Quantitative determination endogenous acid phosphatase activity in vaginal washings

Vaginal washings obtained in 98 patients were analyzed for acid phosphatase activity. A history of recent sexual intercourse was also obtained. Acid phosphatase values of less than 50 IU (obtained by the alpha naphthol phosphate method) correlated with abstinence from sexual intercourse for more than 30 hours, whereas values greater than 50 IU correlated with sexual intercourse in a period up to and including 30 hours (P less than 0.05). The presence or absence of sperm was found to correlate poorly with the time since intercourse.