![]() No, this option is not recommended because on day 4 the embryos are at the morula stage. What are the success rates with blastocyst embryo culture?īy Zaira Salvador B.Sc., M.Sc. For this reason, the current trend in most assisted reproduction centres is to transfer on the fifth day of development. In this sense, we have more information on embryo quality on the 5th day of development and we can better select which embryos are most likely to give an evolving pregnancy. In fact, some embryos that show good characteristics on day 3 do not reach day 5 (they are blocked or their quality is not good enough). The embryos that follow a normal development, on the third day of life have about 8 cells and, on the fifth day of life, they are already a structure called a blastocyst, which has more than 200 cells, with an internal cell mass (the part that will form the baby) and a trophectoderm (the part that will form the placenta) already defined.ĭuring this development process, a first selection already occurs in the laboratory itself, since not all embryos reach the blastocyst stage. (gynaecologist).Įmbryonic development in the first few days of the embryo's life is very fast. For this reason, having the adequate culture media and temperature, humidity, and light conditions can promote embryo development.īy María Arqué M.D., Ph.D. When pregnancy occurs naturally, the embryo travels through the uterine cavity on day 4 and comes into contact with endometrial cells, which produce molecules that nourish it. In spite of all the advantages, it is still possible for genetically normal embryos are unable to make it to blastocyst stage due to inadequate IVF culture media conditions in the lab. In other words, the endometrium is more receptive on day 5.įinally, selecting the embryo with the biggest chance of implanting to the uterus increases the success rates of single embryo transfers, thereby preventing multiple pregnancies. When the evaluation of embryo quality is based on their morphokinetics and morphology, the selection of the embryo with the best implantation potential can be done more accurately.īlastocyst embryo transfers can be synchronized with the endometrial lining, which is a major advantage as well, keeping in mind that embryos do not attach to the uterus until day 5 when conception occurs naturally. The main advantage is that the embryo with the highest implantation potential is selected "naturally"-most embryos with chromosomal abnormalities are unable to make it to day 5-6. In cases where egg fertilization results in multiple embryos, extended embryo culture to day 5 may be a good option. This complicates things a little bit, as the embryologist will have to pay special attention to the metabolic requirements of the embryos, as they change from day 3 onwards.Īs in the case of day 3 embryos, day 5 embryo transfers have a series of advantages and disadvantages that we will explain below: Pros On day 5, the embryos become blastocysts. ![]() Day 5 Embryo TransferĮmbryo culture using sequential media involves keeping the embryos in the culture media for 5 days. ![]() This, at the same time, increases the chances for becoming pregnant with twins or more, with the subsequent risks associated for both the mother-to-be and the babies. Given the high likelihood of early embryonic arrest with SETs, transferring two or even three embryos on day 3 is a common practice. Lesbian Artificial Insemination by DonorĮmbryos that are able to grow from cell stage (day 3) to blastocyst stage (day 5) go through a critical phase that may compromise their viability. ![]()
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