PGT embryo testing: Questions About Purpose and Limitations

Preimplantation genetic testing, or PGT, examines genetic information from an embryo before transfer. Different tests answer different questions. Before agreeing, ask for the full name of the proposed test, the reason it is being offered and the decision the result would change. Embryo testing is not a guarantee of a pregnancy or a healthy child.

Identify which type of testing is proposed

PGT M looks for a particular inherited condition involving a known gene. PGT SR is used when a chromosome structural rearrangement is relevant, such as a known rearrangement in a parent. These tests may help people reduce the chance of passing on a specific condition, including people who do not otherwise have difficulty conceiving.

PGT A screens chromosome number to help with embryo selection. It is not a substitute for testing for a specific familial condition. Ask a genetics professional to explain the scope of the test in ordinary language and to identify conditions it will not assess. The embryo grading guide explains another important distinction: appearance under the microscope is different from genetic testing.

Discuss the practical steps and possible results

Testing involves IVF and sampling cells from embryos. The laboratory may need to develop a test for the specific inherited condition before treatment proceeds. Ask what family reports or samples are needed, how long preparation takes and whether embryos will be frozen while results are awaited.

The process can leave no embryo suitable for the planned transfer. Results may also be inconclusive or require a specialist discussion. Ask how the clinic handles these situations and what would happen before an embryo is excluded from future use. A mosaic chromosome result deserves individual interpretation; it should not be treated as a simple promise of success or failure.

Separate different measures of benefit

For chromosome screening, avoiding some miscarriages and increasing the total chance of a live birth are different outcomes. Evidence does not support promising that routine PGT A will improve the chance of a baby for everyone. Testing can reduce the number of embryos available, and there are risks of inaccurate results and damage during biopsy.

Ask about outcomes across all embryos from a retrieval, including people who never reach transfer. The IVF statistics guide helps you recognise when a quoted success rate counts only selected transfers. Also request the additional costs and the effect on the treatment timetable.

Plan counselling and care after a result

For inherited conditions, genetic counselling should cover alternatives, the test’s limitations and your preferences before treatment begins. Testing remains a choice. You can ask for a second explanation or time to consider a result before making a transfer decision.

PGT M is not perfectly accurate, so prenatal testing should still be offered in an ensuing pregnancy to confirm the result and consider other conditions. Ask what follow up would be recommended in your circumstances. Keep the laboratory report so your pregnancy care team knows precisely what was tested and what uncertainty remains.