Even though survival of embryos upon thaw and their subsequent developmental potential remains uncertain, it is still important to agree ‘a plan’ with respect to the stored embryos. This is not quite as important when there are only a few embryos stored (<3) and multiple embryo transfer would be acceptable. However it is very important when a good number of embryos have been stored, a pregnancy has been achieved from the cohort already and it is desirable that the risk of multiple pregnancies is kept at a minimum.
We therefore need to meet for a follow-up when your history can be updated and new developments if any or their absence is recorded.
At this time you will explore your wishes regarding your future treatment with the consultant considering how effective you want your next cycle to be, how many treatments you envisage from the frozen embryos and how effectively you wish to avoid a multiple pregnancy.
On the basis of your personal plans, we would also discuss your options with respect to how many embryos are to be thawed and whether or not they are to be cultured so that surviving embryos are transferred after they have also demonstrated further growth, thus improving the selection of the most competent embryo.
Such decisions are obviously based on results of thaw and subsequent development going according to that which is expected. There may be modifications necessary if thaw and survival does not go to plan.
We will discuss the outcome of thaw, their growth and the fate of remaining embryos in our stores with you on the day of transfer. Their continued preservation will incur charges from the trust on an annual basis as before.
In this way with our guidance you will have the choice of deciding how many embryos should be thawed and transferred at any one time.
Other points of note:
The frozen embryo transfer cycle can be conducted any time after your initial treatment.
In our programme, the embryos are usually stored individually.
Approximately two thirds of the frozen embryos (60-70%) survive the process of thawing.
Not all cells in an embryo may survive.
Approximately 3-5% of all cycles in our programme would not have any surviving embryos after thaw. Unfortunately you cannot know about the embryo survival until hours before the embryo transfer is scheduled.
Frozen thawed embryos have a lower developmental potential than fresh embryos and hence the success rates are somewhat lower. You can see our annual reports for up to date information.
For a good chance, it is important to have several embryos available for freezing and an ability to select the best graded embryos after thaw. Where ever possible we culture embryos after thawing for 1-2 days in order to assess their continued ability to grow and develop after thaw.
Although frozen thawed embryos have been successfully frozen thawed with a pregnancy, this is not common practice and it would be reasonable to expect a further lowering of the likelihood of a pregnancy with such embryos.
After thaw, embryos are selected for transfer on the basis of their survival, the appearance and number of surviving cells in the embryo.
It has been known for couples to achieve multiple pregnancies with the same batch of embryos.
Transfer of multiple embryos after thaw can lead to a multiple pregnancy.
There is no evidence that embryos are actually affected by the length of time they are frozen.
We understand that any damage caused occurs either during the course of cooling embryos to freezing point or when warming them back to body temperature.