Pre-implantation Genetic Screening
What is PGS?
Pre-implantation Genetic Testing is the analysing of the genetic composition of the embryo to determine the embryo with normal chromosomal content& transferring it. In this technique embryos are individually checked for a chance of implantation by detecting abnormal chromosomes. This helps to select and transfer of genetically normal embryos.
A New Technology to Reduce Implantation Failures
Pre-implantation Genetic Testing can potentially benefit couples who present with the majority of IVF indications, particularly, advanced maternal age couples and families who have had recurrent pregnancy losses both naturally and through IVF.
A declining live birth rate is an increasing problem for families who choose to have children later in life and is strongly associated with late maternal age embryos showing greater levels of chromosomal abnormalities. Pre-implantation Genetic Testing utilizes the most sophisticated and scientifically validated technology for determining the chromosome compliment in a single cell.
Why does IVF fail and what can the fertility clinic do to increase the chance for success on a second IVF?
IVF is a great treatment option for a ton of couples. It can grant people their wish of becoming parents when they didn’t think it was possible. However, the truth of the matter is that IVF doesn’t always work. At least, for many, not on the first try. There are many couples out there that have to go through more than one cycle of IVF before getting pregnant. It can be very hard to accept when your IVF treatment does not work, and it can be very difficult to understand why.
The five main reasons that make IVF to fail are:
1. Female age
2. Embryo quality
3. Ovarian response
4. Implantation issues
5. Sperm Quality and Sperm DNA
Your likelihood of getting pregnant as you get older decreases over time. Since each woman is born with a certain number of eggs, as you age, you use those eggs up. Your likelihood of a live birth after IVF is greater the younger that you are. Some studies show that the likelihood of a live birth after IVF for a woman age 35 is around 32 percent, but only 16 percent for a woman who is 40. Of course, this is not a guarantee that IVF wonâ€™t work for your particular case.
Embryo Quality can be another contributing factor to IVF failure. Some embryos have genetic or chromosomal abnormalities that can make them too weak to work for IVF. Still other embryos don’t have enough cells to survive and are less likely to fertilize. There are quite a few things that can contribute to embryo quality, which can eventually lead to IVF failure.
Sometimes a woman’s ovaries just do not respond properly to the IVF medications that try to get the ovaries to produce multiple eggs. If you already have a reduced number of eggs, are over 35 or 37, or have elevated FSH levels, it might be harder for your body to respond properly to IVF medications. In short, if your body listens to the medication and produces more eggs, your IVF is likely to be successful. If it doesn’t, then your chances that the IVF will fail are greater.
Implantation issues are probably the most common reason that IVF treatment fails. Most of the time when implantation issues occur, it is simply because the embryo stops growing and through no fault of anyone. If there are polyps in uterus or cysts on the ovaries, this can also be a contributing factor to implantation issues. Some research even suggests that chromosomal abnormalities that can cause implantation issues in embryos can be present in as many as 50% of cases!
There is an equation that we can use to illustrate the implantation process:
Embryo quality + receptivity of uterine lining = chance for implantation and pregnancy
Sperm quality and DNA
Increasing sperm DNA fragmentation or damage is associated with:
1. Poorer fertilization
2. Poorer embryo quality
3. Poorer pregnancy rates
4. Increased risk of miscarriage
These are the five most common reasons that IVF treatment fails. Just because you experience a failed IVF attempt doesn’t meant that you should give up trying to get pregnant. That is not the case at all. talk candidly with your doctor about what he or she thinks might have went wrong and if there is anything that you or your partner can do to help things go smoothly the next time around. The most important thing is to stay positive and don’t give up!
Why does an embryo deteriorate or weaken and not implant?
Chromosomal abnormalities in human embryos are the major cause of IVF failure. As women age, the incidence of chromosomal abnormalities in mature eggs increases significantly. Studies have shown that starting in the early 30s, the rate of chromosomal abnormalities in human eggs (and therefore in human embryos) starts to increase significantly.
The rate continues to increase with advancing female age so that by the mid-40s a very high percentage of human embryos are chromosomally abnormal (over 75%). It is believed that this is mainly due to problems with the spindle apparatus in the egg nucleus. The spindle is involved with properly lining up and segregating the chromosomes as the egg matures at the time of ovulation.
Older eggs have an inefficient spindle apparatus that does not line up the chromosome pairs properly and “mistakes” are made when splitting pairs of chromosomes. This leads to eggs that do not have the proper balance of 23 chromosomes – and will result in a chromosomally abnormal embryo if fertilized. It has been shown that about 30% to 40% of human sperm are chromosomally abnormal on the average – as compared to about 20% to 90% of human eggs (depending on female age).
Pre-implantation genetic screening requires the woman to go through a regular IVF/ICSI cycle. The embryos created in the laboratory are then biopsied using highly specialized lasers and a single cell of an embryo is taken out for testing.
These cells are subjected to identify chromosomally normal embryos.
These cells are subjected to identify chromosomally normal embryos.
Step 1. You undergo normal in vitro fertilisation (IVF) treatment to collect and fertilise your eggs.
Step 2. The embryo is grown in the laboratory for two to three days until the cells have divided and the embryo consists of around eight cells.
Step 3. A trained embryologist removes one or two of the cells (blastomeres) from the embryo.
Step 4. The cells are tested to see if the embryo from which they were removed contains the gene that causes the genetic condition in the family.
Step 5. The embryo unaffected by the condition is transferred to the womb to allow it to develop.
Step 6. Any suitable remaining unaffected embryos can be frozen for later use. Those embryos that are affected by the condition are allowed to perish or, with your consent, used for research.
The biopsy does not harm the growth of the baby or cause any abnormality in the baby, if proper equipment and trained personnel perform the same.