Should pre-implantation genetic screening be implemented to routine clinical practice?

The utilization of trophectoderm biopsy combined with comprehensive chromosome screening (CCS) tests for embryonic aneuploidy was recently suggested to improve IVF outcome, however, not without criticisms. Since mosaicism has been reported in as high as 90% of blastocyst-stage embryos, we aimed to evaluate the accuracy of trophectoderm multiple biopsies using next-generation sequencing (NGS). Eight top quality blastocysts underwent three trophectoderm biopsies each, followed by NGS. In four blastocysts, the rest of the embryo, which included the inner cell mass, was also analyzed. Five of the 24 (20.8%) trophectoderm biopsies revealed inconclusive results, while 4 (16.6%) demonstrated embryonic mosaicism. Overall, 10 (35.7%) of the 28 (24 trophectoderms and 4 inner cell masses) biopsies revealed mosaicism or inconclusive results. Our preliminary observations contribute to the ongoing discussion on the unrestricted clinical adoption of PGS, suggesting, that until proper evaluation of its effectiveness and cost-effectiveness will be provided, PGS should be offered only under study conditions, and with appropriate informed consents.