The field of assisted reproductive technology (ART) has grown enormously since the first baby was born by in vitro fertilization (IVF) in 1979. Many new procedures have been developed to enhance ART pregnancy rates and increase reproductive options for infertility patients. These have included freezing (cryopreservation) of embryos and eggs (oocytes). According to the annual CDC report of ART outcomes, which averages the results from all reporting US fertility clinics, approximately 17% of all ART cycles performed in 2008 were from cryopreserved embryos. IVF treatments require the recruitment and retrieval of multiple oocytes. The issue then arises as to how many embryos to develop for optimal reproductive outcomes and what to do with “left over” embryos. The need for reducing high order multiple births (triplets or more) due to IVF, and the high cost of “fresh” IVF cycles, have led to the worldwide use of embryo cryopreservation. Cryopreservation is beneficial since the subsequent use of these cryopreserved embryos is less expensive and less invasive to the patient than another fresh IVF cycle, avoiding the need for repeat fertility drug stimulation and egg retrievals. One of the most important advantages of embryo cryopreservation is the ability to limit the number of embryos transferred in IVF cycles, and therefore reduce the chance of high order multiple births for the patient. Our IVF program supports and adheres as closely as possible to the American Society for Reproductive Medicine's “Guidelines on number of embryos transferred”. These guidelines, which can be found at www.asrm.org , recommend the number of embryos to transfer based on the patient's age as well as other clinical data.

Embryo cryopreservation was previously done only by the “slow-cooling” method. During this slow cooling, embryos are placed into a series of solutions that contain increasing concentrations of compounds called cryoprotectants. Cryoprotectants serve to protect cells from damage caused by low temperatures during freezing. The embryos will then be stored until needed for transfer. The slow cooling cryopreservation procedure is still the most common freezing method used.

In 2008, our program was, to the best of our knowledge, the first in Pennsylvania to perform the newer process of vitrification to freeze embryos. Vitrification uses a higher concentration of cryoprotectants and an ultra-rapid freezing procedure. A glassy coating is formed around the embryo and water molecules generally do not form within it. Therefore, when the embryo is warmed up for transfer, there may be less trauma to the cells from ice crystals formation.

The process of a frozen embryo transfer cycle is much simpler and less costly than fresh cycle treatment. Our patients undergoing a frozen embryo transfer cycle typically have the uterine endometrium prepared with natural estrogen and progesterone supplementation while also using Lupron to suppress ovulation. Embryo transfer is then performed in the same way as in fresh cycles.

The IVF-Fertility Division offers embryo cryopreservation as an option for IVF patients, in addition to limited oocyte insemination and oocyte freezing options.