Uteroplacental Doppler velocimetry during Braxton Hicks' contractions.
Pulsed-wave Doppler ultrasound was used to evaluate the influence of Braxton Hicks' contractions on flow velocity waveforms in the uterine arteries. Flow velocity waveforms were obtained from a standardized site, at the crossing of the uterine artery with the external iliac artery near the uterine wall. Doppler signals were recorded in 16 healthy near-term nulliparous pregnant women. During Braxton Hicks' contractions, a considerable increase in pulsatility index (PI) was found in the uterine arteries increasing from 0.71 +/- 0.21 (mean +/- SD) to 1.14 +/- 0.67 (p < 0.005). Maternal heart rate decreased slightly but significantly during contractions. Despite the high PI values that were found during Braxton Hicks' contractions, a diastolic notch in the flow velocity waveform was never noticed. The findings indicate that during Braxton Hicks' contractions, resistance to blood flow in the uteroplacental circulation is considerably increased.
Oosterhof
H
H
Department of Obstetrics and Gynaecology, State University Hospital, Groningen, The Netherlands.
Dijkstra
K
K
Aarnoudse
J G
JG
D000328:Adult; D001783:Blood Flow Velocity / Q000502:physiology; D005260:Female; D006801:Humans; D010920:Placenta / Q000098:blood supply*; D011247:Pregnancy / Q000502:physiology*; D011673:Pulsatile Flow / Q000502:physiology; D012212:Rheology; D014465:Ultrasonics; D014590:Uterine Contraction / Q000502:physiology*; D014599:Uterus / Q000098:blood supply*