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PGD: Day 5 Embryo Biopsy with Microarray & Blastocyst Transfer
Houston Fertility Institute in Texas — PGD and Blastocyst Transfer
The infertility specialists at Houston Fertility Institute are highly experienced with the latest technologies designed to increase a couple's chances of achieving a successful pregnancy and giving birth to a healthy baby. Two of the technologies offered at our Houston, Texas-area infertility treatment clinic, PGD and blastocyst transfer, may be especially suitable for couples with a family history of genetic diseases and those who would like to increase their chances of implantation, respectively.
Preimplantation Genetic Diagnosis (PGD)
PGD, or preimplantation genetic diagnosis, is a breakthrough technology that improves the likelihood of having a healthy baby. PGD is most commonly performed when one or both partners carry a genetic disease, as it allows the couple to reduce the chance of transmitting the disorder to their children. The physicians and embryologists at Houston Fertility Institute are experts in this new area of reproductive health and have recently published articles on a new embryo biopsy technique that we have pioneered in our embryology laboratories. The importance of having PGD performed at an experienced facility, such as Houston Fertility Institute, cannot be overemphasized.
The PGD Process - Day 5 Embryo Biopsy with Microarray
PGD is performed as a part of an in-vitro fertilization (IVF) cycle, during which multiple eggs are produced, retrieved from the ovaries, and fertilized with sperm in our embryology laboratory. IVF is necessary for the PGD procedure, because it allows us access to the embryos. On day five of embryo culture, the embryos are blastocysts, and typically over one hundred cells in size. One or two cells are removed from each embryo during a process called embryo biopsy, and a genetic evaluation is performed on all the embryos. Only the healthy embryos are then transferred back into the uterus.…
PGD at our Houston, Texas-area clinic can also be utilized to help select embryos of a particular gender, usually to avoid sex-specific diseases (see list below under X-linked diseases), but it can also be performed for family balancing. PGD is normally recommended for couples where one or both of the parents are a known carrier of a genetic disease (e.g., hemophilia, sickle cell disease, cystic fibrosis).
Because PGD is not a routine part of IVF, there is an additional cost for the service. The cost varies depending on the type of genetic testing that is performed.
Fig. 1 & 2 Embryo biopsy
PGD and Pregnancy
One concern of many couples is whether PGD will affect their likelihood of pregnancy or, more importantly, the health of their embryo. Because the procedure is performed so early in the developmental process, at a time when any cell from the embryo can potentially be removed and go on to create another embryo on its own, PGD does not cause any harm to the developing embryo.
However, some medical professionals feel that performing PGD is likely to lessen a couple's chances of a successful pregnancy, as compared to conventional IVF. Others disagree, believing that pregnancy success rates actually increase through the use of PGD. This is because only those embryos that have been shown to be in good health are transferred back to the mother. The bottom line is that the actual biopsy of the embryo does not affect the health of the baby, but there may be a small decrease in the overall chance of getting pregnant.
Diseases Detected with PGD Genetic Testing
The following is a list of some of the genetic diseases for which PGD can screen. This is not a comprehensive list by any means. Most known genetic diseases can be identified with PGD.
Cystic Fibrosis, Sickle Cell Anemia, Thalassemia, HLA genotyping, Epidermolysis Bullosa, Gaucher Disease, Tay-Sachs Disease, Glycogen Storage Disease, Fanconi Anemia, Congenital Adrenal Hyperplasia, Spinal Muscular Atrophy, and Phenylketonuria
Myotonis Dystrophy, Huntington's Disease, Polycystic Kidney Disease types 1 and 2, Familial Adenomatous Polyposis (APC gene), Neurofibromatosis 1 and 2, Li-Fraumeni (p53 gene), Von-Hippel Lindau, Marfan Syndrome, Osteogenesis Imperfecta types I and IV, Charcot-Marie-Tooth type IA, Multiple Epiphyseal Dysplasia, Retinitis Pigmentosa, and Achondroplasia
X Linked Diseases
Fragile X, Hemophilia A and B, Duchenne Muscular Dystrophy, Ornithine Carbamyl Transferase (OTC) deficiency, X-linked Hydrocephalus, and Myotubular Myopathy
Chromosomal translocations and Chromosomal trisomies (like Trisomy 13, 18, or 21, i.e. Down Syndrome)
A blastocyst, by definition, is an embryo that has developed for five to seven days after fertilization and has developed two distinct cell types and a central cavity filled with fluid (blastocoel cavity). The blastocyst culture and day-five embryo transfer procedure for in-vitro fertilization (IVF) facilitates selection of the best quality embryos for transfer. The concept of embryo quality is very important for couples who are experiencing infertility. With blastocyst embryo transfer, we can transfer fewer embryos, thereby reducing risks for multiple pregnancies while still keeping our overall pregnancy rates at our Houston, Texas-area infertility treatment center very high.
During the first five days after fertilization, an embryo rapidly passes through multiple stages:
- On day one, an embryo is typically at the pronuclear stage, commonly referred to as 2PN. It is still a one-cell embryo, because the DNA material from the sperm and the egg has not fused yet.
- Day two after fertilization, the embryo is at the two- to four-cell stage.
- On day three, it is typically at the six- to eight-cell stage. Days two and three are also called the cleavage stage.
- On day four, the embryo is at the morula stage. A morula is a solid sphere that has many cells.
By day five, most embryos have reached the blastocyst stage. The blastocyst stage is the first stage of embryo development in which the different cells are differentiating (developing different functions). A blastocyst embryo has three components:
- An inner cell mass, which ultimately becomes the actual baby
- An outer cell mass, which becomes the placenta
- A fluid-filled space, the blastocoel
Embryo transfers are typically performed on day three (the cleavage stage) or on day five (the blastocyst stage).
Fig. 3 Embryo at blastocyst stage
Advantages of Blastocyst Transfer
Studies have shown that day-three transfers and day-five transfers have comparable pregnancy rates; however, culturing embryos until day five, whenever possible, allows for the selection of the best embryos and the transfer of fewer embryos, which decreases the risk of multiple pregnancies while maintaining high pregnancy rates.
One of the distinguishing qualities of Houston Fertility Institute is the quality of our IVF laboratories. Our laboratories have excellent “blastulation” rates. This means that, with very few exceptions, we are capable of successfully culturing embryos to the blastocyst stage and therefore can take full advantage of performing a day-five transfer. In addition, any excess high-quality embryos on day five that are continuing to develop will be cryopreserved (frozen), which allows them to be used in the future if desired.
Although there are several advantages to blastocyst transfer, a day-three transfer may be more advantageous for some patients. One of our infertility specialists can advise you as to whether you are a suitable candidate for blastocyst transfer.
Contact Our Houston, Texas Area Infertility Treatment Center
At Houston Fertility Institute, we tailor in-vitro fertilization (IVF) to meet each individual patient's needs. Contact our clinic in the Houston, Texas area to learn more about infertility treatment with PGD and blastocyst transfer.