
Genetic Screening Of Embryos (PGD/PGS)
What is the Genetic Screening Of Embryos?
Over the years, embryo selection has become more important than ever as several studies have shown that as much as 50% of embryos have chromosomal abnormality above the age of 37 years and are likely to fail if implanted into the uterus.
With the help of the PGS technique, we can perform an embryo screening for any genetic or chromosomal abnormality before the transfer of the embryos.
These new methods and techniques allow us to select high-quality embryos for transfer thereby reducing the risk of implantation and pregnancy failure. The most common techniques for genetic screening of embryos is PGT or Preimplantation Genetic Testing.
What is PGS?
PGS also is known as PGT, is a screening of chromosomes for aneuploidy. It is used for screening for aneuploidies in embryos. Aneuploidy stands for an abnormal number of chromosomes. The term PGS most often comes in use while discussing infertility with couples who are struggling with issues involving age, repeated IVF failure, recurrent miscarriages, and genetically abnormal pregnancies.
PGS is primarily used for the detection of chromosomally abnormal embryos. The most common technique for PGS is (NGS) Next-Generation Sequencing. This test screens for chromosome syndromes like Down’s Syndrome or Trisomy 21, Trisomy 13, and other chromosomal structural changes.
Indications for PGS testing-
- Repeated IVF failure
- Recurrent miscarriages
- Severe male infertility
- Genetically abnormal pregnancies
Process of PGS-
The procedure is done in three steps. First, the embryos are produced using IVF or ICSI, fertilized embryos are then cultured for 3-5 days. After 3-5 days, embryo biopsy takes place. 2 or more cells are removed after every 3 or 5 days of biopsy for testing. After the cell is biopsied, are placed in test tubes and are sent for further testing. Till then the embryo is frozen and after the test, the embryo is finally transferred into the uterus.
What is PGD?
PGD is a screening method that allows us to test the embryos of those couples who carry a known risk of genetically inherited disorders. With the help of this screening method, only the healthy embryos are selected to replace or transfer to the woman’s uterus to achieve pregnancy.
PGD has been very successful in detecting any kind of genetic alterations in the embryos of those who are known to be at risk of passing it on to their offspring. This test helps to identify chromosomally normal embryos for transfer that helps to improve the success rate of IVF.
This test is especially good for those women who have a history of miscarriage, failed IVF cycles, and are old in maternal age.
PGD is performed with the help of a high-powered microscope. One or more cells from the embryo are tested for the genetic train of interest. After this, the unaffected embryos are identified, separated, and transferred into the uterus.
Indications for PGD Testing-
- Abnormal embryos
- Heredity Genetic abnormalities
- Increased risk of chromosome abnormalities
- Severe miscarriage
- Chromosome defect before pregnancy
Process of PGD-
The embryos are first created in a laboratory and are left for 5-6 days for growing. After 5-6 days, a biopsy is done on developing embryos. The embryos are then stored while genetic abnormalities are tested. After all this, the best embryo is selected and then transferred to the uterus.
What is the difference between PGD and PGS?
PGD diagnoses the embryo for a single gene disorder whereas PGS screens embryos for ANEUPLOIDIES and detects chromosomally abnormal embryos.
What are the benefits of PGD and PGS?
- PGD helps couples to pursue biological children which they wouldn’t be able to pursue otherwise
- PGD reduces the risk of conceiving a child with a genetic factor
- PGD can reduce the need for amniocentesis later in pregnancy
FAQs
What is infertility?
Infertility is the inability of a couple to conceive even after a year of trying to get pregnant through unprotected and well-timed sexual intercourse in which the woman is under the age of 35. If the woman is above 35, it is diagnosed after six months of trying to get pregnant. Infertility can be due to male or female factors or even both. It can also be due to unexplained reasons.
Does age affect fertility and chances of conception?
Yes, age does affect a woman’s ability to have children. More and more women now prefer to wait until their 30s to conceive. A woman’s fertility starts to reduce from her 30s and more after the age of 35. As much as one-third of couples who face fertility problems are those where the woman’s age is above 35.
How does age affect a woman’s ability to have children?
Here are a few ways of how a woman’s ability conceive reduces due to her age:
- The ability of ovaries to release eggs ready for fertilization reduces with age
- The quality of eggs released reduces with an increase in the age of women
- An increase in age can lead to more health problems which may interfere with a woman’s fertility
- The risk of miscarriages increases as a woman ages
- Children born to older women tend to have more abnormalities
How long should women try to get pregnant before visiting a doctor?
Women who are healthy and below the age of 30 need not worry about infertility unless they have been trying to get pregnant for a year or so. If such is the case, they should talk to their doctor for a fertility evaluation. They should also ask their partners to do the same.
Women in their 30s trying to get pregnant should talk to their doctor after trying for 6 months as a woman’s chances of having a baby decline rapidly after the age of 30.
Is infertility only a woman’s problem?
No, infertility can affect both men and women. About one-third of cases of infertility are due to female factors and another one third are due to male factors. The remaining cases are either due to a mixture of both male and female factors or due to unknown reasons.
Can male infertility be treated?
In most cases, male infertility can be treated. Your doctor may suggest you use assisted reproductive technologies (ART) such as IVF, ICSI, TESA and Micro-TESE. Although ART cannot cure or treat the causes of infertility, it can help couples achieve pregnancy even when the male’s sperm count is low or zero.
What are the risk factors for infertility?
There are several external factors, lifestyle choices, and environmental causes that can lead to infertility. Although some risk factors can be gender-specific, some common risk factors are:
- Age
- Smoking
- Alcohol Consumption
- Substance Abuse
- Obesity and Underweight
- Sexually Transmitted Diseases
- Diabetes
- Tubal Disease
- Stress
- Genetic Causes
What are the ways to treat infertility?
There are many ways to treat infertility for both men and women. With advancing medical technologies, you and your partner along with your doctor can decide depending on the options available.
What causes infertility in women?
The most common reason for infertility in women is problems with ovulation. No ovulation or improper ovulation can prevent eggs from fertilizing or there may be no eggs at all. Irregular periods or no periods are a sign of no or improper ovulation. Some other causes of infertility include:
- Endometriosis
- PCOD/PCOS
- Uterine Fibroids
- Blocked Fallopian Tubes
- Physical problems with the uterus
- Pelvic Inflammatory Disease
- Several Miscarriages
- Unexplained Reasons
What causes infertility in men?
Infertility in men can be due to the following:
- Low or no sperm production
- Low motility of sperms- sperms inability to move fast or reach the egg to fertilize it
- Abnormal shape/structure of sperms that prevent it from fertilizing the egg
- Erectile Dysfunction or Retrograde Ejaculation
Sometimes, men may be born with these problems, and the other times, they may develop these problems due to an illness or injury.