Oolemma rupture inside the intracytoplasmic sperm injection needle significantly improves the fertilization rate and reduces oocyte damage

Objective: To compare the effect on fertilization, oocyte damage, embryo freezing, and pregnancy rates of two different techniques for rupturing the oolemma during intracytoplasmic sperm injection (ICSI). Design: Retrospective study. Setting: Fertility Center, Alliant Health System Hospital. Patient(s): Seventy-nine consecutive IVF-ICSI cases. Intervention(s): Patients in group I had ICSI performed by pushing the needle into the oocyte until the oolemma was observed to break outside the needle. In group II the oolemma was aspirated into the needle until it ruptured inside the needle. Main Outcome Measure(s): In group II ICSI resulted in significantly higher fertilization and lower oocyte damage rates (66% and 13%) than in group I (39% and 29%). There were no statistically significant differences in embryo cleavage rates or pregnancy rates per retrieval between the two groups. A greater number of cases had embryos cryopreserved in group II than in group I. Result(s): Rupturing the oolemma by aspirating it into the ICSI needle (group II) improved laboratory outcomes compared with the more traditional technique of breaking this membrane by the stabbing action of the needle (group I). This modification of the ICSI technique also increased the number of patients with cryopreserved embryos and therefore could increase the pregnancy rate per patient. Conclusion(s): The site and technique used to rupture the oolemma during ICSI has a significant effect on the fertilization and damage rates. (Fertil Steril(R) 1998;70:676-9. (C) 1998 by American Society for Reproductive Medicine.).