Changes in vascular resistance in the umbilical and middle cerebral arteries in the human intrauterine growth-retarded fetus, measured with pulsed Doppler ultrasound

Alterations in time intervals of ductus venosus and atrioventricular flow velocity waveforms in growth‐restricted fetuses

“…Women with pregnancies complicated by intrauterine growth restriction (IUGR) ( n = 28) were also recruited at Osaka City University Hospital and Osaka City General Hospital. IUGR was defined as an estimated fetal weight (EFW) <−2.0 SD of the local reference range with an elevated umbilical artery pulsatility index (UA‐PI) > 95th percentile of the reference range. Gestational age was calculated from the last menstrual period and confirmed by crown–rump length measured at 9–11 weeks' gestation.…”

Morphological and functional evaluation of normal and abnormal fetal growth by ultrasonography

“…We previously reported that IUGR per se was associated with a chronic increase in the RI value in the UA, and that cerebral vascular resistance appeared to decrease in conditions with abnormal fetal heart rate tracings [47]. Based on published reports, fetuses with hypoxia and/or acidosis are likely to show elevated placental vascular resistance and/or low cerebral vascular resistance [57], a phenomenon that is most apparent in IUGR cases.…”

“…A uniform decrease in RI and PI values in the UA through the entire gestational period suggests the gradual decrease in placental vascular resistance in the normal development of fetoplacental circulation [48]. On the other hand, the parabolic change in cerebral vascular resistance is thought to be due to the rapidly increasing volume in the cerebral vascular bed in both early and late gestational weeks [47], and redistribution favoring blood supply to the brain, influenced by physiological P O 2 reduction near term [49].…”

“…The most established target vessels in clinical applications in the human fetus are the umbilical and intracranial arteries, predominantly the middle cerebral artery, because fetoplacental and cerebral circulation are essential and decisive for clinical management and fetal outcome [45][46][47]. Although a variety of parameters have been proposed for qualitative analyses of FVWs, the most common parameters are the resistance index (RI), pulsatility index (PI), and systolic/diastolic ratio (S/D ratio), all of which are calculated by the peak-systolic flow, end-diastolic flow, and mean flow velocities (Fig.…”

Timing the delivery of the preterm severely growth‐restricted fetus: venous Doppler, cardiotocography or the biophysical profile?

“…This, in turn, triggers compensatory hemodynamic changes, which include blood flow redistribution towards essential fetal organs (brain, heart and adrenal glands) [7][8][9][10][11][12] at the expense of the other organ systems (lungs, kidneys and bowel) [13][14][15] . This compensatory phase of the disease can be recognized clinically by typical Doppler and ultrasound findings, including decreased pulsatility index in the middle cerebral artery [16][17][18] , decreased amniotic fluid volume 19 and echogenicity of the bowel 20 . The duration of the compensatory phase is variable, sometimes lasting weeks, and appears not to have deleterious short-term consequences [21][22][23][24] .…”