Hello everyone, today we are going to talk about blastocyst quality! do you know? The quality of blastocysts has a crucial impact on the success rate of IVF. So, which one is better, 6-day 4bb blastocyst or 5bb blastocyst? Let’s reveal the secret together!
The meaning of 4bb embryo
4bb refers to the expansion phase, with a small number of internal cells and loose arrangement, while the epithelial cells are composed of small cells and have a loose structure. The \”4\” here represents the embryonic development level, which is in the expansion stage, and the following letters are \”b\” and \”b\” which represent the grading of the inner cell mass and trophoblast cells.
The meaning of 5bb embryo
5bb embryo refers to the incubation period. The number of cells in the embryo is small and the order is loose. The epithelial cell layer of trophoblast cells is composed of a few cells. The \”5\” here refers to the embryonic development process, and \”b\” and \”b\” respectively represent the inner cell mass and trophoblast cell classification.
First, let\’s take a look at what both embryos look like. Both 6-day 4bb and 5bb embryos are considered high-quality embryos, and they have reached a very high level in their development. And according to data, the success rates of these two types of cysts are almost the same!
Then you may ask, \”Since they are both high-quality clumps, what is the difference between them?\”
In fact, in actual operation, there is no clear definition that 4bb is better than 6bb or vice versa. Therefore, the decision on which type of cyst to use when choosing a transplant needs to be made on a case-by-case basis. 
However, please note that once you have hatched and found a place to implant, you may find that 5bb is not as ideal as the other two options. Therefore, when considering transplantation, factors such as hatching status, development stage, grade assessment, and actual operation conditions need to be comprehensively considered.
In general, embryos that are 6 days old, 4bb or 5bb are both high-quality varieties and have similar success rates. High quality means high implantation rate and pregnancy rate, which is very important for people who want to choose high quality and excellent performance for transplantation.
If you are considering an IVF program and want to choose the high-quality type that best suits your needs and situation, please consider the above factors as soon as possible and make the best choice under the guidance of your doctor!
