Better fertilization rates with intracytoplasmic sperm injection (ICSI) in unexplained infertility.

Abstract

Objective: Intracytoplasmic sperm injection (ICSI) has been applied in patients over forty, in tubal infertility, and some have suggested it as the treatment of choice in all in vitro (IVF) cases. Reduced fertilization rates have been documented in IVF cycles done for unexplained infertility. The possible role of ICSI to avoid these fertilization failures in the first IVF attempt has been advocated before. Our objective was to compare the fertilization rates in IVF and ICSI applied on sibling oocytes in unexplained infertility cases. Design: A retrospective analyses was carried out on 161 cases of unexplained and tubal infertility, between January 1997 and December 2000, in which sibling oocytes were subject to two insemination techniques: some were injected with semen by the ICSI procedure and others were inseminated by conventional IVF, using the same sperm preparation. Materials/Methods: Patients included in the study received ovarian stimulation treatment in acceptable protocols, using gonadotropin releasing hormone analogs (GnRHa) and different menotropins. Transfer of embryos was performed either, 48–72 hours after retrieval or at the blastocyst stage. Fertilization rates, embryo quality, as well as pregnancy rates, were compared and analyzed using the SPSS software. Results: The average rate of fertilization of all sibling oocytes, using IVF and ICSI, were 0.5653 and 0.7115, respectively. The difference in fertilization rate, analyzed by paired T-test, was 0.1462 (SD = 0.4232, 95% confidence interval 0.0802–0.2120, p < 0.0001). In 26 cycles (16.1%) total failure of fertilization was observed, using IVF, where as no such failures were noted in the ICSI-inseminated oocytes. Total motile cell in each couple, had no correlation with the difference in fertilization rates. Rates of pregnancy were not significantly different in ICSI, IVF and mixed embryo transfers, accordingly: 44.2%, 54.9%, and 45.9%. There was no significant difference (p = 0.846) in IVF and ICSI fertilization rates between embryo transfers which resulted in pregnancy and those which did not. Conclusions: Our results indicate that ICSI has an advantage over standard IVF in unexplained infertility cases. As such, we suggest that at least half the oocytes be exposed to ICSI in order to obtain information on the sperm’s potential to fertilize the oocytes and prevent total failure of fertilization in the first attempt of such cases.