The effect of peritoneal fluid from patients with endometriosis on human sperm function in vitro

OBJECTIVE: Our purpose was to evaluate the effect of peritoneal fluid from women with endometriosis on sperm motility and function in an in vitro model. STUDY DESIGN: Peritoneal fluid was collected at laparoscopy from patients with and without endometriosis. Human donor sperm was diluted with this fluid, and its effect on sperm function and motility was measured with the zona-free hamster egg sperm penetration assay and computer-assisted semen analysis. RESULTS: The mean number of eggs penetrated by the sperm mixed with peritoneal fluid from patients with endometriosis was significantly fewer than the number penetrated by the sperm mixed with fluid from control patients (22.9 +/- 5.31 vs 44.4 +/- 4.96, p < 0.01, Student t test, n = 20). When evaluated by computer-assisted semen analysis, sperm mixed with peritoneal fluid from patients with endometriosis showed a significant decrease in mean swimming velocity compared with sperm mixed with peritoneal fluid from control patients (54.0 +/- 1.77 vs 59.2 +/- 1.05, p = 0.02, Student t test, n = 20). A significant increase in the fraction of sperm swimming at slower velocities was also found. A trend toward a positive correlation between eggs penetrated and sperm velocity was seen, but statistical significance was not achieved (correlation coefficient 0.4392, p = 0.053, n = 20). CONCLUSION: These data suggest that substances found in the peritoneal fluid of patients with endometriosis could contribute to infertility through impairment of both sperm function and motion kinematics.