O-10: Assessment of Oocyte and Embryo Quality in Different Time between Oocyte Retrieval and hCG Priming

Background: Abnormal oocyte morphology has been associated with the hormonal environment to which the gametes are exposed. In this study, we evaluated the oocytes morphology, fertilization rate, embryos quality, and implantation rate resulted of retrieved oocytes in different times after human chorionic gonadotrophin (hCG) administration. Materials and Methods: A total of 985 metaphase II were retrieved 35, 36, 37 and 38 hours after the injection of hCG (groups 1-4 respectively). Oocyte morphology was divided into 1. normal oocytes, 2. oocytes with extracytoplasmic abnormalities (large perivitelline space and dark zona), 3. oocytes with cytoplasmic abnormalities (dark cytoplasm, granular cytoplasm and aggregates of smooth endoplasmic reticulum) and 4. intracytoplasmic vacuoles. Results: Extracytoplasmic abnormalities were encountered in 17.76% and 31.1% of these oocytes (groups 3 and 4 respectively, p< 0.001) in comparison with 12.23% (group 2). Intracytoplasmic vacuoles rate were 10.52% and 3.12% (group 4 versus group 2, p< 0.01). Cytoplasmic abnormalities differed between the group 4 and other groups. 23.88% (p< 0.01) and 43.25% (p< 0.001) of resulted 2PN (two pronucleus) from groups 3 and 4 showed grade Z3 respectively in comparison to group 2 (16.44%). Normal and various categories of abnormal oocytes did not differ regarding fertilization and cleavage rates (p> 0.05). However, group 4 showed significantly difference in the rate of embryos fragmentation (grade 3 and 4 embryo) in comparison with group 2 (40.96% versus 24.93%, p<0.01). The pregnancy rate was influenced but the implantation rate did not differ. Conclusion: Furthermore, oocyte retrieval time following hCG priming affected on oocyte morphology, 2PN pattern and embryos qualities subsequently.