Pelvic floor biometry in asymptomatic primiparous women compared with nulliparous women: a single-center study in Southern China

OBJECTIVE: This study aimed to investigate pelvic floor biometry of asymptomatic primiparous women compared with nulliparous women by using four-dimensional transperineal ultrasound (4D TPUS). METHODS: From July 2015 to February 2017, 722 women were enrolled and divided into the nulliparous group (n = 292), the vaginal delivery group (n = 272), and the elective cesarean section group (n = 158). The ultrasound parameters of 4D TPUS were compared among the groups. RESULTS: The vaginal delivery group had a significantly greater bladder neck descent (η(2) = 0.04), retrovesical angles on Valsalva maneuver (η(2) = 0.01), urethral rotation (η(2) = 0.01), levator hiatus area on Valsalva maneuver (η(2) = 0.02), urethral inclination angle (η(2) = 0.02), and funneling of the proximal urethra (η(2) = 0.11) than the other two groups. Comparison of the two modes of delivery (vaginal delivery and cesarean section) also showed significant differences in the above-mentioned ultrasound parameters. CONCLUSION: There are significant differences in pelvic floor biometry between asymptomatic primiparous women and nulliparous women, as well as between women with vaginal delivery and those with elective cesarean section.