Journal of Ultrasound in Medicine, Vol 10, Issue 1 37-41, Copyright © 1991 by American Institute of Ultrasound in Medicine
Influence of fetal breathing and movements on variability of umbilical Doppler indices using different numbers of waveforms
J. A. Spencer, J. Price and A. Lee
Institute of Obstetrics and Gynaecology, Royal Postgraduate Medical School, University of London, Queen Charlotte's and Chelsea Hospital, England.
Umbilical artery continuous-wave Doppler ultrasound waveforms were obtained
from three groups of fetuses in late gestation: during quiescence, fetal
breathing movements, and fetal body movements. The coefficients of
variation, calculated from three values for each Doppler index, which were
derived from one, two, four, six and eight waveforms, decreased as the
number of waveforms increased. However, statistical analysis showed no
significant improvement in variance when more than four waveforms were used
during fetal quiescence and breathing and when more than six waveforms were
used during fetal movement. A minimum of six waveforms ensured coefficients
of variation less than or equal to 10% even during fetal breathing and
fetal movements.
