Preimplantation Genetic Testing for Aneuploidy (PGT-A), formerly known as preimplantation genetic screening (PGS), is a technique used during in vitro fertilization (IVF) to screen embryos for chromosomal abnormalities before implantation. Like any medical procedure, PGT-A has both advantages and disadvantages. Pros of PGT-A: Reduced Risk of Aneuploidy: PGT-A helps identify embryos with chromosomal abnormalities, such as aneuploidy, which can reduce the risk of implantation failure, miscarriage, and certain genetic disorders. Improved IVF Success Rates: By selecting embryos with the correct number of chromosomes, PGT-A can enhance the chances of a successful implantation and a healthy pregnancy, leading to improved overall IVF success rates. Reduced Miscarriage Rates: Identifying and transferring embryos with the correct chromosomal makeup may decrease the likelihood of spontaneous miscarriages, particularly in older women who are at a higher risk of producing embryos with chromosomal abnormalities. Family Planning for Genetic Disorders: PGT-A allows couples at risk of transmitting specific genetic disorders to screen embryos for these conditions, enabling them to make informed decisions about which embryos to implant. Cons of PGT-A: No Guarantee of Pregnancy: PGT-A does not guarantee a successful pregnancy. Other factors, such as uterine receptivity, can still impact the success of embryo implantation. False Positives and Negatives: PGT-A is not foolproof, and false positives and negatives can occur. In some cases, embryos identified as abnormal may be viable, leading to the potential discarding of healthy embryos, or vice versa. Invasive Nature: The procedure involves removing a small number of cells from the developing embryo, which some argue could potentially harm the embryo, although the impact is generally considered minimal. Financial Cost: PGT-A adds an additional cost to the already expensive IVF process. The financial burden may be a significant consideration for some couples, especially if insurance does not cover the expense. Limited Scope: PGT-A primarily screens for numerical chromosomal abnormalities and may not detect all genetic disorders or structural chromosomal abnormalities. Additional testing, such as preimplantation genetic testing for monogenic disorders (PGT-M) or preimplantation genetic testing for chromosomal structural rearrangements (PGT-SR), may be necessary for a more comprehensive assessment. In summary, while PGT-A offers potential benefits in terms of reducing the risk of aneuploidy and improving IVF success rates, it is essential for couples to weigh these advantages against the potential drawbacks and consider their individual circumstances, including the financial and emotional aspects of the procedure.

1. Pitfalls of
PGTa
Dr Kaberi Banerjee

2. WHAT IS PGS WHAT IS PGTA PROBLEMS
WITH PGTA
VARIOUS
STUDIES

3. The Earlier
names of
Genetic Tests
on Embryos

4. Current names of Genetic Tests on the
Embryo

5. PGTa claims to reduce
implantation failure in IVF and
reduce the risk of miscarriages.
It is a very expensive test!
Is it true?

7. Some Facts of
PGTa
• All cells in any embryo doesn’t
demonstrate aneuploidies i.e
chromosomal abnormalities.
There are only small number of
cells which shows abnormalities.
If embryo biopsy shows abnormal
DNA, it is not the whole cell will
be abnormal.

8. Some Facts of
PGTa
• It is also observed that abnormal cells
often self-destruct and some cells self-
correct by themselves. This self-correction
happens more in cells which makes baby
than the cells which makes placenta
(trophectoderm). For PGT-a, embryo
biopsy is taken from trophectoderm. This
shows that there is no benefit of doing
blastocyst stage embryo biopsy as cells
which are tested are of outer layer not the
inner layer which forms the baby.

9. Overall same , but can show as 50% and 100%
Depends which data you want to show!
Non PGS-50%?
10
8
6
4
2+2
-ve/+ve
PGS-100%?
10
8
6
4
2
+ve
Extra Cost
Freezing
Transfer Time
Extra Cost
PGS
Personnel
Laboratory
WaitingTime

10. The STAR Study
• A total of 661 women (average age 33.7
± 3.6 years) were randomized to PGT-A (n
= 330) or morphology alone (n = 331).
• PGT-A did not improve overall
pregnancy outcomes in all women, as
analyzed per embryo transfer or per ITT.
There was a significant increase in OPR
per embryo transfer with the use of PGT-
A in the subgroup of women aged 35-40
years who had two or more embryos that
could be biopsied, but this was not
significant when analyzed by ITT.

11. • The STAR study thus reveals that
PGT-A does not beneficially affect
IVF outcomes in confirmation of
another relatively recent study in
women 37 years and older by Kang
et al. Like the STAR study, Kang et
al. reported seemingly improved
live birth rates following PGT-A but
this outcome advantage, actually,
reversed itself after correct intent-
to-treat analysis of outcomes with
reference cycle start: Pregnancy as
well as live birth rates, indeed,
ended up to be significantly higher
in control non-PGT-A patients (49.5
vs 21.5% and 39.8 vs 19.9%).
• Considering all presented
evidence here, it is difficult to
understand what further argument
can be made for the continuous
routine clinical utilization of PGT-A
to improve IVF outcomes.
•

12. • Errors may occur during the genetic analysis of the small
amount of DNA collected.
• Mitotic mosaicism may lead to sampling errors
• Some normal embryos will be discarded, leading to an
overall decrease in the cumulative pregnancy rate
achievable by the eventual transfer of all embryos in the
cohort.
• Real possibility of damage to the blastocyst as result of the
trophectoderm biopsy.
• No studies have addressed the impact of trophectoderm
biopsy in embryos with less than ideal morphologic
characteristics, in older patients, or after an intervening
cryopreservation procedure.

13. Assumptions
• Blastulation Rate- 47%
• Aneuploidy Rate- 59%
• IR-D3 21-50%,
• Non PGS D5 38-47%,
• PGS D5 39-65%
• Mosaicism and Technical
Errors reduce LBR

16. • Any Intervention that claims to
increase the pregnancy rate in IVF
must stand the test of time…till
then must be clearly offered as an
experimental test and at least
should not financially drain the
patient.