Optimization of a dilution method for human expanded blastocysts vitrified using EM grids after artificial shrinkage

Area of Science:

• Reproductive Science
• Embryology
• Cryobiology

Background:

• Vitrification is a key technique in human embryo cryopreservation.
• Optimizing post-thaw dilution protocols is crucial for successful outcomes in assisted reproductive technologies.
• Artificial shrinkage is used to facilitate vitrification of expanded human blastocysts.

Purpose of the Study:

• To evaluate the efficacy of a simplified 2-step dilution method compared to a traditional 6-step method.
• To assess the impact of different dilution methods on the survival and clinical outcomes of vitrified human blastocysts.

Main Methods:

• Human expanded blastocysts from in vitro fertilization cycles were vitrified using artificial shrinkage and EM grids.
• Post-thaw cryoprotectant dilution was performed using either a 2-step or a 6-step protocol.
• Survival rates, implantation rates, and clinical pregnancy rates were analyzed for 151 patients.

Main Results:

• The 2-step dilution method achieved a survival rate of 91.6%, comparable to the 6-step method (89%).
• Clinical pregnancy rates were higher with the 2-step method (45.9%) versus the 6-step method (40.9%).
• Implantation rates also showed a slight advantage with the 2-step method (24.1%) compared to the 6-step method (19.4%).

Conclusions:

• The 2-step dilution method offers a simpler and potentially more effective protocol for human expanded blastocysts vitrified after artificial shrinkage.
• This simplified method may improve clinical outcomes in assisted reproduction cycles.
• Further validation of the 2-step dilution method is warranted for widespread clinical application.