Vaginal Photoplethysmograph

Vaginal photoplethysmography (VPG) refers to measurement of vaginal vasocongestion. A vaginal photoplethysmograph is a clear acrylic, menstrual tampon-shaped device that contains a light source, and a light detector. The light source illuminates the capillary bed of the vaginal wall and the blood circulating within it. As the amount of blood in the vaginal tissue increases, more light is reflected into the photosensitive cell of the device. VPG is the most common way to assess vaginal blood flow and is widely used to measure genital sexual arousal in women.

VPG was designed to be easily inserted by research participants; however, some participants perceive insertion of the VPG to be invasive. Past research suggests that studies using VPG result in small and unrepresentative samples. However, more recent assessments of women’s willingness to participate in sexual psychophysiological research using VPG found no evidence of sampling bias influencing results.