September 17, 2009
We are excited to announce that CCRM has successfully implemented a method of cryopreservation known as vitrification which has allowed us to achieve high success rates with egg freezing. Vitrification, unlike slow cooling which has been used for freezing over the past 20 years, avoids the damage to the cell invoked by ice crystal formation, as well as the “chilling” effects seen with slow cooling. With vitrification, embryos are taken from room temperature to -196º C in a fraction of a second using high concentrations of cryoprotectants.
At CCRM, we performed an initial clinical trial freezing oocytes for patients who desired pregnancy in the near future so that we would be able to thaw those eggs in a short time and determine survival rates, fertilization rates, and pregnancy rates. With this new method of vitrification, we have achieved egg survival rates of approximately 80%, fertilization rates of over 80%, and pregnancy rates above 50%. The outcomes of this study have been accepted for publication in the journal Reproductive Biomedicine Online.
Indeed, these numbers are equivalent to those we achieve with fresh oocytes and suggest that this method of egg freezing will allow patients to preserve their future fertility with great success.
Due to the success of our study with oocyte vitrification, which was performed under the direction an institutional review board, CCRM is now able to offer fertility preservation services through egg-freezing to appropriately evaluated patients and oocyte donor candidates. It is important to note that oocyte vitrification is still considered to be an experimental technology by the American Society for Reproductive Medicine. CCRM is pleased to have sufficient internal clinical data, which was developed under institutional review board supervision, to justify the use of this technology in appropriately evaluated women desiring fertility preservation. Based on CCRM outcome data it is likely that women can expect age-related outcomes from fertility preservation. Given our current data, if a 34-year patient undergoes oocyte vitrification, she can expect a pregnancy rate typical for women of her age when she thaws, inseminates, and transfers resulting embryos, although in rare circumstances it is possible that oocytes may not survive the vitrification and warming process.
The types of patients who may want to access this technology include young women who want to preserve their fertility due to career or lifestyle choices. Such patients may know that having children will not occur until much later in life and are concerned that their fertility may be compromised at that point. The ability to freeze their oocytes at a young age will give them the opportunity to conceive at a later time which may be more appropriate for them.
The second group of patients who are candidates for egg freezing are those young women recently diagnosed with cancer who are not in a relationship. Since most cancer treatments involve radiation, chemotherapy, or a combination of both, ovarian function is often compromised rendering the patient infertile. If the patient is single, the use of donor sperm to create embryos is typically not a first choice and represents an extremely difficult emotional decision. It would, therefore, be much more desirable to freeze her unfertilized eggs and have the opportunity in the future, once her treatment is completed, and she is in a relationship, to use her partner’s sperm to fertilize her eggs and have children.
It is important that the patient be offered egg freezing as soon as possible after her cancer diagnosis so that there is time to proceed with egg collection and freezing prior to the initiation of cancer treatments. In addition, patients with nonmalignant diseases, such as lupus and rheumatoid arthritis, may be on chronic medications that are detrimental to oocyte function. Such patients may also benefit from oocyte cryopreservation.
More information regarding egg freezing can be obtained by setting up a consultation with any of the physicians at CCRM by calling 303-788-8300.
Colorado Center for Reproductive Medicine