What percentage of blastocysts are chromosomally normal

Q: What percentage of embryos come back PGS normal?

Patients often hear PGS-normal embryos have a 60 – 70% success rate.” But that is on a per-transfer basis. Meaning that if you begin a cycle, retrieve eggs, produce embryos, then do PGS testing, and at least one embryo comes back normal, 60 – 70% of the time it will lead to a live birth.

Q: What percentage of embryos are chromosomally abnormal?

It may be a normal phenotype. Previous studies have reported anywhere from 4% to 90% of human embryos with mosaic chromosome counts. Such a wide range is the result of discrepant research using the most prevalent screening in IVF called preimplantation genetic testing, or PGT.

Table of Contents Show

Intervention(s)
Main outcome measure(s)
Conclusion(s)
Cited by (0)
What percentage of embryos come back PGS normal?
What percentage of embryos are chromosomally abnormal?
What percentage of embryos pass PGT A?
Can blastocyst have chromosomal abnormalities?

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Objective

To assess correlation between blastocyst morphology and chromosomal status.

Design

Observational research study.

Setting

An IVF clinic and a specialist preimplanation genetic diagnosis (PGD) laboratory.

Patient(s)

Ninety-three couples undergoing IVF treatment in combination with chromosome screening of embryos.

Intervention(s)

Five hundred blastocysts underwent trophectoderm biopsy and comprehensive chromosome screening using comparative genomic hybridization (CGH). The morphology of the embryos was evaluated using standard methods.

Main outcome measure(s)

Association of aneuploidy and morphologic score.

Result(s)

A total of 56.7% of blastocysts were aneuploid. One-half of the grade 5/6 blastocysts were euploid, compared with only 37.5% of embryos graded 1/2, suggesting an effect of aneuploidy on blastocyst development. Aneuploidy also had a negative effect on inner cell mass and trophectoderm grades. Morphologically poor blastocysts had a higher incidence of monosomy and abnormalities affecting several chromosomes. The gender ratio was significantly skewed in relation to morphology. A total of 72% of blastocysts attaining the highest morphologic scores (5AA and 6AA) were found to be male, compared with only 40% of grade 3 embryos.

Conclusion(s)

Morphology and aneuploidy are linked at the blastocyst stage. However, the association is weak, and consequently, morphologic analysis cannot be relied on to ensure transfer of chromosomally normal embryos. A significant proportion of aneuploid embryos are capable of achieving the highest morphologic scores, and some euploid embryos are of poor morphology. Gender was associated with blastocyst grading, male embryos developing at a significantly faster rate than females.

Key Words

Morphology

chromosome

aneuploidy

blastocyst

preimplantation genetic screening

single embryo transfer

implantation

in vitro fertilization

Cited by (0)

For more than a decade, we have been screening embryos for chromosomal number abnormalities (aneuploidy) at InVia Fertility Specialists. The technical term used for this process is preimplantation genetic screening (PGS) or pre-implantation genetic diagnosis (PGD). By screening out “abnormal” embryos we are now routinely able to achieve excellent pregnancy rates with transfer of single embryos and thus significantly reducing the incidence of multiple pregnancies. PGD or PGS, thus, is the smart thing to do so much that we have coined the term SMART IVF to describe them.

A common question we get asked about the process is, “How many normal (euploid) embryos will I produce?” Demko et al addressed this very issue in a recent publication. They analyzed the relationship between maternal age and the rate of embryos that tested as euploid, the average number and proportion of normal embryos per IVF cycle and the possibility of retrieving at least one normal embryo.

Results of Study on Age and Number of Eggs Obtained After Preimplantation Genetic Screening

The study analyzed more than 46,000 embryos between 2009 and 2014.

In women aged 27 to 35 years, the median proportion of euploid embryos in each cycle remained constant at approximately 35% in day-3 biopsies and approximately 55% in day-5 biopsies, but it decreased rapidly after age 35.
On average, women in their late 20s had four euploid embryos (day 3 or day 5) per cycle, but this number decreased linearly (R2 R 0.983) after 35 years of age.
The effect of maternal age on the possibility of retrieving at least one normal embryo was similar, with a rapid exponential decline (R2 1⁄4 0.986).
At age 35, at least one euploid embryo can be expected in 85% of all cycles; this percentage drops to approximately 75% at age 40, and to approximately 45% by age 44.
Across all maternal ages, the euploid proportion and number of embryos per cycle were counterbalanced, so the number of euploid embryos per cycle was the same for day-3 and day-5 biopsies. This suggests that the loss of embryos from day 3 to day 5 was primarily due to aneuploidy.

They concluded that (1) 33% to 50% of all embryos screened in women aged 18 to 48 years are aneuploid and (2) the number and percentage of euploid embryos decreases with advancing maternal age.

At InVia Fertility Specialists, we have been offering SMART IVF (PGD or PGS) for many years. Currently, using this technology, we are having pregnancy rates approximating 70% with the transfer of a single embryo.

To see a fertility specialist with a high success rate using single embryo transfer, make an appointment at one of InVia's four Chicago area fertility clinics.

What percentage of embryos come back PGS normal?

Patients often hear “PGS-normal embryos have a 60 – 70% success rate.” But that is on a per-transfer basis. Meaning that if you begin a cycle, retrieve eggs, produce embryos, then do PGS testing, and at least one embryo comes back normal, 60 – 70% of the time it will lead to a live birth.

What percentage of embryos are chromosomally abnormal?

It may be a normal phenotype." Previous studies have reported anywhere from 4% to 90% of human embryos with mosaic chromosome counts. Such a wide range is the result of discrepant research using the most prevalent screening in IVF called "preimplantation genetic testing," or PGT.

What percentage of embryos pass PGT A?

Embryo implantation rates were 66% per embryo transferred for each age group using their own eggs. One embryo screened with PGT-A produces very high pregnancy rates after transfer.

Can blastocyst have chromosomal abnormalities?

Chromosomal abnormalities do not impair embryo development as aneuploidy is frequently observed in embryos that reach the blastocyst stage. High-quality blastocysts are not representative of euploidy of chromosomes 13, 14, 15, 16, 18, 21, 22, X and Y.