Electrohysterography of labor contractions: propagation velocity and direction

Objective Electrohysterographic assessment of the propagation velocity of uterine depolarization has been introduced as a promising predictor of preterm labor. Therefore, the objectives of this study were to characterize the uterine electrohysterographic signals during labor and to determine the pro...

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Bibliographic Details
Published in:Acta obstetricia et gynecologica Scandinavica 2013-09, Vol.92 (9), p.1070-1078
Main Authors: Mikkelsen, Eva, Johansen, Peter, Fuglsang-Frederiksen, Anders, Uldbjerg, Niels
Format: Article
Language:eng ; fre ; ger
Subjects:
Adult
Electrodiagnosis - methods
electrohysterography
electromyography
Female
Humans
Labor
Labor, Obstetric - physiology
physiology
power spectrum density
Pregnancy
propagation velocity
Signal Processing, Computer-Assisted
Uterine Contraction - physiology
uterine contractions
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Summary:Objective Electrohysterographic assessment of the propagation velocity of uterine depolarization has been introduced as a promising predictor of preterm labor. Therefore, the objectives of this study were to characterize the uterine electrohysterographic signals during labor and to determine the propagation velocity and propagation direction of electrohysterographic signals. Design Descriptive study. Setting Department of Obstetrics and Gynecology, Aarhus University Hospital, Denmark. Population Eight women in active labor at term. Methods Electrohysterograms (three channels) were recorded using surface electrodes placed abdominally along the vertical median axis with an inter‐electrode distance of 6.5–11.2 cm. In total, 89 contractions were analyzed. Results Electrohysterographic characteristics: The duration of the contractions was 61.0 ± 18.0 s (mean ± SD). The median frequency of the power spectrum density was 0.51 (0.44; 0.51) Hz (median; 10th; 90th percentile). The greatest signal magnitude was obtained by the electrode in the centermost position. The propagation velocity: 2.15 (0.66; 13.8) cm/s in the upper part and 1.53 (0.58; 6.7) cm/s in the lower part of the uterus. Propagation direction: Both downward (58%) and upward (42%) propagation of the electrohysterographic signals occurred. Moreover, downward and upward propagations were recorded simultaneously in the upper and lower part of the uterus, suggesting a multidirectional propagation pattern. Conclusions Labor contractions, expressed by electrohysterographic signals, propagate both in the downward and upward direction, a phenomenon that must be taken into account when determining the propagation velocity for preterm labor diagnostics.
ISSN:0001-6349
1600-0412
DOI:10.1111/aogs.12190