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Hyperstimulation: the need for cryopreservation of embryos
E Van den Abbeel1, J Van der Elst, L Van Waesberghe
1Centre for Reproductive Medicine, Academic Hospital and Medical School, Vrije Universiteit Brussel, Belgium.
Human Reproduction (Oxford, England)
|October 1, 1988
Summary
Choosing the right cryoprotective agent improves embryo survival after thawing during assisted reproduction. Embryo quality before freezing is crucial for successful cryopreservation and subsequent pregnancy rates.
Area of Science:
- Reproductive Medicine
- Embryology
- Cryobiology
Background:
- Assisted reproductive technologies like in-vitro fertilization (IVF), zygote intra-Fallopian transfer (ZIFT), and gamete intra-Fallopian transfer (GIFT) necessitate ovarian hyperstimulation to mature multiple follicles.
- To mitigate the risk of multiple pregnancies, the number of gametes or embryos transferred is restricted, leading to supernumerary embryos requiring cryopreservation for future use.
Purpose of the Study:
- To evaluate the efficacy of different cryoprotective agents (CPAs) and developmental stages on embryo survival rates after cryopreservation and thawing.
- To determine the optimal cryopreservation protocol for maximizing embryo viability for later transfer.
Main Methods:
- Cryopreservation of supernumerary embryos from IVF, ZIFT, or GIFT procedures using either dimethylsulphoxide (DMSO) or 1,2-propanediol (PROH) as CPAs.
- Embryos were frozen at either the pronucleate stage (using PROH) or multicellular stages (using DMSO or PROH).
- Post-thaw survival was assessed based on morphological integrity at different developmental stages and embryonic quality, with pregnancy rates also recorded.
Main Results:
- Pronucleate stage embryos achieved approximately 60% survival when using PROH.
- Survival rates for 2-cell stage embryos were comparable between DMSO and PROH.
- Later stage embryos exhibited better survival with DMSO as the CPA.
- Embryo quality prior to cryopreservation was identified as a critical determinant of post-thaw survival across all stages.
- Both cryopreservation protocols yielded similar pregnancy rates of 12.2%.
Conclusions:
- The selection of an appropriate cryoprotective agent is vital for enhancing embryo survival post-thawing, particularly for high-quality embryos.
- Cryopreservation protocols should consider the developmental stage of the embryo to optimize viability.
- Embryo quality remains a paramount factor influencing the success of cryopreservation in assisted reproduction.