PGD Procedure

Day 3 Embryo
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Each cell is called a blastomere, and all cells are identical copies of each other.
  • During an IVF or ICSI cycle, eggs are retrieved and fertilized in the lab, and the resulting embryos are incubated for 3 days.
  • At this time, each embryo should have 6 to 10 cells. Each cell is called a blastomere. Each cell is identical to the others, because the process of differentiation, where cells form into specific body tissues, has not yet begun.
    Normal-looking embryos are selected for PGD, and an embryo biopsy is performed. The embryologist carefully penetrates the embryo’s outer membrane with a microscopic glass needle, and removes one or two individual cells. This procedure requires great skill, because the entire embryo is only about the size of a tiny grain of sand. After the biopsy, the embryo is returned to the incubator to continue developing.
  • Genetic testing is performed on the removed cell. Although testing accuracy is very high, it is also limited because only one or two cells are available for testing, and because analysis must be completed in just 48 hours, in time for a 5-day embryo transfer.
  • Based on the test results, only embryos free of the tested condition are selected to be transferred to the woman’s uterus.

Can PGD hurt the embryo?

Most of the time, an embryo will continue to grow and develop normally. However, sometimes an embryo will arrest (stop developing) after the embryo biopsy. The decision whether to do PGD may depend on the number of viable embryos available to test, in case some do not survive.

Can the embryo biopsy harm the baby’s development?

No, PGD does not affect the baby’s development. Although the embryo biopsy sounds very drastic – removing one or two cells at a stage when the embryo consists of only 8 to 10 cells – each cell is only a copy of the other cells. No genetic information is lost, because each cell contains its own complete copy of the entire genome in its chromosomes. PGD has been performed thousands of times worldwide since its development in 1989. Babies born after PGD have been found to have no greater incidence of birth defects than the general population.