After the egg harvesting procedure, IVF or ICSI fertilization is performed in the IVF laboratory, and the produced embryos are incubated at room temperature for continued growth. This process is called Blastocyst Culture. The blastocyst is made up of two types of cells: an inner cell mass that develops into the fetus and an outside layer of cells termed trophectoderm that develops into the placenta.
Embryo transfer after IVF or ICSI has often been done on Day 2 or Day 3 after egg collection. However, developments in IVF laboratory technology now allow us to culture embryos for up to five days. This provides the embryos with more chances to demonstrate their developmental potential. Before day 5/6, some embryos remain static. The embryologist can use this 'natural selection of Blastocyst Culture to discover and pick the best embryo/s for artificial insemination.
Blastocyst culture necessitates ideal lab conditions. Around 45 percent of fertilized eggs make it to the blastocyst stage. Because only the most capable embryos develop into blastocysts, allowing embryos to grow and develop in the laboratory until they reach the blastocyst phase allows the most capable embryo/s to be selected for embryo transfer.
In addition, in a normal pregnancy, the embryo travels to the womb five days following fertilization, where it implants. On this day, the uterine lining is very receptive. As a result, performing a blastocyst transfer is more physiological. Some spouses require PGS or PGD. Because embryo biopsy is proposed to be performed at the blastocyst stage rather than on Day 2/3 embryos, blastocyst culture is essential for them.
For patients who have had numerous failed IVF attempts, blastocyst culture is recommended. A blastocyst culture performed on a patient with a history of unsuccessful IVF with day 2/3 embryo transfer can provide more information about the embryos' progress and help improve conception rates. Blastocyst cultivation enables the transfer of only the best embryo, limiting the potential of multiple pregnancies.
For successful blastocyst culture, quality control and proper laboratory culture conditions are required. There's a chance that none of the embryos will develop into blastocysts. If this happens, the embryo transfer process will be canceled in that instance. It may be preferable to transfer a day3 embryo, depending on criteria such as age, medical history, and the amount and quality of embryos, especially for women in their first IVF cycle.