Use of Uterine Electromyography (EMG) for Estimation of Uterine Contractility and Cervical Dilation During the 1st Stage Labor in Pregnant Women

Abstract

Labor and delivery in pregnant women occurs in three stages: The 1st stage begins with the onset of uterine contractility and progressive cervical dilation. The onset and development of labor are commonly monitored with crude and inaccurate instruments and methods: a force transducer (tocodynamometer or TOCO) strapped to the abdominal surface to measure uterine contractility and digital exams to estimate effacement and cervical dilation. Electrical activity is the underlying basis for uterine contractility as it is in all muscles including the heart, skeletal and smooth muscles and electrical activity can be accurately estimated with electromyography (EMG, electrophysiological methods). In the uterus, electrical activity consists of bursts of spikes and the characteristics of the bursts are responsible for the frequency, duration and force of contractions. The goals of this study were to assess: 1) The potential for measuring uterine electrical activity during the 1st stage of labor as the basis for contractility of the uterus; 2) The causal relationship of contractility to and changes in cervical effacement and dilation in pregnant patients , and 3) Define how predicted values of cervical dilation can be obtained from electrical signals and how predicted values of electrical signal characteristics can be obtained from cervical dilation.