Egg Freezing Methods
As with other topics in medicine, the optimal method for egg freezing has been debated by different fertility groups claiming superiority of one method over the other. This misconception often arises from limited knowledge of the fluid dynamics and of the egg’s physical properties. Understanding the movement of fluids both inside and outside the egg is essential to developing the necessary formula to sustain the egg viability.
Egg Freezing Using the Conventional Freezing Method
The conventional freeze program is a more gentle and gradual way to dehydrate the eggs and expose them to our specially developed freezing solutions. By using the principals of osmosis and membrane potential, the water inside the egg is gently dehydrated and exchanged for the cryoprotectant solutions used to prevent ice crystal formation. This physiologic process avoids “shocking” the egg by abrupt fluid changes using toxic concentrations of solutions. The eggs are stored in specially designed straws which are sealed as an extra precaution to prevent possible viral contamination.
Egg Freezing Using the Vitrification (Flash Freeze) Method
The vitrification flash-freeze egg freezing method requires absolute critical time exposure through many different solutions with very specific exposure times. Since the solutions are extremely concentrated and potentially toxic to the eggs, there is very little margin for error.
The flash freeze procedure must be performed with exact precision, requiring special skills and concentration by the embryologist.
Which Egg Freezing Method is Better?
At the American Society of Reproductive Medicine (ASRM) meeting held in 2008, Frozen Egg Bank, Inc. presented data of their 91% survival rate after the eggs are thawed. A recent study presented at the American Society of Reproductive Medicine (ASRM) meeting in October 2012 showed the FEB slow freezing and thawing technique has greater efficiency than the vitrification flash freeze technique among all egg banks sampled in the study.