This original cross-sectional comparative study evaluates pelvic floor morphometry and function in geographically distinct cohorts of healthy young adults, addressing the limited availability of normative data in this age group. We hypothesized that pelvic floor morphometric measurements would differ between cohorts from the United States and the United Arab Emirates, while voluntary pelvic floor muscle contractility would remain comparable after adjustment for anthropometric characteristics.

A total of 314 healthy nulliparous young adults were recruited from the United States (n = 200) and the United Arab Emirates (n = 114). Pelvic floor assessment was performed using standardized transabdominal ultrasound. Bladder base position was measured at rest and during voluntary pelvic floor muscle contraction. Contractility was defined as the displacement difference between resting and contraction measurements. Between-group comparisons were performed using appropriate parametric or non-parametric tests. Analyses of covariance adjusted for age, height, weight, and body mass index.

Participants from the United States demonstrated greater bladder base position at rest compared with the UAE cohort (mean ± SD: 5.25 ± 1.58 vs 4.21 ± 1.68; mean difference 1.04; 24.7% higher; p < 0.001). During voluntary contraction, measurements were also higher in the USA cohort (4.78 ± 1.49 vs 3.79 ± 1.65; mean difference 0.99; 26.1% higher; p < 0.001). However, pelvic floor muscle contractility did not differ significantly between groups (0.47 ± 0.38 vs 0.42 ± 0.26; mean difference 0.05; 11.9% relative difference; p = 0.192). These findings remained consistent after adjustment for anthropometric variables.

The observed higher bladder base position at rest and during voluntary contraction in the U.S. cohort suggests potential anatomical or baseline functional differences in pelvic floor support between populations. These differences could reflect variations in lifestyle, habitual activity, or other population-specific factors influencing pelvic floor morphology. Importantly, despite these structural variations, pelvic floor muscle contractility did not differ significantly, indicating that the functional capacity for active pelvic floor elevation is comparable between cohorts. This dissociation between resting anatomy and contractile function highlights that higher baseline bladder position does not necessarily confer greater functional strength. Adjustments for anthropometric variables confirm that these findings are independent of body size, suggesting intrinsic population-level differences rather than differences driven by physique.

Geographically distinct cohorts of healthy young adults demonstrated significant differences in pelvic floor morphometric measurements, while voluntary pelvic floor muscle contractility was comparable after anthropometric adjustment. These findings support the presence of structural variation with preserved functional performance and highlight the importance of population-specific normative reference values in pelvic floor assessment.

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