Pre-Implantation Genetic Screening (PGS) / Comprehensive Chromosome Screening (CCS)
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Pre-Implantation Genetic Diagnosis and Pre-Implantation Genetic Screening are laboratory techniques to evaluate embryos for genetic abnormalities or familial diseases, before they are transferred into the uterus. These tests are performed in conjunction with an IVF cycle.
Pre-Implantation Genetic Diagnosis (PGD)
PGD is a procedure to test an in vitro fertilized embryo for specific genetic conditions, before transferring it into the uterus. Specific genetic conditions include cystic fibrosis, sickle cell and sex-linked diseases like hemophilia. It can identify which embryos carry or are genetically at risk for a specific genetic disease, like testing for the breast cancer mutation BRCA1 or 2. The main advantage is the ability to increase the likelihood that the implanted embryo will develop into a healthy baby with no genetic disorders. PGD is an adjunct procedure to IVF, and requires in vitro fertilized embryos.
Both parents are genetically screened (from a blood sample) to determine whether either parent is a carrier for a specific genetic disorder. If both are carriers, the objective is to minimize the risk of having an affected child.
Who would benefit from PGD testing?
- Any couple at risk of passing a genetic disease or condition to their offspring.
- Carriers of sex-linked genetic disorders.
- Carriers of single gene disorders.
Benefits of PGD
- PGD can test more than 100 genetic diseases
- It allows a couple to decide whether to continue a pregnancy before implantation
- It enables couples to choose biological children, when they may not have been able to without PGD.
Potential disadvantages of PGD
- PGD can help reduce the chance of conceiving a child with a genetic disorder. But it cannot completely eliminate the risk.
- Further testing may be needed during pregnancy to determine if the genetic factor is still at issue.
- It does not eliminate the need for prenatal testing.
Pre-Implantation Genetic Screening (PGS)
PGS is a procedure to test the entire genetic profile of an embryo before transferring it to the uterus. Its purpose is to screen the embryo for normal chromosome numbers, to gain information about the potential genetic health of a child, and identify embryos at risk for miscarriage. PGS reduces the risk of having a child with a genetic abnormality like Downs Syndrome. It also reduces the risk of miscarriage from genetically compromised embryos. PGS improves the chance of getting pregnant and carrying to term.
Preimplantation Genetic Testing the future of fertility
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Who would benefit from PGS testing?
- IVF patients over age 35. Studies show that even in women younger than this, at least one third of embryos have abnormal numbers of chromosomes. The number of embryos with abnormal chromosomes increases as women age. Aneuploidy means the presence of an abnormal number of chromosomes. Most pregnancies with aneuploidy will miscarry.
- IVF patients of any age when there have been 3 or more failed IVF attempts.
- IVF patients that are carriers of genetic disorders that can put an embryo at risk. PGS can be done with PGD to help discover the healthiest embryo that also does not carry the genetic mutation.
- Men with severe infertility who have a high rate of chromosomal abnormalities.
- IVF patients who have had multiple miscarriages.
- IVF patients who have or are carriers of genetic disorders.
Benefits of PGS
- The probability of delivering a healthy child increases with PGS since only normal, healthy embryos will be transferred to the women’s uterus.
- PGS has been proven to reduce the rate of pregnancy loss by 50% and increase take-home baby rates.
- Embryos can be tested from multiple IVF cycles, frozen and transferred in the future, providing the opportunity to select the best embryo for transfer.
- If these tests reveal high numbers of embryos are adversely affected, couples can choose to use donor eggs and sperm.
Potential disadvantages of PGS
- These tests are highly accurate, but can have a false-positive or false-negative diagnosis.
- PGD/PGS are invasive procedures that can damage, traumatize or destroy the embryo.
- These tests cannot guarantee 100% accuracy. So some genetic problems may not be detected.
- Due to limitations with the current PGD/PGS technology, infertility specialists still recommend prenatal diagnosis via amniocentesis or CVS- chorionic villus sampling and routine first trimester testing.
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The infertility experts at Virginia Fertility Associates are experienced reproductive endocrinologists. Dr. Shah and Tidey has repeatedly been selected for Richmond Magazine’s “Top Docs” in Reproductive Endocrinology and Infertility. We offer the entire range of options to patients who desire to start a family. Our doctors are OBGYNS and reproductive endocrinologists with the most advanced training and education in infertility treatments, miscarriage and reproductive disorders. This is a challenging time. Partner with us. Together we can help make your dreams come true.