Blastocyst culture is a process in which embryos are developed in a laboratory for 5 or 6 days, until they reach the blastocyst stage. At this stage, the embryo is more developed and contains a complex structure made up of inner cells that will become the fetus, and an outer layer of cells that will form the placenta.
Reaching this stage before transferring to the uterus can increase the chances of implantation and pregnancy success.
Once transferred to the uterus, the blastocyst generally takes 1 to 3 days to implant in the uterine wall. During this process, the blastocyst attaches to the endometrium (the uterine lining), starting pregnancy. During this time, the body must be prepared to receive the embryo, often with the help of hormonal medications that create a favorable environment for implantation.
Blastocyst culture is carried out in several phases:
The patient's ovaries are stimulated to produce multiple eggs, which are then retrieved through an ovarian puncture.
The retrieved eggs are fertilized with sperm in the lab, either through IVF (in vitro fertilization) or ICSI (intracytoplasmic sperm injection).
The embryos are placed in a special culture medium and observed over several days until they reach the blastocyst stage.
Once this stage is reached, the best-quality blastocysts are selected for transfer.
The selected embryo is transferred to the woman's uterus.
After the transfer, the blastocyst can implant in the uterus and initiate the pregnancy process.
The decision to transfer embryos at the blastocyst stage depends on various factors. Fertility specialists recommend transferring at this stage in the following cases:
The decision to transfer at the blastocyst stage offers several advantages:
There are different types of embryo cultures depending on the case:
Embryos develop for 3 days before transfer. This is a faster option, but may not be as effective in some cases.
This is the most common when there are enough good-quality embryos, allowing the embryos to reach an advanced stage before being transferred.
A biopsy is performed on the embryo to detect chromosomal abnormalities before transfer.
Advanced technology is used to monitor the embryo's development in real time without altering its environment.
Blastocyst transfer tends to have higher success rates compared to earlier-stage embryo transfers. Implantation rates can be as high as 50-60% in young women or those with a good prognosis. This is because only the strongest and most viable embryos reach this stage, increasing the chances of success.
However, success rates may vary depending on factors such as the woman's age, egg quality, and underlying fertility conditions.