If you and your partner have extra embryos that are not used during initial IVF procedures, these embryos can be frozen, stored, and then transferred at a later date. Known as frozen embryo transfer (FET), this procedure is widely used at our center and has helped many couples achieve pregnancy.

FET was introduced in the early 80's. The procedure is performed with embryos that have been frozen and stored for a period of time. The embryos are replaced in the womb after they have been thawed. Because FET is a relatively non-invasive procedure, it can be successfully performed during a natural cycle, or with a controlled (programmed) cycle.

A fresh embryo transfer can sometimes be postponed when there is a risk of ovarian hyperstimulation syndrome (OHSS), or the patient may be sick due to other reasons. Embryo cryostorage is also a reliable option for a woman with a partner who wishes to have children after cancer therapy. With newer, more reliable freezing protocols, single embryo transfer protocols result in fewer multiple pregnancies.

At our center many couples undergo an FET when they have had extra embryos remaining from previous IVF cycles. Some couples do not like the idea of destroying embryos simply because they are "left over" from an IVF cycle. It is always a good idea to freeze and store any additional embryos in order to maximize chances for pregnancy from a fresh treatment cycle. In addition, FET cycles are less stressful and less expensive. During an IVF cycle numerous embryos are created in order to ensure that healthy and viable embryos are available for transfer. In many couples that choose to do so, our laboratory freezes and stores some of these embryos for later use.

The FET procedure is very simple. The physician will prepare and monitor your reproductive system for ovulation and endometrial development; then your embryos will be thawed and implanted into your uterus at a pre-programmed date and time. As with a fresh IVF cycle, the number of embryos transferred will directly impact the success rate of the FET procedure. Our center follows the ASRM guidelines on number of embryos transferred and makes recommendations based upon your own history and circumstances.

Just as with a fresh IVF cycle, the success rates with FET are affected by multiple of factors, particularly maternal age, presence or absence of male factor, embryo quality post-thaw and number of embryos transferred. Typical success rates are around 20 to 50% per FET cycle. Not all embryos will survive the freezing and thawing process equally; however, newer freezing techniques have allowed us to bump up embryo cryosurvival rates into the 80 to 90% range with excellent pregnancy results.