The role of cervical mucus--semen interaction in infertility of unknown aetiology.

An in-vitro penetration assay, which incorporates measurements of sperm motility and forward velocity, was used to investigate sperm-cervical mucus interaction in 20 couples with unexplained infertility. Evidence of impaired cervical mucus penetration was found in this group of patients and in seven couples the results correlated with previous assessment by laparoscopic sperm recovery. The impairment of cervical mucus penetration was found to be due to defective sperm function rather than to the quality of the cervical mucus itself. Of the criteria of semen quality measured in this study, sperm motility and the zona-free hamster egg penetration test showed significant correlations with cervical mucus penetration.