Correlation of uterine activity using the Term Guard monitor versus standard external tocodynamometry compared with the intrauterine pressure catheter.

Uterine activity monitoring to detect preterm contractions and thus to manage patients in active labor is valuable to the clinician. Uterine activity measured by external devices using the guard ring principle or by standard tocodynamometers has been shown to be accurate concerning the frequency of uterine activity as compared with intrauterine pressure catheter-derived data in the third trimester. In this study, 26 women from 19-34 weeks in documented preterm labor had their uterine activity measured by a standard in-hospital monitor and a Term Guard tocodynamometer simultaneously. The standard monitor reflected 16-91% of the frequency of contractions noted by the Term Guard device, with a reduction in the correlation at gestational ages under 30 weeks. In another 20 patients between 17-36 weeks\u27 gestation, these two methods of external tocodynamometry were compared with a transcervical catheter which measured actual intrauterine pressure and frequency of contractions. There was a good correlation between the Term Guard device and transcervically measured contractions (94.6%). At gestational ages of 28 weeks or less, there was poor performance from standard devices (less than 38% correlation with the intrauterine pressure catheter). These data have important implications for clinicians who monitor preterm patients on an ambulatory basis for early detection of preterm labor and also have clinical impact for the management of patients at early gestational ages in active labor