Preimplantation genetic testing for aneuploidy (PGT-A, PGS) detects chromosome copy number abnormalities of embryos and is an effective method for selecting the best embryos. It helps to achieve better pregnancy results by selecting embryos with normal chromosomes for transfer. The method is particularly beneficial for women over 35 years old and patients with recurrent miscarriages or several unsuccessful fertility treatments. In general, transferring embryos with normal chromosomes produces better treatment results regardless of the woman’s age.
Out of a young woman’s normal looking embryos, 40–50% may have an abnormal number of chromosomes in a cell, i.e. be aneuploid, while for women over 40 this figure may be as high as 75–90%. The majority of chromosomal abnormalities lead to arrested development of the embryo or an early miscarriage. However, variation between patients is high, and unsuccessful treatments are not necessarily a result of chromosomal problems.
Source: US CDC/SART (left), Harton et al. (2013) Fertility and Sterility 106:1695-703 (right)
How is preimplantation genetic screening and testing done?
PGT-A treatment involves taking a biopsy of 5–8 cells from five to six days old embryos, which are then frozen using the vitrification method. Embryos with normal chromosome result can be thawed and transferred into the uterus. PGT-A helps us to avoid unnecessary embryo transfers and allows at best up to 70% pregnancy rates.
In PGT-A treatments, embryos are cultured in the EmbryoScope®, an incubator with a monitoring device facilitating improved embryo selection. Ask us for more details about Ovumia’s PGT-A embryo selection.
