A comparison of the clinical outcomes of embryos derived from intracytoplasmic sperm injection after early fertilization check and conventional insemination using sibling oocytes.

Abstract

In order to identify the real contribution of early fertilization check (EFC) for reproductive outcome, we compared the developmental potential of embryos derived from intracytoplasmic sperm injection (ICSI) after EFS with those from conventional insemination in sibling oocytes. Between April 2009 and April 2012, a total of 3249 oocytes in 386 patients were recruited following conventional insemination. Oocytes showing a second polar body (2ndPB) after an EFC were considered to be fertilized oocytes (IVF group), but, oocytes not showing a 2ndPB after EFC were placed into the ICSI group. The incidence of morphologically good embryos (MGE) on day 3, the blastocyst formation (BL), and the development of full blastocysts (full-BL) on day 5 were compared between the two groups. The clinical pregnancy rate was compared between the cycles with only conventional insemination or ICSI after EFC of the embryos being transferred. The fertilization rates in both the IVF and the ICSI groups were 48.1 and 73.9 %, respectively. The percentage of MGE in the ICSI group (40.8 %) was significantly lower than that in the IVF group (56.1 %, p < 0.01). The percentages of BL and full-BL in the ICSI group were significantly lower than those in the IVF group. The pregnancy rates were similar in both the groups. Checking fertilization earlier than the usual period contributed to an avoidance of lower fertilization. Moreover, the embryos derived from ICSI after EFC possessed a normal developmental potential.