As PGD can be performed on embryos in different developmental stages, the biopsy procedure varies accordingly. In clinical practice, there are two types of biopsy:
Blastomere biopsy – (on day three at cleavage stage embryos) – 1 or 2 cells are removed from 8-cell embryo for genetic analysis
Trophectoderm biopsy – (on day five at blastocyst stage embryos) – 4 or 5 cells are taken from the outer trophectoderm layer without affecting the inner cell mass from which the fetus later develops.
Biopsy procedure involves two steps: opening of the zona pellucida and removal of the cell(s). There are different approaches to both steps, including mechanical and chemical procedures, but we use the most advanced laser technology for breaching the zona pellucida.
Using laser-assisted zona thinning it is possible to create a point of herniation that is less disturbing for embryo than traditional zona-opening. During biopsy we operate with accurately controlled laser beam to release the cells of the day3 or day 5 embryos. Retrieved embryonic cells are then sent for genetic analysis. The embryos under analysis do not leave the IVF clinic, they are returned to the incubator until the test results are available.