18. EUPLOID BLASTOCYSTS IMPLANT IRRESPECTIVE OF THEIR MORPHOLOGY AFTER PREIMPLANTATION GENETIC TESTING-ANEUPLOIDY USING NEXT GENERATION SEQUENCING

Abstract

Introduction In the context of IVF, it has become imperative to emphasize on embryo evaluation in order to maximise assisted conception outcome while minimising the risk of multiple pregnancy. Despite the exponential rise in knowledge and understanding of the dynamic process of embryo development in the laboratory, the classical evaluation methods based on morphology are still considered as the gold standard methods to classify and select embryos. Morphology assessment helps embryologists to detect dysmorphic or arrested embryos but chromosomal abnormalities can still be only identified by preimplantation genetic testing for aneuploidies (PGT-A). It remains controversial the strength of morphology as a tool to ensure replacement of euploid blastocysts. The present research aims to corroborate whether blastocyst morphology, using a modified Gardner and Cornell's group scoring system, correlates with ploidy status of embryos analysed with next generation sequencing (NGS). We also wanted to ascertain whether biopsy of poor quality embryo yield a euploid embryo to transfer and thus result in a favourable outcome. This is the first data set describing the correlation between blastocyst morphology and embryo ploidy status using NGS and clinical outcomes. Materials and Methods 296 patients underwent PGT-A. Of 1,549 blastocysts, 1,410 blastocysts had a conclusive result after PGT-A and were included for analysis. An elective single embryo transfer (eSET) policy was followed in a frozen embryo replacement cycle. A total of 179 euploid blastocysts were thawed and transferred. Clinical outcomes were categorised in four different embryo quality groups: excellent, good, average and poor. Results Euploidy rates were 19/36 (52.7%, 95% CI 37-68), 199/470 (42.3%, 95% 38-47), 156/676 (23.0%, 95% CI 20-26) and 39/228 (17.1%, 95% CI 13-23) in the excellent, good, average and poor quality blastocyst groups, respectively. Fitted logistic regression analysis taking into account the following co-variables; female age, embryo chromosomal status, and day of blastocyst development/biopsy showed that good (OR 0.6; 95% CI 0.4-0.8;p=0.001), average (OR 0.5; 95% CI 0.4-0.7; p=0.001) and poor (OR 0.2;95% CI 0.1-0.5; p=0.005) morphology with excellent morphology being the reference group was predictive of the comprehensive chromosome testing result. A logistic regression analysis was also performed on clinical outcomes taking into account for the effect of blastocyst morphology and day of blastocyst development/biopsy. None of the parameters were shown to be significant suggesting morphology irrespective of the embryo quality category and day of blastocyst development/biopsy do not reduce the competence of euploid embryos (p>0.05). Conclusions After euploid eSET, implantation rate was 80-86%; live birth rate per embryo transfer was 60-73% and clinical miscarriage rate was found to be less than 10% and were not significanlty affected by the embryo morphology category. These results are concordant with those reported when using array compartive genomic hybridization and highlights the competence of poor quality euploid embryos.