Electrohysterogram Signals from Patients with Threatened Preterm Labor: Concentric Ring Electrode Vs Disk Electrode Recordings

Recording of electrohysterogram (EHG) has emerged as a non-invasive method for monitoring uterine dynamics during pregnancy. Usually EHG is picked up using conventional disk electrodes placed on the abdominal surface resulting in a limited spatial resolution due to the blurring effect of the volume conductor. In this respect, concentric ring electrodes have been proposed to pick up uterine myoelectrical activity in term patients so as to improve spatial resolution and to reduce physiological interferences embedded in these records. The aim of the present work is to check the feasibility of recording EHG signals using concentric ring electrodes (BC-EHG) in patients with threatened preterm labor and to compare their capability to discriminate true preterm labor from false alarms with that of conventional EHG bipolar recording. For this purpose, 50 sessions with simultaneous EHG recordings with conventional disk electrodes and concentric ring electrodes were conducted in 26 patients. Compared to conventional bipolar EHG recording, the BCEHG presents smaller amplitude and similar spectral characteristics. Statistically significant differences between women who delivered preterm and those that delivered at term were found for both the average peakpeak amplitude and the dominant frequency in the frequency range 0.2-1 Hz from BC-EHG recordings. Nonetheless no EHG parameter from simultaneous conventional bipolar recording showed statistically significant differences. These results suggest superior performance of BC-EHG recordings in patients with threatened preterm labor for discriminating true preterm labor from term labor.