Preimplantation Genetic Diagnosis

Preimplantation Genetic Diagnosis (PGD) is a genetic examination of embryos before their transfer into a cavity of the uterus, enabling us to find the right embryos (those without chromosomal abnormalities), and thus increasing the chance of pregnancy and delivery of a healthy baby.

The process of the in vitro fertilization (IVF) enables us to examine embryos in test tubes even before they are transferred into the uterus. The examination is usually done in a very early stage of the embryo’s development by collection of 1 to 2 cells, called blastomeres, from a Day 3 embryo. The preimplantation diagnosis allows us to identify embryos without abnormalities of examined chromosomes, which increases the prospects of having a healthy child. Examination of blastomeres of a Day 3 old embryo allows us to diagnose disorders of maternal and paternal origin as well as any changes that have developed after fertilization of the egg.

PGD is highly recommended for the following groups of patients:

• patients over the age of 35
• patients with recurrent miscarriages
• patients with repeatedly failed IVF cycles
• men with a severe fertility disorder (TESE/MESA)

The essential prerequisite for pre-implantation genetic diagnosis is participation of the couple in the IVF program. Your doctor will collect 1 to 2 embryonal cells on Day 3 of the cycle - at this stage all the cells have the same development potential and their collection will not damage further development and growth of the embryo. After the cells are fixed on a cover-slide, the number of copies of examined chromosomes is diagnosed using a FISH method. With this method the chromosomal DNA and DNA of a probe are joined – hybridized under specific thermal and chemical conditions. The probe is marked with fluorescent dye distinct for each examined chromosome, which enables us to make the examined chromosome visible. This mount is evaluated under a fluorescent microscope, and every examined blastomere is documented with custom software. The final report is submitted to the gynecologist, embryologist and patient. According to the outcome of the genetic examination only the embryos with a normal number, i.e. 2 copies of examined chromosomes, are transferred to the patient. Spare embryos suitable for transfer after the PGD are frozen.