EMBRYO FREEZING AND FROSTING

Embryo Freezing and Thawing

Freezing embryos provides many conveniences to couples applying for IVF treatment. After embryo transfer, the remaining embryos are followed by embryologists and, if suitable for freezing, they are frozen with the written consent of the couple and stored in liquid nitrogen at -196°C. When frozen embryos are to be thawed, they are removed from liquid nitrogen, thawed at room temperature, separated from the protective liquid and placed in a special culture medium and placed in the incubator (devices in which the embryos are kept). Embryos that look good on the same day are transferred to the expectant mother.

It may not be possible for all frozen embryos to have the same viability when thawed. However, this rate is about 95% in a good freeze-thaw program. In other words, approximately 10 out of 9 frozen embryos are transferable when thawed. In addition, the viability of embryos can vary from person to person, although it is rare.

Embryos that have been frozen; Frozen embryos belonging to the couple are thawed and transferred if pregnancy is not achieved after in vitro fertilization treatment, if pregnancy is achieved and ends with miscarriage, or when the couple wants a second baby after a pregnancy that ends with birth. Thus, the administration of long-term hormone drugs to the woman is prevented, and since all the necessary stages in the IVF process will be skipped, it also provides a very affordable convenience in terms of cost.

In our center, embryo freezing and thawing is applied in large numbers and successfully. In fact, fresh transfer is not preferred in most patients due to the developing freezing methods and the high viability rate associated with it.

If there is any problem related to the woman during the period when the embryos will be transferred (for example, overstimulation of the ovaries during hormone therapy), then all embryos are frozen, taking into account the risks that endanger the patient's life (OHSS) and the reduced chance of pregnancy due to high hormone secretion. All embryos are frozen and can be thawed and transferred at a safer time. Again, if the uterine lining (endometrium) is not of suitable thickness for pregnancy, the embryos are frozen and stored, then we prefer to transfer them in another period when the inside of the uterus is better prepared.

In the center, vitrification technique is used in the freezing embryo freezing process. Using this method, we achieve very successful results in freezing and thawing embryos. Although they can technically be stored for much longer periods, the freezing period of embryos in our country has been determined as 5 years in accordance with the regulation prepared by the Ministry of Health, the Supreme Board of Assisted Reproductive Techniques. The desire to keep it for a longer period is evaluated by the Ministry of Health.

How are thawed embryos transferred?

First of all, the patient's intrauterine layer, which we call the endometrium, is prepared with the menstrual period. We do this preparation process with natural cycle (ovulation) or estrogen-containing drugs in some patients. We follow the follicle in the natural cycle and wait for the endometrium to thicken on its own. Transfer is usually scheduled 2-3 days after ovulation. We monitor blood hormone levels (E2, Progesterone) throughout this entire process. After the embryos are transferred, we start supportive treatment with progesterone.

In the prepared cycle, we use tapes or pills containing Estrogen. Again, we follow the uterine thickness with ultrasound as well as the hormonal changes in the blood. On average, if the endometrium and hormonal status are suitable, such as 16-18 days of menstruation, we dissolve the embryos and perform the transfer process.