Novel instrumented probe for measuring 3D pressure distribution along the vaginal canal

Abstract

We developed an intravaginal instrumented probe (covered with a 10×10 matrix of capacitive sensors) for assessing the three-dimensional (3D) spatiotemporal pressure profile of the vaginal canal. The pressure profile was compared to the pelvic floor (PF) digital assessment, and the reliability of the instrument and repeatability of the protocol was tested. We also tested its ability to characterize and differentiate two tasks: PF maximum contraction and Valsalva maneuver (maximum intra-abdominal effort with downward movement of the PF). Peak pressures were calculated for the total matrix, for three major sub-regions, and for 5 planes and 10 rings throughout the vaginal canal. Intraclass correlation coefficients indicated excellent inter- and intra-rater reliability and intra-trial repeatability for the total and medial areas, with moderate reliability for the cranial and caudal areas. There was a moderate correlation between peak pressure and PF digital palpation [Spearman’s coefficient r=0.55 (p<0.001)]. Spatiotemporal profiles were completely different between tasks (2-way ANOVAs for repeated measures) with notably higher pressures (above 30kPa) for the maximum contraction task compared to Valsalva (below 15kPa). At maximum contraction, higher pressures occurred in the mid-antero-posterior zone, with earlier peak pressure onsets and more variable along the vaginal depth (from rings 3 to 10-caudal). During Valsalva, the highest pressures were observed in rings 4–6, with peak pressure onsets more synchronized between rings. With this protocol and novel instrument, we obtained a high-resolution and highly reliable innovative 3D pressure distribution map of the PF capable of distinguishing vaginal sub-regions, planes, rings and tasks.