Lack of correlation between oocyte- corona-cumulus complex morphology and nuclear maturity of oocytes collected in stimulated cycles for intracytoplasmic sperm injection

Abstract

Objective: To evaluate the usefulness of morphology grading of the oocyte-corona-cumulus complex (OCCC) as a marker of oocyte nuclear maturity, fertilizability, embryo cleavage, and likelihood of pregnancy. Design: Prospective cohort study. Setting: Academic fertility center. Patient(s): Eighty-three infertile couples undergoing IVF-ET/intracytoplasmic sperm injection treatment. Intervention(s): All patients underwent a long stimulation protocol of GnRH agonist therapy followed by hMG administration and transvaginal oocyte recovery. Main Outcome Measure(s): All OCCCs, oocytes, and embryos were assessed. The relation among OCCC morphology and the nuclear maturity of denuded oocytes, the fertilization rate, and embryo development to the cleavage stage were analyzed. Result(s): Of 909 OCCCs collected from 92 cycles, 2.5%, 4.2%, 79.9%, and 13.4% were prophase I, metaphase I, metaphase II, and degenerating, respectively. No statistically significant differences were found in the percentage of intact metaphase II oocytes, the fertilization rate, or the cleavage rate among complexes with different morphologic grades. The morphologic grade of the OCCCs of transferred embryos in the pregnant group was not different from that in the nonpregnant group. Conclusion(s): Most oocytes were in metaphase II at the time of retrieval after ovarian stimulation. However, no relation was observed between the OCCC morphologic grade and oocyte nuclear maturity, the fertilization rate, or embryo cleavage. These observations suggest that OCCC morphology grading is a poor marker of oocyte quality.