Umbilical artery flow velocity waveforms and twin pregnancy outcome

Two hundred seventy-two twin pregnancies were studied by analysis of the fetal umbilical artery waveforms recorded using continuous-wave Doppler ultrasound. After the first 100 cases, a management strategy was adopted whereby all twin gestations would be studied between 28-32 weeks' gestation and the results made available to the referring obstetrician, thereby influencing clinical management. Perinatal mortality and morbidity, in pregnancies with both fetuses alive at 28 weeks' gestation, were compared between the patients studied in the first group of 100 and those studied after the Doppler examination was introduced as a clinical service. There was a decrease in perinatal mortality, both uncorrected (57.9 per 1000 to 17.9 per 1000; P less than .05) and corrected (42.1 per 1000 to 8.9 per 1000). Fetal deaths were reduced from six to one (P less than .05). This decrease in perinatal mortality was achieved without any appreciable change in the gestational age at delivery or mode of delivery between the two groups. There was a reduction in the number of infants requiring neonatal intensive care (from 38% to 24%; P less than .01).     

Doppler umbilical and uterine flow waveforms in severe pregnancy hypertension

Summary. 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 (≥ 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.     

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.     

正常单胎及双胎妊娠妇女子宫动脉血流变化的比较

目的探讨正常单胎和双胎妊娠妇女子宫动脉血流搏动指数（ＰＩ）在孕期中的变化,并研究子宫动脉血流ＰＩ与胎盘位置的关系。方法采用Ｄｏｐｐｌｅｒ超声诊断仪,对９９例正常单胎妊娠和２４例正常双胎妊娠妇女的子宫动脉血流ＰＩ进行了检测,并同时探测胎盘的位置。结果单胎妊娠妇女的子宫动脉血流ＰＩ无论是胎盘侧或是对侧,均随孕周增加至分娩呈逐渐下降,孕２９周时子宫动脉血流ＰＩ平均值０．７８±０．１３。但双胎妊娠妇女的子宫动脉血流ＰＩ值随孕周逐渐下降至孕２７周后,则维持在一平台水平。孕２９周时子宫动脉血流ＰＩ平均值０．６７±０．１１,无论是单胎妊娠还是双胎妊娠,胎盘侧子宫动脉血流ＰＩ值均较对侧为低。结论单胎或双胎妊娠胎盘侧子宫动脉均较对侧血流丰富;且双胎妊娠时子宫动脉血流阻力较单胎为低。     

Doppler velocimetry in twin pregnancy.

The flow velocity waveform profile in the umbilical artery was measured in 50 pairs of twins during the last week before birth. A significant association was found between high resistance indicies and occurrence of late fetal heart rate decelerations; the higher the resistance, the more frequent the decelerations. Further, the connection between high resistance in the circulation of the umbilical artery and low birth weight was confirmed. Flow velocity measurements in the umbilical artery seem to be a valuable tool in identifying twin fetuses suffering from placental insufficiency.     

Prediction of pregnancy complications by first-trimester maternal serum PAPP-A and free beta-hCG and with second-trimester uterine artery Doppler

BACKGROUND: Previous studies have shown an association between low first trimester maternal serum free beta-hCG and PAPP-A and subsequent development of pregnancy complications. Similarly, uterine artery Doppler in the late second trimester has shown that high impedance to flow is associated with increased risk for preeclampsia and fetal growth restriction. The objective of this study is to determine whether there is an association between the maternal serum concentration of PAPP-A and free beta-hCG at 11-13(+6) weeks with the uterine artery pulsatility index (PI) at 22-24 weeks, and secondly, to compare the screening characteristics of the two methods in the prediction of adverse pregnancy outcome. METHODS: Maternal serum PAPP-A and free beta-hCG at 11-13(+6) weeks and uterine artery PI at 22-24 weeks were measured in 4390 women with singleton pregnancies. Pregnancies with chromosomal defects or fetal anomalies were excluded. The biochemical and Doppler measurements were compared between those with normal outcome and those resulting in spontaneous preterm delivery, pre-eclampsia and fetal growth restriction (FGR). Detection rates using a combination of the biochemical and Doppler measurements were investigated. RESULTS: In the pregnancies resulting in pre-eclampsia (n = 64) and FGR (n = 172), the median PAPP-A was lower (0.844 and 0.813 MoM), the median uterine artery mean PI was higher (1.56 and 1.18) but the median free betahCG was not significantly different (0.923 and 0.933 MoM) than in the normal outcome group. In the preterm delivery group (n = 159), the median free beta-hCG (0.944 MoM) and uterine artery mean PI (1.06) were not significantly different from normal but the median PAPP-A (0.928 MoM) was significantly lower than normal. In screening for pre-eclampsia, the detection rate, for a 5% false-positive rate, was 14.1% for PAPP-A, 54.7% for uterine artery mean PI and 62.1% for a combination of PAPP-A and uterine artery mean PI. CONCLUSION: Maternal serum PAPP-A at 11-13(+6) of gestation is significantly lower in adverse pregnancy outcomes. The combination of first trimester serum PAPP-A and uterine artery mean PI at 22-24 weeks improves the screening efficacy for the prediction of pre-eclampsia.     

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   

Umbilical artery blood flow velocity waveforms in twin pregnancies.

To detect discordant fetal growth in twin pregnancies and assess a possible role for Doppler ultrasound measurements of blood flow velocity waveforms in umbilical arteries in such cases, 32 twin pregnancies were examined on 125 occasions. The last examination was within 14 days of delivery. There was postpartum death of one pair of twins with the twin transfusion syndrome. Birthweight was appropriate for gestational age in 15 twin pairs, both infants were small for gestational age (SGA) in 5, and one of the infants was SGA in 12 twin pairs. The correlation coefficient of RI difference at the last examination and percentage birth weight difference in twin pairs was 0.68. Cutoff points for the delta RI and weight difference were established. The sensitivity of delta RI (0.1) was 77.8%; specificity, 95.8%; positive predictive value, 87.5%; and negative predictive value, 92.0%.     

Value of uterine artery Doppler in the second subsequent pregnancy

AIM: Pre-eclampsia and intrauterine growth restriction (IUGR) are among the most common causes of fetal and maternal morbidity and mortality. The aim of this study was to examine the value of uterine artery Doppler in the second subsequent pregnancy in a low risk population for the prediction of pre-eclampsia and IUGR at any gestational age. METHODS: Patients were randomized into two different groups: group A (nine patients) with positive notching both at week 20 and 24 in both pregnancies; group B (five patients) with bilateral positive notching at week 20 and 24 only in the second pregnancy. RESULTS: During the second pregnancy IUGR rate was 11.1% in patients of group A and 60% in patients of group B (P=0.0949). During the first pregnancy IUGR reached 44.4% in group A and 0% in group B (P=0.2208). CONCLUSION: In conclusion no significant increase of IUGR has been detected if the abnormal maternal Doppler ultrasound recurs in subsequent pregnancies.     

Smoking and buccally administered nicotine. Acute effect on uterine and umbilical artery Doppler flow velocity waveforms

The effects of maternal smoking and buccal nicotine exposure on uterine and umbilical artery blood flow velocity waveforms were studied in 47 healthy women during late pregnancy. Systolic:diastolic ratios of recorded waveforms were calculated before and after each woman smoked one cigarette containing 1.2 mg of nicotine. The same protocol was followed at a subsequent clinic visit, when each woman chewed a piece of nicotine polacrilex containing 2 mg of nicotine. No significant changes could be induced in either nonsmokers or prior smokers, nor were any significant changes measured in the uterine vessels of any patient subgroup. A significant decrease (P less than .01) in umbilical artery diastolic blood flow velocities was measured after smoking in all habitual smokers after chewing nicotine polacrilex and in those who smoked greater than 10 cigarettes per day (P less than .05). All the measured changes returned to baseline levels by 10 minutes after cessation of exposure. Similar changes in the umbilical artery flow velocity waveforms after exposure to a cigarette and nicotine polacrilex implicated nicotine as a probable cause. Failure to observe significant changes except in habitually smoking women suggests a receptor-mediated response. The finding of altered umbilical artery flow velocity waveforms in the absence of demonstrable changes in the uterine vessels indicates a direct toxic effect of maternal nicotine exposure on the fetal cardiovascular system.     

Exercise-related changes in umbilical and uterine artery waveforms as assessed by Doppler ultrasound scans

OBJECTIVE: The purpose of this study was to assess the effect of strenuous symptom-limited exercise on umbilical and uterine blood flow. STUDY DESIGN: Twenty-two primiparous women between 30 and 34 weeks of gestation were recruited. At rest, umbilical and uterine artery waveforms were assessed by measuring the pulsatility index. This was followed by a symptom-limited incremental exercise test. Fetal umbilical and maternal uterine artery circulations were assessed after exercise. RESULTS: Strenuous maternal exercise was demonstrated by the significant change in physiologic parameters, which was associated with an immediate increase in fetal heart rate, a significant increase in the right uterine artery pulsatility index, and a reduction in the umbilical artery pulsatility index. CONCLUSION: The modest change in the uterine artery pulsatility index without an adverse change in the umbilical artery pulsatility index indicates that a single bout of maximum symptom-limited exercise does not have immediate adverse fetal or maternal cardiovascular effects.     

Continuous wave Doppler flow velocity waveforms from the umbilical artery in normal pregnancy

The objective was to establish a normal reference range of the indices of umbilical artery waveforms using continuous wave doppler ultrasound. A prospective longitudinal study was made of 85 uncomplicated singleton pregnancies between 16 and 40 weeks gestation (783 recordings). Pulsatility Index (P.I.), Resistance Index (R.I.) and A/B ratio were measured at each visit. The mothers all delivered normal healthy infants weighing more than the 10th centile for gestational age. All three indices have a positively skewed frequency distribution, a factor not generally appreciated until recently and the ranges are therefore described using non-parametric statistics. Placental resistance decreases as term approaches, the 50% PI at 16 weeks was 2.06, at 32 weeks was 1.08 and at 40 weeks was 0.85. The results show a comprehensive reference of normal values and provides a sound basis for the further study of abnormal pregnancy. It represents the largest published study of its type using continuous wave Doppler.     

The effect of maternal exercise on uterine artery velocimetry waveforms.

One hundred and two subjects in the second half of pregnancy were subject to an acute exercise test lasting 5 minutes on an upright bicycle ergometer. The pulsatility index (using Doppler ultrasound) of the right uterine artery was analysed before exercise and at 2, 4, 6, 8, 10, 12, 16, 20, 24 and 30 minutes after exercise. The mean exercise intensity achieved was 67.2% of sub-maximal exercise (range 51-90%). At 2 minutes post-exercise, the mean uterine artery pulsatility index was increased from the baseline value, reaching a maximum of 0.64 at 8 minutes (baseline 0.583). After 8 minutes there was a gradual decrease in the pulsatility index, and at 24 and 30 minutes the values were significantly lower (P < 0.001 and P < 0.001 respectively). Smokers had significantly higher pulsatility index values than non-smokers (P < 0.004). Primigravidae also had lower resistance indices compared with multigravidae (P < 0.001). We conclude that exercise in the second half of pregnancy appears to cause a transient increase in the maternal uterine artery pulsatility index. We also believe that at this level of exercise intensity there was no evidence of harmful effects on maternal uterine blood flow.     

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.     

The role of uterine artery Doppler in predicting adverse pregnancy outcome

The complications of placental insufficiency, pre-eclampsia and fetal growth restriction (FGR) are major causes of perinatal as well as maternal morbidity and mortality. In normal pregnancy, impedance to flow in the uterine arteries decreases with gestation, and histopathological studies suggest that this is due to trophoblastic invasion of the spiral arteries and their conversion into low-resistance vessels. Failure of trophoblastic invasion is associated with complications of uteroplacental insufficiency. Several Doppler screening studies, both in the second and more recently in the first trimester of pregnancy, have demonstrated an association between increased impedance to flow in the uterine arteries and subsequent development of pre-eclampsia, FGR and perinatal death.