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R.E. Garfield and Leili Shi
Transabdominal Recording of Uterine EMG Activity and Cervical LIF:
Promising Technologies for Obstetrics
Abstract:
Clinically we greatly need better obstetrical instruments or tools that can detect changes in uterine and cervical function during pregnancy. Presently we have crude methods and technology that do not allow us to accurately diagnose true labor at term or preterm. Subsequently we have not developed effective treatment strategies for induction or inhibition of labor. This is particularly true for inhibition of preterm labor, the most problematic issue in obstetrics. Transabdominal recording of uterine EMG activity offers great promise for diagnosis and prediction of true labor and will lead eventually to better treatments. Just as the ECG (electrocardiogram) lead to a better understanding of the heart and to the diagnosis of normal or abnormal heart function, and appropriate treatments, transabdominal EMG will eventually become the cornerstone for uterine contractility analysis and diagnosis of labor. Studies from my laboratory and by others, including the renowned work of Arpad Csapo, suggest that the uterus and cervix pass through an irreversible preparation or conditioning step in the process leading to successful labor. Yet 25 years after Csapo’s death we still do not recognize how to measure this preparation phase of labor and depend clinically on inaccurate and unreliable methodology to stage the labor process. Our studies indicate that the myometrium undergoes dramatic changes in excitability and conduction of electrical activity during the preparation phase of labor that persist into the labor stage to eventually result in birth of the fetus. Using signal processing methods of the electrical bursts recorded transabdominally from pregnant patients we can identify with accuracy when a patient has entered the preparation phase and thus is in “true” labor. Calculation of the positive and negative predictive values for prediction of labor and birth using EMG analysis give values approaching 90%, which is greater than any other present methodology used in obstetrics including tocodynamometry, fetal fibronectin, salivary estriol, or cervical ultrasound. Other studies we have done, such as combination analysis using power density spectral analysis or multiple parameter analysis using artificial neural networks suggest that higher (>90%) predictive values are obtainable. We have also worked on methods to objectively evaluate the cervix using light induced fluorescence (LIF) using an instrument we designed. This device, the collascope, allows for accurate assessment of the collagen content of the cervix during pregnancy and an estimate of cervical softening or ripening. The combination use of EMG with the collascope could provide valuable information about the functions of the uterus and cervix during pregnancy that could result in many benefits in the care of pregnant patients.
Contact:
Reproductive Sciences,
Department of Obstetrics and Gynecology,
University of Texas Medical Branch
301 University Blvd
Galveston, TX 77555-1062, USA
(409) 772-7590- voice
(409) 772-2261- fax
e-mail: leshi@utmb.edu
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