When couples undergo the PGD Procedure vitro fertilization cycle is the first stage, which includes the process of creating embryos. Genetic analysis will then be performed on cells from each embryo transferred into the woman's uterus. The embryo biopsy is usually used on about the third day of its development when the embryo has approximately 6-8 cells. In this procedure one or two cells are usually taken from the embryo. The embryo is usually incubated until testing is complete. Embryos that are not affected by the disorder can be selected and transferred to the uterus in the hope that a normal pregnancy will develop.
During the pgd procedure scientists take cells from the embryo and analysis them using a fluorescence technique. Such analysis uses DNA probes that can attach colors to the chromosomes, which are wanted to be analyzed in order to count them. Each probe is colored with a definite fluorescent dye. With the help of the fluorescent microscope it is possible to determine the number of chromosomes of each type (color). Currently such analysis is used to count the number of chromosomes 13, 15, 16, 18, 21, 22, Xs and Ys. It also gives an opportunity to choose the appropriate embryos for transferring.
In the PGD procedure cells that have the most common chromosome abnormalities from those that do not can be distinguished. The embryos that have the chromosome abnormalities will not be transferred to the woman's uterus. The embryos` gender will not be revealed, except for couples that undergo PGD for a family history of an X-linked condition. In families at risk for an X-linked disease, only female embryos will be transferred. It is important for a couple, which uses PGD not to provide their sexual activity during the cycle of the PGD procedure. Sexual activity during this time could cause a pregnancy with an embryo that has not been tested.
The risk of embryo biopsy exists but doesn't decrease the embryo's chance for living and further development before implantation. Embryo biopsy doesn't increase the children born with congenital abnormalities, birth defects, mental disabilities, or other possible problems with development. PGD procedure may reveal that all embryos are abnormal. However, a normal pregnancy cannot be guaranteed whether or not there is an embryo biopsy. Embryo biopsy, analysis and other issues can show that embryos usually consist of normal and abnormal cells (mosaicism).
If the analyzed cell has normal chromosomal content and the unanalyzed cells have a chromosome abnormality, it could be inaccurately identified that embryo is chromosomally normal. Therefore, the analyzed cell may not present all the cells. According to unavoidable possibility of inaccuracy in PGD analysis still the possibility of less chromosome abnormalities during the testing in early pregnancy is available.
All in all, PGD procedure is an accurate process for determining the chromosomal content of a cell from an embryo. There is a small risk of inaccuracy (incorrect identification of the chromosomal make-up) and/or unclear results in the biopsy of the embryo.