Novel insight into the dynamics of male pelvic floor contractions through transperineal ultrasound imaging

Purpose: Transperineal ultrasound imaging enables the minimally invasive assessment of pelvic floor muscle function. Although commonly used in women, the approach has rarely been reported in men. This approach has advantages because the midsagittal view visualizes a bony landmark and the entire urethral length. This allows investigation of the displacement of multiple points along the urethra and the unique mechanical actions of multiple muscles that could influence continence. We used a new transperineal ultrasound technique to compare the relative displacement of urethrovesical junction, anorectal junction and distal urethra during voluntary pelvic floor muscle contractions in continent men.

Materials and methods: We performed measurement and comparison of urethral displacement at specific urethral regions in 10 continent men (age range 28 to 41 years). Measures made on 2-dimensional midsagittal plane ultrasound images included the displacements of specific points along the urethra. Anatomical considerations suggest that these are caused by contraction of the levator ani, striated urethral sphincter and bulbocavernosus muscles. Pearson's correlation coefficient was used to investigate the relationship between displacements of pairs of points.

Results: Data show individual variation in displacement of the distal urethra (striated urethral sphincter contraction) and urethrovesical junction (levator ani contraction). A strong inverse linear relationship (0.723) between displacements of these points indicates 2 alternative strategies of urethral movement.

Conclusions: Transperineal ultrasound imaging allows the simultaneous investigation of multiple pelvic floor muscles by measuring urethral displacement. The data provide evidence of different but coordinated strategies of urethral displacement in men.