152: Uterine electromyography is comparable to intrauterine pressure catheter for monitoring contractions


      Uterine contractions are traditionally monitored by the tocodynamometer (TOCO) which has low sensitivity and specificity, especially in obese patients. The intrauterine pressure catheter (IUPC) can be used to monitor adequacy of contractions but only after amniotomy. The objective of this study was to compare the TOCO and transabdominal uterine electromyography (EMG) to IUPC in term laboring patients.

      Study Design

      Patients were prospectively enrolled if they were >18 yr of age, had singleton pregnancies, and were in labor with an IUPC. Those with infection, antepartum hemorrhage, known fetal anomaly, or a condition needing urgent delivery were excluded. Root mean square (RMS) plot from the uterine EMG signals over a 45 minute period was compared to the IUPC and the TOCO tracing obtained during the same period. The number of contraction events per unit time was determined for each of the devices. Total contraction frequency, number of corresponding contractions and the difference in contraction peak time values were compared using Student-t test or ANOVA as appropriate (significance: p< 0.05).


      For TOCO vs. IUPC peaks, the mean peak difference between TOCO and IUPC was 0.74 seconds (SE = 2.61), and it was not significantly different from baseline at alpha=0.05 (P = 0.78; SD 10.6). For RMS vs. IUPC peaks, the mean peak difference between RMS and IUPC was 0.12 seconds (SE = 1.88), and it was not significantly different from baseline at alpha = 0.05 (P = 0.95; SD 13.1). The total contraction frequency and number were comparable between IUPC and RMS (p<0.05). Body mass index > 30 or pitocin augmentation of labor did not affect the RMS signal significantly.


      In term patients, there is no significant difference between RMS vs. IUPC and TOCO vs. IUPC peaks at = 0.05 level. Transabdominal uterine EMG can be useful non-invasive method to monitor labor in patients with intact membranes.