When undergoing in vitro fertilization, the embryo will typically be transferred for implantation on the third or fifth day of growth. This gives the embryologist time to see the embryo grow and allow enough time for the fertility specialist to perform any preimplantation genetic screening if needed. Blastocyst transfers, however, are becoming more common since the embryo is not transferred to the uterus until the fifth day of growth. The advantage of waiting until the embryo has reached the blastocyst stage may result in higher success rates.
In natural conception, the egg becomes fertilized by the sperm while still inside the fallopian tube. The embryo does not reach the uterus until about 80 hours after fertilization. This means that for the first three to four days of cellular growth the embryo is still in the fallopian tube. In a typical in vitro fertilization transfer, the embryo is placed in the uterus to attach after just three days. By waiting until the fifth day after the embryo has reached the blastocyst stage, it can be transferred into the uterus, following a more natural cycle.
By waiting until the embryo has reached the blastocyst stage, you can decrease the amount of “guesswork” involved with in vitro fertilization. When embryos are transferred after just three days, it is unsure which ones will reach the blastocyst stages and which ones will not. This means that more than one embryo will need to be transferred into the uterus to increase the chances of pregnancy. Waiting until the embryo hits the blastocyst stage will allow for only one embryo to be placed in the uterus, reducing the risk of multiple births (twins).
Some disadvantages may occur in blastocyst transfers if a fertility facility is not experienced in the procedure. If the culture environment is not optimal, delayed embryo development and even embryo arrest may occur. Beginning in 1997, The Fertility Center of Las Vegas was among the first in the world to standardize blastocyst transfers. Thousands of blastocyst transfers have been performed, resulting in many successful pregnancies.
Contact The Fertility Center of Las Vegas for more information, to schedule a consultation or attend one of our free patient education seminars.