Pre Implantation genetic testing is a well-known method that is comprised of several generic assays that are used to monitor embryos before transferring them to the uterus. It’s a kind of test that’s performed during an IVF cycle. The primary aim behind the conduction of the test is to monitor and select the embryos that have the maximum chances of getting an implant and get develop into a baby by evaluating the chromosome makeup of embryos that are fertilized with the help of in-vitro fertilization before transferring them to the mother’s womb. The testing method however doesn’t increase the cumulative pregnancy rates.
Detailed PGS working
1) Stimulating egg development
The hormones are taken into account for stimulation of a good fellow of eggs to mature. The number of eggs usually varies between 10-15 but can differ for different individuals. The women that have a poorer ovarian reserve comparatively require a higher dose of stimulation drugs than the women with a good reserve. There are many cases of certain women not having the required number of eggs even after the usage of high doses of stimulation.
2) Fertilisation and Developing the embryos
The eggs that are retrieved are then fertilized in the embryology lab. There are two procedures for doing the same.
1) Standard IVF procedure– The eggs are allowed to incubate with the sperm overnight.
2) ICSI (Intracytoplasmic injection)– Under the method, a single sperm cell is directly injected into an egg. The technique is generally considered when the sperm quality is poor.
Day 1(after egg collection)- The eggs are monitored and checked for signs of normal fertilization. Generally, the fertilized eggs consist of 2 small round structures within them called pronuclei. Each one of them represents female and male genetic material respectively.
Day 2- The eggs that are successfully fertilized will divide into 2-4 cells.
Day 3- The eggs are divided into 6-8 cells.
Day 4- The embryo comprises 16-32 cells that are tightly stomped with each other to form a structure known as the morula.
Day 5-6- The embryos are then developed into a blastocyst form. It’s attributed as a structured embryo that comprises a shell of cells (trophectoderm) that will form the placenta and membranes, the central space filled with a fluid known as a cyst, and the inner cell mass. The inner cell mass eventually turns into the embryo.
3. IVF vs PGS
In a standard IVF or ICSI treatment cycle, the embryos can be transferred back to the womb around any point after verifying that fertilization is normal(after seeing two pronuclei on day 1), most of it occurs between day 2 and day 5 after the egg collection is done.
The utmost thing is to confirm the normal development and to race the embryos, the ones that show the best development at particular milestones have higher chances to get an implant and result in a baby. If one day 2 or day 3, the winners of the race are obvious or the patient is left with only two good quality embryos, the embryos can be transferred back to the womb