Changing culture conditions. blastocyst ploidy following standard incubation and uninterrupted culture in the embryoscope (ES)

Abstract

To determine the effect of uninterrupted culture with minimal light exposure, versus standard incubation of embryos in a 5.5% CO2, 5% O2 environment, on the euploid:aneuploid ratio of blastocysts, determined by trophectoderm biopsy. Patients attended for preimplantation aneuploidy screening of their blastocysts. Between November 2009 and April 2011 embryos were cultured in low O2 incubators (Galaxy, SLS, UK) and observed daily. Between April 2011 and April 2012, embryos were cultured uninterrupted in the ES (Unisense, Denmark) and observed using time-lapse images. This study aimed to compare the euploid:aneuploid ratio of embryos developed in these contrasting incubators. Trophectoderm biopsy was performed on 126 blastocysts at CARE Fertility in Manchester, England. Blastocyst chromosome constitution was determined by array comparative genomic hybridisation for 15 patients and single nucleotide polymorphism microarray testing for 18 patients. The euploid:aneuploid ratio from each incubation condition and the proportion of embryos suitable for biopsy were compared using Fisher's Exact Test. 304 embryos were cultured for 33 patients. 41.9% and 41.1% of embryos cultured in the standard and ES incubators respectively underwent biopsy and obtained a screening result. No significant difference in the proportion of euploid and aneuploid blastocysts was observed following standard or ES incubation (P=0.5884,n=52 standard,n=74 ES). Average patient age was 37.1±3.98 and 37.5±4.24 respectively for standard and ES culture. The change from single observation standard incubation to uninterrupted culture has not significantly altered the euploid:aneuploid ratio or the proportion of blastocysts suitable for biopsy. Therefore, the uninterrupted culture, enhanced air quality and decreased temperature fluctuations of the ES appear not to affect chromosome segregation within blastocysts. As patient numbers increase, the analysis will be updated.