Umbilical artery Doppler velocimetry as a labor admission test

Doppler ultrasound of the umbilical artery flow velocity waveform was studied prospectively as an admission test at the labor ward. Recordings were made in 575 women in various stages of labor before, during, and after uterine contractions, and evaluated in relation to intrapartum and fetal outcome variables. No association was found between abnormal flow velocity waveforms and cord complications, meconium-stained amniotic fluid, or abnormal fetal heart rate tracing, nor was there any association with operative delivery for fetal distress or low Apgar scores at 1 and 5 minutes. Small for gestational age fetuses had significantly more abnormal flow velocity waveforms than appropriate for gestational age fetuses, and so had those with umbilical artery acidemia compared with those with normal pH. The results indicate that Doppler recording of the umbilical artery flow velocity waveform as an admission test at the labor ward is not a good predictor of fetal distress in an unselected population.     

Uteroplacental blood flow velocity-time waveforms in normal and complicated pregnancy

Summary. A simple continuous wave Doppler ultrasound system for recording arterial flow velocity waveforms in branches of the uterine artery in the placental bed is described. Twelve normal pregnancies were studied serially from 20 weeks to delivery. The diastolic flow velocity expressed as a percentage of the systolic provides an index of downstream vascular bed resistance and perfusion. This always exceeded 50% in normal pregnancy and there was a small increase with gestational age indicative of a decreasing flow resistance. Of the 91 complicated pregnancies, studied because of potential uteroplacental insufficiency and fetal risk, 25 resulted in the birth of an infant small-for-gestational-age. In 15 the uterine artery flow velocity waveform revealed a pattern of low diastolic flow velocity. It is postulated that these represent a subgroup of growth-retarded fetuses in whom there is reduced uterine artery perfusion. Reduced uterine artery diastolic flow velocity in these patients was associated with reduced umbilical artery diastolic flow velocity on the fetal side of the placenta. In contrast the 10 small-for-gestation infants associated with normal uterine artery waveforms suggest a primary fetal cause. Twelve patients with severe hypertensive disease of pregnancy were studied. Nine were associated with reduced uterine artery diastolic flow velocity (reduced uterine artery perfusion) consistent with vasospasm in the branches of the uterine artery in the placental bed.     

Uteroplacental blood flow velocity-time waveforms in normal and complicated pregnancy

A simple continuous wave Doppler ultrasound system for recording arterial flow velocity waveforms in branches of the uterine artery in the placental bed is described. Twelve normal pregnancies were studied serially from 20 weeks to delivery. The diastolic flow velocity expressed as a percentage of the systolic provides an index of downstream vascular bed resistance and perfusion. This always exceeded 50% in normal pregnancy and there was a small increase with gestational age indicative of a decreasing flow resistance. Of the 91 complicated pregnancies, studied because of potential uteroplacental insufficiency and fetal risk, 25 resulted in the birth of an infant small-for-gestational-age. In 15 the uterine artery flow velocity waveform revealed a pattern of low diastolic flow velocity. It is postulated that these represent a subgroup of growth-retarded fetuses in whom there is reduced uterine artery perfusion. Reduced uterine artery diastolic flow velocity in these patients was associated with reduced umbilical artery diastolic flow velocity on the fetal side of the placenta. In contrast the 10 small-for-gestation infants associated with normal uterine artery waveforms suggest a primary fetal cause. Twelve patients with severe hypertensive disease of pregnancy were studied. Nine were associated with reduced uterine artery diastolic flow velocity (reduced uterine artery perfusion) consistent with vasospasm in the branches of the uterine artery in the placental bed.     

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.     

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

Summary. 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 enddiastolic 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.     

Normal fetal Doppler inferior vena cava, transtricuspid, and umbilical artery flow velocity waveforms between 11 and 16 weeks' gestation.

OBJECTIVES: Our objectives were to determine flow velocity waveform patterns in the fetal inferior vena cava and to relate these waveforms to transtricuspid and umbilical artery waveforms and fetal heart rate in early gestation. STUDY DESIGN: Doppler waveforms were recorded in 40 normal fetuses at 11 to 16 weeks of gestation. Only transvaginal scanning was carried out at 11 to 12 weeks and only transabdominal scanning was used at 15 to 16 weeks. RESULTS: The ratio of time velocity integrals of flow from the inferior vena cava during systole and early diastole, the percentage of reverse flow in this vessel, the pulsatility index from the umbilical artery, and the fetal heart rate were negatively correlated with gestational age. Peak E-wave and A-wave velocities and E/A ratios from the transtricuspid waveforms were positively correlated with gestational age. CONCLUSION: Early normal pregnancies are associated with remarkable changes in fetal flow velocity waveforms at both the cardiac and the extracardiac level.     

Umbilical artery waveforms in triplet pregnancy

Twenty patients with triplet pregnancies underwent continuous-wave Doppler ultrasound umbilical artery waveform studies as part of a multiple-pregnancy surveillance program. One or more infants was small for gestational age in nine of these triplet pregnancies. In all of these cases, at least one abnormal umbilical artery velocity waveform was present. Two infants were stillborn, and both had a grossly abnormal umbilical artery waveform (absent diastolic flow) recorded consistently for several weeks before fetal death. The use of umbilical artery Doppler studies may delineate those triplet pregnancies in which more intensive fetal surveillance is appropriate.     

Blood flow velocity waveforms of the middle cerebral artery and abnormal neurological evaluations in live-born fetuses with absent or reverse end-diastolic flow velocities of the umbilical arteries.

We studied 37 fetuses with absent or reverse end-diastolic flow velocities (AREDFV) of the umbilical arteries with respect to the mode of delivery, fetal acidosis, resistance index of the middle cerebral arteries, and abnormal neurological evaluation at the time of discharge from the department of pediatrics. A control group with normal umbilical artery flow velocity waveforms was matched for gestational age. Fetuses with AREDFV were delivered almost exclusively by cesarean section, in most cases due to fetal distress. Metabolic changes with decreased base excess values were found more often in fetuses with AREDFV, but no difference could be detected with respect to severe fetal acidosis. The number of fetuses with abnormal neurological evaluations during the first 6 months of life was significantly higher in cases with AREDFV than in the control group. More than two thirds of the fetuses with AREDFV showed an abnormal blood flow velocity waveform of the middle cerebral arteries with elevated end-diastolic flow velocities. The combination of extreme premature delivery before 28 weeks of gestation, severe idiopathic respiratory distress syndrome, and a resistance index of the middle cerebral arteries under the 5th percentile seems to be a risk factor for early neurological morbidity in fetuses with AREDFV. Premature delivery of fetuses with AREDFV--as we did during our study in order to prevent intra-uterine death or fetal asphyxia--should therefore be critically regarded in cases under 28 weeks of gestational age and abnormal flow velocity waveforms of the middle cerebral arteries.     

Delayed normalization of uterine artery Doppler waveforms is not a benign phenomenon

OBJECTIVE: To evaluate the pregnancy outcome in patients with abnormal uterine artery Doppler flow velocity waveforms (FVW's) at 19-21 weeks, which were subsequently normal by 24-26 weeks, and to study the effect of low-dose aspirin on these waveforms. DESIGN: The study group consisted of 49 patients who had abnormal uterine artery flow velocity waveforms (FVW's) at 19-21 weeks. These women were initially commenced on 100 mg slow-release aspirin at 20 weeks, which was discontinued at the follow-up visit, after confirming normal uterine artery Doppler FVW. The control group consisted of 730 patients with normal uterine artery Doppler waveforms at 19-21 weeks. The main outcome measures were: small for gestational age (SGA) <10th centile, pre-eclampsia, placental abruption, and perinatal mortality rate (PMR). RESULTS: When compared with the control group, the study group had an increased risk of placental abruption (2% versus 0.27%, P = 0.05) 95% Confidence Intervals CI = 0.01-0.13), low birth weight (3087 versus 3383 gm, P = 0.0003), SGA <10th centile (32.7% versus 11.9%, P 相似文献   

The influence of maternal exercise on the uteroplacental vascular bed resistance and the fetal heart rate during normal pregnancy

The effects of maternal exercise were studied in 20 healthy women with uncomplicated pregnancies. A continuous-wave Doppler ultrasound system was used to record arterial flow velocity waveforms from the ascending vasculature downstream from the uterine artery. The fetal heart rate was monitored with a Doppler ultrasound cardiotocograph. No significant change was found in the uterine blood flow velocity waveform post-exercise, as expressed by the pulsatility index, suggesting absence of change in the uterine vascular bed resistance. The fetal heart rate significantly increased after exercise.     

Blood flow velocity waveforms at late pregnancy and during labor

608 high-risk pregnancies were monitored by repeated Doppler-examinations o of the fetal aortic blood flow. An absent end-diastolic flow pattern was found to reval fetal growth retardation with 73% sensitivity. The positive predictive value of this finding for prediction of fetal growth retardation combined with intrauterine distress (prevalence in the material 8%) was 85%. In the cases with this flow pattern, the cesarean section rate was 72%, and the mean gestational age at delivery was 34 weeks. Normal labor was not associated with any changes of umbilical arterial flow velocity waveforms, but the diastolic flow of the arcuate arteries was decreased during uterine contractions.     

Umbilical and uterine artery flow velocity waveforms in pregnancy associated with major fetal abnormality

Flow velocity waveforms from the umbilical artery and branches of the uterine artery in the placental bed were recorded using continuous wave Doppler ultrasound. The records of 26 patients with pregnancy complicated by major fetal abnormality were reviewed to determine the changes of a primary fetal disturbance. The systolic/diastolic (A/B) ratio was used as an index of blood flow resistance. In 13 of the 26 patients the umbilical artery waveform systolic/diastolic ratio was high. It is postulated that in these patients there is a process of obliteration of small arteries in the placenta that is triggered by the abnormal fetus. In all patients the uterine artery waveform was normal. In seven of these 13 patients the infant had a birthweight greater than 10th centile. Placental weights were examined. A small placenta expressed as either low weight for gestational age or low placental/fetal weight ratio was associated with a normal umbilical artery waveform. It is suggested that fetuses in these groups have a low growth potential. In contrast a high placental/fetal weight ratio was associated with an abnormal umbilical artery waveform pattern.     

Doppler assessment of the cardiac and uteroplacental circulations in normal and complicated pregnancies

Summary. Blood flow velocity waveforms were recorded in four sites in the fetal circulation in a series of 271 normal and 71 complicated pregnancies. The sites were the umbilical artery, the uterine artery branches in the placental bed, and distal to the two arterial valves in the heart. The blood flow through the arterial valves was added to estimate combined cardiac output. Normal ranges for values in all sites were established in our own series, and were similar to other published results. Abnormality of the waveform in the umbilical artery proved the most useful predictor of perinatal morbidity. Reversal of the normal pattern of increasing diastolic flow in the umbilical artery with advancing gestation was an important prognostic finding in the pregnancies studied serially. The combined cardiac output did not fall until late in the course of fetal compromise, and low values were seen only with an abnormal umbilical artery tracing.     

Doppler Ultrasound in Pregnancies with Hypertension

Doppler studies of the arcuate and umbilical arteries were performed longitudinally commencing at 24 weeks or less, in 29 pregnant women with chronic hypertension. The hypothesis was that pregnant women with chronic hypertension who develop superimposed gestational proteinuric hypertension and/or deliver small for gestational age babies are those who have abnormal arcuate and/or umbilical flow velocity waveforms. Abnormal arcuate waveforms occurred in 7 women and abnormal umbilical waveforms in 12. Nine babies were small for gestational age, and 6 of them had abnormal arcuate waveforms. Abnormal arcuate waveforms were significantly associated with the delivery of a small for gestational age baby (p = .001) and identified those babies where early delivery was necessary for fetal reasons. All small for gestational age babies had abnormal umbilical waveforms. Superadded gestational proteinuria (or preeclampsia) occurred in 8 pregnancies, however, only 3 had abnormal arcuate waveforms. An abnormal arcuate waveform did not predict the later development of gestational proteinuria. An abnormal umbilical waveform however, was associated with the subsequent development of gestational proteinuria. We consider that these findings need to be confirmed in a larger study.     

Umbilical and uterine artery flow velocity waveforms in pregnancy associated with major fetal abnormality

Summary. Flow velocity waveforms from the umbilical artery and branches of the uterine artery in the placental bed were recorded using continuous wave Doppler ultrasound. The records of 26 patients with pregnancy complicated by major fetal abnormality were reviewed to determine the changes of a primary fetal disturbance. The systolic/diastolic (A/B) ratio was used as an index of blood flow resistance. In 13 of the 26 patients the umbilical artery waveform systolic/diastolic ratio was high. It is postulated that in these patients there is a process of obliteration of small arteries in the placenta that is triggered by the abnormal fetus. In all patients the uterine artery waveform was normal. In seven of these 13 patients the infant had a birthweight > 10th centile. Placental weights were examined. A small placenta expressed as either low weight for gestational age or low placental/feta1 weight ratio was associated with a normal umbilical artery waveform. It is suggested that fetuses in these groups have a low growth potential. In contrast a high placental/fetal weight ratio was associated with an abnormal umbilical artery waveform pattern.     

Blood velocity waveforms in the fetal aorta and umbilical artery as predictors of fetal outcome: a comparison

In 139 pregnancies in which intrauterine growth retardation (IUGR) was suspected at routine ultrasound screening at 32 weeks of gestation, blood velocity in the fetal aorta and umbilical artery was recorded by a pulsed Doppler ultrasound every second week until delivery. The maximum blood flow velocity waveforms (FVWs) were analyzed for pulsatility index (PI) and blood flow class (BFC). In both vessels, an abnormal PI (greater than mean + 2 SD of the normal population) and abnormal BFC at the final antenatal examination were significantly associated with the occurrence of IUGR (birthweight less than or equal to mean - 2 SD) (p less than 0.001), operative delivery for fetal distress (p less than 0.001), and a low 1-minute Apgar score (less than or equal to 7). PI in the umbilical artery was a better predictor of fetal outcome than was the aortic PI, but the BFC was similarly predictive of fetal outcome in both vessels. The data indicate that a simple umbilical artery examination, which can be performed blindly with the Doppler ultrasound instrument without the help of a real-time scanner, is a reliable method for monitoring fetal status in pregnancies when IUGR is suspected.     

The significance of absent end-diastolic velocity in umbilical artery velocity waveforms

Doppler umbilical artery velocimetry has been used to study high-risk pregnancies. The most extreme waveform abnormality is the absence of end-diastolic velocity. To examine the significance of this finding, events outcome was evaluated in 161 women studied between 31 and 36 weeks. Ten had absence of end-diastolic velocity. When compared with fetuses with normal and less severely abnormal waveforms, there was a higher incidence of intrauterine growth retardation, pregnancy-induced hypertension, cesarean section for fetal distress, neonatal intensive care unit admission, and low Apgar scores. Average birth weight and gestational age at delivery were lower. Five other fetuses with absence of end-diastolic velocity were identified that were delivered between 27 and 30 weeks, making a total of 15 patients with absence of end-diastolic velocity. Of 12 patients monitored, 11 had an abnormal fetal heart rate pattern. Four fetuses had lethal anomalies. There were eight perinatal deaths. Acute or chronic hypoxia was evident in all fetuses with absence of end-diastolic velocity. Absent end-diastolic velocity represents a unique and severe fetal condition that cannot be identified by present surveillance methods and requires a Doppler study for diagnosis.     

Umbilical and uterine flow velocity waveforms in pregnancies complicated by major fetal anomalies

A continuous wave Doppler unit was used to obtain umbilical and uterine artery flow velocity waveforms in pregnancies complicated by a major fetal abnormality. A total of 139 examinations were performed on 32 women between 26 to 41 weeks' gestation, and the records were reviewed to determine the changes associated with fetal malformation. The systolic/diastolic (A/B) ratio was used as an index of blood flow resistance in the umbilical artery and the systolic minus diastolic divided by systolic (A-B)/A for the branches of the uterine artery. Seventeen out of 32 patients showed high systolic/diastolic ratio in waveforms taken from the umbilical artery. In 30 out of 32 patients the uterine artery waveform was normal (in two patients the results were equivocal). It appears that a fetal mechanism may determine the changes in the umbilical placental circulation resulting in an umbilical artery pattern of high flow resistance in more than half of the patients with congenital anomalies.     

Blood velocity in the fetal vein of Galen and the outcome of high-risk pregnancy

BACKGROUND: Pulsation in the flow velocity waveform in the umbilical vein is related to perinatal mortality but the flow velocity waveform in the fetal vein of Galen is normally even and without fluctuation. OBJECTIVES: To establish whether blood flow velocity pulsations in the vein of Galen in high-risk pregnancies are related to outcome. STUDY DESIGN: The vein of Galen was located by colour Doppler ultrasound in 102 pregnancies complicated by severe pregnancy-induced hypertension. The blood velocity waveform was recorded by pulsed Doppler within 2 days of delivery and the presence pulsations related to pregnancy outcome, including emergency operative intervention and neonatal distress. Umbilical artery and vein and uterine artery blood flow velocity waveform were also recorded at the same time. The clinicians managing the women were unaware of the venous flow results. RESULTS: Pulsation were present in the vein of Galen in 68 cases and in the umbilical vein in 21. Both were significantly related to adverse outcome. Pulsations in the vein of Galen were seen in all seven perinatal deaths. CONCLUSIONS: Since umbilical venous pulsation are a late sign of fetal compromise, and pulsations in the vein of Galen seem to appear earlier, thus being an intermediate sign of fetal compromise that might be of great value for fetal surveillance.     

Umbilical artery and uteroplacental velocimetry in pregnancies complicated by idiopathic low birthweight centile.

Umbilical artery and uteroplacental Doppler flow velocity waveforms were studied in 35 pregnancies complicated by idiopathic low birthweight centile. Thirty fetuses (86%) were below the 5th centile birthweight for gestation. Fifteen (43%) had an abnormal umbilical artery systolic to diastolic ratio. Uteroplacental waveforms were recorded in 29 of the 35 pregnancies and five (17%) showed an abnormal systolic to diastolic ratio. Abnormal uteroplacental systolic to diastolic ratios were associated with a significantly earlier gestational age at delivery and significantly more cesarean sections for fetal distress compared with normal uteroplacental systolic to diastolic ratios (p less than or equal to 0.01). The absence of umbilical artery end-diastolic frequencies was associated with a significantly earlier gestational age at delivery compared with the presence of umbilical artery end-diastolic frequencies (p less than 0.005). No differences in pregnancy outcome were observed comparing normal with abnormal amniotic fluid volume assessment. These findings suggest that Doppler studies may be useful in estimating the risk of adverse perinatal outcome for small for gestational age fetuses with no identifiable cause.