M. Tsirigotis et al., EXPERIENCE WITH SUBZONAL INSEMINATION (SUZI) AND INTRACYTOPLASMIC SPERM INJECTION (ICSI) ON UNFERTILIZED AGED HUMAN OOCYTES, Journal of assisted reproduction and genetics, 11(8), 1994, pp. 389-394
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.