Freeze All Embryos IVF Cycles
In a traditional in vitro fertilization (IVF) cycle, eggs are fertilized the day of the egg retrieval and the fertilized eggs (embryos) grow in the laboratory until the best quality embryos are transferred three or five days after the egg retrieval. This is referred to as a “fresh” transfer.
Some patients who undergo ovarian stimulation for IVF do not have a fresh transfer of the embryos, three to five days after the egg retrieval. This is referred to as a “freeze all” where the good quality embryos that are produced are frozen. When there is a planned or unexpected “freeze all” embryos cycle, the developing embryos are frozen by a process called vitrification and stored until they are transferred at a later time.
In the past we preferred to perform fresh embryo transfers for most patients because the embryos had a better chance of implanting and developing into a baby than frozen embryos did. However, for the past 5 years techniques for freezing and transferring the embryos have improved so much that frozen embryos now have an equal or perhaps better chance of implanting than fresh embryos.
Some of the reasons for freezing all of the embryos for a later transfer.
- Planned storage of embryos prior to receiving medical treatment, such as chemotherapy for cancer that can affect future fertility by damaging the eggs in the ovaries. This can also be done for eggs if you are not ready to make embryos.
- To prevent the risk of developing ovarian hyperstimulation syndrome in patients that have developed many follicles and have a high estradiol level. Ovarian stimulation syndrome is a potentially dangerous condition that is increased and worsened when a patient becomes pregnant. By freezing the embryos and transferring them after the ovaries are no longer stimulated it reduces the chances of this condition.
- Preimplantation Genetic Screening or Diagnosis. Some patients chose to have their embryos tested to see if they have a normal set of chromosomes, or to see if they do not contain specific genetic mutations that can cause a disease, such as cystic fibrosis. This testing can be done on embryos by removing a small portion of the embryo and testing the genes in the cells removed. The embryos are frozen after the biopsy and are later transferred once the results from the testing are available. Embryos with a normal set of chromosomes have a very high rate of implanting in the uterus and developing into a baby.
- Physican or patient preference. Some physicians recommend that patients plan to freeze all of their good quality embryos because they think they have a better chance of implanting and developing into a baby than embryos transferred after ovarian stimulation and egg retrieval. There is a concern that the high hormone levels associated with ovarian stimulation might affect the lining of the uterus, making it less likely to for the transferred embryos to implant. We see this particularly in patients who develop higher progesterone levels earlier in the ovarian stimulation cycle.