Different Occurrence Rates of Centrally Located Cytoplasmic Granulation in One Cohort Oocytes Show Distinctive Embryo Competence and Clinical Outcomes

Abstract

Background Centrally located cytoplasmic granulation (CLCG) is a common cytoplasmic dysmorphism in human oocytes retrieved after controlled ovarian hyperstimulation (COH). This study sought to achieve a better understanding of its formation and effects on clinical outcomes. Methods We retrospectively analyzed the data from 422 intracytoplasmic sperm injection (ICSI) treatment cycles. Three groups of patients were classified according to the rates of CLCG occurrence in one egg cohort, as partial (pCLCG) all (aCLCG) and no CLCG (control). Results The pCLCG group had a significantly lower Body Mass Index (BMI) and higher Anti-Mullerian hormone (AMH) level compared to the control or aCLCG groups. Consistent with these distinctive features in the pCLCG group, fertilization and blastocyst formation rates were reduced significantly in the pCLCG group but not in the aCLCG group. Furthermore, the clinical outcomes in fresh embryo transfer cycles were dramatically reduced in the pCLCG group compared with the control group. However, in frozen/thawed cycles, all three clinical outcomes were significantly reduced in the aCLCG group but not in the pCLCG group. Conclusion We propose that pCLCG may reflect a specific population of patients, and that the CLCG structure is sensitive to cryopreservation.