Vaginal probe transducer: characterization and measurement of pelvic-floor strength

The pelvic-floor muscles (PFM) play an important role in urinary and fecal continence. Several investigators have studied the PFM using intra-vaginal pressure measurements, but their methods have not been validated. We describe the characteristics of a probe transducer developed to measure PFM strength according to its dynamic response and the effects of temperature variation. This probe transducer was used to evaluate changes in the contraction strength of pelvic muscles in a group of patients who participated in a PFM training program. Experiments allowed the identification of the probe's characteristics at different temperatures, definition of a calibration equation, and measurements of the dynamic response to pressure pulse. Evaluation of patients before and after the PFM training program showed significant differences in the peak pressure achieved during the contraction (p<0.001) and in pressure-rise time (p<0.01). The tests performed with the probe allowed the characterization of the proposed transducer, and the intra-vaginal pressure measurements in volunteers undergoing a PFM training program allowed a quantitative evaluation of the PFM strength.