63.48%.
Main functions
The functions and effects of frozen embryo technology:
. During the "test tube baby" treatment for infertile patients, ovulation-inducing drugs are generally used to stimulate the number of mature eggs, which can often cause the ovaries to grow more than ten eggs at a time. But in fact, in each "test tube baby" treatment, only 1-3 embryos are transplanted back into the uterine cavity. Implanting too many embryos may increase the risk of multiple births, so the remaining embryos may be cryopreserved. If the treatment cycle is not successful, the preserved embryos can be transplanted back to the mother in the subsequent natural ovulation cycle or hormone replacement cycle, eliminating the need for superovulation. This not only avoids the pain of injections, but also saves a lot of costs.
. In terms of technology, from slow freezing to ice crystallization and rapid freezing (Vitrification), both provide good preservation methods. The Vitrification method is fast but costly because the method is fast and the survival rate and pregnancy rate are quite good.
. When freezing embryos, good quality embryos must be selected, so the embryo scoring standards are also very important. It is hoped that embryos with developmental potential can be frozen so that they can be provided to patients for future use.
. Frozen embryos are the most commonly used method of freezing. However, due to beliefs and legal regulations in some countries, embryos cannot be frozen and only eggs can be frozen. However, embryo freezing is a technically sophisticated method that is used by many patients.
Application areas
Suitable objects (indications) for frozen embryos:
1. The remaining embryos that can be used after embryo transfer during the IVF (ICSI) treatment cycle;
2. Since the uterine environment of the mother during this treatment cycle is not suitable for pregnancy (for example, severe ovarian hyperstimulation or poor endometrium, etc.), the mother can also be frozen and preserved to postpone implantation, and then thawed at the appropriate time;
3. Those who have systemic diseases such as fever and diarrhea during this treatment cycle cannot be transplanted;
4. For patients who are likely to lose ovarian function (for example, undergoing chemotherapy, radiation therapy, or resection surgery, etc.), you can also choose to freeze embryos to preserve their fertility.
