PGT – Preimplantation Genetic Test

The Preimplantation Genetic Test (PGT for its acronym in English) is the technique previously known as Preimplantation Genetic Diagnosis (PGD).

This is performed by means of biopsy or extraction of one or several cells from the embryos obtained after the In Vitro Fertilisation in order to analyse their genetic or chromosomal content. In this way, only those embryos that do not present anomalies and have the best chances of achieving implantation are transferred to the mother’s uterus.  Is performed on the embryo before it is implanted in the womb. PGT provides information on the condition of each of the embryos conceived and only allows the healthy ones to be transferred to the womb.



Institut Marquès
Pregnancy / cycle 90,7%
Clínical pregnancy / cycle 80,4%
Live birth rate / cycle 78,7%
Twin pregnancies 5,0%


At Institut Marquès PGT is performed in all our centres using Next Generation Sequencing (NGS). This is the most innovative method that is currently applied to the embryos’ genetic diagnosis. When the PGT is performed in blastocyst stage, the cryopreservation of the embryo is unavoidable while waiting for the results, which take approximately two weeks. If PGT is performed during day three of the evolution, the diagnosis will be ready when the embryo reaches blastocyst stage and its cryopreservation is not necessary. Institut Marquès has proved that the results of the Preimplantation Genetic Test are equally effective regardless of the day the biopsy is performed.

The genetic diagnosis of embryos will be essential in the future of Assisted Reproduction. New techniques are still in the development phase, such as the Non-Invasive Preimplantation Genetic Test, a procedure that has not yet achieved reliable results.

The PGT technique is the result of the combination of in vitro fertilisation and genetic analysis.
It benefits three groups of patients:

Institut Marquès is an international reference centre for PGT. Our patients  know their chances of pregnancy are increased by means of the technique.

Doctora Lopez Teijon

Physician of the Year in Assisted Reproduction 2019

Dr. Marisa López-Teijón’s opinion

“Preimplantation Genetic Diagnosis allows us to select the chromosomally normal embryos. Hence, we increase the chances of pregnancy and decrease the risk of a spontaneous miscarriage or finding a problem we could’ve prevented during an amniocentesis test”. Read more.

Inquire about your case

Is it possible to perform a genetic analysis of the embryos before they are transferred to the uterus?

Yes. It is possible to analyze genetically the embryos prior their transfer to the uterus. This technique is called Preimplantational Genetic Diagnosis (PGD) or Embryo Genetic Analysis.

Does ‘Embryo Genetic Analysis’ increase pregnancy rate?

Yes, because it avoids the transfer of embryos that contain an abnormal number of chromosomes (aneuploid embryos). Using this procedure, only chromosomally normal embryos with a good morphology are transferred.

Does ‘Embryo genetic analysis’ decrease the rate of spontaneous miscarriage?

Yes. ‘Embryo Genetic Analysis’ can significantly reduce spontaneous miscarriage because most of them are due to genetic anomalies.

Does ‘Embryo Genetic Analysis’ prevent the birth of children with chromosomal abnormalities?

Yes. It can avoid the birth of children with chromosomal abnormalities such as trisomy 21 or Down’s syndrome.

How is embryo genetic análisis performed?

In vitro fertilisation-derived embryos are cultured until Day 3 of development at which stage embryos have 6 to 8 cells or blastomeres. Then, a hole is made in the zona pellucida (the layer that covers the embryo) and one cell is aspirated using a special micropipette (biopsy procedure). The aspirated cell is processed for genetic analysis while the embryo is mantained in culture. Genetically normal embryos are transferred to the uterus the next day.

Could this technique damage the embryo?

The biopsy procedure is highly sophisticated technique that when performed by experienced embryologists should not negatively affect embryo viability.

Is it posible to prevent a genetic disease using ‘Preimplantational Genetic Diagnosis’ (PGD)?

Yes. The group of patients that benefit most from Preimplantational Genetic Diagnosis (PGD) are couples with a history of a genetic disease. This is so because it allows to transfer normal embryos free of the genetic disease and, therefore, pregnancy termination is avoided. There are two types of monogenic disorders: autosomal disorders such as Cystic frybrosis, Myotonic Distrophy, Huntington’s disease or sex-linked disorders as Fragile X Syndrome, Douchenne’s Muscular Dystrophy or Hemophilia.

Can patients with a previous spontaneous miscarriage benefit from ‘Preimplantational Genetic Diagnosis’ (PGD)?

Yes. They can prevent further pregnancy loss by performing Preimplantational Genetic Diagnosis. It is of paramount importance in the management of infertility couples with an embryo factor.

Can any couple benefit from ‘Preimplantational Genetic Diagnosis’ (PGD)?

Yes. Taking into account all the benefits mentioned above, more and more IVF patients choose to perform Preimplantational Genetic Diagnosis (PGD). Specially when the future mother is over 37 years of age or had a previous IVF failure.