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Preimplantation Genetic Diagnosis (PGD) and Recurrent Miscarriage: My Personal Experience
a blog by Krystyn LaBate, Ph.D., July 22, 2013
Due to the fact that we lost four pregnancies (at that time), my husband and I decided to do genetic testing on the embryos from our second IVF cycle. This is referred to as Preimplantation Genetic Diagnosis (PGD). There are different types of PGD with the most common method referred to as FISH. FISH has the ability to look at 5-12 chromosomes within each embryo. This method is a good choice for someone that is looking for a specific disorder or an inherited disease. Since there are 23 unique chromosomes including one that determines gender, FISH is obviously not the choice for someone experiencing recurrent pregnancy loss as 11-18 chromosomes are left untested. Array-Comparative Genomic Hybridization (aCGH), an advanced form of PGD, has the ability to look at all 23 pairs of chromosomes in each cell obtained from an embryo. At the time that we did PGD there were just over 100 cases as it was a relatively new technology, not to mention, quite expensive. Despite my husband and I being genetically normal individuals determined by earlier karyoytyping, an abnormal number of chromosomes can result spontaneously from the maturation of the egg or during the process of embryo division. A common example of this is an extra chromosome number 21 (Down Syndrome or trisomy 21). It has been estimated that embryos fertilized in vitro contain chromosomal abnormalities in 50% or more of cases which leads to miscarriages.
The entire procedure consisted of four steps. All but the third step was performed by my local fertility clinic. The actual testing of the embryos was done by a private genetics laboratory specializing in PGD. While other laboratories may use a different process, these are the steps that were taken during my IVF cycle.
- Embryos were produced as part of my normal IVF cycle. On this particular cycle, 17 eggs were extracted during the retrieval and 13 of these eggs fertilized resulting in 13 embryos.
- On Day 3 the embryos were biopsied where one cell is removed so that it can be sent to the lab and analyzed. One cell was removed from each individual embryo while in the petri dish, in the incubator, using a micropipette. Since we had to pay individually for each embryo to be analyzed, we decided to biopsy anything that had 5 cells or more. In the end, we had a total of 11 embryos analyzed.
- The cells were sent to the genetics laboratory via same day courier where they were analyzed. Results were available within 24 hours at which time we had to decide which embryos to put back. Obviously would only transfer ones that were 100% chromosomally normal.
- Our selected embryo(s) were then transferred back into my uterus on Day 5 by my fertility clinic. Due to my diagnosis of premature ovarian failure, out of the 11 embryos biopsied, only 1 came back chromosomally normal. My husband and I were shocked by these results. Sadly, despite our best efforts, this particular cycle ended in a chemical pregnancy.
I often get asked if I would go through PGD again knowing what I do now. While I can say that the results helped to make sense of my previous losses, it was very hard to accept that a chromosomally normal embryo would result in a failed pregnancy. This experience made me truly realize what a complex process conception is, and that the stars have to line up perfectly for that miracle to happen. I don’t regret doing PGD as it helped me to understand and be at peace with my past losses as I realized that they weren’t the result of me doing something wrong. It truly was something out of my control.