Long-term in vitro cultivation of embryos (LTC-BS - Long Term Cultivation to Blastocyst Stage) is a process whose main goal is to maintain the normal development and viability of embryos as a whole, before they enter the uterine cavity with IVF. This process is rather short in time and takes only 6 days. After this, the embryo should be placed in the uterus for fixation in the endometrium.
What is this kind of procedure?
Long-term embryo cultivation is inherently a high-tech and rather complicated process that requires a special, well-equipped laboratory and expensive equipment. It is in view of this feature that not all centers involved in IVF and pregnancy planning provide such a procedure.
This method involves the cultivation of embryos before the blastocyst stage. Previously used techniques suggested the transplantation of the embryo into the woman's body at the stage of its fragmentation, i.e. in 2-3 days. This fact sharply reduced the success of IVF and the procedure for embryo transfer had to be repeated many times.
The transition to the cultivation of embryos in vitro has made possible a technological breakthrough in the field of embryology, thanks to special developments in the field of reproductive medicine. This method, used in leading reproductive clinics in the world, involves longer contact with the embryo of special environments (SICM / SIBM and Embryo Assist / Blast Assist).
It is also worth noting that this technique could not exist without the use of a special device - a multi-gas incubator. It is in it that several zygotes are placed along with the nutrient medium. After 4-6 days, specialists extract the blastocyst from this device and assess its viability. According to statistical data, approximately from 60-70% of eggs fertilized during IVF, it is possible to get normal embryos.
What are the advantages of prolonged cultivation of embryos?
This method of IVF allows, first of all, to improve the quality of selection (selection) and use only embryos having a sufficiently high so-called implantation potential for transplantation. In simple words, the use of this method greatly increased the probability of pregnancy after IVF.
In addition, among other advantages of long-term embryo cultivation are usually called:
- decrease in the number of chromosomal abnormalities in embryos transplanted in the blastocyst stage;
- this method is more physiological in comparison with embryo transfer up to 3 days;
- at long cultivation it is enough to place 1-2 embryos in a cavity of a uterus, tk. the probability of their consolidation and development is very high;
- the risk of developing such a complication as an ectopic pregnancy is significantly reduced.
What are the disadvantages of this method?
Having understood that this is a long-term cultivation of gametes and embryos, having told about the advantages of this method of IVF, it is necessary not to forget about the shortcomings of this method.
The first of these is the fact that not all cultivated embryos grow to a blastocyst, in most cases only 50% of them reach this stage of development. Given this feature, this method is possible only if by the 3rd day of embryo cultivation, there remain at least 4. At a lower number, the probability of obtaining at least one normal, reaching the stage of blastocyst, is very low.
The second disadvantage can be called the moment that even if the embryo reaches the stage of development necessary for a transplant, this does not give a 100% guarantee that the implantation will be successful and the pregnancy will come.