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The fate of Embryos in Storage July 2001 One of the great advances in assisted reproduction has been the development of a safe and efficient means of cryopreserving human embryos. This enables control over the number of fresh embryos that are transferred and hence, reduces the rate of multiple pregnancy. In the event that a pregnancy does not occur, these frozen embryos can be thawed and transferred in a subsequent cycle of treatment. Although the ongoing pregnancy rate is higher when a fresh embryo is transferred (24.0% v 19.0% in South Australian Clinics), this technology led to a further 131 pregnancies in the year 2000 in South Australia (and over 1100 Australia wide), without subjecting the women to further courses of ovarian stimulation. A question which concerns many people is the fate of embryos which are stored. These embryos carry the full potential for human life and yet are confined to be in an unnatural state of suspended existence. At the end of 2000, 1169 couples had 5566 embryos in storage in South Australia. Most of these embryos are in a brief transitional phase awaiting the outcome of transfer of a fresh embryo. However, if this is successful, the cohort of the frozen embryo may remain stored until a decision is made about a subsequent pregnancy or until 10 years elapses, at which time the embryos must be thawed under the regulations of the South Australia Reproductive Technology Act (1988). If the couple who created the embryos decide against transferring stored embryos, then a number of options exist. These include donating the embryos for an approved research project, donating the embryos to another infertile couple or thawing the embryos and hence disposing of them. Very few embryos are donated for research since the type of research for which the embryos can be used is highly restricted and cannot be destructive. In addition to satisfying the Ethics Committee at the hospital undertaking the research, the project must also be assessed by the Research Subcommittee of the SACRT. Donation of an embryo to another couple is essentially adoption of the embryo. This process requires careful counselling of both the donating and the recipient couple which includes agreement that the child will be made aware of its origin in the future. In 2000, 14 couples donated their embryos in this way. Until 10 years has elapsed, couples who have frozen embryos may elect to continue to have their embryos stored. It is critical during this time that there is continued communication with the Clinic storing their embryos. This may not always be easy with mobility of the population, but is helped by a personal ongoing relationship between the Clinic and the couple. Of course, families do break up and on occasions this may cause problems with "ownership" of the embryos which requires resolution. However, under the legislation, death of one member of the couple, divorce or continued inability to contact the couple are grounds for thawing of the embryos. In general, the Clinics are unwilling to do this without consultation with the couple. When this is not possible, or when agreement cannot be reached, the Clinics seek endorsement from the SACRT of their proposed action to thaw and dispose of the embryos. Only 24 embryos were disposed of in this way during the year 2000. The process of embryo storage remains under continued review by the Clinics, particularly as pregnancy rates from fresh transfer of embryos continues to improve. As confidence in the success rate of fresh embryo transfer grows, it will be possible to use treatment protocols which reduce the degree of ovarian stimulation and hence the number of oocytes collected and the number of embryos created. Already the number of embryos in storage have stabilised over the past three years and we might anticipate a reduction in the years to come. Stephen Judd  PRINT THIS PAGE
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