Repeatability of Female Midurethral Measurement Using High-Frequency 3-Dimensional Transvaginal Ultrasonography

Imaging assessment of the female urethra is critical for diagnosis and treatment of urinary incontinence. High-frequency 3-dimensional (3D) transvaginal ultrasonography (TVUS) is a novel technique for evaluating the female urethra. The aim of this study was to test the repeatability of 3D TVUS between examiners without prior experience with TVUS.

Fifty women underwent 3D TVUS. Two examiners without prior experience analyzed the urethral volumes and measured the urethral parameters. Two-dimensional (2D) parameters included urethral sphincter length and urethral sphincter thickness; 3D parameters included urethral sphincter volume, midurethral complex volume, and inner core volume. One of the examiners repeated the evaluations 1 month later. Subsequently, the measurements were compared.

The mean age of the patients ± SD was 34.1 ± 8.1 (range, 23-55) years; the mean height, weight, and body mass index were 160.44 ± 5.12 (range, 150-173) cm, 61.80 ± 13.64 (range, 45-110) kg, and 23.98 ± 4.91 (range, 17.53-39.92) kg/m² , respectively. The results of our study showed excellent to good intraobserver repeatability (intraclass correlation coefficient [ICC], 0.75-0.87) for the evaluations of all parameters but urethral sphincter length (moderate ICC, 0.53), whereas they showed good to moderate interobserver repeatability (ICC, 0.44-0.77) for all parameters. The repeatability of 3D volumes (ICC, 0.59-0.87) tended to be better than that of 2D parameters (ICC, 0.44-0.76).

The intraobserver and interobserver repeatability of high-frequency 3D TVUS measurements of the female urethra was excellent to moderate between examiners without previous experience. The repeatability of 3D measurements tended to be better than that of 2D parameters.