Oocyte electroactivation after ICSI

Electrical activation of oocytes after ICSI can significantly improve the fertilization rate in selected patients, according to the results of a randomized controlled study.

Specialists from the Egyptian IVF-ET Center in Cairo, Egypt, conducted the study to estimate the effect of electrical activation of oocytes in patients with previously failed or limited fertilization after ICSI, and in patients likely to have failed fertilization due to teratozoospermia.

Previous research has suggested that fertilization failure occurs in an estimated 2-3 percent of ICSI cycles and is often due to the failure of oocyte activation. Past studies have provided some evidence to suggest that electrical activation (or electroactivation) of oocytes can improve success rates.

The researchers studied the effect of electrical activation in 241 ICSI cycles involving couples with severe oligoasthenospermia or azoospermia. Poor or failed fertilization was expected in these cycles because of 100 percent abnormal sperm morphology or totally immotile sperm. In all cases the female partner was under 40 years of age and had a normal hormonal profile and no pelvic pathology.

The oocytes from each patient were randomly assigned on a one-to-one basis to either electroactivation (n = 1,640) or no electroactivation (n = 1,435). Electroactivation was performed 30 minutes after ICSI, using a double-square direct current pulse, and embryo transfer was performed with the best available embryos.

The researchers (Mansour R et al) present their findings in a new paper due to be published in the journal Fertility and Sterility. They report that:

The fertilization rate was significantly higher in the electroactivation group, compared with the control group: 68 percent versus 60 percent respectively (odds ratio 1.40; 95 percent confidence interval 1.20-1.63).
There was no significant difference between the two groups in the oocyte degeneration rate (5.9 percent in the electroactivation group and 4.9 percent in the control group).
There were a total of 112 clinical pregnancies in the study. In 15 of these, the embryos transferred were derived solely from the electroactivated group (out of a total of 34 embryo transfer procedures involving such embryos – a clinical pregnancy rate of 44 percent). In 69 of the clinical pregnancies the embryos transferred were derived solely from the control group (out of a total of 69 embryo transfer procedures involving such embryos – a clinical pregnancy rate of 48 percent). In the remaining 64, the embryos transferred were derived from both groups (out of a total of 138 embryo transfer procedures – a clinical pregnancy rate of 46.4 percent).
The miscarriage rates were: 20 percent (3 out of 15 clinical pregnancies) when the embryos transferred were derived solely from the electroactivated group, 9 per cent (3 out of 33 clinical pregnancies) when the embryos transferred were derived solely from the control group, and 9.4 percent (6 out of 64 clinical pregnancies) when the embryos transferred were derived from both groups.
Total fertilization failure did not occur in the study group, but occurred in five cycles in the control group.
Concluding, the researchers write that electroactivation of oocytes after ICSI can significantly improve the chances of fertilization, but stress: “However, more studies are needed to evaluate the clinical significance and safety of this technique.

“It is recommended in cases of previous failure of fertilization or limited fertilization, as well as in cases of severe oligoasthenospermia or azoospermia with 100 percent abnormal forms or zero motility.”

Source: Fertility and Sterility 2008;in press