#7 Cryopreservation (freezing) Program The purpose of the Embryo Freezing Program is to give a couple participating in the IVF program the best chance to achieve a pregnancy with a maximum of safety. At the end of an IVF cycle there are often multiple embryos available for transfer. It has been found that transferring more than four embryos carries a significant risk of multiple pregnancy, while it does not increase the singleton pregnancy rate proportionately. The advantage of cryopreservation is that there may be an increased chance of pregnancy without the necessity of multiple stimulation cycles and oocyte retrievals. There are other advantages to embryo cryopreservation which include, but are not limited to: avoiding acute illness immediately following oocyte retrieval or other unforeseen conditions that would either prevent or make a fresh embryo transfer less than optimal. For example, if ovarian hyperstimulation syndrome seems likely to occur, all of the embryos should be frozen to prevent exacerbation of the condition, which may require hospitalization. There are various stimulation protocols available to make a frozen transfer successful. You will be instructed by the physician which method may be best for your individual case. The frozen embryo transfer takes place in an identical manner to a fresh embryo transfer. It must be realized that there is only minimal worldwide experience with human cryopreservation and the actual pregnancy rate has yet to be determined. Currently, the longevity of embryos at -196°C is unknown. Extrapolating from information from other mammalian species, embryos that become healthy offspring can be stored up to ten years. There is very limited knowledge regarding the health of offspring from cryopreserved human embryos, but it appears that the spontaneous abortion rate and congenital anomaly rates are not increased over that expected for natural pregnancies. We have data to suggest no difference in pregnancy or abortion rate in embryos stored up to 5 years. Embryos selected for cryopreservation will be frozen up to three days after the egg retrieval. Often prezygotes (2PN) are frozen on the day following retrieval (24 hrs.). The embryos will be placed in a cryopreserved media and frozen in a step-wise manner. At the end of the cryopreservation procedure the embryos will be stored frozen in tanks filled with liquid nitrogen. These cryopreserved embryos can be thawed and transferred at a future date. There is no guarantee of the survival of human cryopreserved thawed pre-embryos. If they have not survived, (as seen at the time of thawing), they will not be transferred. The Cooper Center for In Vitro Fertilization, however, does have a very high survival rate for frozen embryos, for 2PN Embryos our survival rate is 96%. We are pleased to offer our patients years of expertise in the area of cryopreservation. We are considered by many to have one of the most successful cryopreservation programs in the country. The legal ownership of frozen human embryos remains uncertain. We are unaware of any legislative body in the United States that has addressed this issue. We consider couples whose eggs and sperm become an embryo to be the owners and persons who control their embryos. However, there is a time limit on this ownership and control. Our cryopreservation consent form limits this time to the lesser of the female reproductive capacity of a given couple or their mutually married status. Embryos affected by these conditions would revert to the control of the IVF program. There will be an additional cost for storage of cryopreserved embryos. You will receive in the mail a storage fee invoice until the time of transfer of the last stored embryo. If you choose to donate your remaining embryos, we will forgo the storage fees once the donation is complete (consent signed and notarized). This booklet is intended to give you an overview of the human embryo cryopreservation program. The physicians and representatives of the IVF program encourage your questions. Please indicate to the IVF team, prior to oocyte retrieval, whether the concept of embryo cryopreservation is acceptable to you. Your acceptance of embryo cryopreservation may effect the number of oocytes obtained and/or the number of oocytes fertilized. Prior to actually freezing any embryos you will be asked to sign both a frozen embryo consent form and separate legal statement pertaining to disposition of cryopreserved embryos. < Step #6 |
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