Open AccessElectrohysterography of labor contractions: propagation velocity and direction
Author(s) -
Mikkelsen Eva,
Johansen Peter,
FuglsangFrederiksen Anders,
Uldbjerg Niels
Publication year - 2013
Publication title -
acta obstetricia et gynecologica scandinavica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.401
H-Index - 102
eISSN - 1600-0412
pISSN - 0001-6349
DOI - 10.1111/aogs.12190
Subject(s) - medicine , percentile , position (finance) , depolarization , population , geodesy , mathematics , geology , statistics , environmental health , finance , economics
Abstract 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.