PREIMPLANTATION GENETIC DIAGNOSIS (PGD)
Preimplantation Genetic Diagnosis (PGD) helps identify embryos that have recognizable chromosomal abnormalities prior to transfer to the uterus. PGD can be used for patients of all ages who have unexplained fertility, severe male factor, advanced maternal age and several failed IVF cycles with poor quality embryos. This procedure benefits families who have a known history of certain genetic abnormalities.
On the third day of embryo development, a single cell is taken from an embryo through an opening made in the shell of the embryo through assisted hatching. The DNA from that single cell is then analyzed for any chromosomal abnormalities. The analysis usually takes 24-48 hours to complete. The embryologist will determine which embryos are to be transferred based upon the results of the analysis.
BLASTOCYST BIOPSY with aCGH
Delaware Institute now offers blastocyst biopsy with array Comparative Genomic Hybridization (aCGH) to IVF patients. Array CGH is a new technique that tests embryos for aneuploidy, abnormal number of all 22 chromosomes + sex chromosomes (X or Y). Our highly-trained embryologists can remove or biopsy several cells from a day 5 embryo (Blastocyst) for genetic testing.
A blastocyst is comprised of hundreds of cells that have differentiated into an inner cell mass (which will develop into the fetus) and the trophectoderm (which will develop into the placenta). During blastocyst biopsy, a small hole is made in the zona pellucida (the shell surrounding the embryo) and several cells are removed from the trophectoderm for testing. The unharmed biopsied blastocysts are then returned to the incubator.
A major advantage of aCGH is the fast turn-around-time. Reprogenetics, the lab that performs aCGH, is located in New Jersey. The blastocysts can be biopsied on day 5 of embryo culture, and the embryo(s) with the normal number of chromosomes can be transferred on day 6 or frozen and transferred during the next cycle..
The major advantage of blastocyst biopsy compared to conventional day 3 embryo biopsy is that more cells are analyzed, and therefore, the testing is thought to be more accurate. Secondly, trophectoderm cells (future placenta) are biopsied and a smaller fraction of the total embryo is biopsied. In addition, many scientists believe that blastocyst biopsy is less stressful than conventional embryo biopsy on day 3 where 1 cell out 8 is removed from the embryo.
A disadvantage of blastocyst biopsy is that not all embryos will develop to the blastocyst stage by day 5 of culture. Therefore, patients who have poor embryo quality and development may not have any embryos to test or ultimately to transfer.
For more information please contact Katie, Stephanie or Mark in the IVF department.