Pelvic muscle activity in nulliparous volunteers.

The aim of this study was to describe normal characteristics of spontaneous and voluntary pelvic muscle function in nulliparous healthy continent women and to assess the reaction of the pelvic floor to stress and fatigue. Ten nulliparous volunteers were recruited. Pelvic muscle strength was evaluated by palpation and perineal ultrasound. Kinesiological EMG and perineal ultrasound were performed to test for possible fatigue and to assess bladder neck mobility during coughing with a pre-contraction of the pelvic floor muscles. Bladder neck mobility did not increase after attempts to fatigue the pelvic floor muscles. Bladder neck descent was significantly less when the women were instructed to contract the pelvic floor muscles before coughing. The contraction of the pelvic floor muscles stabilizes the vesical neck in nulliparous women.