Preimplantation genetic diagnosis is a highly specialised technique designed to identify chromosomal aberrations (deviations, changes) or monogenic hereditary diseases before an embryo is transferred to the uterus.

During studies of the chromosomal structure of embryos it was determined that an incidence of aneuploidies (deviations in the number of chromosomes) is one of the most common causes of infertility. Examining the chromosomes of an embryo can therefore increase the likelihood of a successful artificial insemination. The objective of preimplantation genetic diagnosis is to select for transfer only those embryos for which no abnormalities have been detected within the scope of PGD.

Indications for preimplantation genetic diagnosis are particularly the following:

  • high risk of chromosomal aberration or severe monogenic hereditary disease in children,
  • genetic defects linked to the child's gender,
  • repeated miscarriages,
  • premature birth or miscarriage with chromosomal disorder in the medical history,
  • numerous unsuccessful IVF cycles.

Preimplantation genetic diagnosis is conducted in the early stage of embryo development. A single independent cell (blastomere) is retrieved from the embryo via the mechanical opening of the zona pellucida, which is then examined with the help of the methods indicated below. A biopsy of the embryo – the retrieval of a single independent cell – is most often conducted 3 days after fertilisation, when the embryo has 6-8 cells. Only those embryos which are healthy from the perspective of the preimplantation genetic diagnosis are subsequently selected for transfer to the uterus.