Genetic Testing

PGT biopsy removes a few cells from an embryo for analysis. Most PGT determines the number of chromosomes present in each cell (PGT-A for Aneuploidy). A normal embryo has 2 complete sets of chromosomes (one set from the female and one set from the male, called euploid). If the embryo contains the incorrect number of chromosomes, then it usually fails to implant, results in a miscarriage or results in an abnormal child such as Downs syndrome. Euploid embryos have the best chance of implantation and delivery of a liveborn child.
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The goal with IVF treatment is to transfer a single embryo resulting in a single healthy birth. Excellent quality research shows euploid embryos increase the probability that the embryo will implant and continue to a live-born pregnancy. PGT also reduces the miscarriage rate by about 50%. PGT research showed that compared to choosing the embryo for transfer based on the morphology (appearance) alone, PGT changed the embryo choice about 15% of the time for women <35 years old and 30% of the time for women 35 years and older. PGT gives patients the confidence to continue single embryo transfer and deliver the healthiest baby possible. PGT can also shorten the time to delivery by efficiently transferring the correct embryo.
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PGT euploid status is about 99.5% accurate and PGT aneuploid status (abnormal embryos) is about 97% accurate. False abnormal rate is 2-3%. Some physicians and researchers debate the exact accuracy but very research suggest these numbers are correct.

PGT biopsy requires embryo culture until Day 5/6 because embryo biopsy on Day 3 results in a 40% lower implantation rate, but biopsy on Day 5 or 6 does not decrease the implantation potential of the embryo. However, not all blastocyst embryos have enough cells to biopsy them without harming their viability. Assuming all the eggs retrieved = 100% of the eggs for that cycle, about 78-80% of the eggs are mature, about 75-80% of mature eggs fertilize normally into zygotes (1-cell embryos) and about 49-51% of them develop into blastocysts. Combining these statistics yields 78-80% x 75-80% x 49-51% = 29-33% of retrieved eggs become usable blastocyst embryos. Our program estimates that about 75% of patients who desire PGT biopsy will achieve at least 1 embryo for biopsy.

In theory, YES – we should screen all embryos to choose the best embryo for transfer. However, cost, fear of embryo damage, ethical perspectives and miscellaneous other reasons lead patients to decline testing. PGT does not increase the overall success rate for the cycle. For example, if you have 5 embryos and we eventually transfer them all (not in a single transfer), then with or without PGT, you should have the same number of babies.