Cumulus oophorus complexes favor physiologic selection of spermatozoa for intracytoplasmic sperm injection

Abstract

To investigate the effectiveness of cumulus oophorus complexes (COCs) in the physiologic selection of spermatozoa for intracytoplasmic sperm injection (ICSI). A prospective sibling oocytes study. Center of reproductive medicine. Couples undergoing ICSI during 2016, females aged ≤38years, and at least six metaphase II (MII) oocytes retrieved. Sixty patients were included in the study. Of 857 MII oocytes, 429 were allocated to the study group and were injected with the sperm selected via COCs; 428 MII oocytes were allocated as controls (C) and fertilized by conventional ICSI. In the study group, ICSI was performed with spermatozoa that traversed the COCs invitro. Blastocyst/top blastocyst formation rate, fertilization rate, and oocyte utilization rate. Oocytes injected with COC-selected spermatozoa had a significantly higher fertilization rate than the conventional ICSI group (85.31% vs. 74.77%). There were no statistically differences in cleavage and top embryo rate on day 3 between the COC-ICSI and C-ICSI groups. However, with day 5 or 6 embryos, compared with conventional ICSI, COC-ICSI significantly improved blastocyst formation rate (64.90% vs. 53.50%), blastocyst formation rate at day 5 (46.52% vs. 38.85%), top blastocyst rate (38.72% vs. 24.20%), and the usable blastocysts formation rate (62.12% vs. 46.82%). The oocyte utilization rate was improved greatly in the COC-ICSI group compared with the C-ICSI group (51.98% vs. 34.35%). Furthermore, the fertilization rate, top embryo rate on day 3, usable blastocyst rate, top blastocyst rate, and day 5 usable blastocysts rate were similar between the conventional IVF and COC-ICSI groups. Single-blastocyst transfer was performed in 82 cycles, including 44 fresh cycles and 38 frozen-thawed cycles. The cumulative embryo implantation rate in the COC-ICSI group was 64.29%, slightly higher than in the C-ICSI group (53.85%), but there was no statistical difference. The use of COCs to select spermatozoa for ICSI appears to be effective and led to a statistically significant improvement in blastocyst development and quality.