Monitoring intrauterine pressure during active labor. A prospective comparison of two methods.

Conventional recording of intrapartum uterine activity uses fluid-filled internal catheter systems requiring periodic maintenance. An intrauterine pressure catheter system, the INTRAN, uses an electronic pressure sensor and theoretically could obtain satisfactory uterine recordings with less maintenance. Simultaneous recordings with the INTRAN and standard fluid-filled systems were made in 40 third-trimester patients using comparably calibrated electronic monitoring systems. Comparisons of the recordings from each patient showed similar mean baseline uterine tone, contraction interval and duration. Mean peak uterine pressures were significantly higher with the INTRAN system (63 vs. 56 mm Hg). Coefficients of correlation for contraction interval, duration, peak intrauterine pressure and resting tone were .99, .87, .84 and .34, respectively. Both systems detected abnormal uterine activity equally well. Major technical failures were equally frequent with both systems; however, the fluid-filled catheters required more frequent readjustment.