Why is vitrification used in egg freezing?

After collection, eggs are treated with protective solutions and cooled very quickly. This changes the material around the cell into a glass-like state instead of allowing larger ice crystals to develop. The eggs are then kept in cryogenic storage. When an egg is needed, the laboratory warms it and removes the protective solutions in a controlled sequence. Not every egg will tolerate freezing, warming or later laboratory steps, so your clinic should explain its own process and outcome measures.

Ask the fertility team how many eggs are expected to be collected, how they will be labelled and stored, and what happens when you decide to use them. Discuss your age, ovarian reserve, medical history and future family plans because these affect whether egg freezing fits your goals. Read the technology overview for [Vitrification](/technology/vitrification/) and the treatment page for [Egg Freezing](/treatments/fertility-and-assisted-reproduction/egg-freezing/).

During the stimulation and collection cycle, contact your clinic urgently for severe abdominal pain, breathing difficulty, faintness, heavy bleeding or rapidly increasing swelling. These can signal a treatment complication and should not be managed by changing medicines yourself. After collection, use the clinic's emergency number if symptoms are sudden or worsening.

Ask how vitrification differs from slower freezing at your clinic, how storage is monitored, and which steps are needed to fertilise and transfer a warmed egg.