What is the Process of Thawing and Transferring a Frozen Embryo for IVF?

The IVF embryo thawing and transfer process consists of endometrial preparation, embryo thawing, embryo transfer, progesterone injection, and pregnancy confirmation. Here are the steps:

1. Endometrial Preparation

Endometrial preparation, along with embryo development and endometrial synchronization, is a crucial factor in determining the success of pregnancy after embryo transfer. There are mainly two methods for endometrial preparation: the natural cycle method and hormone replacement therapy.

(1) Natural Cycle Method: For women with regular menstrual cycles and normal ovulation, transfer should be performed during the ovulation period. Prior to transfer, ultrasound monitoring and a series of blood tests, including endocrine tests, should be conducted.

(2) Hormone Replacement Therapy: For women with irregular menstrual cycles or ovulation disorders, medications are used to promote endometrial growth. Once the endometrial morphology reaches a certain requirement, embryos can be thawed and transferred.

2. Embryo Thawing

The frozen embryos are thawed. If any embryos are damaged during the thawing process, they are discarded. When selecting embryos for transfer, the integrity of the frozen-thawed embryo blastomeres and their ability to further divide are considered. Embryos with intact blastomeres and continued division are preferred.

3. Embryo Transfer

On the day of transfer, three embryos are thawed. If fewer than three viable embryos are available, additional embryos are thawed until there are three viable embryos for transfer.

4. Progesterone Injection

Although frozen embryo transfer can be performed at an appropriate time, since the embryo is not fertilized within the female body, the female's body may not be fully synchronized with the embryo, and may not produce sufficient progesterone for embryo implantation and development. Therefore, progesterone supplementation is necessary.

5. Pregnancy Confirmation

Typically, two weeks after the transfer, if menstruation does not occur, a pregnancy test can be performed at the hospital. If pregnancy is confirmed, progesterone supplementation should continue, and an ultrasound examination should be performed two weeks later.

The timing of frozen embryo transfer depends on the female's menstrual cycle. For women with regular menstrual cycles, transfer should be performed within a few days after ovulation. For women with irregular menstrual cycles, medication may be used to induce ovulation before transfer.

Only a few days after ovulation does the endometrium have the ability to accept and implant the embryo. Prior to embryo thawing, an ultrasound examination and blood endocrine tests should be performed. Once ovulation symptoms appear and endometrial development is adequate, the embryo can be thawed and transferred.

For women with irregular menstrual cycles or ovulation disorders, medications are used to fully promote endometrial growth and simulate the hormonal state during early pregnancy. Patients should start taking estrogen to promote endometrial development from the early menstrual phase. Once the endometrial morphology reaches a certain requirement, progesterone is added, and then the embryo can be thawed and transferred.

If this method is used, since the patient does not ovulate and there is no corpus luteum formation, exogenous hormone support must be continued until the placenta forms and starts to secrete hormones. Gradual tapering and discontinuation of medication usually begin around 45 days after transfer.