Volumetric self-sampling of cervicovaginal fluid: a new approach to ovulation timing.
Cervicovaginal fluid that accumulates in the upper vagina and posterior fornix can be quantitatively correlated with the presumably fertile and infertile phases of the menstrual cycle. With a newly developed Volumetric Vaginal Aspirator that women self-administer, cervicovaginal fluid can be sampled on a daily basis and the sample volume or sample weight recorded. In a total of 18 cycles from 7 different subjects there was a striking 3- to 30-fold increase in sample volume or sample weight above early follicular phase levels that preceded the shift in basal body temperature (BBT) at midcycle. The maximum of sample volume or sample weight near midcycle was defined as "Volume Peak" or "Weight Peak." The magnitude of the Volume Peak or Weight Peak varied in the individual subjects and was between 400 and 1500 microliters or mg. The Volume Peak or Weight Peak generally occurred 1 to 2 days before or on the day of presumptive ovulation. With the BBT shift to luteal phase levels, the sample volume or sample weight sharply declined to early follicular phase levels. The results suggest that changes in sample volume or sample weight of cervicovaginal fluid measured with the self-applicable Volumetric Vaginal Aspirator can be used as an objective basis for approaches to natural family planning and for the assessment of optimal conditions for conception.