pH of human semen.

The World Health Organization (WHO) laboratory manual (1992) states the normal values for pH in liquefied semen to be between 7.2 and 8.0. This implies an adjustment compared with the previous version (WHO, 1987) in which the upper limit was 7.8, whereas in the WHO clinical manual (1993) the normal range of values is still stated to be in the range of 7.2-7.8. In this study pH was measured in ejaculates from 207 men in couples undergoing infertility examination. The pH was measured within 30 and 60 min after ejaculation with both pH paper and pH meter. The mean pH values were consistently well above 8.0 regardless of analysis method and time after ejaculation. Since semen analysis is part of clinical assessment of male infertility and includes pH measurement, our findings suggest that the range of normal values needs to be revised further.