Introduction to Genetic Embryo Testing and Preimplantation Genetic Screening

Dr. Mark Johnson has a rare combination of expertise as both a Reproductive Endocrinologist-Infertility Specialist and Geneticist. Dr. Johnson explains in depth about genetic embryo testing and preimplantation genetic screening.

The Early Stages of Conception

The majority of human conceptions are actually lost in early life because of chromosomal problems associated with the embryo. Now it’s not necessarily the embryos fault that it received abnormal genetic information either from the egg or from the sperm.

At Arizona Associates for Reproductive Health we try to evaluate the embryo when we do our chromosomal pre-implantation genetic screening looking for what we call aneuploidy or abnormal chromosome complement in the embryos.

Pregnancy and Abnormal Embryos

As a result of abnormal embryos a majority of conception ability is lost related to the chromosome problems transmitted to the embryos.
In some cases this can be embryos that are lost the first two weeks after ovulation so you never even know that you conceived during that cycle and all you have is an onset of menses or you see a negative pregnancy test. Other abnormal conceptions end up as miscarriages.

The Preimplantation Genetic Screening Process

It’s important for the Arizona Associate for Reproductive Health to be able to screen embryos for chromosome abnormalities.
At our fertility clinic we biopsy embryos at the blastocyst stage allowing us to remove four to six cells or even more cells for DNA analysis of the embryo.

In general the embryo is frozen immediately after the biopsy, but in some cases it can be transferred within 24 hours if the analysis results are no.

In most cases it takes a little bit longer for the DNA analysis to give us results about the embryo.

The Benefits of Preimplantation Genetic Screenings

The benefits of preimplantation genetic screening is that it can filter out those abnormal embryos and abnormal conceptions prior to us transferring the embryos back into the uterus and producing a pregnancy.
An additional benefit of preimplantation genetic screenings is when our fertility specialists transfer back a single embryo back into the uterus that’s now been shown to be chromosomally normal there is a high chance the embryo will implant with a 65%-70% success rate per transfer of a pregnancy.

Another reason couples may want to consider preimplantation genetic screening of their embryos for the chromosomal complement is the increasing age of the woman.

An important factor to consider is as women go through the normal aging process there is a higher risk that the eggs that she produces are chromosomally abnormal and thus carried over into the embryo causing the embryo to be abnormal.


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Preimplantation Genetic Diagnosis (PGD) is a state-of-the-art procedure used in conjunction with In Vitro Fertilization (IVF). The PGD process allows us to select only the healthiest embryos (fertilized eggs) for transfer into your uterus.
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IVF is a treatment in which an egg and sperm are fertilized outside of a female patient’s body, then transferred to the uterus in hopes that at least one embryo will attach to the uterine wall.