Transrectal sonographic investigation of urethral and paraurethral structures in women with stress urinary incontinence.

Transrectal sonography of the urethra was used in 14 asymptomatic volunteers, 37 women with frequency-urgency syndrome, 42 patients with mild stress urinary incontinence, and 18 with severe stress urinary incontinence. Transverse scanning over the midurethra was performed and cross-sectional images of the urethral and paraurethral structures were compared among the four groups, with P < 0.05 being considered statistically significant. The total cross-sectional area of the midurethra was significantly smaller in patients with stress urinary incontinence than in those without this disorder (86.7+/-29.9 versus 104+/-35.6 mm2, P = 0.005); this difference resulted from a significantly smaller peripheral striated muscle component in patients with stress urinary incontinence (42.8+/-20.7 versus 58.3+/-27.3 mm2, P = 0.001). The thickness of the urethropelvic ligaments was significantly thinner in patients with stress urinary incontinence than in those without (5.9+/-1.7 versus 8.9+/-2.1 mm, P < 0.001). The distribution of the peripheral striated muscle around the urethra was variable: complete surrounding the urethra was noted in 35.7% of the control women and in 48.6% of frequency-urgency patients, but only in 16.7% of patients with mild stress urinary incontinence and 5.3% of patients with severe disease. Bladder neck incompetence was seen in 42 patients with stress urinary incontinence but in none of the control women. The length of the pubourethral ligaments was similar in the four groups. Our finding showed that stress urinary patients had a smaller striated muscle component in the midurethra and thinner urethropelvic ligaments. These defects in the continence mechanisms might have great implications in the pathophysiology of stress urinary incontinence. Transrectal sonography of the urethra is a valuable investigative tool in assessing urethral and paraurethral conditions in patients with stress urinary incontinence before deciding treatment modality.