260: Uterine electromyography before and after administration of epidural anesthesia


      Controversy exists regarding the effect of epidural anesthesia on progress of labor. We sought to determine if epidural anesthesia affects electrical uterine activity during active labor.

      Study Design

      In a prospective double-blind study of women at term with normal labor (Friedman) curves, epidural anesthesia was placed during the active phase of labor. Electrial uterine activity and cervical characteristics were measured at least 30 minutes before administration and within one hour after completion of the epidural anesthesia. Data were recorded and processed by means of a uterine contractility algorithm. The system is comprised of a multi-channel surface electromyogram (EMG) operative that senses electromyographic activity, a three-dimensional position sensor, and a personal computer providing data analysis and a graphical user interface. The data were sent offsite to an individual blinded to the clinical data for analysis.


      Fifteen women with low risk pregnancies participated in the study. The study revealed: (1) cervical dilation prior to administration of the epidural was 4.0 + 0.3 cm, whereas the second evaluation within one hour after placement of epidural was 6.0 + 0.6 cm. The difference between the first and second evaluations was significant, p=0.001. The study also revealed: (2) comparable measurements of electrical uterine activity between the initial and second evaluation (467±89 vs. 506±123) and (3) a positive association was found between the pre and post of electrical uterine activity measurements (r=0.47, p=0.05)


      Our data suggests that epidural anesthesia during the active phase of labor does not affect the electrical uterine activity.