Objective: To characterize atypical dynamic embryo phenotypes identified by time-lapse microscopy, evaluate their prevalence, and determine their association with embryo development.
Design: Retrospective multicenter cohort study.
Setting: Five IVF clinics in the United States.
Patient(s): Sixty-seven women undergoing IVF treatment with 651 embryos.
Intervention(s): Embryo videos were retrospectively analyzed for atypical phenotypes.
Main outcome measure(s): Identification of four groups of atypical embryo phenotypes: abnormal syngamy (AS), abnormal first cytokinesis (A1(cyt)), abnormal cleavage (AC), and chaotic cleavage (CC). Prevalence and association with embryo morphology and development potential were evaluated.
Result(s): A high prevalence of atypical phenotypes was observed among embryos: AS 25.1% (163/649), A1(cyt) 31.0% (195/639), AC 18% (115/639) and CC 15% (96/639). A high percentage of embryos with atypical phenotype(s) had good quality on day 3 (overall grade good or fair): AS 78.6% (70/89); A1(cyt) 79.7% (94/119), AC 86.4% (70/81), and CC 35.2% (19/54), but the blastocyst formation rates for these embryos were significantly lower compared with their respective control groups: AS 21.5% vs. 44.9%, A1(cyt) 21.7% vs. 44.6%, AC 11.7% vs. 43.1%, and CC 14.0% vs. 42.3%.
Conclusion(s): Embryos exhibiting atypical phenotypes are highly prevalent in human embryos and show significantly lower developmental potential than control embryos.
Clinical trial registration number: NCT01369446.
Keywords: Atypical phenotype; abnormal embryo development; embryo selection; embryo viability assessment; time-lapse microscopy.
Copyright © 2014 American Society for Reproductive Medicine. Published by Elsevier Inc. All rights reserved.