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 (eta(2) = 0.04), retrovesical angles on Valsalva maneuver (eta(2) = 0.01), urethral rotation (eta(2) = 0.01), levator hiatus area on Valsalva maneuver (eta(2) = 0.02), urethral inclination angle (eta(2) = 0.02), and funneling of the proximal urethra (eta(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.