Collapse of blastocysts is strongly related to lower implantation success: a time-lapse study

Abstract

Study question: Is there an association between blastocyst collapse patterns and implantation potential?

Summary answer: Embryos that exhibit collapse are as likely to hatch as those that do not, but are less likely to implant and should not be replaced if alternatives are available.

What is known already: Studies of blastocyst collapse in different species of mammals have found that most blastocysts, that experience consecutive weak contractions, hatch successfully whereas those that exhibit strong contractions or collapse, fail to hatch.

Study design, size, duration: Retrospective cohort study. Seven hundred and fifteen transferred blastocysts were analyzed from July 2012 to May 2013.

Participants/materials, setting, methods: University-affiliated infertility center. Participant patients were recipients of oocyte donation and autologous IVF cycles (n = 460). Embryo development was analyzed with a time-lapse imaging system. Variables studied included blastocyst collapse (defined as the separation of ≥50% of the surface of the trophectoderm of the blastocyst from the zona pellucida), kinetic variables, embryo morphology, implantation and clinical pregnancy rates.

Main results and the role of chance: A total of 139 blastocysts presented collapse (19.4%), of these 8 presented 2 collapses and 2 presented 3 collapses. The timings of embryo cleavages and the time taken to reach the morula stage and blastulation were significantly shorter in embryos with collapse than in those without. Implantation rates were compared in cycles where either all or none of the embryos replaced, implanted so that implantation data were known for every embryo. Among 408 embryos without collapse and 94 embryos with at least one collapse (94) the implantation rates were 48.5% (95% confidence intervals (CI) 46.7-53.4%) and 35% (95% CI 25.3-44.9%), respectively. The percentage of embryos that hatched was similar in both groups 28.7 and 31%, respectively.

Limitations, reasons for caution: The retrospective nature of the study limits its potential value.

Wider implications of the findings: Study the collapse pattern of the blastocyst, may assist selection of the blastocysts most likely to implant and increase IVF/ICSI success rates.

Keywords: blastocyst collapse; embryo culture; embryo kinetics; implantation potential; morphology; time lapse.