Preimplantation genetic diagnosis is a technique used to confirm the presence of genetic defects in embryos that are created through in vitro fertilization prior to their implantation in the mother's womb. This is generally done when one or both parents have a genetic abnormality. The embryo is tested to identify the presence of the genetic abnormality. If the embryo is normal, it's implanted in the womb, but if it carries the abnormality it is discarded.
Cleavage Stage Embryo Biopsy
Preimplantation genetic diagnosis is done by performing a cleavage stage embryo biopsy. Embryo biopsy is also known as blastomere biopsy. On the third day, the embryo is at the cleavage stage. It is tested on this day because it has cleaved from a one-cell entity to an eight-cell entity. The outer covering of the embryo or oocyte, also known as the zona pellucida, is punctured with the help of a pipette to remove a cell by aspiration using a micro needle. At this stage, all the eight cells of the embryo have the same potential for development, and the removal of a cell does not harm the developing embryo in any manner.
The cell that has been removed is tested for genetic abnormality. Most laboratories that perform preimplantation genetic diagnosis use cleavage stage biopsies in preference to polar body biopsies and blastocyst biopsies to obtain genetic material for analysis.
Cleavage stage embryo biopsy performed in preimplantation genetic diagnosis procedures can result in the birth of children who are free from any genetic disorders.