Time-lapse videomicroscopyas a tool to predict the development of human embryos to the blastocyst stage

Abstract
Objective: Blastocyst culture is recognised as a suitable tool for the selection of competent embryos, but requires additional laboratory resources and implies supplementary manipulation which may over-expose embryos to inappropriate conditions.
Results: Of 131 fertilized eggs cultured until day 5 (120 h), 55 (42.0%) developed to the blastocyst stage. Thirty-two blastocysts were classified as expanded. In embryos able to develop to blastocysts, the time elapsing between the first and second (2- to 3-cell stage) and second and third (3- to 4-cell stage) divisions tended to be shorter in comparison to embryos that arrested at earliest stages (mean  ±  SD: 10.2  ±  2.7 vs. 11.0  ±  5.1, P>0.05; 2.6  ±  4.3 vs. 6.0  ±  11.5, P¼0.02). By limiting the time-lapse analysis up to the 4- cell stage and considering as predictive criteria evenness and regularity of cleavage, fragmentation < 10%, and intervals between the first-second and second-third divisions of 10-12 h and 0-2 h, respectively, 32 embryos were identified of which 28 developed to the blastocyst stage (95% specificity, PPV 87.5%).
Conclusion: Time-lapse microscopy analysis of early cleavage stages allows the identification of embryos having high capacity to develop to the blastocyst stage. This can have a significant impact on embryo transfer strategies.

Autori: M. Dal Canto, G. Coticchio, M. Mignini Renzini, F. Brambillasca, E. De Ponti, R. Fadini