The objective of this study was to assess the value of Doppler indices calculated from the inferior vena cava and ductus venosus in the identification of acidemia and hypoxemia as determined by pH and gas analysis of fetal blood obtained by cordocentesis in growth-retarded fetuses. Doppler measurements were performed in the inferior vena cava and ductus venosus in 209 normally grown fetuses and in 89 growth-retarded fetuses. All growth-retarded fetuses were free from structural and chromosomal abnormalities, and uteroplacental insufficiency characterized by Doppler changes in the umbilical and middle cerebral arteries was the most likely etiology of the growth defect. In this group of fetuses, Doppler recordings were performed immediately before cordocentesis. Ten different indices were calculated from venous velocity waveforms, and reference limits for gestation were constructed by the cross-sectional analysis of data from normally grown fetuses. Logistic regression and receiver operator characteristic curve analysis were performed to examine the relationship between Doppler indices and acid-base status. The pre-load index (peak velocity during atrial contraction/peak velocity during systole) in the inferior vena cava was the best explanatory variable for acidemia (chi 2 = 48.33; p < or = 0.001). Hypoxemia was predicted less well by venous indices and the best results were achieved by the S/A ratio in the ductus venosus (chi 2 = 9.46; p < or = 0.005). In conclusion, our data suggest that acidosis in growth-retarded fetuses may be non-invasively identified by Doppler measurements of the inferior vena cava and that a higher efficiency can be achieved by the use of the pre-load index.
Intrauterine growth retardation is a pathology which is found in 3–10% of all pregnancies and it is associated with around 20–25% of all fetal intrauterine deaths and with long-term neurologic sequelae. It presents an increased risk of distress during labor and delivery and a greater risk of perinatal mortality. The causes of IUGR and the cardiac and venous Doppler in normal fetuses are analyzed, and the hemodynamic cardiac modifications in IUGR fetus are discussed. The fetal cardiac function in intrauterine growth retardation shows a redistribution of the fetal cardiac output, which tends to favor the left ventricle as the mechanism to compensate for the uteroplacental insufficiency. The Doppler velocity indices are modified as the fetal condition progressively deteriorates and they represent an important tool for the management of the complicated pregnancy.
The objective of this study was to describe blood flow velocity waveforms of fetal peripheral pulmonary arteries in normally grown and growth-retarded fetuses. Doppler studies were performed in 182 normally grown fetuses (gestational age 18-40 weeks) and in 61 growth-retarded fetuses (gestational age 24-36 weeks) that were free from structural and chromosomal abnormalities and whose umbilical and middle cerebral artery Doppler findings suggested uteroplacental insufficiency as the most likely etiology of the growth defect. The pulsatility index was used to quantify the velocity waveforms. Successful recordings were obtained in 90.1% of the normally grown and 93.4% of the growth-retarded fetuses. In normally grown fetuses the pulsatility index values significantly decreased with advancing gestation. In growth-retarded fetuses the pulsatility index values were significantly elevated compared to those of normal fetuses. A significant relationship was observed between the severity of hypoxia and pulsatility index values from the peripheral pulmonary arteries in 29 fetuses in which Doppler recordings were obtained immediately before cordocentesis. In conclusion, these data show that in normal fetuses the Doppler-measured impedance to flow in the peripheral pulmonary circulation decreases with advancing gestation. Impedance to flow in the lungs is elevated in the presence of growth retardation and this increase is related to the severity of fetal hypoxia.
Cervical fetal fibronectin, alpha fetoprotein, C- reactive protein and interleukin 6 can have an overall good diagnostic accuracy in identifying pregnancies at risk of SPTB. Large prospective studies in different sub-set of women are needed to ascertain whether the combination of different serological and imaging marker can improve antenatal prediction of this condition.
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