Comparison of Blastulation and Pregnancy Rates of Fertilized Human Oocytes Obtained after Conventional In Vitro Fertilization and Intracytoplasmic Sperm Injection.

Abstract

A comparison was made of good quality blastocysts obtained after either conventional in vitro fertilization (IVF) or intracytoplasmic sperm injection (ICSI). After IVF or ICSI, fertilized oocytes were kept in culture for a further 5 to 7 days before embryo transfer (ET) or embryo freezing. No differences were found in the number of oocytes showing two-pronuclei between conventional IVF (76.9%) and ICSI groups (85.1%). A cohort of 60 and 74 oocytes in the pronuclear stage were cultured after IVF and ICSI, respectively. The number of fertilized oocytes reaching the blastocyst stage was significantly higher (P<0.05) in the IVF group (73.3%) than in the ICSI group (56.8%). A total of 86 blastocysts were categorized into three grades depending on their morphology. The number of blastocyst embryos achieving blastocyst grade 1 (BG1) was significantly higher (P<0.05) in the IVF group than in the ICSI group, 63.3% and 13.5%, respectively. In the IVF group, 10.0% and 0% of 2PN oocytes developed to BG2 and BG3, and 2.7% and 4.1% in the ICSI group, respectively, with no significant differences between the two groups. Pregnancy rate was higher in the IVF group than in the ICSI group, 50% and 20%, respectively. It was concluded that fertilized oocytes resulting from ICSI cannnot be successfully cultured for 5-7 days for blastulation and blastocyst-ET.