Answers to basic medical questions
How are embryos and eggs frozen? How long are they stored? What are they tested for? How are pathologies detected?
This technique is called vitrification. The ability to give birth to a healthy baby at virtually any age has become real thanks to the technology of ultrafast freezing of germ cells and embryos at extremely low temperatures (-196°C or -320.8°F). This method differs from classical freezing in that the liquid inside the cells does not turn into crystals, thus preventing harm to the structure but immediately going into a 'sleeping state', which ensures the safety of the eggs when being unfrozen any number of years later. Therefore, this technique is the most gentle and effective.
If the eggs mature very well on their own, is hormone stimulation necessary for their retrieval? What if it is not possible? How painful is the egg retrieval?
Today, the most effective strategy in the IVF program is 'one and done, which means that our task when performing one stimulation of follicular growth is to obtain a sufficient number of eggs and, accordingly, healthy embryos for the freezing procedure. Often such a program enables a woman to plan a pregnancy after the birth of her first child by transferring the next embryo without stimulation, moreover, such embryos were obtained at a younger age. This ensures maximum effectiveness, prevents unnecessary visits of the couple to the clinic and frequent testing. This is also important psychologically for a couple and, especially, for a woman as it saves her valuable reproductive time. Since only one follicle matures in the natural cycle (rarely two), it might contain no egg, the oocyte might be immature or not fertilized, ovulation might occur spontaneously before the puncture begins. At the same time, a woman needs frequent ultrasound monitoring of follicle growth, which creates additional intense emotional stress ("What if the follicle already ovulated?" "Will one egg lead to the embryo development?"). For that reason a procedure in the natural cycle is recognized as low-performance and has very limited application.

Follicular puncture
Transvaginal puncture (aspiration) of follicles is carried out with the aim of collecting follicular fluid with oocytes under intravenous anesthesia and lasts 20-30 minutes. After it, the patient is under observation for 1-2 hours.

During puncture in the framework of IVF, the follicular fluid is immediately transferred to the embryological laboratory. The embryologist separates the oocytes, washes them from the follicular fluid, and preliminary evaluates their degree of maturity. After that, all oocytes are placed into a special nutrient medium and transferred to an incubator until fertilization takes place 4 hours after the eggs are retrieved.

How is hormonal stimulation done, how does it feel emotionally and physically?
Stimulation of follicle growth
IVF program begins with a course of drug stimulation of ovulation (superovulation) since successful fertilization requires a number of mature eggs (oocytes) at once within one menstrual cycle, optimally 10-20. The attending doctor prescribes stimulation considering all the individual characteristics of the woman's health and her test results. For this purpose, drugs (gonadotropins) are used in certain doses, usually for 11-12 days, with a mandatory monitoring of follicle growth using ultrasound and (if necessary) hormonal tests. Follicle growth is monitored once every 4-5 days, and when the leading follicles reach 14 mm in diameter, another drug (antGnRH) is prescribed to prevent premature ovulation and subsequent uniform growth.

Finally, when the follicles reach 19-20 mm in diameter, the doctor prescribes an ovulation trigger, which starts the process of final egg maturation and makes it possible to retrieve them during a puncture, which is carried out exactly after 35-36 hours from the moment of injection.

During stimulation, the woman continues her usual lifestyle. Healthy diet is important, as well as exclusion of alcohol and bad habits and restriction of physical activity before retrieving oocytes. Emotionally it is important to be determined and aiming at a good result. Proper stimulation does not cause any painful sensations.
What pathologies can be detected in the embryo?
Preimplantation genetic testing (PGT) identifies and safeguards against occurrence of chromosomal and genetic diseases before the stage of embryo transfer into the uterine cavity.

Today, there are several methods of preimplantation genetic testing:
The most modern and most accurate method of Preimplantation Genetic Testing for aneuploidv (PGT-A) of embryos is the Next Generation Sequencing (NGS). The main task of PGT-A is to assess the state of the embryo in the early stages of development (detection of quantitative chromosome abnormalities, i.e. aneuploidy), selection of a healthy embryo for the embryo transfer.

Preimplantation Genetic Testing for monogenic diseases is a method for determining hereditary diseases, where a DNA sequence of one gene has mutations or irregularities.

Preimplantation Genetic Testing for structural disease is done to detect abnormalities, where the structure of one or more chromosomes is broken. Such abnormalities occur when the chromosome segments are incorrectly connected or broken. There are several types of structural changes: translocation (transfer of a chromosome segment to a nonhomologous chromosome), deletions (loss of a chromosome segment), duplications (doubling of a chromosome segment), inversion (180 degree rotation of a chromosome segment).

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Olesya Solomina
Email: olesyasolomina@gmail.com
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