Mm. Vanzalensprock et al., 1ST-TRIMESTER UTEROPLACENTAL AND FETAL BLOOD-FLOW VELOCITY WAVE-FORMSIN NORMALLY DEVELOPING FETUSES - A LONGITUDINAL-STUDY, Ultrasound in obstetrics & gynecology, 4(4), 1994, pp. 284-288
Citations number
NO
Categorie Soggetti
Acoustics,"Obsetric & Gynecology","Radiology,Nuclear Medicine & Medical Imaging
Our objectives were to obtain a complete overview of uteroplacental an
d fetal hemodynamics early in pregnancy and to record flow velocity wa
veforms in the vitelline artery using color Doppler equipment. Flow ve
locity waveforms were recorded in 18 uneventful pregnancies between 6
and 16 weeks of gestation. Doppler recordings were made of the left an
d right uterine and spiral arteries from 6 weeks of gestation onwards.
Recordings of the umbilical artery, fetal aorta and fetal cerebral ar
teries started in weeks 7, 8 and 9, respectively. Where possible, the
vitelline arteries were also recorded. The resistance and pulsatility
indices and 95% confidence intervals for predictions were calculated.
For the uterine and spiral arteries, characteristics of the waveforms
were assessed. The resistance index of both uterine and spiral arterie
s gradually decreased with advancing pregnancy. For the umbilical arte
ry, aorta and cerebral artery, the earliest possible Doppler recording
s and characteristics of the waveforms were established. The pulsatili
ty index of the umbilical arteries and fetal aorta showed a sharp decr
ease towards the 16th week. The pulsatility index of the fetal cerebra
l artery showed only a mild decrease towards week 16. In a longitudina
l analysis, there were significant changes of the resistance and pulsa
tility indices for each patient. In the vitelline artery, recordings w
ere possible in eight out of 18 fetuses, and only in weeks 7 and 8 of
gestation. The pulsatility index showed a wide range and was not depen
dent on menstrual age. Knowledge of the normal flow velocity waveforms
in the maternal uteroplacental and fetal circulations early in pregna
ncy may lead to a better understanding of physiological mechanisms.