In vitro penetration of human sperm into bovine cervical mucus: effects of sperm washing and exposure to low temperature.

Standardized bovine cervical mucus penetration by human sperm in vitro provides information for evaluating male fertility. Normal semen specimens from 20 sperm donors and 17 infertile men were tested for cervical mucus penetration. Rigorous control of test temperature was necessary to guarantee the reliability and reproducibility of cervical mucus penetration. Sperm washing was found to significantly improve cervical mucus penetration for infertile men, from 18 +/- 2.2 to 27 +/- 3.4 mm, P less than .025. Sperm washing for normal donors had no apparent effect on cervical mucus penetration (58 +/- 1.5 mm prewash, 55 +/- 1.7 mm postwash, P greater than .1). The authors conclude that: 1) temperature for cervical mucus penetration testing is critical to reliability, and 2) cervical mucus penetration is a useful screening tool for in vitro procedures proposed to improve sperm function.