正常中孕胎儿大脑中动脉血流参数比值的正常值范围

目的 确定正常中孕胎儿大脑中动脉血流参比值的正常值范围。方法 应用二维超声、彩色多普勒能量图及脉冲多普勒技术对215例16-31孕周正常胎儿头围、体重及大脑中动脉血流参数进行检测。结果 正常中孕胎儿每分钟单位体重大脑中动脉的最大速度及平均速度随孕周的增加而降低;每分单位头围大脑中动脉的最大速度及平均速度在中孕期间变化小。结论 本研究为多普勒超声早期预测胎儿高动力循环状态提供了理论依据。     

大脑中动脉血流参数在胎儿高动力循环状态中的初步应用

对17例17～31孕周高动力循环状态胎儿的大脑中动脉(MCA)血流参数进行研究,旨在探讨MCA血流参数能否预测胎儿高动力循环状态。现将结果报告如下。     

正常中孕胎儿大脑中动脉血流参数的正常值范围

目的：确定正常中孕胎儿大脑中动脉血流参数的正常值范围。方法：应用彩色多普勒能量图及脉冲多普勒技术对215例16～31孕周正常胎儿大脑中动脉血流参数进行检测。结果：正常胎儿大脑中动脉的最大流速及平均流速随孕周的增加而加快。阻力指数在孕16～24周时随孕周的增加而升高,孕24～31周时保持高水平。最大流速、平均流速及阻力指数与推算出的胎儿体重呈正相关。结论：本研究为多普勒超声早期预测胎儿高动力循环状态提供了理论依据。     

大脑中动脉及脐动脉血流检测在胎儿宫内发育迟缓预测中的意义

目的:应用彩色多普勒检测正常妊娠和胎儿宫内发育迟缓(IUGR)的脐动脉和大脑中动脉血流阻力指数PI、RI值及S/D值,探讨PI、RI及S/D值在IUGR预测中的价值.方法:应用彩色多普勒分别检测了52例正常妊娠(正常组)和IUGR患者(IUGR组)的脐动脉和大脑中动脉的血流,孕28～41周.结果:正常组和IUGR组的脐动脉和大脑中动脉血流指标均随妊娠周数的增高而降低,但IUGR组的脐动脉血流PI、RI、S/D值明显高于正常组(P<0.05).IUGR组MCA多普勒血流阻力指数RI及S/D明显小于正常组(P<0.05).孕30周后,脐动脉血流S/D值>4,提示胎儿预后不良.结论:脐动脉及大脑中动脉血流检测可为IUGR诊断提供一定的依据,对胎儿预后的估计有一定的临床价值.     

超声动态血流监测重度先兆子痫前期孕妇胎儿血流动力学变化的临床意义

目的 探讨彩色多普勒超声动态检测重度先兆子痫前期孕妇胎儿脐动脉和大脑中动脉血流动力学变化的临床价值,为及时采取必要的干预措施提供依据.方法 检测30例正常孕妇(对照组)与30例重度先兆子痫前期孕妇(观察组)胎儿的脐动脉和大脑中动脉血流参数,结果进行对比分析.结果 对照组胎儿脐动脉和大脑中动脉血流阻力指数随着孕龄的增加呈降低趋势,观察组胎儿脐动脉阻力指数较对照组明显增高,而大脑中动脉血流阻力指数和胎盘小血管阻力指数明显下降,两组间比较差异均有统计学意义(均P＜ 0.05).结论 彩色多普勒超声动态血流检测晚孕期胎儿脐动脉和大脑中动脉血流参数指标可了解并评估胎儿宫内状况,为临床医师提供重要的诊断信息,降低孕产妇和新生儿的发病率及病死率.     

彩色多普勒超声观察不同孕周正常胎儿动脉血流的价值

目的：探讨不同孕周胎儿肾动脉（RA）、脐动脉（UA）、大脑中动脉（MCA）血流参数的变化情况,确定正常胎儿RA、UA、MCA血流参考值,并分析RA、UA、MCA血流参数与孕龄的关系。方法选取2013年1～12月在该院行产前检查的185例孕周为4～41周的正常单胎孕妇为研究对象,采用彩色多普勒超声测量胎儿 RA、UA、MCA的阻力指数（RI）、搏动指数（PI）、收缩期峰值流速（PS）及收缩期峰值流速与舒张末期流速比值（S/D）。结果随着孕周的增加,胎儿RA、UA、MCA中PS值显著增加,而RA、UA中RI、PI、S/D值显著减少。经相关性分析可知,RA、UA、MCA中RI、PI、S/D与孕周呈负相关性（P＜0．05）,而RA、UA、MCA中PS与孕周呈正相关性（P＜0．05）。结论应用彩色多普勒测量不同孕周胎儿RA、UA、MCA血流动力学参数能有效了解胎儿颅脑循环、胎盘循环及全身血流循环状态。通过建立正常胎儿血流参数参考范围可为超声预测胎儿宫内生长情况提供参考依据。     

不同孕周脐带绕颈胎儿脐动脉及大脑中动脉血流参数的变化研究

目的：观察及探讨不同孕周脐带绕颈胎儿脐动脉及大脑中动脉血流参数的变化情况。方法：选取2010年10月—2013年5月于本院进行诊治的58例脐带绕颈胎儿为观察组,并以58例正常胎儿为对照组,将两组胎儿的脐动脉及大脑中动脉血流参数进行比较,并比较观察组中不同孕周胎儿的检测结果。结果：观察组胎儿的脐动脉及大脑中动脉PI、RI及S/D水平均高于对照组胎儿,而观察组中孕周37周以上者检测结果则高于28-36周的胎儿,P均〈0.05,均有显著性差异,同时分析检测指标与脐带绕颈的相关性。结论：脐带绕颈胎儿与正常胎儿脐动脉及大脑中动脉血流参数存在明显差异,且不同孕周脐带绕颈胎儿之间也存在显著差异,其与脐带绕颈有密切的关系,对于胎儿预后的价值较高。     

彩色多普勒超声对胎儿血流频谱与宫内缺氧关系的探讨

目的：探讨胎儿脐动脉（UA）及大脑中动脉（MCA）血流频谱改变预测胎儿宫内缺氧。方法：应用彩色多普勒超声检测35例中晚期正常妊娠组及8例宫内缺氧组（窘迫组）UA及MCA收缩期最大血流速度（S）与舒张期末期血流速度（D）的比值（S/D）及阻力指数（RI）。结果：正常组随孕周增加,UA、MCA的S/D及RI值逐渐下降。异常组UA的S/D及RI值均明显高于正常组（P〈0.01）;MCA的S/D及RI值随孕周增加而下降,其与正常组比较差异无显著性（P〈0.05）。结论：通过检测胎儿UA及MCA的S/D、RI值可预测胎儿宫内缺氧、提高围产质量。     

胎儿脐动脉及大脑中动脉血流监测对胎儿预后的作用

目的 评价超声监测胎儿脐动脉及大脑中动脉血流对胎儿预后的作用。方法 应用彩色多普勒监测６９例中晚期正常妊娠及１６例宫内缺氧（窘迫）组及５例围产儿死亡组胎儿大脑中翅膀（ＭＡＣ）、脐动脉（ＵＡ）收缩期最大血流速度（Ｓ）与舒张末期血流速度（Ｄ）的比值（Ｓ／Ｄ）及阻力指数（ＲＩ）并与妊娠结局相对照。结果 正常妊娠时随孕周增加ＵＡ、ＭＣＡ的Ｓ／Ｄ及ＲＩ值逐渐下降;异常组ＵＡ的Ｓ／Ｄ、ＲＩ值均明显高于正常组,     

多普勒超声血流参数在高危胎儿宫内缺氧预测中的应用研究

目的:研究多普勒超声血流参数在高危胎儿宫内缺氧预测中的应用情况。方法:选择在本院接受产检及分娩的单胎孕妇165例作为本次研究对象,依据高危孕产妇评分结果将其分成正常组122例与高危组43例,均接受多普勒超声检查,比较两组胎儿的血流参数。结果:高危组胎儿的胎儿肾动脉(RA)和大脑中动脉(MCA)的阻力指数(RI)比值(RIRA/RIMCA)、RA与MCA的搏动指数(PI)比值(PIRA/PIMCA)、RA与MCA的收缩期峰值流速/舒张末期流速比值(S/D)之比[(S/DRA)/(S/DMCA)]、静脉导管(DV)的RI、DV的PI、DV的S/D均明显高于正常组(P<0.05)。结论:多普勒超声血流参数可预测高危胎儿宫内缺氧情况。     

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

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

Coronary artery blood flow velocities in various fetal conditions.

OBJECTIVE: To determine fetal coronary artery peak blood flow velocities in normal and high-risk pregnancies. METHODS: Coronary artery peak systolic and diastolic blood flow velocities were measured by pulsed-wave Doppler velocimetry after identification of the coronary arteries by color Doppler imaging. Peak blood velocities obtained from normal pregnancies were related to gestational age using linear regression analysis. Blood flow velocities in normal fetuses were compared to measurements obtained in various fetal conditions. RESULTS: In normal fetuses coronary artery blood flow was visualized at a median gestational age of 33 + 6 weeks; median systolic and diastolic peak blood flow velocities were 0.21 and 0.43 m/s, respectively, and showed no significant change with gestational age. In growth-restricted fetuses coronary artery blood flow was visualized significantly earlier in gestation (median 28 + 2 weeks); systolic and diastolic peak blood flow velocities were higher at 0.25 and 0.48 m/s, respectively (P < 0.05). The highest coronary blood flow velocities were observed with fetal anemia. Coronary artery blood flow was also measured in fetuses with ductus arteriosus constriction due to indomethacin. Velocities did not differ from normal fetuses. Both in fetal anemia and ductus arteriosus constriction coronary artery blood flow could no longer be visualized with resolution of the underlying condition. CONCLUSION: Examination of coronary artery blood flow dynamics in the human fetus demonstrates acute increases in diastolic velocities in severe anemia and ductus arteriosus constriction based on the severity of the condition. In fetuses with growth restriction increased coronary blood flow velocities can be appreciated throughout the cardiac cycle. Clinical correlation in the interpretation of coronary blood flow dynamics in the human fetus is essential.     

Increased middle cerebral artery blood flow impedance in fetal subdural hematoma.

This case describes the prenatal diagnosis at 30 weeks' gestation of a posterior fossa subdural hematoma. Doppler velocimetry studies of the middle cerebral artery at that time showed an abnormally high resistance pattern with reverse end-diastolic flow. Ultrasonic assessment of the fetus indicated that there was associated quadriplegia. No cause for the lesion was demonstrated. A fetal blood sample, obtained by cordocentesis, revealed a normal karyotype. Fetal blood gas analysis was also normal. The pregnancy was terminated at the parents' request.     

Color Doppler study of the venous circulation in the fetal brain and hemodynamic study of the cerebral transverse sinus.

OBJECTIVES: To describe the venous circulation in the fetal brain; to describe the normal blood flow velocity waveform in the transverse sinus and to establish normal reference ranges for the second half of gestation. POPULATION: A total of 126 pregnant women with uncomplicated pregnancies at 20-42 weeks of gestation. METHODS: A combination of color-coded Doppler and two-dimensional real-time ultrasound was used to identify the main venous systems in the fetal brain. Blood flow velocity waveforms of the transverse sinus were obtained from a transverse plane of the head at the level of the cerebellum. RESULTS: A waveform could be obtained in the cerebral transverse sinus in 98% of the cases. The waveform obtained was triphasic with a forward systolic component, a forward early diastolic component and a lower forward component in late diastole. Reverse flow during atrial contraction was seen before 28 weeks and the diastolic flow increased with gestation thereafter. Pulsatility and resistance indices decreased and flow velocities increased in the transverse sinus throughout gestation. CONCLUSION: The venous circulation of the fetal brain can be identified by color Doppler. The gestational age-related decrease in resistance and increase in flow velocities suggest that hemodynamic studies of the cerebral transverse sinus might have clinical implications in studying compromised fetuses.     

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.     

Reference ranges for fetal venous and atrioventricular blood flow parameters.

This cross-sectional study establishes reference ranges with gestation for Doppler parameters of fetal venous and atrioventricular blood flow. Color flow Doppler was used to examine 143 normal singleton pregnancies at 20-40 weeks' gestation. Flow velocity waveforms were recorded from the ductus venosus, right hepatic vein and inferior vena cava. The waveforms are triphasic, reflecting ventricular systole, early diastole and atrial contraction. Peak velocities for these parameters were measured with pulsed Doppler and a new index, the peak velocity index for veins (PVIV), was calculated. Similarly, time-averaged maximum velocities for the whole cardiac cycle were measured and the pulsatility index for veins (PIV) was calculated. Flow velocity waveforms were also recorded at the level of the atrioventricular valves and the ratios of peak velocities at early diastolic filling (E) and atrial contraction (A) were calculated. Regression analysis was used to define the association of each measured and calculated Doppler parameter with gestational age. Blood flow velocities in the fetal veins and velocities and E/A ratios across the atrioventricular valves increased significantly with gestation, whereas PVIV and PIV decreased. Blood flow velocities were highest in the ductus venosus and lowest in the right hepatic vein, and PVIV and PIV were highest in the hepatic vein and lowest in the ductus venosus. In the ductus venosus, there was always forward flow throughout the heart cycle, whereas in the inferior vena cava and hepatic vein during atrial contraction, flow was away from or towards the heart or there was no flow. Pulsatility of flow velocity waveforms in the venous system is the consequence of changes in pressure difference between the venous system and the heart during the heart cycle. The finding that PVIV and PIV decrease with gestation is consistent with decreasing cardiac afterload and maturation of diastolic ventricular function.     

探讨提高多普勒超声帧频对产前胎儿大脑中动脉测量的重要性

目的 探讨提高多普勒超声帧频对测量大脑中动脉（MCA）收缩期峰值流速（PSV）和搏动指数（PI）的影响及重要性。方法 应用彩色多普勒超声检测659例孕20-40w的正常胎儿大脑中动脉（MCA）的血流频谱,测量其血流参数：收缩期峰值流速（PSV）和搏动指数（PI）,第一次测量（MCA.g）是在常规设置下进行的,第二测量（MCA.o）是在通过优化设置提高帧频的条件下进行,并将两次MCA血流参数测量结果进行比较。结果 MCA.o优化设置后的PSV、PI值明显高于MCA.g设置（P<0.001）。结论 与常规设置的超声测量技术相比,优化多普勒超声设置提高帧频,可提高胎儿MCA测量血流参数PSV和PI值,其对产前胎儿循环系统的评估起着重要作用,值得临床进一步研究,并调整当前MCA血流参数正常范围的参考值。     

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.     

First-trimester treatment of fetal anemia secondary to parvovirus B19 infection.

Here we report two cases of first-trimester parvovirus B19 (PV-B19) infection that were successfully treated by intrauterine blood transfusion into the umbilical vein. At 13 weeks' gestation both fetuses presented with increased nuchal translucency (NT) and cardiomegaly. In both cases pulsed Doppler ultrasound examination of the fetal middle cerebral artery (MCA) revealed increased peak systolic velocity (PSV), which led to a suspicion of fetal anemia. Maternal PV infection was confirmed by a positive polymerase chain reaction result. Each fetus received a 3-mL intravenous transfusion of packed red blood cells into the umbilical vein, using a 25-G spinal needle. Follow-up ultrasound and Doppler examination demonstrated fetal well-being, decline of the MCA-PSV and resolution of the NT. Case 1 was readmitted at 25 weeks' gestation with severe hydrops fetalis, and both mother and fetus still tested positive for PV-B19 DNA. Three more intrauterine blood transfusions were performed and the fetal hydrops resolved. In Case 2 no additional transfusions were needed. Both babies had a good neonatal outcome and uneventful follow-up. Our findings demonstrate that the MCA-PSV is helpful in establishing the diagnosis of first-trimester fetal anemia. Intravasal transfusion can be attempted as early as the first trimester.