Definition - What does Trophectoderm Biopsy mean?
A trophectoderm biopsy is a test that is performed to examine the chromosomes of a developing blastocyst. It involves removing some cells from the trophectoderm layer of the expanded blastocyst to test for genetic abnormalities. Embryos identified as having a genetic defect will not be transferred into a woman's uterus for implantation.
FertilitySmarts explains Trophectoderm Biopsy
Around 5 days after fertilization, the pre-embryo is called a blastocyst and its outer layer is known as the trophectoderm. This layer is important for providing nutrients to the developing embryo. The cells in the trophectoderm also carry the same DNA as the rest of the embryo. This means that they can provide important information about the genes of the developing embryo.
Some people are known carriers of genetic conditions or diseases. These people may want to have the DNA of their embryo tested to see if it has inherited these conditions. If genetic testing is indicated, preimplantation genetic screening (PGS) can be used to screen for general chromosomal abnormalities or preimplantation genetic diagnosis (PGD) can be performed to test for a specific genetic disorder. At the blastocyst stage, this test is called a trophectoderm biopsy.
During a trophectoderm biopsy, micro tools are used to hold the embryo while a laser removes 5-10 cells of the trophectoderm. Removing a few cells for a trophectoderm biopsy has no impact on the further development of the embryo. The chromosomes of these cells are then examined to look for genetic abnormalities. Embryos free of abnormalities would be used for transfer, whereas those found to have abnormalities in their chromosomes would not be transferred to the woman's uterus.