In previous articles (I and II) we took a look at the clinical background and recent findings in the PGS field. Now it’s time to examine closely concerns and limits related to the procedure. Because, like every other procedure, it does have its risks which, before attempting to setting out on the path hopefully leading to desired pregnancy, should be considered.
Decreased ovarian reserve
Among recurrent pregnancy loss patients with a decreased ovarian reserve (low number of quality viable eggs or oocytes, or with low reproductive potential), the Stanford study demonstrated that those patients would not be likely to benefit from PGS treatment as their ovarian reserve has diminished and may not even be capable of fertilization.
Identifying this ahead of time, and before choosing a procedure like in vitro fertilization, can save a couple not only the heartache of a failed IVF attempt but also the expense. With use of ovarian reserve testing, a couple can make an educated decision about whether or not to go through with the procedure and even whether or not to seek donor eggs for the procedure to increase the odds of pregnancy, and ultimately a healthy birth.
Cause for concern with PGS?
Identifying viable embryos before transfer may be a wise choice for some. More than 50 % of embryos for women over 35 show signs of being abnormal. And only chromosomally normal embryos can become healthy babies. For those with recurrent pregnancy loss, those of advanced maternal age and those with concern about the possibility of passing something on to the next generation the end may justify the means.
As an invasive procedure, PGS does not come without some risks to the embryo as one or more cells must be carefully removed by an embryologist from each embryo to determine any abnormalities. Keep in mind, there is a small chance of compromising the embryo causing it to stop its growth cycle and render itself unusable.
Limiting invasiveness of PGS/PGD on embryos
The efficacy and safety of performing biopsies on cells that are just beginning to take shape is not one to take lightly. Discuss options with your doctor and be aware of the risks involved before taking the leap.
Day 3 blastomere: More invasive to the embryo is a day 3 blastomere biopsy during what is called the cleavage stage of development where 1 or 2 cells are removed from the 8-cell embryo. Afterwards the embryo is put back in culture, with hopes it will continue to develop into a blastocyst days later. With a rather large hole in its shell from the biopsy, it is not always an optimal situation for continued normal growth and development, especially since it has lost about an eighth to quarter of its total mass.
Day 5 trophoectoderm: Less invasive is a day 5 trophoectoderm biopsy during what is called the blastocyst stage of embryonic development. This procedure extracts 4-5 cells from the outer layer of the embryo and does not affect the inner cell mass from which the fetus develops.
How much is PGS/PGD?
From a monetary standpoint, another factor to consider when choosing whether or not to implement using genetic testing procedures like PGS/PGD is the fact that most of the time insurance does not cover it. Procedures like PGS/PGD can add upwards of $ 3 000 – $ 6 000 dollars to the cost of each IVF attempt, and this additional cost may be too prohibitive for some.
Clinical outcome info may prove helpful for some
Among cycles in which PGS was planned and completed, compared with cycles in which PGS was planned and then canceled, the live birth rate was increased and the clinical miscarriage rate was reduced, suggesting that clinical outcomes may actually be improved if patients do complete the planned PGS cycle as intended. For some patients with unexplained recurrent pregnancy loss, pre-implantation genetic screening may provide worthwhile answers and help lower the risk of miscarriage and lead to a healthy baby. It is, however, necessary not to consider it a universally suitable and 100 % effective solution in all cases. Patients should always think about all aspects of the treatment and consult thoroughly with a specialist before making any decisions.