Blastocyst collapse as an embryo marker of low implantation potential: a time-lapse multicentre study

Abstract

SummarySpontaneous blastocyst collapse during in vitro embryo development has been suggested as a novel marker of embryo quality. Therefore, the aim of this multicentre study was to carry out a retrospective multicentre analysis to investigate the correlation between blastocyst collapse and pregnancy outcome. Here, 1297 intracytoplasmic sperm injection (ICSI)/in vitro fertilization (IVF) fresh cycles, with an elective single blastocyst transfer (eSET) were included in this study. Embryos were cultured individually in 6.0% CO2, 5.0% O2, 89.0% N2, using single step medium (GTLTM VitroLife, Sweden) or sequential medium (CookTM, Cook Medical, Australia) and selected for transfer using standard morphological criteria. With the use of time-lapse monitoring (TLM), blastocysts were analyzed by measuring the maximum volume reduction and defined as having collapsed, if there was ≥ 50% volume reduction from the expanded blastocyst and the collapse event. Following embryo replacement, each blastocyst was retrospectively allocated to one of two groups (collapsed or not collapsed). Here, 259 blastocysts collapsed once or more during development (19.9%) and the remaining 1038 either contracted minimally or not collapsed (80.1%). A significantly higher ongoing pregnancy rate (OPR) of 51.9% (95% CI 48.9–59.9%) was observed when blastocysts that had not collapsed were replaced compared with cycles in which collapsed blastocysts were transferred 37.5% (95% CI 31.6–43.4%). This study suggests that human blastocysts that collapse spontaneously during development are less likely to implant and generate a pregnancy compared with embryos that do not. Although this is a retrospective study, the results demonstrated the utility of collapse episodes as new marker of embryo selection following eSET at blastocyst stage.

Longitudinal Surface Measurements of Human Blastocysts Show That The Dynamics of Blastocoel Expansion Are Associated With Fertilization Method And Ongoing Pregnancy

“…In this study, calculation of the expansion rate was made easily applicable for daily clinical practice, by determining the maximal expansion surface and subtracting the minimum surface at tB, divided by the number of hours needed to reach the maximum expansion. However, blastocysts are also known to sometimes collapse the blastocoel during development, with a potential impact on implantation potential (39)(40)(41). The expansion rate we calculated here is independent of these collapses, because we used the maximum size that each blastocoel reached.…”

Extracellular vesicles, microRNA and the preimplantation embryo: non-invasive clues of embryo well-being

“…With certainty, this collapsing phenomenon has been correlated with ongoing clinical pregnancy rate (Marcos et al, 2015;Sciorio et al, 2019;. Only 37.5% of transferred human blastocysts that exhibited at least one total collapse resulted in pregnancy, compared with 51.9% resulting from those with minor or no collapse (Sciorio et al, 2020).…”

“…A blastocyst rupturing strategy wherein its DNA contents are deliberately released into the culture media has improved the concordance of niPGT (Kuznyetsov et al, 2018;Li et al, 2018;Jiao et al, 2019), and such a strategy may be worth investigating to improve extracellular vesicle detectability. The blastocyst cavity naturally contracts to varying degrees repetitively during expansion and, in some cases, complete collapse may occur (Sciorio et al, 2020). With certainty, this collapsing phenomenon has been correlated with ongoing clinical pregnancy rate (Marcos et al, 2015;Sciorio et al, 2019;.…”

Morphogenesis of the human preimplantation embryo: bringing mechanics to the clinics

“…Besides, analysing blastocyst growth rates with higher temporal resolution could give more information on sudden collapses [55,116]. Several studies investigated the relationship between collapses and implantation rates, with sometimes contradictory conclusions [125][126][127]. As collapses may result from cell divisions transiently disrupting the TE seal, they may report on a healthy dividing TE [22,116].…”