Role of umbilical Doppler velocimetry in the biophysical assessment of the growth-retarded fetus. Answers from neonatal morbidity and mortality.

We compared umbilical Doppler velocimetry with biophysical parameters, obstetrical management, and neonatal morbidity. The study of 85 pregnancies was prospective and blind both to the obstetric and pediatric staff. Our results show that under the same biophysical diagnosis, ie, abnormal fetal growth, oligohydramnios, and nonreactive cardiotocographics, the prevalence of neonatal morbidity was significantly higher in fetuses with associated abnormal umbilical pulsatility index (PI) in utero. Newborns with abnormal PI were delivered earlier, mostly for fetal indication, and were smaller and more asymmetrical than newborns with a normal PI in utero. The analysis of morbidity for homogeneous classes of weight showed that in the group of newborns between 1500 and 2500 g, newborns with normal umbilical PI did show only metabolic disturbances and one respiratory distress syndrome. On the contrary, newborns of the same gestational age and of the same weight with abnormal PI had more severe morbid episodes. In the class of weight between 1500 and 1000 g not only the severity but also the prevalence of neonatal morbidity was significantly higher in newborns with an abnormal PI in utero. None of the newborns delivered below 1000 g had a normal umbilical PI. Five died in the early neonatal period. Three suffered from mild neuromotor sequelae. Practical consequences of these findings on fetal management are the scheduled frequency of biophysical examinations, which must be closer and on an inpatient basis whenever abnormal, and the interpretation of other abnormal biophysical parameters, which must be considered as more severe whenever associated with an abnormal umbilical velocimetry.

Doppler velocimetry: critical analysis of umbilical, cerebral and aortic reference values.

Cross-sectional reference standards of the umbilical flow velocity waveforms were investigated from 18 to 38 weeks of gestation on 482 normal pregnancies. A significant decrease in the pulsatility index (PI) and systolic/diastolic (SD) ratio was observed during gestation. This phenomenon was confirmed in a longitudinal study on 150 patients of the same population. The two slopes of cross-sectional and longitudinal data were not significantly different. A bimodal distribution of PI and S/D ratio was observed. Six per cent of data fell above the vast majority of cases. The dimension of the population studied allowed us to consider these findings not as outliers but as an interesting transient phenomenon of very low end-diastolic velocities which can occur in normal fetuses, without concomitant variations on the thoracic aorta and middle cerebral artery. Cross-sectional reference ranges were studied for these vessels on the same population from 26 to 38 weeks of gestation. A significant decrease in the PI of the middle cerebral artery was observed versus a significant increase in the PI of the thoracic aorta. These latter indices could be used to obtain indirect information on the normal redistribution of blood flow in the human fetus in the third trimester of gestation. However, the great variability observed should warn against the risks of a simplistic clinical use of these observations.

Umbilical flow waveforms versus fetal biophysical profile in hypertensive pregnancies.

The pulsatility index (PI) of the umbilical arteries was measured in 40 hypertensive pregnancies. Doppler-velocimetric data were kept unknown to the clinical staff. An abnormal PI was found in 79% of cases in which an abnormal fetal growth in utero had been diagnosed by ultrasonographic measurements. Serial PI findings showed worsening figures in most of the cases with an abnormal fetal growth, irrespective of the last absolute value. Amniotic fluid estimation and PI data were significantly correlated. PI values were markedly abnormal in fetuses with non-reactive heart-rate tracings. A high sensitivity and an optimal specificity were found for umbilical PI versus the diagnosis of fetal growth retardation made by the coexistence of different biophysical criteria. However, false normal results may occur. 62% of the newborns weighed below the 5th percentile. The sensitivity of abnormal PI values to detect these light fetuses resulted to be only 67%. However the prevalence of neonatal morbidity in fetuses with abnormal PI values was 74%, while morbidity occurred only in 14% of cases with normal PI values. In hypertensive pregnancies, this simple velocimetric parameter proved to correlate with abnormal biophysical monitoring and complicated neonatal outcomes.