Egg Freezing

The truth is, many clinics that market egg freezing have a laboratory that has never successfully frozen and warmed a single human egg, let alone done it enough to refine their processes. Thus, we consider it a first order issue to assess the laboratory.

We believe you need to be focused on two questions when judging your laboratory. Is the laboratory experienced and exceptional at:

• Freezing and thawing eggs?
  
  
• Doing IVF?

First, your clinic must prove to you that they have deep experience both freezing and warming eggs within their own laboratory’s four walls. Being excellent at one, but not the other, is insufficient. And no, other laboratory’s results or “industry wide data” are not a proxy for how well your clinic’s laboratory will perform. There are a few ways to probe on this.

First and foremost, when you select a clinic you should ask for their “oocyte cryosurvival rate.” This is the percentage of frozen eggs that survive when a laboratory tries to warm them. We suggest you get this data for eggs the clinic has both frozen and warmed themselves. A passable clinic’s score will be around 80% and superior score will be about 90% or higher. Unfortunately, this data will be “lagging” data and by the time you return to use your frozen eggs (if you do at all) their rates of success may be very different than they are today.

A quick note: this number is measured over a large number of patient’s eggs. It’s distinctly possible that a clinic with a 90% cryosurvival rate will warm your eggs and none, or very few, will survive. Even in good laboratories we estimate this happens in 1 - 10% of cases.

Second, find out if your clinic runs its own internal frozen egg donor program. Generally speaking, clinics that run their own internal frozen egg donor program are more experienced handling frozen eggs, but this is fairly uncommon.

Third, you may want to ask your clinic if they track their success rates with frozen donor eggs, and fresh donor eggs, and how those rates compare. Ideally this would be tracking eggs that they’ve both frozen and thawed, though sometimes you might get information on eggs they’ve just thawed.

If you need to use your eggs, you will be undergoing IVF and so you need to ensure your clinic’s laboratory excels at fertilizing eggs using ICSI, growing embryos, performing biopsies on embryos for genetic testing (optional), and freezing and thawing embryos for future use. Below is our chart on what is passable, and what’s exceptional, for each of these crucial steps. Much of these key performance indicators were developed by lab directors from eighteen different countries in what became knows as the "Vienna Consensus."

Below are the questions we believe you will want to put to your clinic before agreeing to freeze your eggs.