Episode 7 - PGT explained and when it is required - Dr Ying Li
Preimplantation genetic testing: a guide for GPs
Genetic testing can raise as many questions as it answers. Patients may arrive with a family history of an inherited condition, an unexpected carrier screening result or concerns after repeated pregnancy loss. Others want to understand whether testing embryos could be relevant to their IVF treatment. For GPs, the challenge is to help patients understand what different tests can tell them, where uncertainty remains and when specialist advice would be useful.
In this episode of Fertility in General Practice, host Dr Ali Hodgkinson speaks with Dr Ying Li about preimplantation genetic testing, or PGT. They explore the terminology, the testing process and the importance of matching a test to a patient's circumstances, rather than treating PGT as a routine answer for everyone.
Understanding the different types of PGT
PGT is an umbrella term for genetic testing of embryos before transfer during IVF. Dr Li explains how it has replaced older terminology such as preimplantation genetic screening and preimplantation genetic diagnosis. Using consistent language helps patients and clinicians understand what is actually being assessed.
PGT-M looks for a particular monogenic, or single-gene, condition. It may be considered when a known inherited condition or carrier screening result identifies a risk to a future child. The relevant genetic change needs to be understood before a suitable test can be prepared. In some situations, testing must be tailored specifically to the family.
PGT-A assesses chromosome number, while PGT-SR relates to structural chromosome rearrangements. These tests address different questions. Understanding that distinction is a useful starting point when patients ask whether genetic testing might help them.
What happens during testing?
PGT requires embryos created through IVF. Dr Li describes how a small sample of cells is taken from the outer part of a developing embryo for genetic analysis. These are cells associated with the tissue that goes on to form the placenta, rather than the inner cell mass that develops into the baby.
Not every embryo reaches a stage suitable for biopsy. That is an important expectation to discuss before treatment, alongside the risks and limitations of the procedure. A test result is one part of the clinical picture; it cannot guarantee implantation, a continuing pregnancy or a healthy baby.
Why individual circumstances matter
The episode explores how age, embryo numbers, previous pregnancy losses and the reason for testing influence the conversation. A patient with a known inherited condition faces different decisions from someone considering chromosome testing during IVF without an identified genetic diagnosis.
Dr Li also discusses mosaic results, where the sampled cells do not all show the same chromosome findings. These results need careful interpretation and specialist counselling. They should not be reduced to a simple reassuring or concerning label without considering the details of the result and the patient's options.
The discussion also considers testing during pregnancy. Patients may assume that an embryo test removes the need to discuss antenatal screening or diagnosis. Instead, the available options and any uncertainty should be reviewed with the treating team, with clear advice about what further results might mean.
The role of genetic counselling and GP referral
Pre-test and post-test support are central to the discussion. Genetic counselling can help patients understand what a test covers, what it does not cover and what the possible findings could mean for their reproductive choices. A clinical geneticist may also be involved when a specific inherited condition is being assessed.
For GPs, a relevant family history, known genetic condition, concerning carrier screening result or recurrent pregnancy loss can prompt a discussion about referral. Dr Li encourages practitioners to seek advice when they are uncertain rather than waiting until every detail has been worked out. A clear history and copies of existing genetic results can help the specialist team identify the right next steps.
Listen to the episode
Listen to Dr Ying Li and Dr Ali Hodgkinson discuss how to explain PGT clearly, support informed decisions and connect patients with appropriate genetic and fertility expertise. The episode offers a practical introduction to a technical topic without losing sight of the people making these decisions.
About Dr Ying Li
Dr Ying Li is a CREI-qualified fertility specialist with expertise in complex fertility care, male infertility, reproductive surgery and recurrent pregnancy loss. He consults at Genea Sydney CBD and Genea Sydney South. His training includes specialist obstetrics and gynaecology, advanced laparoscopic and endoscopic surgery, and subspecialty training in reproductive endocrinology and infertility. His approach brings together investigation, clear explanations and individualised planning for patients facing a wide range of fertility concerns.
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