Preimplantation Genetic Testing (PGT)

Overview

Preimplantation Genetic Testing (PGT) is the process of screening embryos for chromosomal abnormalities before they are transferred to the uterus. It is performed alongside IVF to select embryos with normal chromosomes, reducing miscarriage risk and increasing the chance of a successful pregnancy.

After eggs are retrieved and fertilized in the lab, embryos are cultured to the blastocyst stage (day 5-7). A few cells are then carefully removed from each embryo for genetic analysis. Tested embryos are frozen while awaiting results, and only chromosomally normal embryos are transferred in a subsequent frozen embryo transfer (FET) cycle.

Types of PGT

The process

1. Standard IVF cycle — ovarian stimulation, egg retrieval, fertilization
2. Embryo culture — embryos grown to blastocyst stage (day 5-7)
3. Embryo biopsy — 3-5 cells removed from the trophectoderm of each embryo
4. Freeze embryos — all embryos vitrified while awaiting results
5. Genetic analysis — results available in 1-3 weeks
6. Transfer normal embryo — chromosomally normal embryo transferred in a subsequent FET cycle

Who is this for?

• Women aged 35 and older (higher risk of chromosomal abnormalities)
• Recurrent pregnancy loss (2 or more consecutive miscarriages)
• Repeated IVF failure with no identified cause
• Couples who are carriers of a known genetic condition
• Parents with a balanced chromosomal translocation or inversion
• Sex selection for medical reasons (e.g., avoiding X-linked diseases)

Pros and limitations