Genética humana y embriología

Morphological and Kinetic Embryological Criteria and Correlation with Aneuploidy Rates: How Might they Be Used to Choose the Best IVF Embryo for Transfer?

Abstract

Coates A, Coate B, Holmes L and Griffin DK

Abstract
Objective: To test the hypothesis that embryos reaching a certain developmental stage at a fixed time point (indicative of growth rate) and those of better morphology are more likely to be euploid than those reaching an earlier stage at the same point and those with poorer morphology. To test the hypothesis that quality of the inner cell mass (ICM) and trophectoderm (TE) independently predict ploidy status. 5 specific age groups were tested
Design: Observational research study, retrospective analysis
Setting: Clinical IVF laboratory, comprehensive chromosome screening (CCS) outsourced to specialist laboratory
Patients: Those undergoing IVF with Comprehensive Chromosome Testing (CCS) by array Comparative Genomic Hybridization (aCGH).
Interventions: All embryos grown to day 5 and 6. Those that formed advanced blastocysts were biopsied and cells were analyzed using aCGH
Main Outcome Measures: developmental stage reached by a fixed time point and morphology of whole embryos and quality of ICM and TE; correlation to rates of aneuploidy for all chromosomes.
Results: In addition to confirming a maternal age effect, evidence suggested that embryos reaching a more advanced stage of development on day 5 were more likely to be chromosomally normal than those not reaching the same stage until day 6. The poorer quality embryos were more likely to be aneuploid in the most age groups but this effect was seen more markedly in the trophectoderm (TE) than the inner cell mass.
Conclusions: When comparing aneuploidy to growth rate, a complex pattern emerges in that, in the whole data set, it is the slower growing embryos that appear to be more likely to be aneuploid (but only in the younger and older age groups). By isolating the slower growing cohort (those not ready to biopsy until day 6) however, it seems that the relatively faster ones that continue to grow to day 6 are more likely to be aneuploid. Moreover, TE quality appears to be an important consideration for choosing embryos in all age groups.