Oocyte morphology on day 0 correlates with aneuploidy as detected by polar body biopsy and FISH

Abstract

For better selection of oocytes and embryos, preimplantation genetic screening (PGS) was introduced. As from the beginning of IVF, morphology was used as selection criteria; we investigated the combination of both. If there was a correlation between phenotype and genotype, invasive PGS might be replaced. Therefore, 104 cycles with PGS were done by biopsy of the first polar body and FISH with five chromosomes. Morphology of the oocyte was recorded digitally and noted for 12 categories in 4-13 values; evaluation of the chromosomes was noted for five chromosomes in five values. Morphology and genetics were correlated to each other. Correlations between morphology and genetics for day 0 were found: oocytes with an irregular or dark zona are less probable to have a normal chromosome 13 (80 vs. 53 %, p = 0.001). A medium amount of detritus in the perivitelline space makes it more probable to have a normal chromosome 18 (94 vs. 78 %, p = 0.001). A halo in the cytoplasm makes it less probable to be euploid for chromosome 22 (56 vs. 75 %, p = 0.018). For day 1, pattern "1, 2, 3 and fine" in the pronuclei makes it more probable to be euploid for chromosome 22 (78 vs. 63 %, p = 0.002). There are correlations between the oocyte genome and its morphology also on day 0. These correlations are not sufficient to replace PGS.