The relationships of urethral and pelvic floor muscles and the urethral pressure measurements in women with stress urinary incontinence.

OBJECTIVES: To investigate the relationships between urethral and paraurethral anatomy and urethral pressure measurements in women with stress urinary incontinence (SUI).
MATERIALS AND METHODS: A total of 83 women with SUI and 33 with frequency urgency syndrome but not SUI were included in the study. The parameters of transrectal sonography of the urethra and urethral pressure profilometry were compared among the subjects with each of four types of SUI and non-SUI subjects.
RESULTS: Videourodynamic study revealed that 26 women had type 0 SUI, 39 had type 1 SUI, 19 had type 2 SUI and 9 had type 3 SUI. The urethral striated muscular area was significantly smaller in subjects with type 3 SUI than in subjects with type 0 SUI and in non-SUI subjects. The thickness of the urethropelvic ligaments was thinner in subjects with SUI than in non-SUI subjects. Maximal urethral closure pressure (MUCP) was also significantly smaller in subjects with SUI than in non-SUI subjects. Pressure transmission ratio (PTR) was lower in subjects with type 1, 2 and 3 SUI than in subjects with type 0 SUI and no SUI. Pelvic floor contractility was significantly lower for subjects with type 3 SUI than for the other groups of subjects. Leak point pressure (LPP) showed a significantly progressive decrease from type 1 to 3 SUI subjects.
CONCLUSIONS: This study found that SUI in women is a condition in which the urethral and paraurethral structures become progressively deficient. The intrinsic and extrinsic structural deficiencies result in a lower MUCP, smaller PTR, insufficient pelvic floor contractility on the urethra, and a lower LPP in SUI patients.