Preimplantation Genetic Testing (PGT): When to Consider it & What Are the Success Rates?

What is Preimplantation Genetic Testing? 

Preimplantation Genetic Testing (PGT) is a cutting–edge prenatal screening test used to identify serious diseases caused by genetic abnormalities and/or chromosomal abnormalities in preimplantation embryos created via IVF (In Vitro Fertilization). PGT allows transferring genetically normal embryos into the intended mother’s or surrogate mother’s uterus for further gestation. 

Who is it for? 

• Singles and couples with a history of recurrent implantation failures and/or recurrent miscarriages.
• Singles and couples with a male factor infertility.
• Singles and couples with a history of genetic diseases.
• The single/couple is anxious about reproductive risks, even though there is no specific indication that they are at increased genetic risk.
• Singles and couples wishing to do Gender Selection. 

When to try it? 

The current indications for PGT include recurrent implantation failures, recurrent miscarriages, advanced maternal/paternal age, male factor infertility, and genetic disorders in the mother or/and father including mosaicism of sex chromosomes, structural rearrangements in chromosomes, and monogenic genetic diseases.  

What types of PGT are there? 

• Preimplantation Genetic Testing for Aneuploidy — PGT–A 
• PGS (Preimplantation Genetic Screening)/CCS (Comprehensive Chromosome Screening)/PGT–A (Preimplantation Genetic Testing for Aneuploidy) involves checking IVF embryos for abnormalities in the number of chromosomes. 
• Preimplantation Genetic Testing for detecting monogenic disorders — PGT–M
• PGT–M involves checking IVF embryos for monogenic disorders caused by mutations in a single gene to avoid the transmission of single gene disorders to a future child.
• Preimplantation Genetic Testing for detecting structural chromosomal rearrangements — PGT–SR
• PGT–SR is used for screening IVF embryos for structural chromosomal rearrangements caused by balanced translocations and inversions including duplications, deletions, translocations, insertions, inversions, and ring chromosome formation.

Who should consider PGT–A?

• Women with an age of 35 years and above.
• Women with a history of recurrent implantation failure (RIF) who had previously undergone at least three Embryo Transfer cycles using top–quality embryos (cleavage embryos or blastocysts).
• Women with a history of recurrent pregnancy loss after successful transfer and implantation. 
• Men with a history of high sperm DNA fragmentation levels.
• Patients with a diagnosis of a chromosomal abnormality.
• Couples with severe male factor infertility.

Who should consider PGT–M?

• Couples in which one partner has a genetic disorder.
• Couples in which the mother is a carrier of a genetic disorder.
• Couples in which both partners are carriers of a genetic disorder. 

Who should consider PGT–SR?

• Couples in which one partner is a carrier of a structural chromosomal abnormality.
• Singles who are the carriers of a structural chromosomal abnormality.

How long does Preimplantation Genetic Testing take?

The Preimplantation Genetic Test itself takes a few seconds to remove the genetic material (removing one or more cells) from an IVF embryo. It could take 12, 24, or 36 hours to do the genetic test depending on the testing and the quality of the genetic lab. PGT results usually take 1–3 weeks, depending on the type of testing being performed. Once PGT results are received, an embryo transfer can be scheduled.

PGT Success Rates

PGT–A, like all Screening Tests (PGT–M and PGT–SR), is not 100% accurate. Most PGT labs report an accuracy rate of 97–99%, meaning there remains a 1–3% rate of a false negative or false–positive result. 

For a fresh cycle with PGT–A to identify chromosomal abnormalities in IVF embryos, the pregnancy rates are around 56 to 72%. For a frozen cycle with PGT–A, the pregnancy rates are a little bit lower — around 54 to 65%. 

For IVF cycles with PGT–M for detecting monogenic disorders in IVF embryos, the cumulative pregnancy rates are around 54 to 90%, with ongoing pregnancy rates around 49 to 75%. 

For IVF cycles with PGT–SR, the cumulative pregnancy rates are around 70 and 88%, with ongoing pregnancy rates around 43 to 70%.