Disposable vaginal surface electrode for urethral sphincter electromyography.

During the last 2 years we have developed a disposable vaginal surface electrode for electromyographic (EMG) recording from the urethral striated sphincter. We describe the design of the electrode and report the results of laboratory testing, including directional selectivity of the electrode, electrode impedance, testing for movement artefacts and stability of position. Clinical studies which included 138 cystometries with sphincter EMG, 133 pressure-flow EMG studies and four urethral pressure profile studies with sphincter EMG, demonstrated that the electrode gave technically good and reliable electromyographic data. The registration caused no discomfort to the patient and did not disturb the act of micturition. We recommend this technique for the evaluation of urethral striated muscle activity during urodynamic studies in women, since it is simple, inexpensive and reliable.