PGD - How accurate is it? PGD is approximately 90% accurate for detecting the most common aneuploidies. However, one-third of all chromosome abnormalities that can be found by chorionic villi sampling and amniocentesis are not detectable by PGD. For example:

• PGD cannot detect abnormalities of chromosomes which are not included in the test
• PGD cannot detect structural chromosome abnormalities (unless a specific translocation analysis is requested)
• PGD cannot detect mosaicism, which is the occurrence of chromosome abnormalities in some cells but not in other cells of the same embryo.