Doppler Flow Velocity Waveforms Research Articles

Umbilical artery Doppler flow velocity waveforms and maternal prostaglandin E 2 and F 2α metabolite concentrations during cervical ripening with prostaglandin E 2

In 20 women, the umbilical artery flow velocity waveform (FVW) was recorded immediately before and 30–40 min after administering vaginal or extraamniotic prostaglandin E 2 to ripen the cervix. Maternal plasma concentrations of prostaglandin E 2 (PGE 2) and prostaglandin F 2α (PGF 2α) metabolites (bicyclo-PGEM and PGFM, respectively) were measured at the time of the Doppler recordings. The administration of prostaglandin E 2 was associated with a significant rise in maternal plasma PGFM and bicyclo-PGEM concentrations, but there was no change in the umbilical artery FVW Pulsatility index (PI). These results suggest that cervical ripening with local prostaglandin E 2 has no effect on the umbilical artery FVW.

Use of Doppler Flow Velocity Waveform Analysis in Detection of Initial Diabetic Microangiopathy

Doppler flow velocity waveform analysis (FVWFA), recorded from the dorsalis pedis artery (DPA) and the radial artery (RA), was performed on 36 women in attempting to detect an initial diabetic microangiopathy (DM). The study comprised two groups of women affected by non-insulin-dependent diabetes mellitus, 6 patients (pts) of reproductive age (1), 12 pts in menopause (II), and two groups of age-matched healthy controls (C) (III and IV). Clinical signs of initial DM were present in group I. All the examined pts were nonsmokers and normotensive and without cardiopathy, signs of diabetic macroangiopathy, collagen vascular disease and/or Raynaud's phenomenon, and renal failure. Four waveform dimensions capable of separating different degrees of peripheral obstructive arteriolar disease were determined on velocity tracing and the results used in a single best discriminant equation. The resultant discriminant score (DS), derived by FVWFA on DPA, showed a highly accurate rate of separating the young pts with DM from both C and the pts in menopause without DM. Furthermore, the resultant DS was statistically not different in groups II, III, and IV. In conclusion, FVWFA on DPA, in this experience, has proved to be an accurate and sensitive method in the detection of initial DM.

The effect of intravascular transfusion for rhesus haemolytic disease on umbilical artery Doppler flow velocity waveforms

The effect of intravascular transfusion for rhesus haemolytic disease on umbilical artery Doppler flow velocity waveforms

Uterine and fetal umbilical artery flow velocity waveforms in normal first trimester pregnancies

In 85 normal singleton pregnancies between 8 and 13 weeks gestation, Doppler flow velocity waveform recordings were attempted from the left and right uterine artery and fetal umbilical artery. Acceptable waveforms were obtained from the uterine arteries in 83 and from the fetal umbilical artery in 61 of the 85 pregnancies. There was virtually no difference between the left and right uterine artery on average. The marked decrease in pulsatility (PI) and resistance (RI) indices from both uterine arteries reflects the ongoing process of secondary trophoblast invasion into the muscular part of the spiral arteries. Absent end-diastolic velocities were observed in 59 of 61 fetal umbilical artery flow velocity waveform recordings. PI values from the fetal umbilical artery suggest unaltered umbilical placental vascular resistance during the first trimester of pregnancy.

An Evaluation of the Efficacy of Doppler Flow Velocity Waveform Analysis as a Screening Test in Pregnancy

An Evaluation of the Efficacy of Doppler Flow Velocity Waveform Analysis as a Screening Test in Pregnancy

Correlation between Doppler flow velocity waveforms and cord blood viscosity

The contribution of rheological factors to the impedance of blood flow in the umbilical artery as determined by continuous-wave Doppler ultrasound was investigated. Of the 51 pregnancies recruited, six were complicated by pre-eclampsia, 10 by intrauterine growth retardation, 15 by both pre-eclampsia and fetal growth retardation, and there were 20 controls. A significant correlation was demonstrated between both plasma viscosity and gestational age and the resistance index used to characterize the Doppler waveform. Multiple regression analysis demonstrated that changes in plasma viscosity explained 55% of the variance seen in the resistance index and that this was statistically significant. This finding is, however, unlikely to be of clinical significance as whole blood viscosity had an insignificant effect on the impedance in the umbilical artery. We postulate that vascular factors such as the number and calibre of the placental arterioles are a more important determinant of umbilical artery impedance.

An evaluation of the efficacy of Doppler flow velocity waveform analysis as a screening test in pregnancy

In a prospective double-blind study of 535 medium-risk pregnancies, growth data obtained by ultrasonography and Doppler flow velocity waveform systolic to diastolic ratios were recorded at 18, 24, 28, and 34 weeks' gestation. A significant association was observed between uteroplacental systolic to diastolic ratios at 24 weeks' gestation and subsequent fetal hypoxia with a sensitivity of 24.0% and a specificity of 93.9%. However, 70% of abnormal results were not followed by fetal hypoxia. Umbilical artery systolic to diastolic ratios at 24, 28, and 34 weeks' gestation were found to be predictive of intrauterine growth retardation. This predictive capability was enhanced in those growth-retarded fetuses in which hypoxia developed, but was weak when umbilical artery systolic to diastolic ratios were evaluated as primary screening tests for fetal hypoxia. The results confirm a role for Doppler systolic to diastolic ratios in the evaluation of high-risk pregnancies but do not support a role for their use as primary screening tests in low-risk obstetric populations.

Doppler umbilical and uterine flow waveforms in severe pregnancy hypertension

Doppler studies of the umbilical and uteroplacental bed arterial flow velocity waveforms were performed in a series of women suffering from severe proteinuric pregnancy hypertension. Ninety-five women were studied and the mean interval between the last study and delivery was 1.4 days. An abnormally elevated umbilical artery systolic:diastolic (AB) ratio was present in 61 (64%) of the women. All 10 perinatal deaths were associated with pregnancies with an abnormal umbilical artery AB ratio. An elevated umbilical artery AB ratio was significantly associated with small-for-gestation and neonatal morbidity. Infants associated with extremely high umbilical artery AB ratios (greater than or equal to 99th centile) spent twice as long in the neonatal nursery as those with a lower value. There was no relation between the duration of hypertension and the umbilical study result. The uteroplacental bed artery flow velocity waveform did not correlate with fetal or neonatal mortality or morbidity. Patients with abnormal uteroplacental AB ratios also had abnormal umbilical artery AB ratios. We conclude that an abnormal fetal umbilical artery Doppler flow velocity waveform correlates with adverse fetal outcome in severe proteinuric pregnancy hypertension and suggest that the associated placental lesion may precede the maternal hypertension.

The effect of heart rate on Doppler flow velocity systolic-diastolic ratios in umbilical and uteroplacental arterial waveforms

In an analysis of the influence of heart rate on Doppler flow velocity waveformsystolic/diastolic ratios from 1555 umbilical artery waveform studies and from 1497 uteroplacental waveform studies, a negative correlation was observed between the ratio and the corresponding heart rate. This relationship was not influenced by gestational age and was similar in pregnancies with normal outcomes when compared with all pregnancies. The magnitude of this inverse relationship is such that the effect of heart rate on systolic/diastolic ratios must be considered when Doppler flow velocity waveform analyses are used as experimental tools to assess placental vascular resistance but it does not appear to be an important factor in general clinical practice when measurements are made during fetal inactivity and when heart rates are within normal ranges.

Pulsed Doppler Flow-Velocity Waveforms in the Prediction of Fetal Hematocrit of the Severely Isoimmunized Pregnancy

Pulsed Doppler Flow-Velocity Waveforms in the Prediction of Fetal Hematocrit of the Severely Isoimmunized Pregnancy

Effect of placental laterality on uterine artery resistance and development of preeclampsia and intrauterine growth retardation

We studied 153 pregnant women with normal pregnancies and 147 women with complicated pregnancies (diabetes, hypertensive disorders, and intrauterine growth retardation) to evaluate the association of placental location and the development of preeclampsia, intrauterine growth retardation, and uterine artery resistance. The placental location was determined by real-time ultrasonography, and the uterine artery resistance was determined by continuous-wave Doppler flow velocity waveform analysis. In the presence of preeclampsia or intrauterine growth retardation, up to 75% of the patients had unilaterally located placentas and 25% central placentas, whereas in the absence of these two conditions only 51% of the patients had unilateral and 49% central placentas (p less than 0.02). In patients with unilateral placentas, the incidence of preeclampsia and intrauterine growth retardation was 2.8-fold and 2.7-fold greater than in patients with central placentas (p less than 0.03 and p less than 0.01). Among all patients unilateral placental location was more likely to be associated with abnormal artery flow velocity waveforms than central placental location (p less than 0.001). We conclude that unilateral placental location may predispose to the development of preeclampsia and intrauterine growth retardation by its effect on uterine artery resistance.

Effect of nifedipine on Doppler flow velocity waveforms in severe pre-eclampsia.

Effect of nifedipine on Doppler flow velocity waveforms in severe pre-eclampsia.

Correlation between Doppler flow velocity waveforms and cord blood viscosity.

The contribution of rheological factors to the impedance of blood flow in the umbilical artery as determined by continuous-wave Doppler ultrasound was investigated. Of the 51 pregnancies recruited, six were complicated by pre-eclampsia, 10 by intrauterine growth retardation, 15 by both pre-eclampsia and fetal growth retardation, and there were 20 controls. A significant correlation was demonstrated between both plasma viscosity and gestational age and the resistance index used to characterize the Doppler waveform. Multiple regression analysis demonstrated that changes in plasma viscosity explained 55% of the variance seen in the resistance index and that this was statistically significant. This finding is, however, unlikely to be of clinical significance as whole blood viscosity had an insignificant effect on the impedance in the umbilical artery. We postulate that vascular factors such as the number and calibre of the placental arterioles are a more important determinant of umbilical artery impedance.

Uteroplacental Doppler flow velocity waveforms in the second trimester. A complex circulation.

Continuous wave Doppler ultrasound was used to examine the uteroplacental circulation of an unselected group of 977 [corrected] women between 16 and 24 weeks gestation. Reference ranges for resistance index (RI) were determined and throughout this gestation range there was a significant fall in RI with increasing gestation. The RI was lower from placental than non-placental sites and from distal 'arcuate' than proximal 'uterine' sites. There is a need to define fixed standardized sites for sampling and for normal ranges to account for variables such as placental site.

The effect of intravascular transfusion for rhesus haemolytic disease on umbilical artery Doppler flow velocity waveforms.

To test the hypothesis that an increase in fetal blood viscosity is associated with an increase in resistance to flow, the effect on Doppler flow velocity waveforms of percutaneous umbilical blood sampling and intravascular transfusion was studied in 20 patients undergoing a total of 35 procedures. All but four of the 22 transfusions were associated with a decrease in resistance to flow, as shown by a reduction in the umbilical artery systolic/diastolic ratio, and this also occurred on 10 of the 13 occasions when blood sampling only was performed. These findings suggest that acute changes in blood viscosity following intravascular transfusion are not associated with an increase in resistance to flow as assessed by Doppler velocimetry. Umbilical blood sampling per se may be associated with a humorally mediated reduction in placental vascular resistance to flow.

Pulsed Doppler flow-velocity waveforms in the prediction of fetal hematocrit of the severely isoimmunized pregnancy

We previously reported a significant relationship between the hematocrit levels of anemic fetuses and information derived from ultrasonographic and Doppler flow-velocity waveforms. In this study we prospectively tested two formulas for the prediction of hematocrit values, by use of gestational age, presence or absence of hydrops, and Doppler indices. Although one of the two formulas predicted hematocrit values significantly, the only component of the formula that made a significant contribution was fetal hydrops. We conclude that currently available fetal Doppler measurements are unable to be applied in the prospective prediction of hematocrit values in anemic fetuses of isoimmunized pregnancies.

Pulsed Doppler flow-velocity waveforms before and after intrauterine intravascular transfusion for severe erythroblastosis fetalis

Pulsed Doppler flow-velocity waveforms before and after intrauterine intravascular transfusion for severe erythroblastosis fetalis

Doppler blood flow velocity waveforms in the fetal renal artery.

In 19 out of 20 human fetuses we recorded blood velocity waveforms in the renal artery by means of a duplex Doppler sector scanner. One fetus was at 22 weeks gestation, 7 fetuses were between 32 and 35 weeks, and 12 fetuses between 36 and 40 weeks. There was no evidence of intrauterine growth retardation and there was a normal quantity of amniotic fluid in all pregnancies. We also recorded waveforms in the umbilical artery, the descending aorta, and the internal carotid artery. The RI in these vessels showed normal values in all cases. There was no end-diastolic flow in four of the seven fetuses studied at 32 to 35 weeks gestation. The mean RI of fetuses with end-diastolic flow was 0.86 (SD 0.03). The interpretations of these results, and ideas for future studies are discussed.

Umbilical artery doppler flow velocity waveform: the outcome of pregnancies with absent end diastolic flow

We have studied doppler recordings of flow velocity waveform of the umbilical artery in 380 high-risk pregnancies and 160 patients with uncomplicated pregnancies. The results were not used in clinical management. In 24 cases, all in high-risk pregnancies, there was absence of end diastolic flow (AEDF). Four babies died, 22 out of 24 weighed less than the 5th centile for gestation and 20 were delivered by Caesarean Section. With only four exceptions, all fetuses showed other evidence of antenatal fetal compromise, though this was delayed in some cases for up to 24 days. AEDF does not appear to prejudice neonatal outcome. All six babies born weighing 750–999 g survived. In addition, 4 patients continued their pregnancy for 3–6 weeks after the first doppler with AEDF. Only one of the 4 developed other evidence of fetal compromise and two had vaginal deliveries. In our experience, AEDF is found only in abnormal pregnancy, and is a very serious sign of likely fetal compromise. It is an indication for extremely careful surveillance but not necessarily an indication for delivery.

Pulsed Doppler flow-velocity waveforms before and after intrauterine intravascular transfusion for severe erythroblastosis fetalis

Pulsed Doppler studies of the fetal and maternal circulations were carried out before and after 64 intrauterine transfusions performed on 24 fetuses. A model was derived for the prediction of hematocrit before the first transfusion: Hematocrit = 7.778 − (0.088 × peak velocity in descending aorta) + (0.968 × gestational age [weeks]) − (10.911 if hydrops present) (r = 0.876, p < 0.0001). An alternative formula, excluding hydrops, was slightly less predictive: Hematocrit = 45.312 − (56.261 × umbilical cord Pourcelot index) − (0.128 × peak velocity in descending aorta) + (1.042 × gestational age) (r = 0.822, p < 0.001). Neither model was accurate in the prediction of hematocrit before second or subsequent transfusion. A third model was derived from second-transfusion data: Hematocrit = 40.524 − (0.045 × peak velocity in descending aorta) − (10.693 × pulsatility index of maternal uterine artery) (r = 0.81, p < 0.003). However, this model was unable to predict hematocrit before third or later transfusions. No changes in Doppler parameters before and after transfusion were found. We conclude that pulsed Doppler ultrasound may be helpful in the evaluation of isoimmunized pregnancies, in differentiating anemic from normal fetuses. It does not appear to be useful in determining the timing of later transfusions. The lack of change before and after transfusions suggests that these vessels will not provide significant information concerning the effect of rapid volume and hematocrit changes in the fetus.