Objective: We aimed to evaluate the performance of a non-invasive EMG electrical uterine monitor (EUM) versus tocodynamometry (TOCO) by comparing both to internal uterine pressure catheter (IUPC).
Study design: Prospective observational trial. Uterine activity was recorded continuously and simultaneously, in women during active term labor, with TOCO, EUM and IUPC. Uterine activity tracings were analyzed by three blinded physicians.
Results: Overall, 385 tracings from 43 women were analyzed. A similar rate of interpretable tracings between physicians was demonstrated for EUM (87%; 95% CI 80.9-92.7%) and IUPC (94.8%; 95% CI 83.4-96.3%), with a significantly lower rate for TOCO (67.5%; 95% CI 59.4-76.8%, p < 0.001). There is a significant difference in the contraction frequency for EUM versus IUPC (0.77 ± 2.3) compared to TOCO versus IUPC (-3.34 ± 4.97). There is a high variability between the timing of TOCO contractions as compared to IUPC (4.74 ± 10.03 seconds), while a gap of 8.46 ± 4.24 seconds was detected for EUM. The sensitivity, positive predictive value and false positive rate for individual contraction identification by TOCO and EUM are 54.0%, 84.4%, 15.6% and 94.2%, 87.6%, 12.4%, respectively.
Conclusion: EUM is efficient as IUPC for uterine activity assessment and both techniques are superior in comparison to external tocodynamometry. Our results support the use of non-invasive EMG technology to monitor uterine activity.
Keywords: Contractions; EMG; electrical uterine monitor; internal uterine pressure catheter; labor; tocodynamometer.