Morphometry of the nulliparous pelvic floor

ABSTRACT Objectives To describe morphometry of the pelvic floor in a large population of nulliparous women, comparing those with and those without pelvic pain. We also aimed to assess its association with characteristics such as age and body mass index (BMI). Methods This was a prospective study performed between January 2013 and November 2015 in non‐pregnant nulliparous women attending a general gynecology clinic. Following collection of demographic data, women were examined using translabial four‐dimensional (4D) ultrasound. Dynamic volumes of pelvic floor muscle were obtained at rest, on maximal contraction and on Valsalva maneuver, and analyzed at a later date by an assessor blinded to demographic details. Standard measurements for each volume included levator hiatal area and anteroposterior and transverse diameters, and pubovisceral muscle length and width. Subanalysis was performed comparing women with and those without pelvic pain. Linear regression analysis was performed to assess the association between characteristics, including age and BMI, and levator hiatal area at rest. Results Three hundred and sixty eight nulliparous women were examined using translabial 4D ultrasound. Median levator hiatal area was 10.62 cm2 at rest, 11.95 cm2 on Valsalva maneuver and 8.18 cm2 on maximal contraction. There was no difference between women with and those without pelvic pain when comparing biometric measurements of the pelvic floor musculature, except for in pubovisceral muscle width during the contraction phase. Regression analysis demonstrated that higher age and BMI were associated with increased levator hiatal area measurement. Conclusions Pelvic floor morphometry in nulliparous women is unchanged by pelvic pain, but levator hiatal area is increased in women with higher BMI and age. Copyright © 2018 ISUOG. Published by John Wiley & Sons Ltd.