Embryo Diagnostics (PGT, Preimplantation Genetic Testing)

Embryo diagnostics is a genetic examination in which embryos produced through fertility treatments are examined for genetic diseases or chromosomal abnormalities.

There are three main types of embryo diagnostics, which differ in terms of genetic analysis:

PGT-A (Preimplantation Genetic Testing for Aneuploidies), embryo chromosomal testing

The purpose of the examination is to identify embryos obtained during fertility treatment that do not exhibit chromosomal numerical abnormalities or major structural deviations based on genetic analysis. Better pregnancy outcomes are achieved when chromosomally tested embryos are selected for transfer. This reduces miscarriages and avoids unnecessary treatments by identifying chromosomally abnormal embryos before embryo transfer.

In patients over 40 years old using their own gametes in treatments at our clinic, the rate of clinical pregnancies per embryo transfer is 46.2% when using chromosomally tested embryos. Without embryo chromosomal testing, the rate of clinical pregnancies in the same patient group is 26.1% per embryo transfer.

*Source: Dextra Fertility Clinic, 2018–2023.

PGT-M (Preimplantation Genetic Testing for Monogenic Diseases), examination of an embryo’s single gene defect

The examination identifies a known single gene defect in the embryo. Patients benefiting from this examination are those at risk of severe inherited disease or disorder due to a known single gene defect. By transferring embryos determined to be free of the tested disease, the risk of the disease being inherited by the child is minimized. When PGT-M testing is combined with embryo chromosomal testing, embryos are also examined for chromosomal abnormalities.

PGT-SR (Preimplantation Genetic Testing for Structural Rearrangements), examination of an embryo’s inherited chromosomal structural abnormality

The examination identifies a known inherited chromosomal structural abnormality, such as translocation. Chromosomal structural abnormalities often do not cause symptoms in carriers, unlike when inherited by a child. PGT-SR testing helps prevent miscarriages caused by chromosomal structural abnormalities, thereby improving the chances of having a healthy child.

Implementation of Embryo Diagnostics

For embryo diagnostics, a cell sample is taken from the blastocyst-stage embryo on the 5th to 7th day after egg retrieval. Blastocyst-stage embryos are immediately frozen after the sample collection and stored at our clinic awaiting the results of embryo diagnostics and frozen embryo transfer.

We have been performing embryo diagnostics at our clinic from the very beginning. We have extensive experience in embryo biopsy and have biopsied thousands of blastocysts. Our clinic performs approximately 70%* of embryo chromosomal testing (PGT-A) carried out in Finland.

*Source: THL Fertility Treatment Statistics