Cumulus cell-oocyte complexes retrieved from antral follicles in IVM cycles: relationship between COCs morphology, gonadotropin priming and clinical outcome

To assess retrospectively the developmental potential of different types of cumulus cell-oocyte complexes (COCs) derived from IVM cycles. IVM cycles were performed in natural cycles or after HCG, FSH, or FSH/HCG priming. COCs recovered were morphologically characterized in different types: compact (CC) or expanded (EC) cumulus mass but including an immature oocyte, and expanded cumulus mass enclosing a mature oocyte (EC-MII). Embryo developmental competence was investigated analysing exclusively cycles in which all transferred embryos derived from the same COC category. Fertilization rates did not differ significantly. Significant differences in pregnancy rates (14.5 %, 10.0 % and 27.6 % in the CC, EC, and EC-MII categories, respectively) were observed. Likewise, significant differences in implantation rates (8.9 %, 6.3 % and 19.1 % in the CC, EC, and EC-MII categories, respectively) were found. Overall, priming with FSH/HCG had a beneficial effect on pregnancy and implantation rates, while no priming or HCG alone generated oocytes with poor competence. In IVM cycles, morphological evaluation at the time of collection can predict the developmental ability of different COCs. FSH/HGC priming has a positive effect on oocyte competence.