The Preimplantation Genetic Test (PGT for its acronym in English) is the technique previously known as Preimplantation Genetic Diagnosis (PGD). Is a new diagnostic method that is performed in the embryo before its implantation in the uterus. The PGT informs about the state of each one of the embryos conceived, and allows only the healthy ones to be transferred to the uterus. The PGT technique is the result of the combination of an in vitro fertilization and genetic analysis. Institut Marquès has proved that the results of the Preimplantation Genetic Test are equally effective regardless of the day the biopsy is performed.

How is Preimplantation Genetic Test performed?

  1. In Vitro Fertilization to obtain embryos.
  2. Embryo biopsy. The embryo biopsy is performed 72-76 hours after the recovery of the ovules, when the embryo is in a 6-8 cell stage. It consists of extracting a cell from the embryo without compromising its normal development. Once the biopsy is done, the embryo is returned to the laboratory incubator, where it will be kept in in vitro culture with the appropriate environmental conditions to continue its development until the moment of transfer to the patient’s uterus.
  3. Test genetic analysis. The cell obtained by biopsy is processed for analysis and subjected to genetic study.
  4. Embryonic transfer. The result of the genetic analysis is transmitted to the assisted reproduction team through a detailed report and it is decided which embryos will be transferred according to the chromosomal endowment and the morphological characteristics of embryonic viability.

The transfer is made immediately after the analysis, usually 4 or 5 days after the recovery of the ovules.

Can the embryo be damaged by extracting a cell?

At the moment in which the biopsy is carried out, each cell of the embryo contains all the genetic information, the extraction of one cell does not affect the correct development of the rest of the cells of the embryo.

This technique requires great precision, performed by experts does not alter the evolution of the embryo. The risk of embryonic block is 0.67%.

What types of Preimplantation Genetic Test (PGT) can be performed?

You can basically perform three types of PGT:

  • PGT ​​for the study of aneuploidies: in cases of sterility, it is common to perform this type of analysis in embryos. The chromosomal envelope of the embryo is studied, that is, the number of chromosomes that the embryo has. This allows to select only those embryos with the correct number of chromosomes. It is recommended when:
  • PGT for the study of chromosomal abnormalities: when one of the two members of the couple is a carrier of a chromosomal abnormality in the karyotype (for example: translocation, inversion, …). In these cases, the embryos are analyzed in order to select those that are healthy or balanced for the chromosomal anomaly studied.
  • PGT ​​for the study of monogenic hereditary diseases: when one of the two members of the couple is a carrier of a hereditary monophonic disease (for example: cystic fibrosis, muscular dystrophy, …)

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