Introduction: It is now well established that the most frequent cause of fertilization failure is missing or disturbed oocyte activation. Artificial oocyte activation can be induced using chemical activation substances such as calcimycin (A23187). The oocyte activation is characterized by a dramatic rise in intracellular calcium concentration leading to calcium oscillation which may influence not only fertilization but also embryo development and implantation. So far we have shown in our previous study an improvement in ICSI outcome in cases where Calcium Ionophore (CaI) was used.
Aim: To analyze the effect of artificial oocyte activation using A23187 in sibling oocytes in patients with severe male factor.
Materials: The study included 22 cases with previous low fertilization rates (<20%) after ICSI. The mean age of the patients was 30.1± 5.37y. In 10 cases ejaculated sperm was used and in 12 testicular sperm. Oocytes were divided into two groups: half of them were treated with 10 µM Calcium Ionophore solution (A23187) for 10 minutes immediately after ICSI. The sibling oocytes were the untreated group (control). The mean number of oocytes per case was 6.4±2.12 in the study group and 7.3±3.30 in the control. A total number of 133 eggs was treated with CaI and 152 were untreated oocytes. Rates of fertilization, cleavage, and embryo quality on day 2 and 3 were measured.
Results: Artificial oocyte activation with Calcium Ionophore after ICSI with thawed testicular sperm, yielded a fertilization rate of 53.5% compared with 21.0% in the untreated oocytes (P<0.01). Fertilization rate in the activated oocytes undergoing ICSI with ejaculated sperm was 58.3% whereas in the non activated ones 32.5% (P<0.001). Cleavage rates of both groups, those with testicular sperm and ejaculated one, were comparable 86.0% vs 96.2% (NS). Embryos on day 2 had similar number of blastomeres and quality: 3.8± 0.91 vs 3.4±1.24 in the treated and the untreated groups. Also the day 3 embryos had a comparable number of blastomeres between the treated group and the untreated one: 7.1±2.21 and 7.5 ±2.25 blastomeres, respectively. Three clinical pregnancies were established in the group with the ejaculated sperm and three in the testicular sperm.
Conclusions: Artificial oocyte activation with CaI increases significantly the fertilization rate in patients with severe male factor, resulting in many more embryos and thus improve the chances to achieve a pregnancy. Since this fact is well proved, CaI activation should be performed routinely in cases with severe male factor with low fertilization rate.
