Doppler Velocimetry in the Evaluation of Fetal Well-Being
Abstract: Ultrasound Doppler velocimetry was used to predict fetal well-being. The uterine artery blood velocimetry seemed to be a good predictor of perinatal outcome in high-risk pregnancies and a complement to umbilical artery velocimetry. The fetal middle cerebral artery blood velocimetry might be an early sign of fetal hypoxia. In pregnancies with decreased perception of fetal movements, the non stress test seemed to be a better predictor of outcome than Doppler velocimetry. Ductus venosus blood velocimetry seems to be a poor indicator of adverse perinatal outcome. Fetal splenic artery vascular resistance decreased after 33 weeks of gestation in normal pregnancy and high-risk pregnancies usually have normal vascular resistance. The Color Doppler Velocity (CDV) technique has become a "mile stone" in ultrasound. The recent Color Doppler Energy (CDE) technique has further improved visualization of fetal organ blood perfusion. Computer analysis of CDE images has shown a reliable reproducibility. The CDE signal intensity is influenced by fluid flow felocity, depth and different instrument settings. In normal pregnancies, placental and fetal kidney, liver and lung CDE signals indicated increasing intensity until 33 weeks, with a decrease thereafter. Fetal splenic CDE signal in normal pregnancies increased until 33 weeks, being constant thereafter. The fetal CDE brain shown exponentially increasing CDE values at the end of normal pregnancy. A decrease in fetal organs perfusion, with increased fetal brain perfusion might indicate centralization of fetal circulation in normal pregnancy at term, as a response to decreased placental perfusion. High-risk pregnancies had less placental and fetal organs signal intensity, and increased brain and splenic signal intensity, suggesting more pronounced centralization of fetal circulation. The CDE might therefore open up new ways of evaluating fetal well-being.
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