Introduction: Subchromosomal abnormalities in preimplantation embryonic aneuploidy screening.

The application of next generation sequencing platforms for embryonic aneuploidy screening provides enhanced resolution that allows routine evaluation of subchromosomal copy number abnormalities and mosaicism. Approximately 20% of embryos that would be designated as euploid using the conventional 24-chromosome aneuploidy screening will have evidence of a subchromosomal abnormality or mosaicism. This new information brings many challenges. Understanding the impact of these abnormalities on implantation and delivery rates is key to optimizing clinical counseling and management.