[Usefulness of urethral descent for evaluating the type of female stress urinary incontinence]

To select suitable treatment for stress urinary incontinence (SUI), both urethral function and urethral mobility must be assessed. Abdominal leak point pressure (ALPP) is considered to be useful to evaluate urethral function, and radiographic findings are effective to evaluate urethral mobility. However no adequate methods to measure urethral mobility with videourodynamics study (VUDS) exist. We measured the downward movement of the membranous urethra at the same time as ALPP was measured on VUDS, and examined whether or not the urethral descent on VUDS is useful to evaluate urethral mobility.

The subjects were 28 women with over grade II SUI (according to McGuire's grading) who underwent bead chain cystography and VUDS. As a classical index of urethral mobility, we measured the change of posterior urethrovesical angle (PUVA) and vesical neck descent during Valsalva maneuver on bead chain cystography. The videourodynamic urethral catheter had a radiographic marker that permitted the identification of the location of the urethral pressure sensing aperture. The catheter was fixed at the position where the urethral pressure aperture reached the point of highest pressure. The urethral descent was defined as the downward movement of the urethral marker during Valsalva maneuver while measuring ALPP. According to the urethral descent the patients were classified as follows: 1) hyper-mobile group; urethral descent was over 5 mm. 2) non-mobile group: urethral descent was under 5 mm. The severity of SUI was evaluated with 1 hr. pad weighting test, ALPP and maximum urethral pressure.

The urethral descent was significantly related to vesical neck descent and PUVA change. In the non-mobile group (11 cases), ALPP was significantly lower, and urine loss on the pad weighting test was significantly greater than that in the hyper-mobile group (17 cases). The non-mobile group exhibited more severe incontinence than the hyper-mobile group. When the patients were classified according to Blaivas's classification, all patients in type III and 2 in type I were in the non-mobile group. These 2 type I patients had low ALPP (40 cm. water and 70 cm. water) and a history of radical hysterectomy. Therefore these patients were diagnosed with ISD due to the fixed urethra.

Urethral descent is an useful index of urethral mobility. In the non-mobile group, the pathophysiological cause of SUI was not urethral hypermobility but ISD, and it was diagnosed as type III SUI without urethral mobility. We consider that urethral descent assesses urethral mobility more accurately than vesical neck descent, and that urethral descent is a valuable parameter on VUDS.