Are there age-related changes in the measurements of the urethral sphincter complex in nulliparous women? A three-dimensional ultrasound assessment.

Introduction and hypothesis: The objective was to determine age-related changes in measurements of urethral sphincter complex components in asymptomatic nulliparous women. Methods: Eighty nulliparous women ≥18 years underwent 3D ultrasound of the anterior pelvic compartment in a cross-sectional study. Measurements of the urethral sphincter components (smooth muscle sphincter [SMS] and striated urinary sphincter [SUS]) and urethra including area, length, width, and distance of the SUS and SMS from the urethrovesical junction were obtained. The women were grouped into four age groups: < 30 years (group A), 30 to < 45 (group B), 45 to < 60 (group C), and ≥ 60 years (group D). Age-related differences in the measurements were determined. Inter-rater and intra-rater agreement were performed for 20 nulliparous women. Results: There were 24, 18, 26, and 12 women in groups A, B, C, and D respectively. None of the urethral sphincter complex measurements was significantly associated with age (p > 0.05). No differences were found between the groups for any measurements using one-way ANOVA and multiple comparison pairwise comparison (p > 0.05) other than width of SMS (C > A), urethral length (C > A), and distance of SUS from urethrovesical junction (C > D). Inter-rater and intra-rater agreement were moderate for area, length, and width of SUS (intraclass correlation 0.6) and good (intraclass correlation above 0.8) for the remaining measurements. Conclusion: Other than width of SMS, urethral length, and distance of SUS from urethrovesical junction, the dimensions of urethral sphincter complex components, as visualized by 3D endovaginal ultrasound, do not vary with age. [ABSTRACT FROM AUTHOR]