Egg Cryopreservation (oocyte freezing)
The freezing of oocytes have recently been found to survive well using improved cryoprotectant solutons and techniques. We use a process of vitrification with a sage medium and this new development odfers hope for preserving fertility for a large number of women who may be cancer patients or who wish to delay family building by storing their eggs at a younger age.
Options avaiable to women to preserve fertility:
Freezing of eggs through a multi-step laboratory procedure to preserve viability of the eggs. Eggs can later be thawed and fertilized, and embryos implanted to achieve pregnancy.
Who does egg freezing benefit?
Professional, career minded women or women without a partner who wish to have children at a later date, when career demands and pressures are less.
Women who are confronted with the decision to undergo radiation or chemotheray duwe to the onset of cancer at an early age, or faced with the possibility of having their ovaries removed.
Egg Freezing Process:
Eggs have been found to survive well using improved cyropreservation solutions and techniques. These new developments offer the hope of preserving fertility for a large number of clients.
- Egg retrieval: Using fertility drugs, the ovaries are stimulated to produce several high quality eggs for retrieval. When the follicles are ready for egg retrieval, a needle is inserted into the ovaries using ultrasound quidance to locate each follicle. Fluid from the follicles is drawn into a test tube to retrieve the eggs. The patient is sedated during the process and antibiotic and pain relief medication administered. The procedure lasts about 15 minutes. The eggs are identified with a microscope and collected for freezing.
- The eggs must be treated with a cyroprotectant before they can be frozen. A cyroprotectant is added until the desired concentation is reached. The sample, processed at ambient temperature is now ready for freezing.
- The temperature of the sample is reduced from 20degrees to -7degrees centigrade(the temperature of ice nucleation) at 2degree centigrade/mınute and then held for 10 mınutes. Cooling is then resumed at a rate of -0.5degree centigrade/minute to 30 degree centigrade. The frozen eggs are then plunged into liquid nitrogen for storage.
Egg Fertilisation:
When ready to have children, one or more of the eggs is thawed. After thawing, surviving eggs are fertilised through the ICSI method. The fertilised eggs usually develop nto multi-celled embryos. Using a catheter, one or more embryos are then simply placed in the uterus, hopefully establishing a pregnancy.
We currently have 6 on-going pregnancies from thawed frozen embryos using vitrification. The first delivery of twins is due in September 2008.
Recent Paper presented to the British Fertility Society Summer College 2008
P9: High ongoing pregnancy rates with a new vitrification
medium after oocyte vitrification and thawing
Onder Coban1, Oguzhan Hacifazlioglu1, H. Ibrahim Tekin1,
Mustafa Bahceci2, & H. Nadir Ciray2
1OrtaDogu ve Balkanlar IVF Center, Magusa, Cyprus and
2Bahceci IVF Center, Istanbul, Turkey
Vitrification of oocytes is a relatively new method and its
superiority over slow freezing is under debate. More vitrification
media became commercially available compared with several years
ago. The present study reports outcome of cycles in which oocytes
were frozen and subsequently thawed (and transferred) with a
recently introduced vitrification media (SAGE Biofarma, Thornbull).
Metaphase II oocytes were frozen in SAGE Vitrification
Media at *3 h after retrieval immediately after denudation. The
vitrification procedure was performed according to the Kuwayama
protocol (Kuwayama et al., 2005) using the Cryotop
technique in high security straws (CBS, Paris). The thawing
procedure has been performed as described previously (Kuwayama
et al., 2005). In seven donor cycles, transfer embryos were
obtained from oocytes that have been vitrified and subsequently
thawed (Table 1). From 96 vitrified Metaphase II oocytes, 69
survived (% mean+SD; 69+18) and were subsequently
subjected to ICSI. The fertilization rate was 71+26 (%). All
cycles resulted in embryo transfer. The results have been
obtained in four transfers of whom three were positive and all
are currently ongoing (between 9 and 15 weeks). The implantation
rate was 36% (4/11). These results showed that high ongoing
pregnancy rates can be obtained after vitrification and thawing of
oocytes in SAGE media. The survival rate can be improved after
an extended time period when the embryologists get experienced
and by reducing the number of oocytes that were subjected to
vitrification in each straw.
Reference
Kuwayama, M., Vajta, G., Kato, O., & Leibo, S. P. (2005). Highly
efficient vitrification method for cryopreservation of human
oocytes. Reproductive Biomedicine Online, 11, 300–308.
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