Spindle and Chromosome Analysis of Non-Fertilized Oocytes from Conventional in vitro Fertilization for Non-Male Factor Infertiliy: Significance of Rescue ICSI?

ObjectiveTo determine whether rescue intracytoplasmic sperm injection (ICSI) is associated with improved outcomes for non-male factor infertility.MethodsThe changes of micro-structure, including meiotic spindle and chromosome distribution, sperm penetration, as well as oocyte activation were compared in IVF (in vitro fertilization) fertilization failure (IVF FF) patients, ICSI patients with non-fertilized oocytes (ICSI NF) and oocytes in vitro maturation (IVM).ResultsA total of 164 unfertilized oocytes (93 oocytes in IVF and 71 oocytes in ICSI) and 56 IVM oocytes were available for this study. The abnormality of spindle and chromosomes was significantly higher in IVF FF group than that in ICSI NF group or IVM group (abnormal spindle rates were 80.6%, 64.8% and 57.1%, respectively; abnormal chromosome rates were 91.4%, 80.3% and 75.0%, respectively). No sperm penetration after IVF and sperm expulsion after ICSI were 78.5% and 40.8%, respectively. Activation failure occurred in 16.1% of the IVF FF cases and 49.3% of ICSI NF oocytes.ConclusionRescue ICSI of fertilization-failed oocytes fails to lead outcome improvement due to the internal defects of oocytes.