EXPERIENCE WITH SUBZONAL INSEMINATION (SUZI) AND INTRACYTOPLASMIC SPERM INJECTION (ICSI) ON UNFERTILIZED AGED HUMAN OOCYTES

Objective: The aim of this study was to assess the fertilizability of unfertilized aged human oocytes from failed in vitro fertilization (IV F) cycles using SUZI and ICSI. Methods: A total of 363 oocytes which s howed no fertilization after conventional IVF was subjected to assiste d fertilization using SUZI or ICSI. The microinjected oocytes which we re derived from 72 patients undergoing their first IVF treatment had a n intact polar body and no signs of degeneration. SUZI was carried our in 265 oocytes and ICSI in the remaining 98. Results: Significantly m ove oocytes were damaged after ICSI (9 vs 0.3%, P < 0.01). Normal fert ilization rates were higher at 24 hr in both groups and occurred more frequently after ICSI, although the difference did not reach statistic al significance. Abnormal fertilization occurred significantly more of ten after SUZI at 48 hr (P < 0.005), but not at 24 hr. Cleavage rates were significantly higher after ICSI (94.4 vs 57.1%, P < 0.025) at 24 hr, but this was nor observed at 48 hr, although the ICSI group still showed better cleavage rates (33.3 vs 19.1%1. There was no difference in embryo quality in either group. Conclusions: Our results indicate t hat micromanipulation rather than reinsemination should be carried out on unfertilized human oocytes from failed IVF attempts. Both techniqu es can be used to achieve fertilization which occurs more often after ICSI. However, the trauma from the former technique on the microinject ed oocytes may impair the potential of the generated embryos to achiev e pregnancy compared to SUZI. Prospective randomized trials are necess ary to address the problem.