Umbilical cord morphologic characteristics and umbilical artery Doppler parameters in intrauterine growth-restricted fetuses.

OBJECTIVE: To compare prenatal morphometric changes of umbilical cord components in intrauterine growth-restricted fetuses with and without abnormal umbilical artery Doppler parameters. METHODS: Consecutive singleton intrauterine growth-restricted fetuses at a gestational age of older than 20 weeks were compared with matched appropriate-for-gestational-age fetuses. Intrauterine growth restriction was defined in the presence of a sonographic abdominal circumference below the 5th percentile for gestational age at the time of sonography and a birth weight below the 10th percentile. The sonographic examination included pulsed Doppler measurements of the umbilical artery resistance index and measurements of the umbilical cord cross-sectional area and the umbilical cord vessel area. RESULTS: A total of 84 intrauterine growth-restricted fetuses and 168 appropriate-for-gestational-age fetuses were included in the study. All umbilical cord components (umbilical cord cross-sectional area, vein area, artery area, and Wharton jelly area) were smaller in the intrauterine growth-restricted fetuses. The prevalence of lean umbilical cords (cross-sectional area < 10th percentile for gestational age) was significantly higher in intrauterine growth-restricted fetuses compared with appropriate-for-gestational-age fetuses (73.8% versus 11.3%; P < .0001). A significant and progressive reduction of the umbilical vein area corresponding to the degree of umbilical artery Doppler parameter abnormality was found. The umbilical artery area was not related to the hemodynamic changes of the blood flow in the umbilical arteries. CONCLUSIONS: The proportion of lean umbilical cords was higher in intrauterine growth-restricted fetuses than in appropriate-for-gestational-age fetuses. Umbilical vein caliber decreases significantly with worsening of umbilical artery Doppler parameters.     

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.     

脐带打结的超声诊断及其对胎儿围产期结局的影响

目的 分析超声对脐带打结的产前诊断价值及脐带打结与围产期结局的关系.方法 回顾性分析2015年1月至2019年12月间在安徽医科大学第一附属医院妊娠晚期出生或引产胎儿的产前超声及相关临床资料.总结分析脐带打结发生率及其与围产期结局的关系、产前二维超声和三维超声对脐带打结的诊断价值并归纳其声像图特征;并以产后诊断有脐带打...     

Fetal adrenal artery velocimetry measurements in appropriate-for-gestational age and intrauterine growth-restricted fetuses.

OBJECTIVE: To investigate adrenal artery blood flow in the fetus. DESIGN AND METHOD: Sixty-two appropriate-for-gestational-age (AGA) and 20 intrauterine growth-restricted (IUGR) fetuses were recruited to this cross-sectional study between 22 and 42 weeks of pregnancy in a tertiary referral fetal medicine unit of a university hospital. ENDPOINTS: Doppler velocimetry of the fetal adrenal, umbilical (UA), renal and middle cerebral arteries (MCA). Pulsatility index (PI), resistance index (RI), peak systolic velocity (PSV), time-averaged maximum velocity (TAMXV) and cerebroplacental ratio (MCA RI/UA RI; CPR). Obstetric outcome. RESULTS: The adrenal artery was detected in 82% of the fetuses. All flow velocity waveforms obtained from the adrenal artery indicated low impedance blood flow. No significant changes in PI, RI, PSV and TAMXV occurred with advancing gestation. The blood flow parameters of the adrenal artery did not differ between AGA and IUGR fetuses. In five IUGR fetuses with signs of redistribution of cardiac output in favor of the brain, the adrenal artery velocimetry results were unremarkable. The adrenal artery PI, RI, PSV and TAMXV values were higher in female fetuses than in male fetuses (P < 0.05). A relationship was observed between the velocity measurements and the estimated fetal weight (P < 0.01). CONCLUSIONS: The fetal adrenal artery could be readily detected. We observed no redistribution of blood flow in favor of the fetal adrenals in IUGR fetuses which were not severely compromised.     

Fused umbilical arteries: prenatal sonographic diagnosis and clinical significance.

This report describes a series of 5 fetuses with fused umbilical arteries that had the prenatal feature of a single umbilical artery near the placental insertion and the normal 2 umbilical arteries at the fetal end of the cord. In 1 case this vascular anomaly was associated with unilateral renal agenesis in a fetus with a subsequent diagnosis of Hallermann-Streiff syndrome. No perinatal complications were identified in the remaining 4 fetuses. Postpartum examination of the cord revealed that the 2 umbilical arteries fused to form 1 artery for a long segment of the distal portion of the cord. Our findings suggest that the prenatal evaluation of the umbilical cord to document the number of vessels should include multiple views of the cord and demonstration of the 2 intra-abdominal umbilical arteries with color Doppler imaging for a confident diagnosis. Our observation also suggests that, at least in some cases, single umbilical artery may result from incomplete splitting of the single artery normally present in early human embryos.     

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.     

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.     

彩色多普勒血流显像检测胎儿脐带绕颈方向的研究

目的探讨彩色多普勒血流显像检测脐带绕颈方向的类型,为临床干预提供科学依据。方法通过观察胎儿脐带的血流方向,结合胎方位,判断脐带绕颈的走向,根据缠绕方向及缠绕程度进行分型。结果214例观察对象中,绕1周189例,占88.32%,绕2周15例,占7%,绕3周1例,占0.47%,"L"型者9例,占4.21%。按缠绕方向:从左向右者102例,其中臀位20例;从右向左103例,其中臀位13例。9例"L"型者未统计方向。按缠绕程度:"C"型者76例,"O"型者39例,"α"型者90例,"L"型者9例。结论彩色多普勒血流显像能准确判断脐带绕颈的缠绕方向。     

Is fetal cerebral vascular resistance affected by the presence of nuchal cord(s) in the third trimester of pregnancy?

OBJECTIVE: To assess whether fetal cerebral vascular resistance is affected by the presence of nuchal cord(s) in the third trimester. METHODS: A set of 115 patients with well-established dates and singleton, appropriate for gestational age (GA), non-anomalous fetuses with nuchal cord(s) diagnosed with prenatal color Doppler imaging, between 28 and 41 weeks and 115 controls matched for GA, were studied. Patients with hypertension, diabetes and autoimmune conditions were excluded. Doppler indices were obtained from the umbilical artery (UA) and the fetal middle cerebral artery (MCA) upon initial diagnosis of the nuchal cord. RESULTS: Of 115 GA-matched pairs of pregnancies, 103 fetuses had a single nuchal cord and 12 a double nuchal cord. No significant differences were noted in patient age, gravidity, parity, sonographically estimated fetal weight (SEFW), and growth centile at ultrasonographic diagnosis. Mean UA systolic/diastolic ratio (S/D) was 2.28 +/- 0.32 and 2.36 +/- 0.33 (P = 0.03) and UA resistance index (RI) 0.55 +/- 0.06 and 0.57 +/- 0.06 (P = 0.02) among study and controls, respectively. Mean fetal MCA S/D and RI did not differ significantly between the two groups (fetal MCA S/D 5.01 +/- 1.28 and 5.04 +/- 1.71 (P = 0.86), and mean fetal MCA RI 0.78 +/- 0.06 and 0.78 +/- 0.05 (P = 0.88)). No significant differences were noted in GA at delivery, incidence of meconium-stained amniotic fluid, birth weight, mode of delivery, neonatal gender, 1 and 5 minute Apgar scores, or UA pH and base excess, between study and control patients. CONCLUSION: Fetal cerebral vascular resistance is not affected by the presence of nuchal cord(s) in the third trimester of pregnancy.     

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.     

脐带绕颈对胎儿脐静脉血流的影响

目的 探讨妊娠晚期脐带绕颈对胎儿脐静脉血流的影响。方法 随机选择孕龄36~40周,脐带绕颈但尚无产兆的孕妇65例,观察在无胎动、无胎儿呼吸运动时脐静脉血流速度并记录。结果 有脐带绕颈的胎儿,脐静脉血流速度明显低于对照组(P<0.05)。结论 无产兆的胎儿处于静息状态时,脐带绕颈对胎儿脐静脉血流速度有一定影响。其原因是脐带缠绕形成局部环状管道,血流的离心力增加了系统的阻力,导致动能减少,血流速度下降。     

彩色多普勒超声监测妊高征胎儿主要血管血流动力学变化

应用彩色多普勒超声对30例正常足月孕妇及30例妊高征孕妇的胎儿进行全面监测脐带动脉、主动脉、肾动脉及大脑中动脉血流动力学变化.结果发现:脐动脉、脑动脉、肾动脉及主动脉血流动力学参数变化是一致的,有显著相关性.当胎儿宫内缺氧时,脐动脉、肾动脉及主动脉血流速度降低,阻力增加,脑动脉血流速度增加,阻力降低.结果表明:彩色多普勒超声全面评价胎儿重要靶器官的血流动力学参数,能更敏感准确地反映高危妊娠胎儿血流动力学改变,是有价值的胎儿监测手段.     

Temporal sequence of abnormal Doppler changes in the peripheral and central circulatory systems of the severely growth-restricted fetus.

OBJECTIVE: To identify the temporal sequence of abnormal Doppler changes in the fetal circulation in a subset of early and severely growth-restricted fetuses. METHODS: This was a prospective observational study in a tertiary care/teaching hospital. Twenty-six women who were diagnosed with growth-restricted fetuses by local standards before 32 weeks' gestation and who had abnormal uterine and umbilical artery Doppler velocimetry were enrolled onto the study. To compare Doppler changes as a function of time, pulsed-wave Doppler ultrasound was performed on five vessels in the fetal peripheral and central circulations. Doppler examinations were performed twice-weekly and on the day of delivery if the fetal heart rate tracing became abnormal. Doppler indices were scored as abnormal when their values were outside the local reference limits on two or more consecutive measurements. Biometry for assessment of fetal growth was performed every 2 weeks. Computerized fetal heart rates were obtained daily. Delivery was based on a non-reactive fetal heart rate tracing and not on Doppler information. Patients with a severely growth-restricted fetus who were delivered for maternal indications such as pre-eclampsia were excluded. Perinatal outcome endpoints included: intrauterine death, gestational age at delivery, newborn weight, central nervous system damage of grade 2 or greater, intraventricular hemorrhage and neonatal mortality. RESULTS: Mean gestational age and newborn weight at delivery were 29 (standard deviation (SD), 2) weeks and 818 (SD, 150) g, respectively. The sequence of Doppler velocimetric changes was described by onset time cumulative curves that showed two time-related events. First, for each vessel there was a progressive increase in the percent of fetuses developing a Doppler abnormality. Second, severely growth-restricted fetuses followed a progressive sequence of acquiring Doppler abnormalities which were categorized into 'early' and 'late' Doppler changes. Early changes occurred in peripheral vessels (umbilical and middle cerebral arteries; 50% of patients affected 15-16 days prior to delivery). Late changes included umbilical artery reverse flow, and abnormal changes in the ductus venosus, aortic and pulmonary outflow tracts (50% of patients affected 4-5 days prior to delivery). The time interval between the occurrence of early and late changes was significantly different (P < 0.0001) and late changes were significantly associated with perinatal death (P < 0.01). CONCLUSIONS: Doppler velocimetry abnormalities develop in different vessels of the severely growth-restricted fetus in a sequential fashion. Late changes in vascular adaptation by the severely growth-restricted fetus are the best predictor of perinatal death.     

彩色多普勒超声评价双胎输血综合征受血儿心功能的临床价值

目的探讨彩色多普勒超声评价双胎输血综合征(TTTS)受血儿右心心肌运动功能的临床价值。方法选取16例确诊为TTTS的孕妇为研究对象,应用彩色多普勒测量两组胎儿脐静脉、脐动脉、大脑中动脉、静脉导管、半月瓣、房室瓣的血流频谱、右心心肌做功指数及胎儿心胸面积比值。结果 TTTS受血儿体质量、心胸面积比值、右心心肌做功指数、左心心肌做功指数显著高于供血儿(均P0.05)。TTTS受血儿静脉脉搏动征(PUV)、静脉导管A波缺失或反向(ARDV)、三尖瓣反流(TR)、三尖瓣舒张期血流单峰(ATVI)比率显著高于供血儿,差异有统计学意义(P0.05)。结论彩色多普勒超声能有效评价TTTS受血儿心功能尤其是舒张功能异常,可为TTTS产前诊断提供有效重要的信息。     

Fetal acidosis and Doppler velocimetry of the umbilical arteries in labor.

The objective of the study was to determine whether Doppler velocimetry indices of the fetal umbilical arteries change with the development of acidosis during labor. Repeated Doppler velocimetry was performed in selected patients with high-risk labors for the purpose of evaluating whether this might be a useful test of fetal well-being in labor. The study sample comprised 36 women with singleton pregnancies, complicated either by gestational proteinuric hypertension or by intrauterine growth retardation (or both) with a normal cardiotocographic tracing at the onset of labor. The acid-base status of the fetus was assessed after delivery by analyzing the umbilical artery blood. A total of 27 fetuses were followed through labor. Six were born with an umbilical artery base deficit of more than 10 mmol/l. No change in mean Pourcelot ratio (resistance index) was noted in both normal and acidotic fetuses. None of the acidotic fetuses showed a change in Pourcelot ratio of more than 0.03. We conclude that Doppler velocimetry of the umbilical arteries, as measured by the Pourcelot ratio, does not contribute to the diagnosis of fetal acidosis in labor.     

Middle cerebral artery peak systolic and ductus venosus velocity waveforms in the hydropic fetus.

OBJECTIVE: The purpose of this study was to assess whether Doppler assessment of the middle cerebral artery (MCA) peak systolic velocity (PSV) and ductus venosus (DV) velocity waveforms during sonography of hydropic fetuses may specify the cause of fetal hydrops. METHODS: A level II sonographic examination was performed in 16 hydropic fetuses, and the MCA PSV and DV velocity waveforms were assessed. The MCA PSV values divided hydropic fetuses into anemic (group 1) and nonanemic (group 2) fetuses. In group 2 fetuses, the DV was defined as normal or abnormal. Sonographic examination and Doppler assessment of these vessels specified the cause of hydrops and indicated the use of specific investigations for diagnosing the etiology of fetal hydrops. RESULTS: Seven of 16 fetuses had MCA PSV values greater than 1.50 multiples of the median (group 1). Nine of 16 fetuses had normal MCA PSV values (group 2); among them, 7 of 9 had either absent or reversed flow in the DV, and 2 had a normal DV. In group 1, the cause of fetal anemia was investigated by maternal serum tests, and 5 cordocentesis procedures were performed. In group 2, 7 of 9 fetuses had reversed flow in the DV, which suggested a cardiac abnormality confirmed by echocardiography. Five cordocentesis procedures were performed for fetal karyotype, and in 2 fetuses, the cause of hydrops was idiopathic. CONCLUSIONS: Our data suggest that assessment of the MCA PSV and DV velocity waveforms in the hydropic fetus may further our knowledge of the etiology of hydrops and may indicate which investigations among the many available should be used for diagnosing the cause of fetal hydrops.     

Fetal arterial Doppler studies in twin-twin transfusion syndrome.

This cross-sectional study investigates the circulatory profile of the donor and recipient fetuses in pregnancies with twin-twin transfusion syndrome manifested by acute polyhydramnios during the second trimester of pregnancy. Doppler investigations of the umbilical arteries and of the fetal descending thoracic aortas and middle cerebral arteries were performed in both fetuses of 27 pregnancies with twin-twin transfusion syndrome at 18 to 25 (mean, 21.7) weeks' gestation. Significant differences from normal values were increased umbilical artery pulsatility index and decreased aortic mean velocity in both donor and recipient fetuses, decreased middle cerebral artery pulsatility index in recipients and decreased middle cerebral artery mean velocity in donors. Increased umbilical artery pulsatility index in some donor and recipient fetuses may be the consequence of abnormal placental development and polyhydramnios-related compression, respectively. Doppler findings in the fetal circulation are compatible with hypovolemia in the donor and hypervolemia with congestive heart failure in the recipient.     

Three-dimensional power Doppler sonography in the prenatal diagnosis of a true knot of the umbilical cord: value and limitations.

OBJECTIVE: The purpose of this study was to examine the value of 3-dimensional power Doppler sonography in the prenatal diagnosis of a true knot of the umbilical cord. METHODS: Cases in which the diagnosis of a true knot of the umbilical cord was suspected by prenatal 2-dimensional sonography were reviewed. The presumably affected segment of the cord was examined with 3-dimensional power Doppler sonography for further characterization. Confirmation of the prenatal diagnosis was sought by reviewing the delivery records and contacting the referring obstetrician and the patients themselves. RESULTS: Eight consecutive cases were studied. Three-dimensional power Doppler sonography displayed a vascular spatial configuration pattern consistent with a true knot of the umbilical cord in all of them. However, the prenatal diagnosis was confirmed at delivery in only 5 cases (62.5%). Although there were no cases of a false knot mimicking a true knot of the umbilical cord, all incorrect diagnoses in this series were associated with multiple loops of the umbilical cord in the third trimester. CONCLUSIONS: Three-dimensional power Doppler sonography seems to be helpful in determining the presence of a true knot of the umbilical cord in utero, especially in the second trimester. However, this should not be considered a definitive method for the diagnosis because multiple loops of the umbilical cord lying close to each other can generate a sonographic image that can be undistinguishable from a true knot of the umbilical cord prenatally, especially when located in a small pocket of amniotic fluid. Therefore, the presumable diagnosis of a true knot of the umbilical cord in utero should be taken with caution.     

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.     

Ductus venosus blood flow velocity characteristics of fetuses with single umbilical artery.

OBJECTIVES: Sonographic Doppler evaluation of the fetal ductus venosus has been proved to be useful in the evaluation of fetal cardiac function. The aim of this study was to investigate the ductus venosus blood flow profile in fetuses with single umbilical artery and to correlate it with the umbilical cord morphology. METHODS: Fetuses at >20 weeks' gestation with single umbilical artery who were otherwise healthy were consecutively enrolled into the study. The sonographic examination included evaluation of the following Doppler parameters: umbilical artery resistance index, maximum blood flow velocity of the ductus venosus during ventricular systole (S-peak) and atrial contraction (A-wave), ductus venosus time-averaged maximum velocity (TAMXV), and pulsatility index for veins (PIV). The cross-sectional area of the umbilical cord and its vessels were measured in all cases. The Doppler and morphometric values obtained were plotted on reference ranges. RESULTS: A total of 88 fetuses with single umbilical artery were scanned during the study period. Of these 52 met the inclusion criteria. The S-peak velocity, A-wave velocity, and TAMXV were below the 5th centile for gestational age in 57.7%, 59.6%, and 57.7% of cases, respectively. The PIV was within the normal range in 80.1% of cases. The umbilical vein cross-sectional area of fetuses with single umbilical artery was above the 95th centile for gestational age in 34.6% cases. CONCLUSIONS: The ductus venosus blood flow pattern is different in fetuses with single umbilical artery from that in those with a three-vessel cord. This difference may be caused in part by the particular morphology of umbilical cords with a single artery.