Is the success rate of transplanting frozen blastocysts high?

Generally speaking, there are three types of embryo transfers for in vitro fertilization: fresh embryo transfer, blastocyst transfer or frozen embryo transfer. Among these three types of transfers, blastocyst transfer generally has the highest success rate. However, no matter which type of embryo transfer, you need to stay in bed after the transfer. Try not to do strenuous exercise, pay more attention to rest, maintain a good attitude, eat more fresh vegetables, and keep your bowel movements smooth.

1. What is blastocyst transfer?

Blastocyst refers to an embryo that has been cultured for 5 days with more than 100 cells. The blastocyst transfer technology imitates natural pregnancy and transplants the blastocyst into the mother's uterus. Under natural conditions, the human embryo is implanted into the mother in the form of a blastocyst, which can achieve a higher embryo implantation rate. Blastocyst technology can more intuitively and reliably identify the quality of embryos, and this process can eliminate poor quality or even defective embryos.

Ordinary embryo transfer involves selecting embryos that have been cultured for 3 days for transplantation, at which time the embryo has developed to 8 cells. Compared with blastocysts cultured for 5 days, ordinary embryos cannot be visually identified as good or bad, and inferior embryos cannot be removed through artificial intervention, thus failing to achieve the goal of eugenics.

What are the advantages of blastocyst transfer?

1. Blastocyst is more in line with the physiological state of the uterus

Ordinary embryo transplantation will cause it to face different concentrations of carbohydrates and amino acids in the uterus than normal. The embryo must adjust itself to adapt to the environment, which will inevitably reduce the vitality of the embryo. Current studies have shown that the pregnancy rate obtained by transplanting ordinary embryos into the uterus is not as high as that of blastocysts.

2. It is beneficial to the assessment of embryo development potential and the selection of transplanted embryos

Crucial to early embryonic development is the transition from maternal gene transcription to embryonic gene transcription. Only when the blastocyst stage is reached can it be confirmed which embryos have restricted development or no developmental potential. Therefore, after 5 to 6 days of blastocyst culture, embryos with strong implantation ability and the best quality can be selected more accurately, and the embryos after blastocyst culture can better adapt to the uterine environment.

3. Improve the implantation rate of IVF

In a typical non-blastocyst transfer IVF cycle, the transfer usually takes place on day 3 or 4. Since it is not certain which embryo has better potential, multiple embryos need to be transferred to increase the live birth rate, and the incidence of multiple pregnancies is high. The acquisition of blastocysts gives clinical physicians more certain choices when performing transplantation. Since blastocysts have stronger adaptability and vitality and are easier to implant, the number of transplanted embryos can be reduced. Usually only 1 to 2 embryos are transplanted, which can reduce the incidence of multiple pregnancies. And as the embryo evaluation standards continue to improve, the embryo implantation rate will continue to increase, eventually making single embryo transplantation possible.

3. The process of blastocyst culture for IVF

After induction of ovulation for in vitro fertilization, the ovum is broken with an injection when the follicle is of the right size. The eggs are retrieved 34-36 hours later and fertilized with sperm a few hours later (or intracytoplasmic sperm injection is performed). This day is generally designated as day 0.

Day 1: After overnight, observe the eggs in the morning to see if they are fertilized (whether they have two pronuclei).

Day 2: Observe whether the fertilized egg has divided, how many cells it has (4 cells are best), whether it has fragments (no fragments are better), and whether it is symmetrical (symmetrical is better).

Day 3: Same as Day 2, check the number of cells (8-10 cells are best), check for fragments and check for symmetry. Most centers choose 2 embryos (for women younger than 35 years old) or 3 embryos (for women older than 35 years old or thawed embryos) for transplantation on day 3.

Day 4: Embryo develops to the morula stage.

Day 5: Embryo develops to the blastocyst stage.