Polar body diagnostics allows for the genetic examination of an oocyte for chromosomal defects in the framework of an IVF treatment. The method aims at achieving a higher rate of implantation as well as lowering the risk of miscarriage.
The success rate of an IVF treatment is highly dependent on the genetic health of the oocyte and sperm cells. While genetic defects in sperm cells are relatively seldom there is a higher risk of such defects in oocytes, especially for older patients. 50% of oocytes in 35 year old patients show chromosomal maldistributions whereas in 40 year old patients the number increases to 70%. This is an important indicator as to why older patients have a lower pregnancy rate and are subject to a higher risk of miscarriage. Preimplantation diagnostics is conducted in many countries, however, in Austria it is forbidden. Another possible method is the analysis of the polar bodies. These develop during the first and second meiosis and are not necessary for the further development of the embryo. They offer an indirect, genetic mirror of the oocytes. This diagnostic is not a recent innovation in Austria. In the last years it has been possible to remove and analyze polar bodies using the „FISH“-technique.
The Kinderwunschzentrum Goldenes Kreuz has decided to analyze the polar bodies exclusively using state-of-the-art methods. The newest method (“Array-CGH”) does not just analyze each chromosome but also the complete genetic material of the polar bodies. The oocytes remain untouched during this procedure. Through the combination of polar body analysis with CGH and subsequent blastocyst culture we can choose embryos with a high success rate for implantation.
We recommend polar body biopsy only to patients who will profit from this method in the subsequent treatment:
- Reduced ovarian reserve (increased FSH parameter): An increased basal FSH parameter is regardless of age considered to be connected to a higher chromosome maldistribution and thus represents an indication for polar body diagnostics.
- Increased ovarian reserve: When due to hormonal stimulation an increased amount of oocytes form, these have a statistically higher risk of chromosome maldistribution than oocytes in reference groups with inconspicuous responses to the hormonal stimulation.
- Several unsuccessful IVF attempts with unexplainable missing implantation of the embryo. The reason can be a higher rate of oocytes with chromosome maldistribution leading to a lack of implantation.
- Advanced age (>37 years) with the related risk of a chromosomal maldistribution in the child.
- Known genetic disorder (balanced translocation) in the woman.
- Recurring abortions in the past.
- A pregnancy with chromosomal defects in the past.
One disadvantage of this method is the fact that only the genetic health of the oocyte can be tested. Chromosomal maldistributions which arise during the further embryonic development or result from the sperm cell cannot be found with this method.