Impact of Embryo Quality on Developmental and Aneuploidy Rates After Blastomere Biopsy for PGD

Abstract

To examine the impact of cleavage stage embryo quality on subsequent embryonic development and aneuploidy rates following blastomere biopsy. Retrospective. Embryology data and PGD records for 189 embryos, which underwent day 3 blastomere biopsy for PGD of aneuploidy at our center were reviewed. Embryos were divided into euploid or aneuploid based on FISH analysis of 9 chromosomes (X, Y, 13, 15, 16, 17, 18, 21 and 22). The Mean patient’s age for all cases in the study (n=22) was 37.0±5.6. Assessment of embryo morphology, blastomere biopsies and nuclei fixation were performed by the same embryologist. All biopsies were performed on day 3 and all FISH analysis were performed at Reprogenetics, N.J. Our laboratory uses a strict embryo morphology assessment system whereby embryos are evaluated systematically once every 24 hr period and assigned a quality grade ranging from A to E. Top quality embryos fall in categories A/B, Mid quality embryos fall in category C, Low quality embryos are assigned scores D/E. All data were compared using the Fisher’s exact test. Out of 189 embryos that were biopsied 88% had one blastomere removed, and 12% required an additional blastomere to be obtained. The distribution of 5 to 8 cell embryos at 60-62 hrs in culture was similar among those that were subsequently reported as aneuploid or euploid (94% vs. 93%, respectively). There was no difference in blastulation rate in embryos with one vs. those with two blastomeres removed. Overall, blastulation rates for Day-3 Top, Mid and Poor quality embryos were 65% (43/66), 56% (62/111), 17% (2/12), respectively. Accurate FISH results were available in 77% of all embryos biopsied. In this cohort, 72% (105/146) were determined aneuploid and 28% (41/146) euploid. Day 3 Top quality euploid embryos had higher blastulation rate, 83% (19/23), as compared to their aneuploid counter parts, 56% (18/32), (P=0.04). There was no significant difference in the blastulation rate of Mid and Low quality Day 3 euploid embryos when compared to their aneuploid cohorts. The table below summarizes aneuploidy / euploidy rates for Top, Mid and Low quality blastocysts. Tabled 1 In our initial experience, biopsy of one or two blastomeres does not appear to affect blastulation rate. However, day 3 embryo quality was associated with blastulation rate following biopsy. Based on FISH results, Top quality day 3 euploid embryos demonstrated greater blastulation potential. Approximately 50% of Top quality blastocysts were aneuploid. Furthermore, the aneuploidy rate was higher in Mid and Low quality blastocysts. Therefore, FISH results are necessary for adequate selection of euploid embryos for transfer.