[Value of sperm acrosin activity detection in selecting the method of assisted reproduction for patients with unexplained infertility]

Objective: To investigate the clinical significance of sperm acrosin activity detection in selecting the method of assisted reproduction for patients with unexplained infertility (UI).

Methods: This retrospective study included 49 UI couples treated by IVFET (49 cycles) after three failures in intrauterine insemination (IUI) and another 95 couples with uterine tube obstruction (UTO) treated by IVF (131 cycles). We analyzed the laboratory data, clinical outcomes and sperm acrosin activity in the two groups of patients. According to the level of sperm acrosin activity of the males, we further divided the UI patients into two subgroups, a < 36 IU/106 sperm group (20 cycles) and a ≥36 IU/106 sperm group (29 cycles), and compared the fertilization rates between the two groups.

Results: Compared with UI couples treated by IVFET, the UTO couples treated by IVF had a significantly lower rate of fertilization (67.0% vs 76.4%, P < 0.05) and a higher rate of remedial intracytoplasmic sperm injection (ICSI) (20.4% vs 6.1%, P < 0.05), but showed no statistically significant differences in the rates of MII oocytes, available embryos, highquality embryos, implantation, and clinical pregnancy from the latter group (P >0.05). The sperm acrosin activity was remarkably lower in the UI than in the UTO patients (36.03 vs 61.98 IU/106, P < 0.01), and so was the fertilization rate in the < 36 IU/106 than in the ≥36 IU/106 sperm subgroup (47.7% vs 80.3%, P < 0.01).

Conclusions: The low fertilization rate caused by decreased sperm acrosin activity may be the main cause of infertility and the potential factor of UI. When sperm acrosin activity is < 36 IU/106 sperm, IVF plus shortterm fertilization by remedial ICSI should be preferred to IUI.