UNEXPECTED FAILURE OF FERTILIZATION IN CONVENTIONAL IVF CYCLES: RE-INSEMINATION BY ICSI OR INDICATION FOR ICSI IN SUBSEQUENT CYCLES?

Objective: To compare the results of cycles with complete failure of fertilization in which rescue ICSI was performed
with a matched control group of ICSI cycles, both in terms of fertilization and pregnancy outcome and to answer the
question whether rescue ICSI is worth trying.
Design: Retrospective clinical study.
Setting: Private assisted reproduction unit.
Material and Methods: The study included 24 patients (group I) undergoing a first trial conventional IVF for non-male
factor infertility, and in whom unexpected total failure of fertilization was discovered. A rescue ICSI procedure was
performed where at least three metaphase II (MIl) oocytes were available. A control group (group II) was
retrospectively selected and included 27 couples undergoing ICSI for male factor infertility during the same period.
Patients were matched for age, duration of infertility, type of ovarian stimulation and number of oocytes retrieved.
Results: The fertilization rate, expressed as the percentage of 2PN oocytes per injected oocytes (47% vs. 70.3%), was
significantly higher in group II (P<0.05). The proportion of grade I embryos, however, assessed on day 2 was
comparable in both groups (47.2% vs. 51.2%). The percentage of cycles with transfer (66.6% vs. 92.6%) and the mean
number of embryos transferred (J .66 vs. 2.9) were significantly higher in the control group (P<0.05). Nine pregnancies
were obtained in the control group (clinical pregnancy rate of 33.3% per cycle and 36% per transfer). In group I patients
with rescue ICSI, no pregnancies were obtained. .
Conclusion: Rescue ICSI performed on I-day-old unfertilized oocytes, although resulting in fertilization, gives poor
results in terms of pregnancy. Ageing of the ooeytes presumably affects the developmental capacity of the embryo. We
recommend that resuce ICSl of l-day-old oocytes be limited as a diagnostic method that serves as an indication for
ICSI in subsequent cycles.