[Contribution of embryo vitrification procedure to ART efficiency]

Area of Science:

• Reproductive Medicine
• Embryology
• Cryobiology

Context:

• Assisted Reproductive Technology (ART) management for infertile couples.
• Comparison of embryo cryopreservation techniques: vitrification versus slow freezing (SF).
• Evaluation of frozen-thawed embryo transfers (FETs).

Purpose:

• To assess the impact of embryo vitrification on management of infertile couples.
• To compare vitrification with SF regarding embryo survival and clinical pregnancy rates.
• To analyze the effectiveness of vitrification at different embryo developmental stages.

Summary:

• Vitrification demonstrated significantly higher survival rates (SR) and intact survival rates (ISR) compared to SF (97.0% vs. 72.7% for SR, 91.5% vs. 49.8% for ISR, P<10(-4)).
• Clinical pregnancy rates (CPR) were significantly higher following vitrification (26.5%) versus SF (18.1%, P=0.0002).
• At the blastocyst stage, vitrification yielded a substantially improved ISR (94.5% vs. 21.4%, P<10(-4)) and increased FETs at this stage (18.1% vs. 2.5%, P<10(-4)).

Impact:

• Vitrification enhances embryo preservation and increases pregnancy rates after thawing in ART.
• The procedure supports the trend towards extended embryo culture and vitrification in fertility treatments.
• Further prospective randomized studies are needed to confirm improved cumulative birth rates at the blastocyst stage.