Vitrification

Vitrification is the gold standard for cryopreserving eggs and embryos. Unlike slow freezing, which allows ice crystals to form and damage cellular structures, vitrification cools samples at an extremely rapid rate (20,000°C/min) using high concentrations of cryoprotectants, turning the water inside cells into a glass-like solid with no ice formation.

Survival rates for vitrified blastocysts exceed 95% in most programs, and FET success rates now match or exceed fresh transfers. Egg vitrification (for fertility preservation) has similarly improved dramatically — the technology has been widely adopted since 2012. Sperm can be frozen with slower, simpler methods. Vitrified eggs and embryos can be stored for many years without deterioration.