Noninvasive chromosome screening improves the clinical outcomes in frozen-thawed single blastocyst transfer cycles

Abstract

To perform a clinical evaluation of the efficacy of single embryo transfer at blastocyst stage selected using the noninvasive chromosome screening (NICS) assay, which involves the sequencing of free genomic DNA in the culture medium of individual blastocysts for obtaining chromosomal ploidy information. A retrospective observational study from September 2015 to September 2016. A total of 353 frozen-thawed single blastocyst transfer (SBT) cycles were divided into three groups with different blastocyst selection criteria: the first was the No-choice group which had only one blastocyst for transfer for each patient (n=285). The second was the Morphology group. The patients of this group had at least two blastocysts available and blastocysts were selected for single blastocyst transfer on the basis of traditional morphological assessments (n=41); the third was the NICS group that had at least two blastocysts for each patient and the euploid blastocysts were selected using NICS for single blastocyst transfer (n=27). The biochemical pregnancy rate in the No-choice group, the Morphology group and the NICS group was 65.3%, 65.9% and 85.2%, respectively (P=0.232). Among three groups, the NICS group had the highest implantation rate (63.0%) (P=0.193), compared with 56.1% and 45.3% in the Morphology group and the No-choice group, respectively. There was no incidence of early miscarriage in the NICS group, while the early miscarriage rate in the No-choice group and the Morphology group was 21.1% and 13.0%, respectively (P=0.094). A significant difference was found in the ongoing pregnancy rate among the three groups, which was highest in the NICS group (63.0%) and lowest in the No-choice group (37.9%) (P=0.016). NICS is a novel genetic testing that allows an accurate selection of blastocysts with better developmental potential for transfer and might improve the clinical outcomes.