The previous post discussed egg freezing which is a much more difficult technique compared with embryo freezing which has a much longer, proven track-record. We will discuss egg freezing some other time. In general, if there are high quality embryos that are not going to be transferred it is always a good idea to consider freezing them for future use. However, the mere fact that these embryos exist has led to other concerns that are not only medical but social, philosophical, ethical, and moral. What obligations do a couple have to their frozen embryos? Several years ago over 4000 frozen embryos were destroyed in England because the couples who had created them had abandoned them and the clinics had no other option given that the status of these embryos was uncertain.
In this country several high-profile law suits have grown out of disputes following divorce of who controlled the embryos. Similarly a clinic in New England was sued by a man whose ex-wife had undergone a frozen embryo transfer following their divorce without informing the clinic of her change in marital status. In this case the clinic ended up paying a pretty hefty settlement as the man argued that his decision to NOT reproduce should have trumped her decision to reproduce with embryos that were from his sperm...yikes.
So although I am all in favor of freezing these extra embryos one must proceed with caution. If you are still with me then read on as we cover today's Question of the Day from 100 Questions and Answers about Infertility: the book that still needs all (?some) of you to write some reviews on Amazon.com as they keep rejecting the ones that my mother has sent in..
75. What is embryo freezing, and how successful is it?
On the day of embryo transfer, the couple may learn that they have additional embryos of good quality in addition to those embryos that have been selected for embryo transfer. These embryos can be cryopreserved by freezing them in liquid nitrogen. Through a series of carefully orchestrated steps, the embryos are ultimately frozen at a temperature of –196 °C, leaving them in a state of suspended animation in which they can remain for many years. Embryos that have been stored for more than 10 years have successfully generated pregnancies (although most patients tend to use their frozen embryos within 3 to 5 years after they are produced). The pregnancy rates associated with replacing frozen embryos depend on the age of the patient and the quality of the embryos at the time of cryopreservation. Top-quality embryos from young patients may yield pregnancy rates around 50%, whereas poor-quality embryos may not even survive the thawing process. In some clinics, more than 75% of embryos survive the freeze–thaw cycle. Many couples are often concerned about their moral obligations concerning their frozen embryos. In such cases, couples may elect to defer embryo freezing, choose to alter their stimulation or pursue natural cycle IVF so as to avoid this problem of excess embryos. Extra embryos that are not used to initiate a pregnancy could represent a source of embryonic stem cells. This potential use of extra embryos lies at the heart of the recent political debate in the United States regarding government funding of stem cell research. Clearly, patients should carefully consider the implications of excess frozen embryos as they embark on an IVF cycle. However, not all patients will have extra embryos of high enough quality to be considered for embryo cryopreservation.