What is the optimal timing of intracytoplasmic sperm injection (ICSI) after EGG retrieval? A randomized controlled trial

Purpose: To determine if oocyte denudation and ICSI at 36.5 versus 39 h post HCG and/or Lupron trigger (2.5 h versus 5 h post-oocyte retrieval) influences fertilization and blastulation rates in good prognosis couples Methods: We performed a prospective, randomized controlled trial of 12 patients undergoing IVF with ICSI at an academic fertility center, resulting in 206 MII oocytes analyzed. At time of retrieval, patients with more than 10 oocytes retrieved had their oocytes randomized into two groups—one group for oocyte denudation and ICSI at 36.5 h post HCG and/or Lupron trigger and the other group for these procedures at 39 h post HCG and/or Lupron trigger (2.5 and 5 h after oocyte retrieval). Primary outcomes were fertilization and blastulation rates. Results: No difference was observed in fertilization rate, total blastulation rate, or day of blastulation based on timing of denudation and ICSI (all p > 0.05). Multiple regression analyses for fertilization and blastulation controlling for age and BMI revealed no difference in fertilization based on time of ICSI (p = 0.38, 0.71, respectively). A conditional logistic regression to account for multiple oocytes derived from each patient also found no difference in fertilization or blastulation based on timing of ICSI, even when controlling for age and BMI (p = 0.47, 0.59, respectively). Conclusion(s): In good prognosis couples, we observed no difference in fertilization or blastulation rates based on timing of ICSI within the currently accepted 2- to 6-h window post-retrieval based on a 34-h trigger. The oocyte appears to have a physiological tolerance for fertilization during this window of time, and variability in the timing of ICSI during this window is unlikely to have an impact on cycle outcome.