Embryo transfer

From ArticleWorld

The process of embryo transfer is just one in a series of steps involved in many in-vitro fertilization programs. This step occurs after several eggs have been fertilized in the laboratory with sperm cells, after they have gone through a 2-3 day period of development in the laboratory and once they have reached the stage of becoming an eight-cell embryo.

Preparation

For an embryo transfer to result in a successful pregnancy, both the embryos and their receptacle (the recipient’s uterus) must be carefully prepared in synchronicity with one another. The embryo preparation is essentially described above. The recipient’s uterus must also be prepared hormonally so that the inserted embryos can implant and develop. In some cases, the female can be allowed to undergo a natural cycle, particularly in conditions where she has normal ovulation but carries unacceptable eggs or eggs which don’t reach the uterus.

At the point in the cycle when the uterus reaches the luteal stage, there is a window of time most favorable for implantation, called the implantation window. Unless the timing of the uterus and embryos are perfect, the recipient must use frozen or “cryopreserved” embryos. In other situations, the uterus is prepared artificially through the use of estrogenic medication. When this happens, the likelihood of being able to time the maturities of the uterus and embryos together is higher.

If an embryo is to be transferred at the eight-cell stage, one or more of the cells can be extracted from the embryo and evaluated for genetic abnormalities. Such a process is called pre-implantation genetic diagnosis (PGD). Theoretically, the same process could be used to detect the gender of the embryo if a couple expresses a gender preference.

The embryos are transferred after being aspirated into a needle which is then inserted through the cervix and into the uterus. Depending on the practices of the in-vitro fertilization clinic, different numbers of embryos can be implanted. In all such procedures, the expectation is that only one or two embryos will implant, however, the risk of having a high multiple pregnancy always exists.