Recording of uterine activity from the abdominal lead EMG

Abstract

With external tocography some form of pressure or force transducer is fastened to the abdominal wall by means of an elastic belt. Uterine contractions produce changes in the displacement of a sensor pin which acts on the transducer, producing an electrical signal that corresponds to the relative uterine pressure. External tocography, however, has the drawback that it is subject to many factors which may influence the results of the measurement. We feel that the limitations of tocography cannot be eliminated by technical improvements of the measuring equipment, and therefore the possibility of recording the uterine contractions from the abdominal lead electromyogram (EMG) without losing any information regarding tocography has been studied. As a result of the study it has become evident that the recording of uterine activity using the EMG is more reliable than tocography and offers even additional information about the excitation and propagation of the contractions. The basic methods that have been developed and the results of clinical tests are presented here.