Ethnic differences in the levator hiatus and pelvic organ descent: a prospective observational study

To date, most studies on functional anatomy of the pelvic floor have focused on Caucasian women. There is scant information on this topic involving other ethnic groups. The aim of this study was to investigate levator hiatal area and pelvic organ descent in three racially diverse ethnic groups of healthy nulliparous South Asian, Caucasian and black South African women, using three/four-dimensional (3D/4D) transperineal ultrasound (TPS).

Nulliparous women aged 18-40 years from three different ethnic groups were recruited for this prospective observational study between June 2012 and April 2015. After informed consent and clinical examination of the pelvic floor, all patients underwent a 3D/4D-TPS examination. Ultrasound volumes were captured at rest, on maximum pelvic floor muscle contraction (PFMC) and on maximal Valsalva maneuver. Analyses of variance and covariance were performed to compare the three ethnic groups, and a post-hoc Bonferroni pairwise test was applied.

A total of 207 nulliparous women were recruited, comprising 41 South Asian, 69 Caucasian and 97 black women. After controlling for age and body mass index, all measurements of mean levator hiatal area at rest, on PFMC and on Valsalva were higher in black women (all P < 0.0001). Post-hoc Bonferroni pairwise comparison revealed that black women had greater pelvic organ descent and levator hiatal area compared with South Asian and Caucasian women (P < 0.0001).

This comparative study indicates that there are significant differences in levator hiatal area and pelvic organ mobility between Caucasian, South Asian and black ethnic groups. Copyright © 2016 ISUOG. Published by John Wiley & Sons Ltd.