First-trimester uteroplacental and fetal blood flow velocity waveforms in normally developing fetuses: a longitudinal study.

Our objectives were to obtain a complete overview of uteroplacental and fetal hemodynamics early in pregnancy and to record flow velocity waveforms in the vitelline artery using color Doppler equipment. Flow velocity waveforms were recorded in 18 uneventful pregnancies between 6 and 16 weeks of gestation. Doppler recordings were made of the left and right uterine and spiral arteries from 6 weeks of gestation onwards. Recordings of c the umbilical artery, fetal aorta and fetal cerebral arteries started in weeks 7, 8 and 9, respectively. Where possible, the vitelline arteries were also recorded. The resistance and pulsatility indices and 95% confidence intervals for predictions were calculated.For the uterine and spiral arteries, characteristics of the waveforms were assessed. The resistance index of both uterine and spiral arteries gradually decreased with advancing pregnancy. For the umbilical artery, aorta and cerebral artery, the earliest possible Doppler recordings and characteristics of the waveforms were established. The pulsatility index of the umbilical arteries and fetal aorta showed a sharp decrease towards the 16th week. The pulsatility index of the fetal cerebral artery showed only a mild decrease towards week 16. In a longitudinal analysis, there were significant changes of the resistance and pulsatility indices for each patient. In the vitelline artery, recordings were possible in eight out of 18 fetuses, and only in weeks 7 and 8 of gestation. The pulsatility index showed a wide range and was not dependent on menstrual age.Knowledge of the normal flow velocity waveforms in the maternal uteroplacental and fetal circulations early in pregnancy may lead to a better understanding of physiological mechanisms.     

Correlations in umbilical blood flow Doppler velocities in the human fetus during breathing.

We hypothesized that changes in intrathoracic pressure during fetal breathing episodes result in quantifiable variations in umbilical arterial and venous blood flow velocities, and that these variations are related to compliance properties of each system. We further hypothesized that these variations in velocities are different in fetuses with normal and abnormal umbilical arterial Doppler velocities. Umbilical arterial and venous Doppler velocities were measured simultaneously during breathing episodes in 15 normal fetuses and 14 fetuses with elevated systolic-to-diastolic (S/D) umbilical arterial Doppler velocity ratios. Umbilical arterial end-diastolic velocity changes were less than umbilical venous velocity changes in normal fetuses, but were significantly greater in four fetuses with elevated S/D ratios (p < 0.004). Furthermore, umbilical arterial diastolic velocity minima preceded umbilical venous velocity minima by a time lag that was greater in fetuses with elevated S/D ratios (p < 0.002). These results suggest that differences in umbilical arterial and venous velocity variation during fetal breathing episodes may be related in part to vascular compliance, which may be altered in fetuses with abnormal umbilical arterial Doppler velocity.     

Doppler sonographic characteristics of umbilical and uterine arteries during oral glucose tolerance testing in healthy pregnant women

PURPOSE: Studies have shown that maternal hyperglycemia may be associated with increased placental resistance to blood flow and possibly adverse perinatal outcomes. The aim of this study was to determine whether Doppler velocimetric dynamics change in the uterine and umbilical arteries in healthy pregnant women (without gestational diabetes) during acute hyperglycemia induced by oral glucose tolerance testing. METHODS: Flow in the umbilical and right and left uterine arteries was assessed by spectral Doppler sonographic examination of healthy pregnant women at 24-28 weeks' menstrual age. Four Doppler studies were conducted for each woman: 1 before oral administration of 100 g of glucose and 3 more at 1, 2, and 3 hours after glucose administration. The systolic-to-diastolic ratio was calculated for the umbilical artery, and the resistance index was calculated separately for the left and right uterine arteries. RESULTS: All results of oral glucose tolerance testing were normal, and Doppler signals were obtained in all 30 patients enrolled. No abnormal systolic-to-diastolic ratios or resistance indices were detected in any of the examinations. No significant differences in waveforms or resistance indices between the right and left uterine arteries were found during the various testing intervals. CONCLUSIONS: Acute hyperglycemia induced in healthy pregnant women does not affect blood flow velocimetric characteristics in the umbilical or uterine arteries at any stage of oral glucose tolerance testing.     

Middle cerebral artery Doppler in fetuses with transposition of the great arteries.

OBJECTIVE: A previous anthropometric study has shown that neonates with transposition of the great arteries have a smaller head circumference and intracranial volume, which may be related to a lower oxygen content of blood delivered to the head and upper extremities. The aim of this study was to compare Doppler blood flow velocity waveforms in fetuses with transposition of the great arteries with those in healthy fetuses. METHODS: Doppler blood flow velocimetry was performed in the middle cerebral artery, the umbilical artery, the aorta and the ductus venosus in a consecutive series of 23 fetuses with transposition of the great arteries between 36 and 38 weeks' gestation. The control group consisted of 40 healthy fetuses matched for gestational age. RESULTS: There was no significant difference in pulsatility indices in the umbilical artery, the aorta and the ductus venosus between fetuses with transposition of the great arteries and controls. The median middle cerebral artery pulsatility index in the group with transposition of the great arteries was 1.37 (range, 1.10-2.02) and was significantly lower than that in the control group (median, 1.68; range, 1.46-2.04) (P < 0.001, Mann-Whitney test). CONCLUSIONS: The lower pulsatility indices observed in the middle cerebral artery of fetuses with transposition of the great arteries may reflect a trend towards cerebral vasodilation. This phenomenon could be an indicator of hypoxemia and/or hypercapnia restricted to areas perfused by the preisthmus aorta and be related to the characteristics of the circulation in fetuses with transposition of the great arteries.     

Qualitative venous Doppler flow waveform analysis in preterm intrauterine growth-restricted fetuses with ARED flow in the umbilical artery--correlation with short-term outcome.

OBJECTIVE: The aim of this retrospective study was to examine the significance of severe Doppler waveform abnormalities in the ductus venosus (DV) and the umbilical vein (UV) for the prediction of adverse outcomes in very preterm growth-restricted fetuses with absent or reversed end-diastolic flow in the umbilical artery (UA) at 24-34 weeks of gestation. METHODS: Seventy-four fetuses with intrauterine growth restriction (IUGR) and absent or reversed end-diastolic (ARED) flow in the UA at 24-34 weeks of gestation, which were delivered before 34 weeks' gestation, were examined. Absent or reversed flow during atrial contraction (a-wave) in the DV and pulsatile flow in the UV were examined to predict severe perinatal outcomes (stillbirth, neonatal death, perinatal death, acidemia, 5 min Apgar < 7, intraventricular hemorrhage and elevated nucleated red blood cell counts at delivery). RESULTS: Twelve (16.2%) perinatal deaths, of which eight were stillbirths (10.8%), and two (2.7%) neonatal deaths occurred among 74 fetuses. Logistic regression analysis confirmed that abnormal DV Doppler waveforms (R2 = 0.57, P < 0.001) together with gestational age at delivery (R2 = 0.57, P < 0.001) showed the strongest association with perinatal death, whereas only gestational age was significantly related to neonatal death (R2 = 0.67, P < 0.05). Abnormal DV Doppler waveforms (R2 = 0.86, P < 0.001) and gestational age (R2 = 0.49, P < 0.05) were strongly associated with adverse outcome (including stillbirth, perinatal death or neonatal death). Abnormal venous Doppler flow patterns performed better in the prediction of fetal or perinatal demise than did ARED flow or brain sparing. CONCLUSION: Abnormal venous Doppler waveforms in preterm IUGR fetuses with ARED flow are strongly related to adverse fetal and perinatal outcomes before 32 weeks of gestation. The possible benefit of prolonging these pregnancies can only be evaluated in a prospective randomized study.     

Myocardial contractility in the anemic human fetus.

Severely anemic fetuses in Rh-isoimmunized pregnancies are often found to have hydrops and the etiology is debated. Fifteen fetal blood samplings were performed in nine fetuses for determination of the degree of anemia and of the acid-base balance. Waveform analysis was performed on the maximum blood velocity curve in the umbilical arteries and the ascending fetal aorta, obtained by means of a pulsed Doppler technique. The blood acceleration in the ascending aorta increased down to a hematocrit of 0.18 and a hemoglobin concentration of 65 g/l, which might constitute a cardiac response to the anemia aimed at maintaining the peripheral blood circulation. Below these levels there was a decrease in blood acceleration, which could be caused by impaired cardiac oxygenation. This relationship could be described as a six-power function (r = 0.87; p = 0.032). A second-power relationship was found between the umbilical artery pulsatility index and the blood acceleration in the fetal ascending aorta (r = 0.64; p = 0.0418), which suggests that the cardiac pump function can alter the blood velocity waveform in the umbilical arteries.     

Fetal middle cerebral to uterine artery pulsatility index ratios in normal and pre-eclamptic pregnancies.

OBJECTIVES: To calculate the normal range for the fetal middle cerebral artery (MCA)/uterine artery pulsatility index (PI) ratio in the third trimester of pregnancy and to assess its value, compared with that of the MCA/umbilical artery PI ratio, in predicting an unfavorable outcome of pregnancies complicated by pre-eclampsia. METHODS: Doppler blood flow velocimetry of the uterine and umbilical arteries and fetal MCA was performed. We calculated the ratios between 1) the PI of the MCA and the mean PI value of both uterine arteries and 2) the PI of the MCA and the PI of the umbilical artery. All women were examined at or beyond 26 weeks of gestation. A cross-sectional study of 231 normal pregnancies was conducted to construct the reference range. Values below the 5th percentile or an MCA/umbilical artery PI ratio lower than 1.08 were defined as brain-sparing. A further 115 pregnancies with pre-eclampsia (50 mild and 65 severe) were assessed prospectively and the results were related to perinatal outcome. The accuracy of MCA/uterine artery and MCA/umbilical artery PI ratios for prediction of unfavorable pregnancy outcome was compared. RESULTS: Normal MCA/uterine artery PI ratios decreased with advancing gestational age. Redistribution of the fetal circulation indicated by a low MCA/uterine artery PI ratio was seen in 30% of the mild (n=15) and 46% of the severe (n=30) pre-eclamptic cases. There was a significant difference between those without and those with signs of brain-sparing, respectively, in mean birth weight (2456.0 vs. 1424.5 g), gestational age at delivery (35.6 vs. 31.3 weeks) and gestational age at the time of examination (34.9 vs. 30.9 weeks). Furthermore, there was a significantly higher rate of small-for-gestational-age (SGA) neonates (57.8% vs. 25.7%), preterm delivery (100% vs. 81.8%) and Cesarean section (90.7% vs. 66.7%) in cases with an MCA/uterine artery PI ratio below the 5th percentile. However, there was no difference between the groups in the rate of low 5-min Apgar scores, admission to the neonatal intensive care unit, or deliveries before 34 weeks. The MCA/uterine artery and MCA/umbilical artery PI ratios were similar in the prediction of adverse perinatal outcome. Both ratios were better at predicting the outcome of pregnancy than were signs of increased vascular impedance in either the umbilical or uterine arteries. CONCLUSIONS: Normal MCA/uterine artery PI ratio decreases with gestational age. Abnormally low MCA/ uterine artery PI ratios are related to unfavorable pregnancy outcome. The predictive value of the MCA/uterine artery PI ratio is similar to that of the MCA/umbilical artery PI ratio.     

Fetal and uteroplacental blood flow in prolonged pregnancies. A clinical study.

In a prospective study during 1 year, 102 women with prolonged pregnancies (more than 294 completed gestational days) were followed with serial pulsed Doppler blood flow examinations every 2nd day, either to spontaneous onset of labor (n = 82) or to induction of labor due to subsequently occurring complications (n = 20). Mean aortic blood velocity did not change significantly with gestational age beyond 294 days either in fetuses with normal outcome or in fetuses that developed asphyxia at birth. The flow velocity waveforms in the descending aorta, the umbilical artery, the common carotid artery and the uterine artery did not change significantly compared to the values at term. Abnormal flow velocity waveforms in the fetal descending aorta, umbilical artery or uterine artery had no significant relationship to fetal asphyxia. Absence of diastolic flow velocities was not found in any of the vessels examined, indicating that the fetuses did not suffer from chronic hypoxia in utero and that aging of the placenta did not alter fetal and uteroplacental blood flow. Notching of the aortic flow velocity waveform was a common finding among prolonged pregnancies. The hemodynamic implications and consequences of this phenomenon are discussed.     

Uterine and fetal cerebral Doppler predict the outcome of third-trimester small-for-gestational age fetuses with normal umbilical artery Doppler.

OBJECTIVE: To assess the value of different admission tests in predicting the outcome of small-for-gestational age (SGA) fetuses with normal Doppler waveforms in the umbilical artery. METHODS: Criteria for admission into this retrospective study included: singleton pregnancy with a birth weight < 10th centile; absence of severe maternal complications; no evidence of fetal anomalies on the sonogram; normal umbilical artery Doppler; and availability of complete follow-up. At the first antenatal sonogram classifying the fetus as SGA, Doppler analysis of the uterine and middle cerebral arteries was performed and amniotic fluid volume was assessed. Outcome variables included adverse perinatal outcome (perinatal death, severe morbidity) and emergency Cesarean section for fetal distress. RESULTS: Two hundred and thirty-one pregnancies were included in the study. The mean +/- standard deviation birth weight and gestational age at delivery were 2222 +/- 502 g and 37.3 +/- 2.9 weeks, respectively. In 37 cases (16%), an emergency Cesarean section was performed. There was one intrauterine death and three fetuses delivered by emergency Cesarean section developed severe morbidity. Logistic regression demonstrated that abnormal velocimetry of the uterine arteries and fetal middle cerebral artery were independently correlated with the occurrence of Cesarean section. CONCLUSIONS: SGA fetuses with normal umbilical artery Doppler waveforms and abnormal uterine arteries and fetal middle cerebral artery waveforms have an increased risk of developing distress and being delivered by emergency Cesarean section. Particularly when both uterine and fetal cerebral waveforms are altered at the same time, the risk is exceedingly high (86%) and delivery as soon as fetal maturity is achieved seems advisable. On the other hand, when both vessels have normal waveforms, the chances of fetal distress are small (4%) and expectant management is the most reasonable choice.     

Correlation of Doppler and placental immunohistochemical features in normal and intrauterine growth-retarded fetuses.

The aim of this study was to correlate and compare Doppler and anatomical placental findings obtained from 48 normal and 35 intrauterine growth-retarded (IUGR) fetuses. The IUGR group consisted of 19 fetuses from pregnancies complicated by pre-eclampsia and 16 from healthy mothers. Color Doppler evaluation of umbilical, spiral and uterine arteries was performed. Placental specimens from both normal and growth-retarded fetuses were obtained at the time of delivery. Placental specimens were evaluated using histochemical and immunohistochemical techniques. A progressive decrease in the pulsatility index was observed in umbilical, spiral and uterine arteries throughout pregnancy in the normal-growth fetuses. High umbilical artery pulsatility index values were obtained in 29 out of the 35 growth-retarded fetuses, six of them showing absent or reversed end-diastolic umbilical artery flow pattern. A total of 13 IUGR fetuses showed high resistance uterine artery flow velocity waveforms. Increased pulsatility index values were obtained from the spiral arteries of 16 growth-retarded fetuses. Abnormal histological and histochemical placental patterns were observed in all the growth-retarded fetuses with umbilical artery Doppler abnormalities. The presence of a peculiar dendritic cell subpopulation, strongly resembling the Langerhans cells, expressing the HLA-DR+/CD1+ phenotype, was detected in all growth-retarded fetuses, whether there was maternal pathology or not. Our data show uterine and spiral artery data as being ineffective in the monitoring of IUGR fetuses. The placental extracellular matrix seems to play an important role in the regulation of the umbilical circulation. The presence of CD1+ cells as a sign of a possible immunological mechanism in the pathogenesis of the intrauterine growth retardation is discussed.     

Angiogenic growth factor levels in maternal and fetal blood: correlation with Doppler ultrasound parameters in pregnancies complicated by pre-eclampsia and intrauterine growth restriction.

OBJECTIVES: To correlate levels of angiogenic growth factors with Doppler ultrasound parameters in pregnancies complicated by pre-eclampsia and intrauterine growth restriction (IUGR). METHODS: In 16 women with pre-eclampsia and 15 women with isolated IUGR, pulsatility indices (PI) in the umbilical and uterine arteries were measured by Doppler ultrasonography. At delivery, maternal and fetal blood (umbilical vein and artery separately) was sampled and angiogenic growth factors measured by means of enzyme linked immunosorbent assay (ELISA). RESULTS: Umbilical artery PI was significantly higher in women with IUGR than in those with pre-eclampsia, whereas uterine artery PI was not statistically significantly different. Maternal soluble fms-like tyrosine kinase-1 (sFlt-1) levels were higher in women with pre-eclampsia than in those with IUGR (P < 0.0001). Umbilical vein basic fibroblast growth factor (bFGF) levels were lower in women with pre-eclampsia than in those with IUGR (P < 0.05). Placental growth factor (PlGF) levels in the umbilical vein were below the detection limit in nearly all samples of IUGR fetuses and lower than in those with pre-eclampsia (P < 0.001). Maternal PlGF levels were inversely correlated with PI values of both vessels. In the umbilical vein sFlt-1 was positively and soluble kinase insert domain receptor (sKDR) negatively correlated with umbilical artery PI. No correlation could be found in the serum of the umbilical artery for all growth factors and for vascular endothelial growth factor (VEGF) in all compartments. CONCLUSIONS: The correlations between maternal and fetal angiogenic growth factor serum levels and Doppler ultrasound indices of uterine and umbilical arteries in pre-eclampsia and IUGR reflect the severity of the disorders especially for the fetus. A combination of both measurements may be useful in future screening for early prediction of pregnancy complications. Published by John Wiley & Sons, Ltd.     

Does the measurement of four fetal arteries provide more information than the measurement of just two arteries in prenatal Doppler sonography?

OBJECTIVE: The objective of this study was to evaluate whether the measurement of two or more fetal arteries provides more information and leads to a selection of fetuses at higher risk. DESIGN: In 244 pregnancies Doppler examinations in four fetal arteries (fetal aorta, common carotid artery, middle cerebral artery, umbilical artery) were performed. The evaluation of the results was made by means of a Doppler score for standardization and systematization. The results were divided into four groups (normal, pre-pathological, pathological, highly pathological) and the individual correlations with fetal outcome parameters were investigated. The results from measuring only two fetal arteries (the fetal aorta and middle cerebral artery) were then compared with those from all four arteries. RESULTS: Increasing pathology of the Doppler score correlated with fetal outcome parameters. The results showed that if the Doppler result in the two-vessel measurement was normal (n = 180), pre-pathological (n = 29) or highly pathological (n = 12) then measuring four vessels generally brought no additional information. However, the four-vessel measurement was of advantage in the pathological group (n = 23) because it selected the high-risk fetuses (30.4%), as categorized by outcome. CONCLUSIONS: Differentiating between several degrees of pathology is important for the estimation of fetal risk. In cases of pathological Doppler findings, the measurement of more than two vessels is important in order to select fetuses at increased risk.     

Umbilical vein blood volume flow rate and umbilical artery pulsatility as 'venous-arterial index' in the prediction of neonatal compromise.

OBJECTIVE: To assess the diagnostic power of the umbilical venous-arterial index (VAI) for the prediction of poor fetal outcome. SUBJECTS AND METHODS: This was a retrospective, cross-sectional clinical study in which normalized umbilical vein blood volume flow rate (nUV) (mL/min/kg estimated body weight), umbilical artery pulsatility index (UAPI), the newly developed VAI (nUV/UAPI), and the uterine artery resistance index (UTRI) were determined in 85 fetuses once (17-41 gestational weeks) during pregnancy using standard ultrasound Doppler equipment. A risk score based on umbilical blood pH, 1-min Apgar score, birth weight, duration of gestation, type of respiratory support, and referral to the pediatric department was constructed, and fetuses were assigned to a control or a pathological group accordingly. Logistic regression and analysis of fitted receiver-operating characteristics curves were performed to evaluate the diagnostic power of nUV, UAPI, UTRI, and VAI. RESULTS: The incidence of compromised neonates was 17.6%. The area under the receiver-operating characteristics curve was larger for VAI than for UTRI or for UAPI (P < 0.002). At a cut-off value of 100 mL/min/kg, the sensitivity of VAI to predict poor neonatal outcome was 85% with a 15% false-positive rate. CONCLUSION: Determination of the VAI has a greater diagnostic power to predict poor fetal outcome than the pulsatility index in the umbilical artery or the resistance index in the uterine artery.     

Nifedipine therapy for preterm labor: effects on placental, fetal cerebral and atrioventricular Doppler parameters in the first 48 hours.

OBJECTIVE: To assess the effect of nifedipine tocolysis on Doppler parameters of the uterine, umbilical and fetal middle cerebral arteries and atrioventricular valves in the first 48 h of therapy. METHODS: Doppler waveforms of uterine, umbilical and middle cerebral arteries and both atrioventricular valves were measured from 28 pregnant women and fetuses prior to and during nifedipine therapy for preterm labor. Maternal and fetal heart rates (FHR), maternal systolic and diastolic blood pressure, and the Doppler pulsatility index (PI) of the uterine, umbilical and middle cerebral arteries were measured. The cerebroplacental ratio (middle cerebral artery PI/umbilical artery PI) was calculated. The total time velocity integrals (TVIs) of tricuspid and mitral valves and their E- and A-wave peak velocity ratio (E/A) were measured. Friedman repeated-measures analysis of variance was used to compare the variables before and after nifedipine therapy. If significant differences were found, Wilcoxon's signed ranks test was used to analyze the difference between the two variables. A P-value of < 0.05 was considered significant. RESULTS: Nifedipine maintenance was associated with a significant decline in maternal systolic and diastolic blood pressure after 24 h, while maternal heart rate and FHR were unaffected. The uterine artery PI had decreased significantly at 24 and 48 h, while the umbilical artery PI did not change significantly. The middle cerebral artery PI had decreased significantly at 24 and again at 48 h. A significant fall in the cerebroplacental Doppler ratio was maintained beyond 24 h. The mean E/A values, TVIs and TVI x FHR values at 24 and 48 h were unchanged from the baseline values. CONCLUSIONS: Nifedipine maintenance tocolysis is associated with a significant decline in uterine artery and middle cerebral artery Doppler indices 24 h after the first dose. Fetal cardiac diastolic function is unaffected and the significant redistribution observed after 24 h is likely to be attributable to altered cerebral blood flow.     

Prenatal color Doppler sonographic evaluation of nuchal encirclement by the umbilical cord

PURPOSE: The aim of this study was to assess whether Doppler flow velocimetry of the fetal middle cerebral and umbilical arteries is affected by nuchal encirclement by the umbilical cord (nuchal cord) in the prenatal period. PATIENTS AND METHODS: The position of the fetal umbilical cord was assessed on color Doppler sonography in pregnant women who were referred to our radiology department between September 14, 1998, and January 14, 2000. Pulsatility and resistance indices and the ratio of peak systolic blood flow velocity to diastolic velocity of the umbilical arteries and middle cerebral arteries of all fetuses were prospectively obtained with Doppler flow velocimetry. The fetuses were categorized into 2 groups: group 1 consisted of fetuses without sonographic evidence of nuchal cord and group 2 of fetuses with sonographic evidence of nuchal cord. The results were statistically analyzed with independent-groups t test. A p value of less than 0.05 was considered significant. RESULTS: During the study period, 230 pregnant women underwent sonographic examination of the fetus, and 68 fetuses were delivered. The sonographic examinations were performed at 24-41 weeks' menstrual age. Of the 46 fetuses in group 1, 1 fetus had nuchal cord at delivery; of the 22 fetuses in group 2, 4 did not have nuchal cord at delivery. The sensitivity of color Doppler sonography in detecting nuchal cord was 95% (18 of 19 fetuses), the specificity was 92% (45 of 49), the negative predictive value was 98% (45 of 46), and the positive predictive value was 82% (18 of 22). No statistically significant differences in middle cerebral artery or umbilical artery Doppler flow velocimetry values were detected between the 2 groups. CONCLUSIONS: Color Doppler sonography is a sensitive and specific method of diagnosing nuchal cord, but fetal middle cerebral artery and umbilical artery Doppler flow velocimetry values are not affected by the presence of nuchal cord in the prenatal period.     

Fetal cerebral blood flow redistribution in late gestation: identification of compromise in small fetuses with normal umbilical artery Doppler.

OBJECTIVE: To evaluate the role of middle cerebral artery Doppler in small fetuses during the late third trimester. DESIGN: Prospective observational study of structurally normal fetuses with an estimated fetal weight < 5th percentile for gestation. Perinatal outcome was determined using a structured datasheet sent to each referring obstetrician. SUBJECTS: Structurally normal fetuses at 35 or more weeks of gestation referred during a 2-year period to the fetal growth clinic of a regional fetal medicine unit in North London. Fetuses with aneuploidy and/or major structural abnormalities were excluded. METHODS: Umbilical artery and middle cerebral artery (MCA) Doppler waveforms were recorded and considered abnormal if above 95th or below 5th percentiles, respectively. Amniotic fluid was considered reduced if the maximum vertical cord-free pool was < 2 cm. The placenta was considered mature if the Grannum grade was II or III. The head circumference (HC)/abdominal circumference (AC) ratio was considered abnormal if > 95th percentile for gestation. Fetal growth, amniotic fluid, biophysical profile score and umbilical artery Doppler were used to advise the referring obstetrician about fetal well-being and he/she independently decided both the timing and mode of delivery. RESULTS: Forty-seven fetuses fulfilled the entry criteria. Thirty-four (72%) demonstrated normal umbilical artery Doppler waveforms. Sixteen (34%) demonstrated middle cerebral artery redistribution, of which nine (56%) had normal umbilical artery Doppler waveforms. MCA blood flow redistribution was associated with an increased incidence of cesarean delivery and need for neonatal admission. Of all gray-scale parameters, an elevated HC/AC ratio has the strongest association with MCA blood flow redistribution (15/16 vs. 1/31; P < 0.01). CONCLUSIONS: MCA Doppler may be a useful tool to assess the health of small fetuses in the late third trimester. Redistribution may occur in the presence of normal umbilical artery Doppler and should be suspected when the HC/AC ratio is elevated.     

The assessment of normal early pregnancy by transvaginal color Doppler ultrasonography

Transvaginal color Doppler was performed in 198 volunteer pregnant women whose menstrual age ranged from the fifth to the twelfth week. In all patients an attempt was made to obtain signals from both uterine arteries, peritrophoblastic/retroplacental vessels, umbilical arteries, fetal aorta, intracranial vessels, and corpus luteum flow. With the combination of color and pulsed Doppler transvaginal sonography, detection of vascular structures was greatly facilitated and the amount of time for examination significantly reduced. Flow velocity waveforms were measured and results were analyzed by calculation of the Resistance Index. During the early stage of pregnancy, we were able to locate both uterine arteries in all cases and continuous diastolic shift signal was found. Flow in the peritrophoblastic/retroplacental area was observed with an overall success rate of 94%. Blood flow in the umbilical artery and fetal aorta was visualized by color Doppler starting from the seventh week. Intracranial blood flow could be visualized starting from the tenth week in some cases. Diastolic flow in these vessels was detectable starting from the twelfth week. Corpus luteum flow was found in 148 cases (75%) and the Resistance Index decreased as pregnancy progressed © 1993 by John Wiley & Sons, Inc.     

New implanted Doppler sensors for the assessment of the main fetal hemodynamics.

If the fetal Doppler examination during human pregnancies provides useful information to the obstetrician, it does not allow us to collect all the biological and haemodynamic data required to understand the physiopathological mechanisms involved in the development of intrauterine growth retardation (IUGR) and hypoxia. With the animal model, it is possible to have access to the blood pressure, the blood velocity and volume, to collect blood sampling and to perform pharmacological tests, or to simulate some human pathology. Several studies have been already carried out on lamb fetuses using electromagnetic flowmeters placed around the cord and catheters, with pressure sensors placed inside the fetal aorta. Most of the time only the umbilical flow was assessed on the fetal side. The aim of the present work was to develop a new Doppler system able to monitor in real time and simultaneously, the fetal cerebral and the umbilical arterial flows as well as the uterine circulation. New flat Doppler probes have been designed, to be implanted on the fetus and on the mother, which makes possible the atraumatic assessment of fetal and maternal flows during approximately 20 days. The 4-MHz CW Doppler probe consists of two rectangular piezoelectric transducers of 13-mm wide, preoriented at 45 degrees from the surface of the probe, placed in a 6-mm-high plastic case in which small holes are made to sew the probe on the fetal skin. The sensors are fixed on the fetal skin, facing the umbilical cord, the fetal cerebral arteries and in front of the uterine arteries.(ABSTRACT TRUNCATED AT 250 WORDS)     

Transvaginal color Doppler imaging

Transvaginal color Doppler was used to assess circulation in pelvic vessels in a group of 64 patients including 15 patients with fertility problems, 18 patients with pelvic tumors, 2 cases of suspected ectopic pregnancy, and 29 pregnant patients with fetuses between 6 weeks and 10 weeks, menstrual age. Blood flow was successfully displayed by color Doppler in the external and internal iliac arteries, and the uterine arteries, but flow in ovarian arteries could not be visualized. In the subgroup of patients with pelvic tumors, neovascularization of tumor tissue was documented in 6 out of 10 cases of uterine fibroma and in 2 cases of ovarian cancer. In 6 cases involving benign ovarian pathology, no abnormal blood supply was observed. A comparison between the characteristics of blood flow within uterine fibromas and ovarian malignancies showed lower impedance and higher blood velocity in cases of malignancy. In early pregnancy blood flow in the umbilical artery could be visualized by color Doppler starting from the 6th week and flow in the aorta from the 8th week. Flow in the trophoblasts was observed with an overall success rate of 59% and successfully demonstrated in 1 out of 2 cases of ectopic pregnancy.     

超声监测胎儿血流动力学变化预测胎儿生长发育的价值

【目的]探讨超声检测胎儿动静脉的血流动力学参数和径线对预测胎儿生长发育的价值。【方法】回顾性分析产前二维超声及彩色多普勒血流显像对170例胎儿进行各项参数测定,根据测定结果,将其分为正常对照组和宫内生长迟缓（IUGR）组,测量脐动脉、大脑中动脉、颈内动脉和腹主动脉的搏动指数（PI）、阻力指数（RI）及脐动脉收缩期最大流速与舒张末期流速的比值（S／D）,测量胎儿静脉导管血流量（QDV）和脐静脉的血流量（QuV）,计算静脉导管（DV）分流率,测定胎儿升主动脉和肺动脉收缩期峰值速度（PFV）,测量一般径线包括胎儿的双顶径、头围、腹围、股骨长度,测量产后胎儿体重并进行Apgar评分。【结果]IUGR组脐动脉和腹主动脉的PI、RI及S／D测值明显比对照组增高,IUGR组大脑中动脉和颈内动脉的PI、RI及S／D测值比对照组低,IUGR组升主动脉和肺动脉的PFV明显低于对照组胎儿,差异具有统计学意义（P〈0．05）。两组胎儿的QDV无明显差异,但IUGR组的QuV显著下降且DV分流率显著升高,差异均有统计学意义（P〈0．05）。36周IUGR组的胎头双顶径（BPD）、胎儿头围（HC）、胎儿腹围（AC）和胎儿股骨长（FL）明显比对照组低,差异有统计学意义（P〈0．05）。【结论】超声通过综合监测胎儿血流动力学和一般径线的变化,可以全面、客观地评价胎儿生长发育情况。