Not only does EUM enable non-invasive evaluation of the beginning, time to peak, duration and frequency of uterine contractions, it also evaluates their intensity. Furthermore, since it is non-invasive and does not require ruptured membranes, it can be used as a diagnostic tool for uterine contractions in suspected preterm labor. It also allows ambulation during monitoring.
EUM has been shown to correspond strongly with the tocodynamometric sensor in measuring contractions and predicting preterm labor.
The combination of predictive tests was used when a positive result in 1 or more of the included tests was considered predictive of preterm delivery. The combination of EUM with CL increased the negative predictive value to 84%, whereas the combination of EUM and FFN increased the negative predictive value to 89%. Using the 3 predictive tests in conjunction further increased the negative predictive value to 92% .
The predictive value of different test alone and in combination
|EUM plus CL||41||80||84||35|
|MEU plus NFf||53||71||89||40|
|EUM + FFN + CL||55||80||92||30|
NPV, negative predictive value, PPV, positive predictive value. Most. Myometrial electrical activity to identify patients in preterm labor. Am J Obstet Gynecol 2008.
Accurate assessment of frequency, duration, and intensity of contractions is even more critical when evaluating premature uterine contractions. It is well established that prematurity is a leading cause of fetal mortality and morbidity, yet over half of preterm labor episodes do not result in preterm births, meaning that there is overtreatment and many unnecessary hospitalizations for premature uterine contractions and suspected preterm labor. Therefore, better tools for diagnosing true preterm labor are essential .
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We used 9 electrodes evenly spaced on the patient’s abdomen to optimize the signal to noise ratio. Whereas previous EMG studies were conducted without a position sensor, the novel approach of the TrueLaborTM (EUM-100) is that it applies both multi-channel surface EMG and a 3-dimensional position sensor that enables mapping of each electrode’s location within 1 mm. This represents an accurate localization of the myometrial activity of the uterus in 3 dimensions.
In the current study we found a very strong correlation between measurement of uterine contractions by EUM and IUPC. Our results demonstrate the accuracy of EUM in measuring the onset, time to peak, duration, and intensity of uterine contractions compared to IUPC measurements. The accepted method for measuring the intensity of uterine contractions is by IUPC using mm/Hg units and calculating Montevideo evaluation.
The excellent correlation between Montevideo and the total uW during the 10-minute intervals and the area under the curves in both methods that was observed in the current study supports the reliability of EUM of uterine contractions.
Accurate monitoring of the uterine contractions curve is an essential part of the cardiotocogram and should be obtained by the best method available. It might help to prevent fetal acidemia by detecting excessive uterine activity during labor.
This is particularly important during a protracted active phase of labor or induction of labor when knowledge of the intensity of the contractions is essential for clinical decision making.
Intrauterine pressure measurement is considered the most objective way of measuring uterine activity in labor, and in this respect it is superior to clinical assessment or external tocography. However, there are technical difficulties while using the IUPC. In 14.85% of the cases in our study, we had poor quality during part of the recordings, problems with balancing the baseline before measuring contractions, or difficulties with an occult or displaced catheter that had to be resolved prior to assessing uterine activity. We encountered no difficulties with the EUM, which points to another benefit of this method. Published data supports that electrohysterographic contraction detection correlates with IUPC better than tocometry in patients with high body mass index."
Correlation between contraction intensity measured by IUPC and EUM was calculated by summing intensities of the area under curves measured at 10-minute intervals, similar to the accepted method of calculating Montevideo when using IUPC; correlation between methods was calculated for all intervals.