Dynamic transurethral sonography and 3-dimensional reconstruction of the rhabdosphincter and urethra: initial experience in continent and incontinent women.

OBJECTIVE: The purpose of this study was to evaluate the female urethra and the striated urinary sphincter, the rhabdosphincter (RS), by means of dynamic transurethral sonography and sonographic 3-dimensional (3D) reconstructions.
METHODS: In 15 female patients with urinary stress incontinence (mean age, 67.5 years) and 5 continent women (mean age, 48.3 years), morphologic characteristics and function of the RS and urethra were examined with a 10-MHz transurethral ultrasound transducer. With the help of a mechanical pullback system, the transducer was slowly retracted to scan the whole urethra and the RS from the bladder neck to the urethral orifice. Subsequently, 3D reconstructions of the urethra using an integrated computer system were performed. The RS as well as the length of the urethra were investigated under contracted and noncontracted conditions to measure contractility of the RS and dynamic changes of the lower urinary tract.
RESULTS: Partial or complete loss of RS function was detected in patients with stress incontinence. The findings on sonography were found to correlate well with the grade of incontinence. Furthermore, under contraction of the RS, a median increase in urethral length was observed. In incontinent patients, the increase in the urethral length was statistically significantly less (P = .04), which was related to the reduced contractility of the RS.
CONCLUSIONS: Dynamic transurethral sonography with subsequent 3D reconstructions allows for assessment of function and morphologic characteristics of the RS and urethra. Normal contraction of the RS results in an elongation of the urethra.