Abstract

The purpose of this study was to test the ability of uterine electrical activity recorded by electrohysterography (EHG) from abdominal electrodes during pregnancy to provide reliable information about uterine contractions. In this preliminary study, abdominal EHG was used to monitor the uterine contractions of eight women, three of whom were having spontaneous contractions related to preterm labor and five of whom were having medical abortions after intrauterine fetal death. The EHG signal consisting of one electrical burst (EB) correlated with a single episode of mechanical activity (MA) in more than 66% of the recorded contractions. When mechanical or electrical activity identified as artifactual was excluded, the temporal correlation of EBs with MA was found in 89% of the recorded contractions. Furthermore, the electrical bursts detected had temporal and spectral characteristics similar to those described previously. Reliable detection of mechanical activity during early pregnancy remains problematic. Nevertheless, abdominal EHG appears suitable for noninvasive monitoring of pregnancies at risk. Further studies are needed to elucidate the significance of the EHG signal in both normal and abnormal pregnancies. It may eventually be possible to use EHG as an ambulatory monitoring tool for the early diagnosis of preterm labor.

PIP:

Obstetrician-gynecologists used abdominal electrohysterography (EHG) to monitor uterine activity in 8 women admitted to the hospital in Amiens, France. The 1st group consisted of 3 women experiencing spontaneous contractions at 19-34 weeks gestation relating to preterm labor. The 2nd group were women undergoing induced abortion at 18-26 weeks gestation after intrauterine fetal death. Researchers wanted to test the feasibility of using EHG to detect uterine contractions. Physicians placed 1 Ag-AgC1 Beckman electrodes on the abdominal wall halfway between the uterine fundus and the symphysis on the medial vertical axis of the uterus and the ground electrode in a lateral position on the hip. An electrical burst correlated with 1 episode of mechanical activity in 215 (66.2%) of 325 uterine contractions. When the researchers excluded those cases with a full bladder or mechanical artifacts due to patient movement, this percentage rose to almost 89%. The temporal and spectral characteristics of the detected electrical bursts matched those from published reports. EHG was able to identify spontaneous contractions as early as 19 weeks gestation and induced contractions as early as 18 weeks gestation. The researchers still considered reliable detection of contractions during early pregnancy to be a problem, however. Regardless, they concluded that EHG is an appropriate way to monitor pregnancies at risk in a noninvasive fashion. They called for studies to determine the significance of the ENG signal in both normal and abnormal pregnancies. Perhaps, EHG can eventually be used as a home monitoring device to prevent preterm labor in women with a high risk pregnancy.