Direction sensitive sensor probe for the evaluation of voluntary and reflex pelvic floor contractions.

AIMS The development of a vaginal probe for the evaluation of the dynamics of pelvic floor function is described. Fundamental criteria in the design of this probe involves the incorporation of a means of assessing whether the isotonic forces closing the vagina are equally distributed or whether they are greater in some directions than others. The aim of this study is to present the design of directionally sensitive multi-sensor probe, having circumferential spatial resolution, constructed to identify the distribution of anisotropic forces acting on the vagina following voluntary and reflex pelvic floor contractions. MATERIALS AND METHODS Probe system consists of four pairs of force/displacement sensors mounted on leaf springs enabling isotonic measurements of voluntary and reflex contractions. Assembly is retractable to 23 mm for insertion, and expandable to 60 mm for measurement. Simultaneous measurements were made of force and displacement with the sensors oriented in the anterior/posterior and left/right orientation of the vagina. Using this probe, measurements were carried out to identify the temporal and spatial characteristic response of the vaginal wall. Data were analyzed with respect to voluntary pelvic floor and cough-induced contractions of nine subjects having a mean age of 64 years. RESULTS A robust probe system was developed and measurements were successfully made. Initial results show that the maximum force and displacement occurs during reflex contractions in the anterior aspect of the vagina validating the anisotropic nature of the forces acting on the vaginal wall. The data also show that both the force and displacement produced by the cough-induced has a higher magnitude than voluntary pelvic floor contraction. CONCLUSIONS A directional multi-sensor vaginal probe has been developed to evaluate the force and displacement produced during isotonic pelvic floor contractions. Analysis of the results provided new biomechanical data demonstrating the anisotropic nature of vaginal closure as a consequence of pelvic floor contractions.