Cough-induced microtransducer movements in the urethra affecting pressure measurements

Ratios of the amplitudes of the pressure increments in the urethra and vagina during coughing have been measured with two types of microtransducer catheters in fixed and loose positions. The data obtained from 14 urge incontinent women clearly indicate an artifactual contribution to the cough-induced urethral pressure increment measured by a semirigid microtransducer catheter attached to a withdrawal apparatus. This contribution due to urethral movement over the microtransducer catheter is negative in the proximal urethra and positive distally and accounts for the S-shaped distribution of transmission ratios along the urethra, as has been described for continent women. Transmission ratios exceeding 100 per cent were found over at least a part of the urethra. This excess proved to be present in all four versions of measurement and consequently cannot be considered as artifactual.