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Transvaginal Doppler Ultrasonography in Early Pregnancy: Blood Flow Development in the Umbilical Cord
Author(s) -
FUNK A.,
JÖRN H.,
FENDEL H.
Publication year - 1990
Publication title -
echocardiography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.404
H-Index - 62
eISSN - 1540-8175
pISSN - 0742-2822
DOI - 10.1111/j.1540-8175.1990.tb00406.x
Subject(s) - gestation , blood flow , diastole , medicine , fetus , umbilical cord , umbilical artery , cardiology , placental circulation , hemodynamics , pregnancy , ultrasound , placenta , blood pressure , anatomy , biology , radiology , genetics
The umbilical arterial and venous blood flow of 60 pregnancies between the sixth and fifteenth week of gestation was investigated using Doppler ultrasound technology. Although fetal heart activity was detected from the fifth week, umbilical arterial blood flow was not identified until the sixth week, and venous flow was not seen until the seventh week. The characteristics of the Doppler velocity waveform changed significantly as gestation progressed. Initially, the waveform showed a short flat systolic component without diastolic flow. Systole gradually increased in duration and peaked. The diastolic component increased and became continuous at 14 weeks. After the fourteenth week, the velocity waveform did not differ greatly from those of later gestation. Arterial blood flow changes evidenced by a serial decline in the pulsatility index presumably reflects decreasing resistance of the embryonic and fetal placental vessels associated with maturation of the fetoplacental unit.