Trophoblast biopsy is the newest technique for obtaining cells from a developing embryo for genetic testing. As an embryo is developing, it continues to divide. In healthy embryos, by the 5th day of development, the embryos is divided into approximately 100 cells and forms a fluid filled sphere. The embryo at this stage is known as a blastocyst. A blastocyst is composed of two cell types. The inner cell mass is a small clump of cells that go on to form the fetus. The majority of cells (which make up the sphere) are called trophoblast cells. The trophoblast cells will eventually go on to form the placenta and other non-fetal tissues. The advantage of trophoblast biopsy is that several cells can be obtained without affecting the development of the embryo. By obtaining several cells, more genetic information is available. This will increase the accuracy of the results.
Trophoblast biopsy may be the safest form of embryos biopsy. A recent study (2011) found that trophoblast biopsy did not affect the ability of the embryo to implant and become a pregnancy.
The pictures below show the process for trophoblast biopsy:
A hole made in the shell surrounding the embryo allows some of the trophoblast cells to squeeze outside.
The cells are aspirated into a large pipette
A laser is used to “cut” the attachment of the cells to the rest of the trophoblast