Correlations in umbilical blood flow Doppler velocities in the human fetus during breathing.

We hypothesized that changes in intrathoracic pressure during fetal breathing episodes result in quantifiable variations in umbilical arterial and venous blood flow velocities, and that these variations are related to compliance properties of each system. We further hypothesized that these variations in velocities are different in fetuses with normal and abnormal umbilical arterial Doppler velocities. Umbilical arterial and venous Doppler velocities were measured simultaneously during breathing episodes in 15 normal fetuses and 14 fetuses with elevated systolic-to-diastolic (S/D) umbilical arterial Doppler velocity ratios. Umbilical arterial end-diastolic velocity changes were less than umbilical venous velocity changes in normal fetuses, but were significantly greater in four fetuses with elevated S/D ratios (p < 0.004). Furthermore, umbilical arterial diastolic velocity minima preceded umbilical venous velocity minima by a time lag that was greater in fetuses with elevated S/D ratios (p < 0.002). These results suggest that differences in umbilical arterial and venous velocity variation during fetal breathing episodes may be related in part to vascular compliance, which may be altered in fetuses with abnormal umbilical arterial Doppler velocity.     

Umbilical venous blood flow and its measurement in the human fetus

In this review, we evaluate the published methodologies to describe a noninvasive technique for the quantitative assessment of umbilical venous blood flow in the human fetus. We identify a number of variations in the reported methodologies and address some of the common errors associated with Doppler assessment of umbilical venous flow volume. The potential role of umbilical venous flow volumetry in the management of intrauterine growth restriction is briefly evaluated including its utility and reliability in everyday clinical practice. © 2012 Wiley Periodicals, Inc. J Clin Ultrasound 40:502–511, 2012     

Ductus venosus blood velocity and the umbilical circulation in the seriously growth-retarded fetus.

Based on the assumption that the ductus venosus is regulator of oxygenated blood in the fetus, the present study investigated the blood flow velocity of the ductus venosus in relation to the umbilical circulation in the that seriously growth-retarded fetus. The study group of 38 fetuses (gestational week 17-39) had no chromosomal aberrations or structural malformations and had an ultrasonographic biometry of < 2.5th centile and birth weight of 相似文献   

Relationship between umbilical and fetal cerebral blood flow velocity waveforms and umbilical venous blood gases.

Nineteen women (mean +/- SD: 28 +/- 5 years) with small fetuses relative to gestational age (mean +/- SD: 32 +/- 2.2 weeks of gestation) were referred to our unit for cordocentesis for the determination of fetal karyotyping. Four of these 19 patients had small-for-gestational-age ultrasound-derived measurements under the third centile for gestational age. Fetal blood gases were measured in the umbilical vein. Umbilical artery and fetal internal carotid artery Doppler examinations were performed 15 min before cordocentesis. The results showed a progressive and proportional increase in umbilical artery resistance index with hypoxia (p < 0.001), hypercapnia (p < 0.025) and acidosis (p < 0.005). Moreover, the results showed a progressive and proportional decrease in fetal internal carotid artery resistance index with hypoxia (p < 0.01), hypercapnia (p < 0.01) and acidosis (p < 0.025). Fetal blood gases are therefore related to umbilical circulatory function and cerebral vasodilatation, suggesting fetal vascular redistribution.     

The anatomy of the umbilical, portal and hepatic venous systems in the human fetus at 14-19 weeks of gestation.

BACKGROUND: Ultrasound imaging of the fetal ductus venosus is becoming increasingly commonplace in clinical practice. The true anatomical relationships of the fetal umbilical and portal venous systems have not been clearly defined due to paucity of published data on the relevant anatomy. This has led to confusing terminology when describing the fetal umbilical, portal and hepatic circulations. The aim of the present study was to examine and document the anatomy of the umbilical, portal and hepatic venous systems and to propose a standardized nomenclature. METHODS: This was a prospective study on 11 fetuses obtained from medical termination of pregnancies between 14 and 19 weeks of gestation. The liver was microdissected to expose the branching pattern and anatomical relations of the umbilical, portal and hepatic venous systems. RESULTS: A wide L-shaped venous confluence at the terminal end of the umbilical vein, termed the portal sinus, was identified. The portal sinus was connected to the right and left hepatic lobes, by the right and left intrahepatic portal veins, respectively. The extrahepatic portal vein drained into the portal sinus just before the origin of the right intrahepatic portal vein. The ductus venosus, a branchless straight vessel, originated from the portal sinus and ascended steeply in the direction of the diaphragm. Numerous small vessels draining the liver converged into three main hepatic veins, which open into the subdiaphragmatic vestibulum. CONCLUSION: Based on detailed sequential anatomical dissection and clear illustrations, the present study documents the anatomy of the umbilical, portal and hepatic venous systems. Taking into account the embryological origin of the vessels, a new anatomically appropriate and simplified nomenclature of these venous systems is proposed. In clinical practice, the consistent use of the suggested terminology would allow collection of comparable data between units and enable operators to be confident of which vessels they are sampling by Doppler ultrasound.     

Umbilical venous volume flow in the normally developing and growth-restricted human fetus.

OBJECTIVE: To determine the reproducibility of measurement of umbilical venous volume flow components and to calculate umbilical venous volume flow in normal and growth-restricted (small-for-gestational age) fetuses in a cross-sectional study. METHOD: Using Labview and Imaq-vision software, the cross-sectional inner area of the umbilical vein was traced. Vessel area (mm2) and Doppler-derived time-averaged flow velocity (mm/s) were multiplied to calculate volume flow (mL/min) including flow per kg fetal weight. The coefficient of variation for vessel area and flow velocity scans and tracings were determined (n = 13; 26-35 weeks). Normal charts for components and volume flow were constructed (n = 100; 20-36 weeks) and related to data from growth restricted fetuses (birth weight < 5th centile) (n = 33; 22-36 weeks). In growth-restricted fetuses the umbilical artery pulsatility index was also obtained. RESULTS: Reproducibility: The coefficient of variation was 5.4% (vessel area) and 7.3% (time-averaged velocity) for scans and 6.6% and 10.5% for measurements, resulting in a coefficient of variation of 8.1% (scans) and 11.9% (measurements) for volume flow. A gestational age-related increase exists for vessel area, time-averaged flow velocity and umbilical venous volume flow from 33.2 (SD, 15.2) mL/min at 20 weeks to 221.0 (SD, 32.8) mL/min at 36 weeks of gestation, but there is a reduction from 117.5 (SD, 33.6) mL/min to 78.3 (SD, 12.4) mL/min for volume flow per kg fetal weight. In small-for-gestational age fetuses, the values were below the normal range in 31 of 33 cases for volume flow and in 21 of 33 cases for volume flow per kg fetal weight. Umbilical artery pulsatility index was significantly different between the subsets with normal and those with reduced volume flow per kg fetal weight. CONCLUSIONS: Measurements of umbilical venous vessel area and time-averaged velocity resulted in acceptable reproducibility of volume flow calculations, which show a seven-fold increase at 20-36 weeks of gestation. In growth-restricted fetuses, volume flow is significantly reduced. When calculated per kg/fetus, the values were reduced in 21 (63.6%) out of 33 cases.     

The arterial blood supply to the liver in cirrhosis

Of 21 patients with cirrhosis of the liver 9 had collateral arterial flow to the liver from the superior mesenteric artery. The degree of collateral arterial flow in cirrhosis was related to the presence of centrifugal portal flow, the degree of bilirubinemia and the presence of a markedly enlarged spleen with increased splenic blood flow.Of 27 non-cirrhotic patients 6 had collateral arterial flow to the liver from the superior mesenteric artery. The greatest degree of collateral arterial flow was associated with celiac stenosis in 4/6 patients. One patient had pancreatitis and an explanation was not evident in one patient.     

Portal blood flow in cirrhosis of the liver

Direct measurements of portal flow and pressure in a relatively large number of patients with cirrhosis show a marked reduction in flow associated with a nearly constant plateau of portal pressure. This lack of correlation indicates the complex relationships of resistances in the splanchnic, collateral, and hepatic circuits determining the division of the available splanchnic flow between the portal vein and the collateral pathways. Subtracting the measured portal flow from well-established estimates of total hepatic blood flow in cirrhosis suggests that the hepatic artery contributes more than one-half of the blood perfusing the cirrhotic liver. There was no instance of retrograde portal flow during the preshunt measurements, although such reversal was frequent after side-to-side portacaval anastomosis. Attempting to explain the plateau of portal pressure in the face of an increasing outflow resistance presumably associated with progress of the disease, we postulate that an augmented inflow resistance to the splanchnic chamber reduces splanchnic flow in cirrhosis. End-to-side portacaval anastomosis did not return normal portal flow, although it decreased pressure to accepted control levels. The assumption is that most of the splanchnic blood was flowing through the shunt, leading to a high splanchnic resistance in the immediate postshunt status. If this resistance was previously elevated, as suggested by the plateau of portal pressure, the mechanism responsible for the elevation was not immediately deactivated after the shunt, and the true effect of the operation upon splanchnic flow may not be measurable at such time.     

Vitamin D supply to the rat fetus and neonate.

The prevention of neonatal rickets by oral supplementation with vitamin D2 (ergocalciferol) has tended to obscure our ignorance of the natural mechanism by which young mammals receive an adequate supply of vitamin D. To investigate the possibility of specific intrauterine transfer and storage of vitamin D in fetal tissues, vitamin D-deficient female rats were given depot injections of 3H- or 14C-labeled vitamin D3 (cholecalciferol) before mating and the 3H-labeled animals were killed at stages during the last third of gestation. Analysis of lipid extracts from whole fetuses revealed a linear increase in the concentration of 25-hydroxyvitamin D3, 24,25-dihydroxyvitamin D3, and D3 itself between days 14 and 19 of gestation. During this period the elimination half-time of 3H-labeled molecules in maternal plasma fell from 27.1 to 4.4 d, suggesting that a specific mechanism was transferring vitamin D molecules into the fetuses. The vitamin was stored predominantly as 25-hydroxyvitamin D3 and 24,25-dihydroxyvitamin D3, with the highest concentrations in fetal muscle. Immediately after birth, pups from 3H- and 14C-labeled mothers were exchanged and later killed after 1-3 wk of suckling. Analysis of total lipid extracts for 3H and 14C content determined the relative contributions of vitamin D supplied before birth via the placenta and after birth in the maternal milk. The vitamin D content of the rat milk was relatively high, between 1.0 and 3.5 micrograms/liter. Nevertheless, the supply of vitamin D in utero, rather than from milk, was the main determinant of vitamin D status in early neonatal life. This is the first indication in a mammal of a specific transfer mechanism that allows the fetus to accumulate vitamin D from the mother during the last third of gestation.     

胎儿呼吸运动对于脐静脉血流的影响及意义

目的探讨妊娠晚期胎儿呼吸运动对脐静脉血流的影响及意义.方法随机选择75例孕龄36～40周,无产兆的正常孕妇,用脉冲多普勒观察胎儿呼吸运动时脐静脉血流的频谱形态、速度,并与无呼吸运动时进行自身对照.结果妊娠晚期胎儿呼吸运动时,脐静脉血流频谱形态、速度与非呼吸运动时明显不同.胎儿呼吸运动状态下,脐静脉血流频谱表现为周期性、波浪状静脉血流频谱,并且血流瞬时平均速度明显高于后者(P＜0.05).结论呼吸运动时脐静脉血流速度暂时、波浪式增加,间断性地提高了心脏的前负荷,促进着胎儿心脏收缩功能的发育.     

Developmental variation in stem-cell markers from human fetal liver and umbilical cord blood leukocytes

Fetal tissues containing haematopoietic stem cells (HSC) are of potential value for allogeneic transplantation and gene therapy. Flow cytometry was used to investigate CD34+ cells from human fetal livers and umbilical cord (placental) blood (UCB). CD34+ cells, expressed as a proportion of CD45-positive leukocytes, were much more abundant in fetal livers (mean 38%) than in UCB (mean 0.3%), but fetal liver cells had lower proportions of CD34+HLA-DR+ and CD34+ CD38+ subsets. In fetal liver, there was a strong and highly significant inverse correlation between CD34+ cells (as a proportion of total leukocytes) and gestational age; no such relationship was found for subsets of CD34+ cells coexpressing CD38 or CDw90 (Thy-1), but CD34+HLA-DR+ cells were less abundant in first- compared to second-trimester livers. In UCB, a trend towards decreasing CD34+ cells (as a proportion of total leukocytes) with increasing gestational age in late pregnancy was also observed. The composition of fetal leukocytes changes during development, and therefore the timing of fetal HSC harvesting could be of relevance to transplantation outcome.     

Methodology and basic problems related to blood flow studies in the human fetus

A method was developed for non-invasive measurement of human fetal blood flow. The method combines real-time ultrasonography with 2 MHz pulsed Doppler technique. The blood flow is calculated from the blood velocity, estimated from the Doppler spectrum, and the vessel diameter, measured in the real-time image. Time-distance recording was applied for measurements of the pulsatile diameter changes in the fetal aorta. The method proved to possess a good accuracy and reproducibility when tested in vitro experiments and in a comparison with electromagnetic flow measurements in animals. Possible sources of error were analysed and recommendations for minimizing the risk of errors are presented.     

Carbohydrate fermentation in the human colon and its relation to acetate concentrations in venous blood.

There is now substantial evidence that some dietary polysaccharides, notably dietary fiber, escape absorption in the small bowel and are then broken down in the large intestine of man. The main end products of this colonic digestive process, which is anerobic, are short chain fatty acids (SCFA), and acetic, propionic, and butyric acids. Although these acids are known to be absorbed from the colon, their subsequent fate and significance is unknown. We have measured venous blood SCFA levels in healthy subjects after a 16-h fast, and then following oral doses of either 50 mmol SCFA, 5, 10, or 20 g doses of the fermentable carbohydrate lactulose, or 20 g of pectin. Fasting venous blood acetate was 53.8 +/- 4.4 mumol/liter (SEM) (n = 14). Fasting arterial blood acetate, taken simultaneously with venous blood in six subjects, was higher; 125.6 +/- 13.5 mumol/liter (arterial) vs. 61.1 +/- 6.9 mumol/liter (venous). Significant levels of propionate or butyrate were not detected in any blood samples. Following an oral dose of 50 mmol mixed SCFA, venous blood acetate reached a peak of 194.1 +/- 57.9 mumol/liter at 45 min and returned to fasting levels at 2 h. Blood acetate also rose in response to lactulose, peak levels occurring 2-4 h after the dose: 5 g, 98.6 +/- 23.1 mumol/liter; 10 g, 127.3 +/- 18.2 mumol/liter; and 20 g, 181.3 +/- 23.9 mumol/liter. Pectin fermentation was much slower, with blood acetate levels starting to rise after 6 h and remaining elevated at about twice fasting levels for the subsequent 18 h. However, areas under the blood acetate curves were closely related (r = 0.97; n = 5), whatever the source of acetate. These studies show that the large intestine makes an important contribution to blood acetate levels in man and that fermentation may influence metabolic processes well beyond the wall of this organ.     

Acceleration time in normal fetal umbilical artery at term and its relationship to the cord blood hematocrit

The purpose of this study was to test the hypothesis that the acceleration time (AT) of the fetal umbilical artery remains constant at term for normal pregnancies. In addition, we also examined whether the AT has any correlation with umbilical cord blood hematocrit (Hct). In total, 539 normal-term fetuses with menstrual ages (MA) ranging from 37 weeks to 42 weeks were enrolled in a cross-sectional design. The AT of the fetal umbilical artery was measured prior to delivery using a high-resolution, real-time Doppler scanner. All were delivered within 2 days of the ultrasound examination. At parturition, blood from the umbilical vein was collected and the red cell indices, including the Hct, were determined. The results indicated that the mean values of AT of the umbilical artery remained constant during normal-term pregnancies from 37 weeks to 42 weeks, menstrual age (mean: 0.104 sec, SE: 0.001 sec, n = 539). Although the AT was thought to be affected by the Hct, the AT had no correlation with umbilical venous Hct (n = 539, r = 0.002, p > 0.05). This constant value of the AT may be used as a reference for fetal physiology and perinatal medicine. © 1995 John Wiley & Sons, Inc.     

胎儿宫内发育与脐血瘦素及血脂关系的研究

目的研究胎儿发育与脐血瘦素及血脂代谢的关系。方法以2009年1月至2010年6月青岛市城阳区人民医院产科分娩的符合纳入标准的新生儿共132例为研究对象,测定脐血瘦素、胆固醇及甘油三酯。按不同出生体质量、胎龄及不同胎龄与出生体质量的足月儿进行分类研究。结果脐血瘦素及甘油三酯在巨大儿组明显高于正常出生体质量儿组（P〈0.05）,低出生体质量儿组则明显降低（P〈0.01）,足月儿较早产儿明显升高（P〈0.05）。妊娠34周以前脐血瘦素水平很低,随着妊娠时间的延长,脐血瘦素水平提高,特别是妊娠34周以后,脐血瘦素水平增高明显（P〈0.01）,宫内发育迟缓足月儿脐血瘦素明显降低,甘油三酯及胆固醇无明显改变。结论脐血瘦素水平可以反映胎儿脂肪组织的含量,可作为评价胎儿宫内营养状态的指标。     

The significance of high umbilical venous blood flow measurements in a high-risk population.

We report a statistical analysis of 893 high-risk patients who underwent Doppler sonographic estimation of umbilical venous blood flow within 2 weeks of delivery. Patients with red cell isoimmunization were excluded. In a total of 84 patients, the umbilical venous flow rate was above the 95th centile for normal pregnancy. This finding was associated significantly with an increased prevalence of maternal diabetes mellitus, polyhydramnios, fetal abnormalities, premature delivery, low 5 min Apgar scores, and neonatal death. Umbilical venous flow rates per kilogram of fetal weight above the 95th centile were recorded in 93 patients. This finding was associated significantly with an increased rate of antepartum hemorrhage, premature delivery, low 5 min Apgar scores, longer stays in intensive care nursery, and neonatal death. Low umbilical venous blood flow rates have been investigated extensively and associated with impaired perinatal outcome. The work reported in this paper indicates that a percentage of fetuses will have abnormally high umbilical venous flow rates and that this is also indicative of increased risk.     

胎羊间断性脐带闭塞的血气及血流动力学变化分析

目的 探讨胎羊间断性脐带闭塞后的血流动力学特点及与脐动脉血气变化的关系。方法 12只晚孕山羊于妊娠116～130d行宫内外科手术，用套囊充气闭合器完全夹闭脐带，每次钳夹90s，间隔30min，重复5次。于第一次钳夹前5min、每次钳夹后3min均应用彩色多普勒血流显像技术检测血流参数，抽取胎羊脐动脉血做血气分析。结果 实验组钳夹后脐动脉搏动指数（PI）、肾动脉（RA）、静脉导管PI、左心室Tei指数、右心室Tei指数均升高（P〈0．（15），并且高于对照组（P〈0．05）；动脉血酸碱度（pH）、动脉血氧分压（PaO2）下降（P〈0．05），动脉血二氧化碳分压（PaCO2）升高（P〈0．05），与对照组比较差异有统计学意义（P〈0．01）。实验组脐动脉PI、肾动脉PI、静脉导管PI、右心室Tei指数、左心室Tei指数与血PH呈负相关（r=-0．431，r=-0．5（16，r=-0．358，r=-0．538，r=-0．681，P〈0．01），与血Pa02呈负相关（r=-0．446，r=-0．478，r=-0．435，r=-0．684，r=-0．725，P〈0．01），与血PaCO2呈正相关（r=0．410，r=0．524，r=0．699，r=0．682，r=0．780，P〈0．01）。结论 晚孕期脐带间断闭塞可导致胎羊宫内缺氧及多项血流动力学指标变化，静脉导管PI和Tei指数与血气指标的相关性好。因此，静脉导管PI和Tei指数可能成为预测胎儿宫内缺氧简便而有效的指标。