The survival rate of embryos after the freezing (cryopreservation) procedure depends on the freezing technique used. Modern methods such as vitrification provide very high survival rates, often close to or above 90%.
Embryo Survival Rate After Freezing
1. Slow Freezing Method
- The older slow freezing technique typically results in about 80-86% of embryos surviving the freeze-thaw process.
- Survival rates can vary slightly depending on the exact protocol and embryo quality.
2. Vitrification (Rapid Freezing)
- Vitrification, the more advanced modern method, yields significantly higher survival rates around 90-99%.
- Many clinics report post-thaw survival rates of 95% or higher with vitrification.
3. Impact of Storage Duration
- Embryo survival rates may decrease slightly with very long-term storage (several years), but survival remains high within typical clinical storage times.
- Studies show survival rates from about 98% for embryos stored less than a year to approximately 71% for those stored over 7 years.
Conclusion
Embryo cryopreservation today, especially using vitrification, has a very high survival rate of about 90-99% after thawing, making it a reliable option in IVF treatments. This high survival contributes significantly to the success rates of frozen embryo transfers.