The status of preimplantation genetic testing for aneuploidy (PGT-A) – A critical appraisal

Abstract

Preimplantation genetic testing for aneuploidy (PGT-A) relies on extended embryo culture and trophectoderm biopsy at the blastocyst stage. Its utility is thus dependent on obtaining an adequate embryo yield and blastulation rates. i.e. before embryos can be evaluated at the blastocyst stage, they must first survive extended culture and reach that stage for biopsy. Maternal age notably influences these parameters, with increased age associated with declining euploidy rates and higher oocyte requirements to obtain euploid blastocysts. This limits PGT-A’s applicability in poor-prognosis patients. Moreover, the biological and technical limitations inherent to PGT-A including intra-embryonic mosaicism and chromosomal heterogeneity pose significant challenges to its accuracy and clinical application. Multiple studies have demonstrated discordance between trophectoderm (TE) biopsies and inner cell mass (ICM) chromosomal constitution, raising questions about the reliability of TE biopsies as a surrogate for whole embryo chromosomal status. Several studies also suggest that PGT-A does not universally improve live birth rates and may inadvertently exclude embryos with reproductive potential, especially in patients with few blastocysts. Professional societies, including PGDIS, highlight favorable outcomes but may underemphasize conflicting evidence. Currently, the broad application of PGT-A is not supported, especially in low embryo yield scenarios. Individualized counseling, transparent laboratory reporting, and further prospective trials are essential to define PGT-A’s role in modern IVF.