Answer:

Preimplantation genetic testing (PGT) is a technique that involves taking cells from an embryo to screen for chromosomal or genetic abnormalities before transfer to the uterus. This technique helps increase the chance of selecting embryos with good implantation potential, reducing the risk of failed embryo transfer, miscarriage, or a pregnancy with genetic abnormalities.

For biopsy, embryos must develop to the blastocyst stage, typically on day 5 or day 6 after fertilization. At this stage, the embryo has differentiated into hai parts: the inner cell mass (ICM), which develops into the fetus, and the trophectoderm (TE) layer, which develops into the placenta.

Embryologists perform embryo biopsy to screen for chromosomal abnormalities. *Illustration: IVF Tam Anh*

In your situation, the fact that mot blastocyst is eligible for biopsy while the other, despite also being a day 5 embryo, is not, typically relates to the quality and developmental stage of each embryo. Even day 5 blastocysts can vary in their expansion, as well as the quantity and quality of their trophectoderm layer. Some embryos expand well, have a clear trophectoderm, and enough cells for safe sampling. Others develop slowly, have collapsed blastocysts, or too few trophectoderm cells, making them ineligible for biopsy.

Biopsying an embryo that does not meet standards can reduce its viability after thawing or impact its implantation potential. An inadequate biopsy sample can also decrease the accuracy of genetic testing, thereby affecting embryo transfer decisions, lowering IVF success rates, or increasing the risk of miscarriage.

At IVF Tam Anh, women who are older, have experienced multiple failed embryo transfers, recurrent miscarriages, or carry abnormal genes are often advised by doctors to undergo PGT to select embryos with normal chromosomes. Specialists use a specialized needle to extract around 8-10 cells from the trophectoderm layer for genetic analysis, while preserving the inner cell mass. The entire procedure takes place in an ultra-clean, standard laboratory system, ensuring accuracy and minimizing impact on the embryo.

The Time-lapse embryo culture system, equipped with continuous monitoring cameras and integrated artificial intelligence (AI), allows observation of embryo development, supporting the selection of potential embryos for preimplantation screening and improving successful embryo transfer rates.

Master Le Thi Thu Thao

Deputy Lab Head, Center for Reproductive Assistance

Tam Anh General Hospital Ho Chi Minh City