Causes & Treatment

IVF – What is PGT and is it Necessary? Clinica Tambre Answer your Questions

Eloise Edington  |   2 May 2020

Your IVF PGT questions, answered

We recently ran a poll asking what you’d like to know more about from our leading experts. The resounding answer was PGT. So, we gathered your questions via Instagram and put them to trusted fertility clinic, Clinica Tambre in Madrid, Spain.

Read below what Dr Laura Garcia, Medical Director at Clinica Tambre has to say on the subject. | @clinicatambre

What is PGT / PGS  / PGD? What is the Difference?

  • PGT: Pre-genetic testing (includes PGS and PGD). It is a test carried out on the embryo (usually on Day 5), which consists of a biopsy, in order to study some of its cells.
  • PGS: Pre-genetic screening is a type of genetic test to study aneuploidy in embryos – possible abnormal chromosomes disorder
  • PGD is pre-genetic diagnostic, and usually refers to the genetic test done to study genetically transmitted mutations in embryos – transmitted from the mother or the father.

Firstly, can we Talk about Genetic Compatibility Tests for the Mother and Father?  What do these Involve and When do You Think they are a Good Idea?

It is recommended to offer these tests to all our patients before a fertility treatment (egg donation, IVF, double donation). It is a test to study possible incompatibility between both parents regarding recessive diseases such as cystic fibrosis muscular atrophy, and many others diseases that we are all at risk of carrying.

Pre-implantation Genetic Diagnosis (PGD) of Embryos is a Little Confusing because of the Different Acronyms. Please Explain Each One:

PGDS; PGD-A studies the karyotype of embryos (euploid and aneuploid embryos); PGD-M studies monogenic diseases that one of the parents could transmit to their embryos; PGD-SR is a type of genetic diagnostic for people having a chromosome rearrangement that could lead to an increased risk of creating embryos with incorrect chromosomes, number or structure.

For which Patients / Cases are Such Tests Recommended?

  • PGS/PGTA: Women with advanced maternal age, repeated miscarriages, previous IVF failure.
  • PGD-M: Women or men that have risk of transmitting genetical illnesses to their embryos.
  • PGD-SR: Women or men having abnormalities in their karyotypes.
PGT testing Clinica Tambre

Some have read that PGT can be controversial, with some clinics saying that PGD-A can be inaccurate and give false positives for abnormality, leading to perfectly good embryos being discarded; also, that a day 5 blastocyst which shows abnormal chromosomes can self-correct and produce a perfectly healthy baby. 

What do you Feel about this Stance and what in your View are the Pros and Cons?

Of course, all medical tests are not 100 % certain. But, when there is a high risk of creating abnormal embryos that could lead to miscarriages or babies with syndromes, or even implantation failures, it is recommended to discuss individually with each couple or woman before starting the treatment, and to explain the pros and cons of this test.

Please can you Define the Term ‘Mosaic Embryo’?  Do you think they Should be Transferred or Discarded?

The mosaic embryo is an embryo that has both normal and abnormal cells (some of its cells are absolutely normal in terms of chromosomes, whereas others are abnormal). The recommendation to transfer or not depends on different aspects: the number of chromosomes involving the mosaicism-for instance sexual chromosomes, 21, 13 and 18 should be excluded, the number of chromosomes involved in the abnormality (one or more chromosomes), etc.

Can Testing Harm the Embryo?

Naturally, it is an invasive test that could eventually harm the embryo. That is the reason why it is extremely necessary to do it in a very good clinic with a high-tech laboratory and senior biologists.

Do People use this Method to Find Out the Sex of their Embryo?

It could be the case in some countries, but it is not possible in Spain.

How much does PGT Cost?

It depends on the type of genetic testing. For instance, in PGT-A, it depends on the number of embryos biopsied. Our team of Patient Care coordinators will be more than happy to answer this type of question if you send an e-mail to

For Someone who has Few Embryos, a low AMH and is over 40, would you recommend PGT?

Women with a low ovarian reserve, or with only one embryo are the ones that benefit less from this technique. On the other hand, if a woman is older than 40, there is a high risk of abnormality and then it is necessary to discuss with them if they want to carry on with the test or not.

Thanks to Clinica Tambre for answering our readers’ questions. Watch back their #fertilityexpertslive all about PGT here. Make sure to tune in on Instagram to hear more on the topic!

If you’d like further information on PGT or anything related to this matter, please message us here.

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