Assisted reproductive technology (ART) has advanced to the point where one can assess the best candidate(s) to transfer before implantation. These advancements include both preimplantation genetic diagnosis (PGD) and preimplantation genetic screening (PGS), although differentiated and defined by their respective names and purposes. As the Difference Between PGD and PGS is critical to their understanding, we recognize its importance for the couples in their IVF (in vitro fertilization) journey.
Difference Between PGD and PGS
What Is Preimplantation Genetic Diagnosis (PGD)?
PGD (Preimplantation Genetic Diagnosis) is a specialized genetic test performed on embryos created through IVF to detect specific genetic or hereditary diseases. It’s used when one or both parents are known carriers of a genetic disorder, and there’s a risk of passing it to their child.How PGD Works:
- The couple undergoes IVF to create embryos in the lab.
- On Day 5 (blastocyst stage), a few cells are gently removed from each embryo.
- These cells are tested for specific gene mutations or chromosomal abnormalities.
- Only genetically healthy embryos are transferred into the uterus.
Example:
If a couple carries Thalassemia, Cystic Fibrosis, or Sickle Cell Anemia, PGD helps identify embryos free from these mutations before implantation.PGD Is Recommended For:
- Couples with known genetic diseases in the family
- Carriers of single-gene disorders (like Tay-Sachs, Duchenne Muscular Dystrophy)
- Couples with repeated miscarriages due to genetic causes
- Previous IVF cycles with chromosomal abnormalities in embryos
What Is Preimplantation Genetic Screening (PGS)?
PGS (Preimplantation Genetic Screening), now more commonly called PGT-A (Preimplantation Genetic Testing for Aneuploidy), is used to check the number of chromosomes in embryos — not specific diseases. This helps detect aneuploidy (extra or missing chromosomes), a common reason for failed implantation or miscarriage.How PGS Works:
- Embryos from IVF are cultured to the blastocyst stage.
- A few cells are biopsied and sent for chromosomal analysis.
- The test checks if the embryo has the normal 46 chromosomes (23 pairs).
- Only chromosomally normal embryos are chosen for transfer.
Example:
PGS can detect conditions like:- Down Syndrome (Trisomy 21)
- Turner Syndrome (Monosomy X)
- Klinefelter Syndrome
PGS Is Recommended For:
- Women aged 35 and above (higher risk of chromosomal errors)
- Couples with repeated IVF failures or miscarriages
- Those with unexplained infertility
- To select the healthiest embryos for better IVF success
PGD vs. PGS: The Key Differences
| Feature | PGD (Preimplantation Genetic Diagnosis) | PGS (Preimplantation Genetic Screening / PGT-A) |
| Purpose | Detects specific inherited genetic diseases | Screens for abnormal chromosome numbers |
| Who Needs It | Couples who are genetic disorder carriers | Older women, recurrent IVF failure, or miscarriage |
| What It Tests | Single-gene mutations (e.g. Thalassemia, CF) | Chromosome count (e.g. Down syndrome) |
| Outcome | Prevents transmission of genetic disorders | Increases IVF success and reduces miscarriage risk |
| Complexity | More targeted and complex testing | Broader screening of embryo chromosomes |
| Also Known As | PGT-M (Preimplantation Genetic Testing for Monogenic Disorders) | PGT-A (Preimplantation Genetic Testing for Aneuploidy) |
Why PGD and PGS Matter in IVF
Both PGD and PGS dramatically improve IVF outcomes by helping select embryos with the highest chance of resulting in a healthy baby.Benefits Include:
- Reduced risk of genetic diseases
- Fewer miscarriages
- Improved implantation rates
- Reduced emotional and financial stress from failed cycles
- Peace of mind knowing the embryo is chromosomally normal
When to Discuss PGD or PGS with Your Doctor
You should discuss these options with your fertility specialist if you:- Are above 35 years old
- Have experienced 2 or more miscarriages
- Have a family history of genetic disorders
- Have had failed IVF attempts
- Are planning IVF with donor eggs or sperm
Emotional Side of Genetic Testing in IVF
It’s natural to feel anxious about genetic testing — it involves advanced science and big decisions. But at Vrinda Fertility, couples receive emotional counseling, clear guidance, and complete transparency to help them feel confident and informed.Vrinda Fertility Expertise in Genetic Testing
At Vrinda Fertility, we integrate world-class embryology labs, genetic testing technology, and compassionate counseling to ensure that every couple receives the best possible care. Our PGD and PGS programs are handled by highly skilled geneticists and IVF specialists who prioritize:- Embryo safety during biopsy
- Accurate, rapid results
- Tailored embryo transfer plans for maximum success.
Conclusion: PGD vs. PGS — Choosing What’s Right for You
Both PGD and PGS play vital roles in ensuring a healthy, successful pregnancy.- Choose PGD if there’s a risk of genetic disease.
- Choose PGS to ensure your embryos have normal chromosomes and improve IVF outcomes.
Frequently Asked Questions (FAQ)
1. Are PGD and PGS painful?
No. The testing is done on embryos in the lab — not on the patient.
2. Does genetic testing damage embryos?
At advanced IVF labs like Vrinda Fertility, embryo biopsy is performed with high precision. The embryos remain safe for transfer.
3. Can PGD/PGS guarantee a healthy baby?
No test can guarantee it 100%, but they significantly reduce the risks of genetic or chromosomal problems.
4. Are these tests expensive?
They add to IVF cost but increase success rates, often saving money and emotional stress from failed cycles.
5. What’s the success rate of IVF with PGS or PGD?
Studies show 30–40% higher success rates in selected patients using these tests.
