Pelvic floor muscle function in continent and stress urinary incontinent women using dynamometric measurements

AIMS: To compare the pelvic floor muscle (PFM) function in continent and stress urinary incontinent women using dynamometric measurements. METHODS: Thirty continent women and 59 women suffering from stress urinary incontinence (SUI), aged between 21 and 44 and parous, participated in the study. An instrumented speculum was used to assess the static parameters of the PFM: (1) passive force at 19 and 24 mm of vaginal aperture (antero-posterior diameter), (2) maximal strength in a self-paced effort at both apertures, (3) rate of force development and number of contractions during a protocol of rapidly repeated 15-sec contractions, and lastly (4) absolute endurance recorded over a 90-sec period during a sustained maximal contraction. The parameters described in the two latter conditions were assessed at the aperture of 19 mm. Analyses of covariance were used to control the confounding variables of age and parity when comparing the PFM function in the continent and incontinent women. RESULTS: The continent women demonstrated higher passive force at both openings and a higher absolute endurance as compared to the incontinent women (P < or = 0.01). In the protocol of rapidly repeated contractions, the rate of force development and number of contractions were both lower in the incontinent subjects (P < or = 0.01). The differences between the two groups for maximal strength at the 19- and 24-mm apertures did not reach the statistically significant level. CONCLUSIONS: The PFM function is impaired in incontinent women. The assessment of PFM should not be restricted to maximal strength. Other parameters that discriminate between continent and incontinent women need to be added to the PFM assessment in both clinical and research settings.