title: Relative kinetic expressions defining cleavage synchronicity are better predictors of blastocyst formation and quality than absolute time points.
abstract: OBJECTIVE
  Morphology alone is not enough for the selection of the embryo (s) with the highest implantation potential and time-lapse imaging has added embryo development kinetics as another selection criterion. Therefore, a combination of morphology with kinetics has inspired a new field termed "morphokinetics", providing a new way of evaluating and selecting embryos. The aim of the study was to identify a criterion solely based on morphokinetic data and available up to the 8-cell stage (t8) to predict blastocyst formation and quality.
  
  
  METHODS
  The study included 3,354 embryos, with annotations up to t8, and cultured until day 5 from 626 infertile patients. A total of 17 kinetic expressions, either absolute cleavage timings and time intervals or time ratios were tested retrospectively for the prediction of blastocyst formation and quality.
  
  
  RESULTS
  Relative timings (t8-t5, the cleavage synchronicity from 4 to 8 cells and from 2 to 8 cells) were found to be better indicators of blastocyst formation and quality when compared to absolute time-points. Especially, the cleavage synchronicity from 2 to 8 cells (CS2-8) = ((t3-t2) + (t5-t4))/(t8-t2)) was found to be the best predictor available on day 3 for blastocyst formation and quality (AUC:0.786; sensitivity: 83.43; specificity: 62.46).
  
  
  CONCLUSIONS
  Time intervals and relative ratios based on selected cleavage cycles defining synchronicity allowed a specific analysis providing high predictivity of blastocyst formation and quality.
authors.affiliation: Istanbul Memorial Hospital, Assisted Reproductive Techniques and Reproductive Genetics Center, Piyale Pasa Bulvari, 34385, Okmeydani, Sisli, Istanbul/Turkey, muratcetinkaya01@gmail.com.
authors.forename: Murat
authors.initials: M
authors.lastname: Cetinkaya
authors.forename: Caroline
authors.initials: C
authors.lastname: Pirkevi
authors.forename: Hakan
authors.initials: H
authors.lastname: Yelke
authors.forename: Yesim Kumtepe
authors.initials: YK
authors.lastname: Colakoglu
authors.forename: Zafer
authors.initials: Z
authors.lastname: Atayurt
authors.forename: Semra
authors.initials: S
authors.lastname: Kahraman
mesh_terms: D000328:Adult; D001755:Blastocyst / Q000502:physiology* / Q000648:ultrastructure; D010064:Embryo Implantation; D004624:Embryo Transfer; D047108:Embryonic Development; D005260:Female; D006801:Humans; D007246:Infertility / Q000175:diagnosis / Q000473:pathology; D008297:Male; D011247:Pregnancy; D018873:Pregnancy Rate; D059008:Time-Lapse Imaging