Embryos that show normal development are biopsied with micromanipulation techniques involving the use of very fine glass needles and tools under microscopic observation and control to obtain sufficient cells (blastomeres) for analysis. Based on animal experiments as well as 10 years of experience with PGD in humans, including over 200 normal births, it is felt that removal of small numbers of cells is unlikely to affect the continued development of a healthy embryo and foetus. The cells removed from each individual embryo are analyzed by genetic testing using either PCR-based DNA amplification, or fluorescent in situ hybridization (FISH). Those embryos considered to be unaffected on the basis of this testing will then be available to be transferred into the woman's uterus or cryopreserved for future use. But in the future this technology could give parents who are willing to select everything from their babies eye and hair colour to its intelligence level.
This technique can be used for positive purposes, such as eliminating diseases. Another aspect of this is