What is blastocyst? How is it different from a cleavage embryo?

Blastocyst is Blastocyst embryo that develop 5-6 days (D5-D6) after sperm-egg combined fertilization. Blastocysts is a staged product of embryonic development (it’s similar to the concepts of high school students and college students, if the D3 cleavage stage embryo is compared to high school students, then blastocysts are college students), which is the highest stage that human embryos can reach in vitro. Blastocysts have higher implantation rates, pregnancy rates, and lower abortion rates than cleavage embryos.

What is blastocyst culture?

Blastocyst culture refers to the process of further cultivating the cleavage stage embryos on the third day after egg retrieval, so that its growth and development reach a higher stage (blastocyst).

Why to do blastocyst culture?

(1) Mbryos need to be developed into blastocysts before they can be implanted into the uterus. Culturing blastocysts successfully is the only way to successful pregnancy.

(2) Blastocyst culture can eliminate some abnormal cleavage stage embryos, such as chromosomal abnormalities, abnormal cell structure, and other developmental stagnation.It has higher development and planting potential, and can obtain more pregnancy rate after transplantation(the current pregnancy rate of transplanted resuscitation blastocysts is higher than the pregnancy rate of transplanted resuscitation cleavage embryos), so it is recommended that eligible patients firstly culture blastocyst in vitro and then transplant or freeze, which can save transplantation cost and shorten baby-holding time.

(3) It has better synchronization with the endometrium. During the process of blastocyst culture, we found that some high-quality cleavage stage embryos have a slow development and delayed blastocyst formation. If this delayed-developing cleavage embryo is transferred ,it will cause that endometrial development is out of sync, and pregnancy rate drop . However, if the cleavage stage embryo is cultured into a blastocyst and then transplanted, there will be no out-of-sync situation.

(4) Blastocyst culture is more favorable for the cycle. The number of blastocyst cells is large.multiple trophectoderm cells are taken for genetic testing, which not only improves the accuracy and effectiveness of the test, but also does not affect the development of the inner cell mass, thereby avoiding adverse effects of biopsy on fetal development.

(5) Blastocyst is the highest stage that human embryo can reach in vitro culture at present, and it is one of the important indexes to measure the level of embryo culture room. The center has been developing blastocyst culture technology since 2009 and has established a complete blastocyst culture system.

What is the pregnancy rate and risk of failure in blastocyst culture?

The success of blastocyst culture is closely related to the scoring of the embryo on the 3rd day. The center began to develop blastocyst culture technology in 2009, and had a complete blastocyst culture system and rich clinical experience.

For "whole embryo blastocyst" patients without blastocyst formation, it is generally believed to be related to factors such as embryo genetic abnormalities,if the mechanism of this occurrence is still unclear,. Even if these embryos undergo cleavage stage embryo transfer or freeze-thaw retransplantation on 3rd day, it is likely that pregnancy will not be obtained. If this happens, a new ovulation promotion is needed.

For patients who do not qualify for "full embryo blastocysts", there are two main reasons for the low blastocyst formation rate: 1) the quality of the embryos used for blastocysts is poor or less; 2) the quality of the embryos itself is problematic, and have low ability to develop.

When is it appropriate to cultivate a blastocyst?

All embryos need to be developed into blastocysts before they can be implanted into the uterus. In theory, blastocyst culture can be performed in all cases. However, we will carry out a comprehensive assessment based on statistical data and the patient's embryo status, and then provide patients with the best embryo treatment program. Therefore, it is recommended that embryos be handled in accordance with our recommendations. If there are special circumstances, you can also inform us in advance and discuss together to decide whether to perform blastocyst culture.

The quality of cleavage embryos is poor. Will the blastocysts formed be bad? The formation rate of blastocysts is closely related to the score rating on the 3rd day. The lower the score, the lower the blastocyst formation rate is. For the poor quality D3 cleavage stage embryos, once the blastocysts are formed, the pregnancy rate after transplantation and the health status of the infants after delivery are basically the same as those of blastocysts derived from D3 superior embryos. That is to say, there is a difference in the rate of blastocyst formation between superior embryos and non-optimal embryos, and there is no significant difference in the health level of the offspring.