Preimplantation Genetic Diagnosis is a lab technique used to find defects in the chromosomes of the embryo. A common misconception is that PGD discovers individual diseases, but it does not. The embryos that are tested are usually the end result of an IVF treatment.
Once IVF creates a suitable embryo, a doctor then extracts a single cell or a small group of cells to be examined closer. By viewing the cells up close the doctor can rigorously examine it and check for anything that may be out of the ordinary. Each and every embryo you have available is checked and if a defect is found, you can choose not to include that specific embryo. This process helps boost the likelihood of a successful pregnancy because it only lets the best embryos through.
Success Rates of PGD
While using PGD is a great way to help ensure that your baby is born healthy and without any major problems, it is also not 100% accurate. There have been cases of bad embryos producing a viable pregnancy at the same time as there have been cases of apparently good embryos producing nothing at all. The fact of the matter is that women who are over 35 have shown consistent success using PGD, and patients who have had failed IVF also successfully turn to PGD. About 35% of women become successfully pregnant after using PGD. This is most likely because the doctors nowadays can determine the usefulness of the embryo much sooner than they were able to in the past.