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.     

Intrauterine death of one twin, with rescue of the other, in twin-twin transfusion syndrome.

Single intrauterine death may occur in twin-twin transfusion syndrome. We investigated why the outcome of the surviving twin is fairly good when the donor twin dies first compared with when the recipient twin dies first. A detailed hemodynamic study was performed using Doppler ultrasound in a twin pregnancy affected by twin-twin transfusion syndrome before and after a single intrauterine death that occurred in the donor twin at 26 weeks' gestation. The recipient twin was expected to die due to severe right cardiac failure with functional stenosis of the pulmonary artery 2 days before the cotwin's death. The donor twin's death caused a prompt resolution of cardiac failure and improvement in other indices, including flow velocity waveform patterns of the umbilical vein, the middle cerebral artery and the ductus venosus. A healthy, premature female neonate weighing 1630 g with a hemoglobin concentration of 17.8 g/dL was delivered by Cesarean section following rupture of the fetal membranes 28 days after the episode. Hemorrhaging from the surviving twin to the dead twin that occurred just before or after the cotwin's death may have contributed to the decrease in volume overload in the recipient twin, leading to a prompt amelioration of the critical hemodynamic indices. The early death of the donor twin may thus have played a significant role in improving the status of the recipient twin in this case of twin-twin transfusion syndrome.     

Arterial Doppler ultrasound in 115 second- and third-trimester fetuses with congenital heart disease.

OBJECTIVE: To assess the influence of isolated congenital heart disease (CHD) on fetal arterial Doppler blood flow velocity waveforms. METHODS: Doppler flow velocimetry was performed in the umbilical artery and middle cerebral artery in 115 consecutive fetuses with antenatally diagnosed CHD. Gestational age ranged between 19 and 41 weeks. Fetuses with isolated CHD were defined as group A (n = 55), showing cardiogenic hydrops fetalis in six cases; group B included 60 cases complicated by chromosomal or non-chromosomal extracardiac malformation, uteroplacental dysfunction or non-cardiogenic non-immune hydrops fetalis. The control group comprised 100 healthy fetuses of uncomplicated pregnancies. Individual pulsatility index measurements were converted into their Z-scores (delta values) for statistical analysis. RESULTS: In regard to the umbilical artery pulsatility index, 115 fetuses with CHD showed a significantly greater (P < 0.001) difference from the normal mean for gestation (delta values) than the control group. However, 29 of the 33 cases with indices above the 95% reference interval were additionally associated with extracardiac malformations, uteroplacental dysfunction or non-cardiogenic non-immune hydrops fetalis. While fetuses with isolated CHD still showed significantly higher values than healthy fetuses (P < 0.01), only in 4 of 55 (7%) fetuses did the measured umbilical artery pulsatility index exceed the 95% reference interval. There was no significant difference from the control group, in which 4 of 100 cases showed an umbilical artery pulsatility index above the 95% reference interval. Elevated umbilical artery pulsatility indices were seen in only four cases of severe obstruction of the outflow tracts leading to reverse perfusion of the affected great artery and in one case of Ebstein's anomaly with pulmonary insufficiency. Although all four fetuses with isolated CHD and elevated umbilical artery pulsatility index died, 14 of 18 fetuses with lethal outcome had normal pulsatility index values in the umbilical artery. Investigations of the middle cerebral artery blood flow revealed no significant difference between fetuses with and without CHD or any subgroups. CONCLUSIONS: This study shows that arterial blood flow velocity waveforms in fetuses with isolated CHD do not show sufficient alterations to be of diagnostic value. Only in severe outflow tract obstructions due to a 'steal effect' or in significant insufficiencies of semilunar valves leading to an impaired 'wind-kessel function' may the special hemodynamic changes induced by CHD result in a significant increase of pulsatility index in the umbilical artery. In the majority of cases with CHD the increase of pulsatility index of umbilical arterial blood flow velocity waveforms, however, results from extracardiac anomalies, especially uteroplacental dysfunction and chromosomal abnormalities. Furthermore, umbilical artery Doppler sonography is not clinically helpful in predicting fetal outcome.     

Impact of laser coagulation in severe twin-twin transfusion syndrome on fetal Doppler indices and venous blood flow volume.

OBJECTIVE: To evaluate the impact of fetoscopic laser coagulation of placental anastomoses in severe twin-twin transfusion syndrome on fetal Doppler indices and umbilical vein blood flow volume as calculated with Doppler and two-dimensional ultrasound. METHODS: Thirty-two cases of second-trimester severe twin-twin transfusion undergoing laser therapy were examined with serial ultrasound before and 1, 3 and 5 days after therapy. Pulsatility indices in the umbilical artery and ductus venosus were measured. Blood volume flow at the level of the intra-abdominal umbilical vein was calculated by means of Doppler and two-dimensional ultrasound. The development of hydropic signs in donors was recorded. Perinatal outcome in terms of neonatal survival was recorded for all cases. RESULTS: In recipients, ductus venosus pulsatility index decreased progressively after therapy and, by day 5, median pulsatility index was significantly lower than that before therapy (0.97 vs. 0.82, P < 0.0001). Umbilical vein blood flow volume in recipient twins showed no significant variations before and after laser. In donors, umbilical artery pulsatility index decreased significantly by the first day following therapy (2.1 vs. 1.6, P < 0.0001). Previously absent or reverse umbilical end-diastolic flow reappeared after therapy in 46% (7/15) of donors. Ductus venosus pulsatility index in donors increased significantly by day 1 after therapy (0.99 vs. 1.35, P < 0.0001) but, over days 3 and 5, it returned towards preoperative values. Umbilical vein flow volume measurements (mL/min/kg) in the donor increased by approximately 50% the day after treatment (151 vs. 232, P < 0.0001) and remained elevated. Umbilical vein flow volume before laser therapy was significantly lower in donors compared to recipients (151 vs. 260, P < 0.0001), but the difference was non-significant after treatment (240 vs. 267). One or more hydropic signs developed in eight (25%) donors during the 5 days' observation after therapy. CONCLUSIONS: Laser therapy induced important changes in fetal hemodynamic parameters, resulting in a reversion of the disturbances associated with severe twin-twin transfusion syndrome. The recipient twin showed a progressive improvement of previous signs of right cardiac overload. The donor experienced a substantial increase in umbilical vein blood volume flow accompanied by a transitory state of relative right overload, which may explain the development of transient hydropic signs in a proportion of donors.     

Serial sonographic findings of four fetuses with homozygous alpha-thalassemia-1 from 21 weeks onwards.

OBJECTIVES: To evaluate the potential usefulness of noninvasive ultrasound assessment of fetal anemia in the diagnosis and management of fetuses with homozygous alpha-thalassemia-1. METHODS: We describe four pregnancies complicated by fetal homozygous alpha-thalassemia-1. They presented with ultrasound abnormalities before the development of hydrops. As part of evaluating the fetal condition, we performed ultrasound and Doppler studies aimed at identifying fetal anemia. These studies included evaluation of intrahepatic umbilical venous maximum flow velocity, middle cerebral artery peak flow velocity, fetal liver length and spleen perimeter. RESULTS: In all four fetuses, ultrasound and Doppler studies suggested the presence of fetal anemia. Homozygous alpha-thalassemia-1 was diagnosed in all cases, with fetal blood sampling confirming anemia in three fetuses. The majority of the intrahepatic umbilical venous maximum flow velocity and middle cerebral artery peak flow velocity measurements were above the 95th centile. Two fetuses underwent intrauterine transfusion and fetal blood flow velocities returned to normal after correction of the fetal anemia. The fetal liver length and spleen perimeter measurements showed a similar trend, although they were less consistent before 28 weeks. CONCLUSION: Non-invasive ultrasound parameters, in particular quantification of intrahepatic umbilical venous maximum flow velocity and middle cerebral artery peak flow velocity, were found to be useful in the diagnosis and management of fetal anemia in pregnancies with fetal homozygous alpha-thalassemia-1.     

Changes in fetal hemodynamics with ritodrine tocolysis.

OBJECTIVE: To evaluate the effect of ritodrine on the fetal cardiovascular system. METHODS: Cardiac and extracardiac Doppler waveforms were recorded in 12 fetuses prior to and during ritodrine therapy used for preterm labor. Maternal and fetal heart rates, the Doppler pulsatility indices of the umbilical artery, middle cerebral artery, descending thoracic aorta and renal artery, and time velocity integrals of the atrioventricular valves and the ductus arteriosus, were measured. RESULTS: Ritodrine infusion caused an increase in maternal and fetal heart rates, the left cardiac output as measured by the product of time velocity integral and heart rate, and the pulsatility index of the middle cerebral artery, and a decrease in the pulsatility index of the umbilical artery. CONCLUSIONS: Ritodrine infusion may alter placental and cerebral blood flow and may have a selective effect on the left side of the heart.     

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.     

Middle cerebral artery Doppler in severe intrauterine growth restriction.

OBJECTIVE: To examine longitudinal changes in middle cerebral artery blood flow assessed by Doppler in severely growth restricted fetuses. METHODS: Eighteen structurally normal singleton pregnancies complicated by suspected intrauterine growth restriction were monitored by serial measurement of the pulsatility index of the middle cerebral artery over 7 to 72 days. Outcome measures included indication for delivery, umbilical venous pH and admission to and length of stay in neonatal intensive care. RESULTS: Thirteen fetuses demonstrated severe intrauterine growth restriction based on subsequent birth weights being below the 2.5th centile, two had intrauterine growth restriction (birth weights between the 2.5th and 5th centiles), and three had birth weights between the 5th and 50th centiles. The middle cerebral artery pulsatility index showed rapid and sharp changes between examinations in those severely growth restricted fetuses which required delivery before 34 weeks. This pattern was not obvious in severely growth restricted fetuses delivered after 34 weeks, or in those less severely growth restricted, regardless of the gestation at delivery. Changes in middle cerebral artery pulsatility index contributed to the decision to deliver in three cases. The middle cerebral artery pulsatility index demonstrated greater variation in those fetuses with cord pHs of less than 7.25. The length of stay in neonatal intensive care decreased with increasing gestational age and birth weight. CONCLUSIONS: The difference in the pattern of change in middle cerebral artery pulsatility index in intrauterine growth restricted fetuses may be a reflection of maturity in addition to the degree of fetal compromise. The decision to deliver was multifactorial. The middle cerebral artery pulsatility index only influenced the decision to deliver when changes in other parameters were evident.     

Prognostic factors in severe twin-twin transfusion syndrome treated by endoscopic laser surgery.

OBJECTIVE: The aim of this study was to investigate clinical and sonographic parameters, in particular Doppler blood flow measurements, in severe second-trimester twin-twin transfusion syndrome before and after endoscopic laser coagulation of the placental vascular anastomoses, to correlate these data with fetal outcome and to determine whether fetal blood flow measurements could help to estimate the probability of fetal survival. METHODS: In 121 cases of severe twin-twin transfusion syndrome examined between 17 and 26 weeks of gestation, the following investigations were performed: fetal biometry, placental location, deepest pool of amniotic fluid, echocardiography and Doppler sonography of the umbilical arteries and the ductus venosus of both twins before and after fetoscopic laser ablation of the placental anastomoses. RESULTS: The overall survival rate was 64% (156/242). Both fetuses survived in 48% (58/121) and one fetus survived in 33% (40/121), resulting in 81% (98/121) of pregnancies with at least one survivor. Gestational age at the time of the procedure and placental location had no significant influence on fetal survival. The amniotic fluid volume drained after laser coagulation correlated significantly (p = 0.038) with the risk of miscarriage or extremely premature delivery within 4 weeks of the procedure. Intertwin discrepancy in abdominal circumference showed a significant negative correlation (p = 0.004) with the probability for survival of donor fetuses. Before the procedure, 19% (23/121) of donor twins and 5% (6/121) of recipient twins showed absent or reversed end-diastolic flow in the umbilical artery (p = 0.001). This finding had no significant influence on the survival rate of donors. An increase of waveform indices in the umbilical artery 1 day after the procedure compared to immediately after the procedure correlated significantly with a lower probability for survival of donors (p = 0.042) and recipients (p = 0.018). Before the procedure, 37% (45/121) of recipient twins and 9% (10/113) of donor twins showed absent or reversed flow during atrial contraction in the ductus venosus (p < 0.0001). This finding had a significant negative influence on the survival rate of recipient fetuses (p = 0.02). Furthermore, an increase of waveform indices in the ductus venosus 1 day after the procedure compared to immediately after the procedure correlated significantly with a lower probability of survival in recipients (p = 0.005). CONCLUSIONS: Fetoscopic laser coagulation of the placental vascular anastomoses in severe mid-trimester twin-twin transfusion is a potentially corrective and effective, minimally invasive procedure. Doppler investigation of the umbilical and fetal circulations provides important information on the fetal condition, prognosis and therapeutic effects of the intervention. Signs of congestive heart failure in the recipient may reduce the probability of survival, whereas increased placental resistance in the donor before the procedure is not necessarily associated with a reduction in the probability of survival after laser coagulation.     

Umbilical artery Doppler flow-velocity waveforms and fetal acid-base balance in Rhesus-isoimmunized pregnancies

Pulsed Doppler blood-flow velocity waveforms in the umbilical arteries, as well as blood gases, hematocrit, and lactate concentration in umbilical venous blood, were examined in 21 patients undergoing 49 cordocentesis, 34 of which were followed by fetal blood transfusion into the umbilical vein. The aim of the study was to evaluate the correlations, if any, between the Doppler indices from the umbilical artery (pulsatility index, resistance index, systolic/diastolic ratio) and the blood gas values (pO₂, pCO₂, O₂ content, pH) and lactate content in the umbilical vein. The only correlation confirmed in this study was in the subgroup of anemic fetuses undergoing fetal blood transfusion, where correlation existed between A/B and the initial O₂ content (r = ?0.41, p < 0.02). We conclude that, in Rhesus-isoimmunized pregnancies, in contrast to other pregnancies, a close correlation does not exist between the Doppler indices in the umbilical artery and the fetal blood gas values. © 1994 John Wiley & Sons, Inc.     

The role of Doppler studies in predicting individual intrauterine fetal demise after laser therapy for twin-twin transfusion syndrome.

OBJECTIVE: To investigate the role of Doppler studies in predicting individual fetal demise in patients scheduled for selective laser photocoagulation of communicating vessels (SLPCV) for twin-twin transfusion syndrome (TTTS). METHODS: Doppler studies of the umbilical artery, umbilical vein, ductus venosus, tricuspid valve regurgitation and middle cerebral artery were performed in the donor and recipient twins before and 24 hours after SLPCV. Results were analyzed cross-sectionally and longitudinally. As multiple comparisons were made, an a priori alpha rejection was set at P < 0.001. RESULTS: One hundred and ten consecutive patients were available for analysis. Overall fetal survival was 68.6% (151/220) with at least one survivor in 88.2% (97/110) of cases. Absent or reversed end-diastolic velocity in the umbilical artery of the donor twin was the only preoperative Doppler result predictive of intrauterine fetal demise (IUFD) (10/15, 66.7%, P < 0.001). Postoperatively, reversed flow during atrial contraction in the ductus venosus of the donor twin showed a trend towards prediction of IUFD of this fetus (4/5, 80%, P = 0.007). No other Doppler studies, including the longitudinal analyses, were predictive of IUFD. CONCLUSIONS: Our data suggest that preoperative absent or reversed end-diastolic velocity in the umbilical artery may be useful in predicting individual fetal demise of the donor twin in TTTS patients scheduled for SLPCV. This may reflect the role of decreased individual placental mass that may be associated with some donor twins. The inability of other Doppler studies to predict individual IUFD may be explained preoperatively by the effect of the interfetal vascular connections on the individual Doppler signals and postoperatively by the effect of surgery or the timing of the assessment. Our findings may be important in patient counseling, in furthering understanding of the disease, and perhaps in improving surgical technique.     

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.     

多普勒超声心动图对胎儿充血性心衰的研究

目的应用多普勒超声心动图研究、探讨胎儿充血性心力衰竭(CHF)的病变机制,为早期宫内诊断和治疗及疗效评价提供准确依据。方法超声心动图检出并诊断41例CHF胎儿及正常对照组50例。结果(1)41例胎儿中先天性心脏病14例;重症心律失常15例,胎儿肿瘤5例,双胎输血综合征5例和胎儿贫血2例;(2)均出现胎儿水肿;心脏显著肥厚扩大,表现为心胸比例增大,心房、心室的不对称增大或心肌肥厚。心室缩短率(FS%)及心输出量(CCO)降低(P<0.001);(3)中至重度二、三尖瓣返流(MRTR),9例肺动脉瓣返流;(4)32例胎儿脐动脉PI值增高或舒张期血流相消失及大脑中动脉PI值降低。37例出现脐静脉搏动性血流及41例均示下腔静脉内径增宽及血流频谱改变。结论应用多普勒超声心动图评价胎儿CHF的导致因素,通过主动脉和肺动脉CO的总和CCO可无创获得心输出量的指标及计算FS以达到量化胎儿心功能的目的。可直观地显示胎儿心脏结构,检测瓣膜返流及评价外周血流动力学变化。     

Changes in umbilical artery,middle cerebral artery,and aorta blood flow Doppler waveform pulsatility indices after funisocentesis

This study evaluates the effect of funisocentesis on umbilical artery, fetal cerebral artery, and aortic circulation. The pulsatility index in the umbilical artery, fetal middle cerebral artery, and descending aorta was measured by pulsed Doppler ultrasonography before and after 41 diagnostic funisocenteses. Percutaneous umbilical artery blood sampling was associated with a significant decrease in umbilical artery pulsatility index (mean -0.132, standard deviation 0.259, P = 0.002) and in middle cerebral artery pulsatility index (mean -0.143, standard deviation 0.260, P = 0.001). The decline in resistance to flow of the umbilical artery (r = 0.340, P = 0.029) and middle cerebral artery (r = 0.457, P = 0.002) was correlated with gestational age at sampling. These findings suggest that alterations in the waveforms from both the umbilical and the fetal cerebral circulations can be induced by fetal blood sampling.     

Relationship between arterial and venous Doppler and perinatal outcome in fetal growth restriction.

OBJECTIVE: The aim of this investigation was to assess the relationship between abnormal arterial and venous Doppler findings and perinatal outcome in fetuses with intrauterine growth restriction (IUGR). METHODS: Doppler velocimetry of the umbilical artery (UA), middle cerebral artery (MCA), inferior vena cava (IVC), ductus venosus (DV) and free umbilical vein was performed in 121 IUGR fetuses with a UA pulsatility index (PI) > 2 SD above the gestational age mean and subsequent birth weight < 10th centile for gestational age. Groups based on the last Doppler exam were: 1 = abnormal UA-PI only (n = 42, 34.7%), 2 = MCA-PI > 2 SD below the gestational age mean (= 'brain sparing') in addition to abnormal UA-PI (n = 29, 24.0%), 3 = DV or IVC peak velocity index (PVIV) > 2 SD above the gestational age mean and/or pulsatile UV flow (n = 50, 41.3%). Z-scores (delta indices) were calculated for Doppler indices. Perinatal mortality, respiratory distress (RDS), bronchopulmonary dysplasia (BPD), intraventricular hemorrhage (IVH), necrotizing enterocolitis (NEC), circulatory failure and umbilical artery blood gases were recorded. RESULTS: Absence or reversal of umbilical artery end-diastolic flow was observed in 4 (9.5%) of fetuses in group 1, 10 (34.5%) fetuses in group 2 and 41 (82%) fetuses in group 3. A low middle cerebral artery pulsatility index was found in 39 (78%) fetuses in group 3. Multiple regression analysis with gestational age at delivery, delta indices and cord artery blood gas as independent parameters and individual perinatal outcomes as dependent variables was performed. In this analysis the association was strongest with gestational age for each complication. There were no significant differences in Apgar scores between groups. At delivery, 'brain sparing' was associated with hypoxemia and abnormal venous flows with acidemia. Perinatal mortality was highest in group 3 and stillbirth was only observed when venous flow was abnormal. All postpartum complications were more frequent in fetuses with abnormal venous flows. The only statistically significant relation between Doppler indices and outcome was the association between abnormal ductus venosus flow and fetal death (r2 = 0.24, P < 0.05). CONCLUSION: Growth restricted fetuses with abnormal venous flow have worse perinatal outcome compared to those where flow abnormality is confined to the umbilical or middle cerebral artery. In fetuses with low middle cerebral artery pulsatility, venous Doppler allows detection of further deterioration. While abnormal venous flows can be significantly associated with fetal demise, gestational age at delivery significantly impacts on all short-term outcomes.     

Instability of Doppler cerebral blood flow in monochorionic twins.

OBJECTIVE: The purpose of this study was to evaluate Doppler flow velocity changes in cerebral vessels of monochorionic twins with twin-twin transfusion syndrome (TTTS). METHODS: Repeated Doppler umbilical and cerebral blood flow studies were performed in 7 twin pairs with TTTS. Eight monochorionic twin pairs and 11 dichorionic twin pairs served as control groups. The following Doppler parameters were assessed: umbilical artery pulsatility index (PI), middle cerebral artery (MCA) PI, cerebroplacental ratio, delta PI between the umbilical artery and MCA, and peak systolic velocity (PSV) in the MCA. RESULTS: Significant variations in PSV in the MCA and cerebral indices were found in the study group of monochorionic twins with TTTS. Periods of high PSV with low PI in the MCA were followed by lower PSV in the same fetus. Repeated measurements in the comparison groups were stable without significant variations. The delta cerebroplacental ratio was significantly higher in the study group (0.38 versus 0.09 and 0.19 in the comparison groups; P < .02). CONCLUSIONS: Significant changes in Doppler flow velocity and indices suggest instability of cerebral blood flow with episodes of "hyperperfusion" in monochorionic twins with TTTS. Further studies are needed to elucidate the relationship of these transient changes to neurologic sequelae in the neonate.     

超声对双胎输血综合征宫内术前诊断与术后效果观察的应用

目的 探讨超声对双胎输血综合征宫内术前诊断与术后效果观察的价值.方法 回顾分析10例双胎输血综合征并超声引导下行胎盘血管交通支激光阻断术病例,分析其二维声像图特征及彩色多普勒检测结果.结果 共有5个胎儿存活,输血胎与受血胎双顶径和股骨径差距缩小或持平,两侧羊膜囊内羊水指数正常,受血胎皮下水肿减轻.彩色多普勒血流图示：存活胎儿脐动脉血流指数PI值、S/D值较术前明显下降（P〈0.01）.结论 双胎输血综合征可被超声检查发现;双胎输血综合征有其特有的异常表现,并可在超声引导下行宫内手术.     

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.     

Fetal cerebral blood flow velocity during labor and the early neonatal period.

This study was performed to elucidate circulatory changes in the fetal cerebral circulation during uncomplicated labor and in early neonatal life. Eighteen healthy term singleton fetuses were followed longitudinally during labor. Using the transabdominal approach, and the color Doppler technique, the middle cerebral artery was identified and Doppler flow velocity waveforms recorded between and during uterine contractions. Neonatal recordings were made by insonating the middle cerebral artery from the temporal region before and immediately after the cutting of the umbilical cord, and at 1 hour and 1 day after birth. The recorded Doppler signals were evaluated for pulsatility index, heart rate, peak systolic flow velocity, end-diastolic flow velocity and time-averaged maximum velocity. There was no change in the pulsatility index between and during contractions (1.39 +/- 0.36 and 1.40 +/- 0.39, respectively, mean +/- SD). A significant decrease in the pulsatility index compared to fetal values was seen 4 min after birth (1.06 +/- 0.30, p < 0.01). One hour after birth, the pulsatility index values increased significantly (1.52 +/- 0.25, p < 0.001), to fall again between I hour and 1 day after birth (0.95 +/- 0.26, p < 0.001). Mechanical compression of the skull, blood gas changes and a decrease in ductal shunting may all have contributed to these changes. The present study has shown physiological neonatal circulatory adaptation and onset of breathing to cause manifest changes in cerebral blood flow velocity.     

Regional cerebral flow velocity waveforms in the human fetus.

The purpose of this study was to determine regional cerebral flow velocity waveforms in the human fetus. Flow velocity waveforms were determined at the level of the middle cerebral artery, vertebral artery, and intracerebellar arteries in 25 fetuses between 23 and 39 weeks' gestation. The pulsatility index was used to quantify the waveforms. Technically acceptable waveforms were obtained at all three vessels in 20 fetuses. The pulsatility index was lowest for the intracerebellar artery in all the fetuses studied. The pulsatility indices of the vertebral artery and middle cerebral artery were not significantly different. These data suggest that significant fetal regional cerebral blood flow differences occur in utero, with intracerebellar arterial resistance being lower than resistance in other regions of the brain.