Vaginal Vasomotion-Its Appearance, Measurement, and Usefulness in Assessing the Mechanisms of Vasodilatation

Because of vasomotion, the vaginal microcirculation can react to a vasodilatory stimulus with one of four theoretical photoplethysmographic responses, viz., Type 1 (full response), where there is a significant increase in the amplitude of the h-VPA signal and the number of l-VPAs are greatly reduced with a near corresponding increase in the h-VPAs; Type 2 (partial response), where the amplitude (and in some cases the number) of the h-VPAs increases but there is no decrease in the number of l-VPAs; Type 3 (partial response), where the amplitude of the h-VPAs changes little but the number of l-VPAs is reduced and the number of h-VPAs are correspondingly increased; and Type 4, where neither the amplitude of the h-VPAs (or their number) nor the number of the l-VPAs change significantly (a noneffective stimulus). This new analysis allows a more comprehensive and better discriminatory assessment of vaginal vasodilatation (genital arousal) and its return to the basal state in response to sexual arousal and now includes a new measure that is independent of an increase in the h-VPA maximum amplitude (Type 3 response). Levin RJ, and Wylie K. Vaginal vasomotion-Its appearance, measurement, and usefulness in assessing the mechanisms of vasodilatation.