Rescue intracytoplasmic sperm injection (ICSI) - salvaging in vitro fertilization (IVF) cycles after total or near-total fertilization failure

Objective: To evaluate the effectiveness of delayed oocyte reinsemination b y ICSI (rescue ICSI) after total or near-total fertilization failure (less than or equal to 25%) in IVF. Design: A retrospective clinical study. Setting: Non-hospital-based NF prog ram. Patient(s): Thirty IVF cycles with total fertilization failure and two cycl es with less than or equal to 25% initial fertilization. Main Outcome Measure(s): Fertilization and pregnancy rates after rescue ICS I. Intervention(s): Rescue ICSI 19-22 hours after initial oocyte insemination. Result(s): A fertilization rate of 60.2% was achieved with rescue ICSI (141 of 234 oocytes, 29 of 32 patients). Of 30 patients with total fertilizatio n failure, 27 had fresh transfers with rescue ICSI embryos. Two additional patients with less than or equal to 25% initial fertilization had subsequen t replacement of frozen-thawed rescue ICSI embryos. Six pregnancies resulte d, including three singleton, one twin, one missed abortion, and one ectopi c pregnancy (20.7%). One of the singleton pregnancies resulted from replace ment of four frozen-thawed embryos and is the first known pregnancy achieve d from cryopreserved rescue ICSI embryos. Conclusion(s): Rescue ICSI should be considered in the presence of total or near-total fertilization failure in IVF. Early application of rescue ICSI (19-22 hours after insemination) may be critical for establishing fertiliza tion within an optimal window and producing viable embryos and pregnancies. (C) 2000 by American Society for Reproductive Medicine.