Embryo freezing (cryopreservation) and transfer:
Cryopreservation refers to the freezing of tissues/gametes to allow for later use. At our center, we provide cryopreservation of eggs, embryos and sperm. The science of cryopreservation has improved dramatically in the last several years, and the survival rates of frozen tissue have likewise improved significantly. This has benefited our patients greatly.
Embryo cryopreservation is performed primarily when there are surplus good quality embryos following a fresh embryo transfer (i.e. we have already transferred to best quality embryo(s) and there are good quality embryos remaining). Embryos must obtain a certain stage within the laboratory to be eligible for cryopreservation because we only freeze embryos that we think will survive the freeze/thaw process and provide you with a reasonable chance of pregnancy. Therefore, the majority of patients will not have surplus embryos for cryopreservation, so do not despair if embryos are not cryopreserved during your cycle. Embryo cryopreservation is also performed when medically indicated, such as in cases of ovarian hyperstimulation or in cases of poor uterine lining develop (although these situations are not common).
For those patients that return to use their frozen embryos, we schedule them for a frozen embryo transfer (FET) cycle. During this period, we administer oral and/or vaginal medications to facilitate the development of the uterine lining. However, you do not need to be on stimulation medications during this time period nor is the monitoring as frequent as a fresh IVF cycle. Due to the improvements in freezing technology, the pregnancy rates of frozen embryo transfers are approaching those of fresh embryo transfers. Our overall pregnancy rate for the years of 2009-2012 was nearly 40% for FET cycles.