Since 2008, CT Fertility has offered an Egg Bank using frozen (vitrified) donor eggs which has resulted in over 40 successful pregnancies.
The advancement of egg freezing (or oocyte vitrification) goes a step beyond the slower freeze methods, which have been traditionally used to freeze sperm and embryos. The slower freeze methods have proven less desirable for preserving human eggs, because of the increased damage risk of ice crystals forming within the egg upon freezing. Vitrification is a "quick -freeze" technique that minimizes the formation of ice crystals. This is achieved by using high concentrations of cryoprotectant with rapid freezing to solidify the cell. The frozen eggs are then flash-frozen in a tiny droplet of media on a very thin plastic stick.
This technology has allowed us to freeze healthy eggs from young egg donors and store or “bank” them for your future use. The Egg Bank allows you to choose and receive eggs from a proven egg donor who may no longer be donating. It also eliminates the need to synchronize both the donor and the recipient or carrier. Also, because eggs are banked in groups of ten, we can pass on cost-savings aspect to you. However because you only receive ten eggs, it may only be the ideal choice for a person or couple with one dad who is looking to have one baby.
The good news is that CT Fertility’s success rates with frozen eggs are extremely promising, with over 40 pregnancies from eggs derived from our Donor Egg Bank.
Are vitrified donor oocytes comparable to fresh donor oocytes?
Stehlik, J.C.; Stehlik, E.F.; Doyle, M.B.; Williams, S.; Roseman, H.; Kuwayama, M.
A retrospective analysis of our donor oocyte program’s success rates elucidated similar results for recipients of both fresh donor oocytes (FDO) and vitrified donor oocytes (VDO). We have been utilizing the Minimal Volume Cooling Method (MVCM) with the Kitazato Cryotop (Kitazato, Fuji-shi, Japan) for cryopreservation of oocytes since 2002 when our group reported the first pregnancies in the US from vitrified oocytes (Katayama, et. al. Fertility & Sterility 2002).
Materials & Methods:
The study included 1626 donor oocytes from FDA screened donors who agreed to both fresh donation and/or vitrification of their oocytes with the intent to donate them to recipients for in-vitro fertilization (IVF). The oocyte donors were suppressed with luteal Lupron and stimulated with mixed gonadotropin (rFSH/hMG). Ninety-four recipients were counseled appropriately prior to admission to the donor oocyte program and agreed to utilize either fresh or vitrified donor oocytes for their IVF cycle. Gestational surrogates were utilized for 51.8% (44/85) of the FDO embryo transfers and 55.6% (5/9) of the VDO embryo transfers. The embryo transfer recipients were down-regulated with Lupron and primed via hormone replacement therapy (Estrace/Progesterone). Intracytoplasmic Sperm Injection (ICSI) was performed as needed for the fresh donor oocyte recipients and for all of the vitrified donor oocyte recipients (due to the modifications to the zona pellucida during cryopreservation). The MVCM was accomplished in two main phases, equilibration and vitrification according to our previously published protocol (Stehlik, E et.al, RBM Online 2004) with modification in timing and temperature adjusted specifically to oocyte vitrification. The thawed VDO were cultured for a minimum of three hours prior to ICSI injection and 98.2% (108/110) survived the thawing process.
The FDO recipients received an average of 17.8 mature oocytes each (1518/85) with a 85.6% (1299/1518) fertilization rate. The VDO recipients received an average of 12 oocytes each (108/9) with a 85.2% (92/108) fertilization rate. The FDO recipients transferred an average of 2.3 embryos whereas the VDO recipients transferred an average of 3.6 embryos. The subsequent clinical pregnancy rates were 69.4% (59/85) for the FDO recipients and 66.7% (6/9) for the VDO recipients. This resulted in clinical implantation rates of 43.8% (85/194) for the FDO recipients, and 31.3% (10/32) for the VDO recipients.
There was no significant statistical difference in fertilization rates (p > 0.5), clinical pregnancy rates (p > 0.5), implantation rates (p > 0.1) for the FDO and VDO recipients by Chi Square analysis utilizing one degree of freedom. Therefore it would appear that for our donor oocyte program the efficacy of VDO has approached that of FDO. The availability of cryopreserved donor oocytes presents our patients with previously unrealizable advantages such as infectious disease quarantine testing and simplifies recipient synchronization to that of a frozen embryo replacement cycle. Moreover the use of VDO allows the ability to convert poor response donor oocyte cycles without cancellation, and the ability to extend matching options for “retired” or inactive donors (e.g.: use for future siblings).
Vitrification has been shown to minimize ice crystal formation during the freezing process and in experienced hands, yield the highest available rates of success. When they are eventually thawed, about 90% survive and they are fertilized through in vitro fertilization in the “usual” way. Pregnancies from frozen eggs or embryos do not have an increased risk of miscarriage, birth defect or any other imperfection.