How should patients be counselled regarding PGT-A benefits and limitations?

[Verified against ESHRE PGT good practice recommendations 2020 and ASRM RPL 2026] ESHRE specifies what counselling must cover before PGT. For PGT-A the essential items: Chromosomal mosaicism is an inherent biological phenomenon in human preimplantation embryos, and should be explained as such — including how it may affect diagnosis and the centre's embryo transfer policy. The possibility of misdiagnosis, with error rates expressed as false negative or false positive results. These should be based on the centre's OWN in-house work-up and follow-up analysis, not on published figures from elsewhere. The option, and in some cases recommendation, of prenatal diagnosis to confirm the PGT result if pregnancy occurs. On mosaic and segmental results specifically: The clinical significance of transferring mosaic embryos is currently unknown. Each centre decides whether or not to report mosaicism, based on internal validation and current literature — so practice legitimately differs between clinics, and patients moving between centres should be told this. The centre's policy on identifying and transferring mosaic or segmental-aneuploid embryos must be documented and shared with the patient during genetic counselling. Where such an embryo is transferred and pregnancy occurs, appropriate follow-up should be arranged. On efficacy, be direct: PGT-A has not been shown to increase live birth rate or reduce time to pregnancy versus expectant management. It can reduce the chance of transferring an aneuploid embryo, which is a different claim. Practical: results should be discussed with the couple BEFORE embryo transfer, and must not be communicated orally — a written or electronic report is required.