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Preimplantation Genetic Testing, PGT

Preimplantation genetic testing can increase the chance of an ongoing pregnancy

Every patient who visits Texas Fertility Center (TFC) wants the best chance of bringing home a healthy baby. Preimplantation genetic testing (PGT) can make this possible for a wide range of patients, especially women older than 35, couples who have faced recurrent miscarriage and IVF cycle failure, and women and men with inheritable genetic illnesses. Our San Antonio infertility doctors offer PGT along with IVF, and provide extensive counseling on how this advanced genetic testing can help certain patients.

A look at preimplantation genetic testing

When patients are considering preimplantation genetic testing, our San Antonio infertility doctors will explain how PGT works and the different types of testing available. With improvements in testing platforms even in the past five years, detailed testing can be done to look for specific genetic problems in embryos.

  • Absence or duplication of chromosomes (PGT-A and PGT-A+, for aneuploidy)
  • Absence or presence of a disease-causing gene (PGT-M, for monogenic disorders)
  • Rearrangements of chromosomes (PGT-SR, for chromosomal structural rearrangement)

Each of the PGT tests available can look for the presence or absence of a known flag in the embryo’s DNA. With the right number of signals, the advanced scientists at our partner genetic testing centers can determine whether an embryo appears to have the right number and makeup of chromosomes. This testing can also be used to identify disease-causing genes for certain conditions for which patients know they are at risk, such as for sickle-cell trait, cystic fibrosis or Huntington’s disease.

Different types of testing can help different types of patients. Our San Antonio fertility specialists will be able to counsel patients about the best type of testing available for their situation.

How PGT works

PGT, or preimplantation genetic testing, occurs exclusively during an IVF cycle, between the steps of fertilization and embryo transfer. It cannot be used in IUI or intercourse cycles because in those cases, the developing embryo stays inside the body.

During an IVF cycle, after the egg and sperm have fertilized and the cellular mass, or embryo, has grown for five to six days, the embryologists can carefully biopsy, or sample, the cells growing on the perimeter of the embryo, as a representation of the cells of the entire embryo. While the embryo gets cryopreserved and stays at the IVF laboratory, the biopsy tissue is sent off to a specialized lab for genetic testing, where the DNA is amplified (recopied and made larger), and specialized bioinformatics are performed to identify the correct balance of chromosomes.

Once the test results are available, our embryology and clinical teams will be able to interpret these results for patients to understand which embryos are suitable for transfer. While genetic testing cannot yet correct DNA problems in the embryo, identifying that the embryo has 46 chromosomes is a big step when it comes to achieving a successful pregnancy, especially for older women. This is why PGT can be used to help improve per-transfer success rates for women of advanced maternal age.

Contact us to schedule a consultation with our San Antonio infertility doctors, who have received extensive fellowship training in advanced testing such as preimplantation genetic testing. We will get you on the right next steps toward parenthood.