The egg is the largest cell in the body and is contained mostly of water. The classic problem with freezing eggs has been that as the temperature drops below freezing point, ice crystals form inside the egg and cause damage to the genetic material. Vitrification is an ultra rapid cooling technique that allows the water inside and surrounding the egg to instantaneously super cool into a solid state with no ice crystal formation at all.
Vitrification has shown pregnancy rates of 30%-40%, which is comparable to the use of fresh eggs. The technique involves removing water from the eggs then freezing them at high speed in liquid nitrogen to prevent any damaging crystals from forming. Studies have shown that vitrification results in higher post-warming survival, fertilisation, embryo development and pregnancy rates. There are many situations when it may be suitable to store eggs, these may include:
- When a younger woman wants to preserve her fertility and store eggs while she is still young;
- When a single woman is at risk of losing her fertility as a result of chemotherapy or other cytotoxic therapy; or
- Egg Vitrification
The latest breakthrough on this technology is the use of a process for storage called vitrification. It works by removing nearly all the water from the egg cell by osmosis.
The egg can then be stored at the same low temperatures as frozen eggs without damage. Published results indicate that there is negligible damage to the egg caused by these procedures, resulting in success rates, after fertilisation, which are identical to fresh eggs.
It is important to realise that the decline in fertility is due to the “age of the eggs” and therefore fertility preservation should apply only to women who are less than 35 years.