P-704: Comparison of embryology and clinical outcome between IVM cycles with and without mature oocytes collected following HCG priming

Abstract

It has been known that mature oocytes (metaphase-II stage) can be retrieved from relatively small follicles after human chorionic gonadotropin (HCG) priming from infertile women with polycystic ovaries (PCO). However, there is no report to compare the clinical outcome between in vitro maturation (IVM) treatment cycles with mature oocytes and without mature oocytes collected. Retrospective analysis between treatment cycles with (group 1) and without (group 2) MII-stage oocytes collected. IVM was performed in 58 PCO patients (60 cycles) from June 2005 to March 2006. Egg collection was performed between day-9 and -16 of menstrual cycle based on the patient’s cycle length and endometrium thickness (> 6 mm). The patients were administrated 10,000 IU of HCG subcutaneously 36 h prior to egg collection. The largest follicle size and endometrium thickness were measured right before egg collection. After collection, the oocyte maturity was assessed under the dissecting microscope with high magnification using sliding method. The mature oocytes were inseminated by intracytoplasmic sperm injection (ICSI) and the remaining immature oocytes were cultured for IVM until 48 h in IVM medium (Coopersurgical/SAGE Company) supplemented with 75 mIU/ml FSH and LH. Fertilized zygotes were cultured in Embryo Maintenance Medium (Coopersurgical/SAGE Company). The correlation of the follicular size with the mature oocytes collected was analyzed. In addition, oocyte IVM, fertilization, and cleavage as well as pregnancy rates between two groups were analyzed. At egg collection, total 15% (91/629) of oocytes collected were MII stage in group 1. The MII-stage oocytes were obtained from the follicles sized 10-14 mm diameter. Morphology of cumulus-oocyte complex (COC) with MII-stage oocytes was different between the size of follicles < 12 mm and ≥ 12 mm follicles. There were no difference in the mean number of oocytes collected (20.9 vs. 19.3) and IVM rates (67.8% vs. 62.7%) between groups. Although the fertilization rate in group 2 (86.8 %) was higher than that of group 1 (71.3 %), the cleavage rate were comparable between two groups. The clinical pregnancy rate was significantly higher (P < 0.05) in group 1 (40%, 12/30) than that of group 2 (23.3%, 7/30). These results imply that mature oocytes can be retrieved from the follicle sized small as 10 mm in diameter following HCG priming in infertile women with PCO. It seems that there is correlation between COC morphology and oocyte maturity and quality.