[Studies on the electromyogram of the maternal abdominal surface--the significance and the clinical application]

The study made me recognize the significance of the electromyogram of the maternal abdominal surface (MAS-EMG), which is taken in a non-invasive and by a non-biding procedure, and also it has been proven that I can get practical and objective information from the MAS-EMG during labor in 40 primiparous and 50 multiparous. That is to say that: I can record the MAS-EMG by using the right filters [low cut filter (time constant 0.003s), high cut filter (150 Hz), notch filter (50 Hz)] in order to eliminate noise constituents. The MAS-EMG appears intermittently in the acceleration phase to the maximum slope phase when uterine contraction occurs and keeps the rhythmic MAS-EMG increased dynamically along with the progress of delivery. the available frequency zone in the MAS-EMG is from 10 Hz to 110 Hz, information which I obtained during delivery. The characteristic of the amplitude in the MAS-EMG is that the left side is larger than the right side-especially the left m. externus abdominus shows a high electrical potential. The following order of MAS-EMG occurred frequently: left m. obliquus externus abdominus----left m. obliquus internus abdominus----left m. transversus abdominus and right m. obliquus externus. The peak-hold curve of the MAS-EMG shows a great difference between normal delivery and abnormal delivery patterns. The wave forms for amplitude in the MAS-EMG constitute a practical body of information for the evaluation of involuntary and reflective bearing down action during delivery.