PGD (Embryo Biopsy)
PGD is a reproductive option for couples at risk of passing a specific genetic disease or chromosome imbalance to their children. PGD involves screening IVF generated embryos for genetic conditions prior to embryo transfer, with only unaffected embryos transferred to the uterus. This provides the opportunity to screen embryos for genetic conditions before a pregnancy is established .
Couples choose PGD over prenatal diagnosis for many reasons including objection to termination of pregnancy,
loss of a child from the genetic disease, recurrent implantation failure or recurrent miscarriage.
Preimplantation Genetic Diagnosis (PGD) is a reproductive option for couples at risk of passing on a specific genetic disease or chromosomal imbalance to their children. PGD involves screening IVF generated embryos for genetic disease prior to embryo transfer. This provides the opportunity to determine the genetic status of an embryo before a pregnancy is established. Couples choose PGD over prenatal diagnosis for many reasons including objection to termination of pregnancy, loss of a child from the genetic disease, repeat implantation failure or repeat miscarriage.
PGD testing may be appropriate for:
- Couples at risk of passing a single gene disorder on to their children
- Couples at risk of having children with a particular X-linked disorder
- Couples where one partner carries a balanced chromosomal rearrangement
- Couples with advanced maternal age (>36)
- Couples who have experienced repeated miscarriage
- Couples who have experienced repeated IVF failure
- Couples who have previously had a pregnancy with a chromosomal abnormality
Genetic counselling is an important step to ensure that PGD is the right option for each couple.
What does PGD involve?
All couples requesting PGD must first undertake an IVF cycle to stimulate the woman's ovaries to produce a number of eggs. These eggs are collected and fertilised using the male partner's sperm. The resulting embryos are cultured in the laboratory. Embryo biopsy is performed on Day 3 after egg collection . Embryos that have developed to at least 5 cells are suitable for biopsy. A hole is drilled in the outer shell of the embryo and 1 or 2 cells are removed for genetic analysis
The embryos are kept in culture while the testing of the biopsied cells proceeds. Genetic test results are usually obtained within 24 hours of embryo biopsy. A qualified PGD scientist will discuss the PGD results with the couple at the completion of testing. When available, one or two unaffected embryos can be transferred on Day 4 or Day 5. When a number of embryos are identified as being genetically suitable for transfer, morphological criteria are used to determine the best embryo/s for transfer. The couple's IVF nurse will organise a pregnancy test to be performed on Day 16.Surplus unaffected embryos will be grown in culture to Day 5 or Day 6. If they reach an appropriate stage of development (ie: form a good quality blastocyst) they will be frozen. These embryos may be used in a subsequent IVF cycle if the couple do not achieve a pregnancy with the fresh embryo/s.Embryos that are affected or have a chromosome abnormality are discarded or donated to research with the couple's consent