Objective The aim of this article was to compare clinical interpretation of uterine activity tracings acquired by tocodynamometry and electrohysterography with the gold standard, intrauterine pressure. Study Design Using data from a previous study, subjects who had simultaneous monitoring with all three uterine activity devices were included in this study. These were parturients who required intrauterine pressure catheter (IUPC) placement for obstetric indication. A Web-based application displayed scrolling 30-minute segments of uterine activity. Two blinded obstetricians and two blinded obstetric nurses independently reviewed the segments, marking uninterpretable segments and the peak of each contraction. Interpretability was compared using positive percent agreement. False positives are contractions marked in the noninvasive strip that have no corresponding contraction in the IUPC strip. False negatives are the reverse. Results A total of 135 segments, acquired during either Stage 1 (active labor) or Stage 2 (pushing), from 105 women, were included in this analysis. For all four observers, both interpretability and sensitivity of electrohysterography exceeded that of tocodynamometry (p < 0.0001). This remained true for the obese population (96 segments). Conclusion Compared with the IUPC, electrohysterography is more sensitive and provides tracings that are more often interpretable than tocodynamometry for intrapartum monitoring; electrohysterography is also less affected by increasing maternal body mass index.
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