经阴道彩色多普勒超声对正常早期妊娠的研究

应用阴道彩色多普勒超声观察了９２例正常早期妊娠妇女的子宫、胎盘后或滋养层外及卵巢黄体血流状况。结果表明：滋养层外或胎盘后血流从孕５周开始被显示，孕７周前显示率为８２％，孕７周后为１００％，呈高舒张期低阻力连续波；双子宫动脉显示率１００％，两者血流量均随妊娠进展增加。并早孕期妊娠黄体侧卵巢内可显示出丰富的高舒张期低阻力连续波血流信号，血流显示率８１．５２％。经阴道彩色多普勒超声为研究早期妊娠提供了一个有效的方法     

经阴道二维,彩色血流多普勒在早期妊娠的研究

本文研究目的是了解经阴道二维，彩色血流多普勒在早期妊娠的诊断价值。１４９例人流患者自愿接受本项检查。研究结果表明，经阴道超声（ＴＶＳ）对早期妊娠结构，如孕囊、卵黄囊、胎心搏动，胎头及胎体辨别、颅骨、脊柱、心脏等均较经腹部超声（ＴＡＳ），提前１～２周显示，且结构更清晰。经阴道彩色多普勒（ＴＶＣＤ）在早期妊娠全部病例均可测到双侧子宫动脉血流，９７％测到滋养层血流，７８％可测到妊娠黄体血流，５周以后９２％可测到胎儿主动脉血流，７周以后８８％可测到脐动脉血流，９周以后可测到脑动脉血流。     

Transvaginal color Doppler imaging

Transvaginal color Doppler was used to assess circulation in pelvic vessels in a group of 64 patients including 15 patients with fertility problems, 18 patients with pelvic tumors, 2 cases of suspected ectopic pregnancy, and 29 pregnant patients with fetuses between 6 weeks and 10 weeks, menstrual age. Blood flow was successfully displayed by color Doppler in the external and internal iliac arteries, and the uterine arteries, but flow in ovarian arteries could not be visualized. In the subgroup of patients with pelvic tumors, neovascularization of tumor tissue was documented in 6 out of 10 cases of uterine fibroma and in 2 cases of ovarian cancer. In 6 cases involving benign ovarian pathology, no abnormal blood supply was observed. A comparison between the characteristics of blood flow within uterine fibromas and ovarian malignancies showed lower impedance and higher blood velocity in cases of malignancy. In early pregnancy blood flow in the umbilical artery could be visualized by color Doppler starting from the 6th week and flow in the aorta from the 8th week. Flow in the trophoblasts was observed with an overall success rate of 59% and successfully demonstrated in 1 out of 2 cases of ectopic pregnancy.     

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.     

Early fetal circulation in pregnancies complicated by retroplacental hematoma

The objective of this study was to investigate the effects in early gestation of retroplacental hematomas on Doppler indices measured in different fetal vascular districts and to relate these changes, if any, to the volume of hematoma and pregnancy outcome. Thirty-eight pregnancies complicated by bleeding and ultrasonographic findings of retroplacental hematomas were considered for this study. Menstrual age ranged between 9 and 14 weeks. Blood flow velocity waveforms were measured in the umbilical artery, descending aorta, middle cerebral artery, and inferior vena cava. The pulsatility index in arterial vessels was calculated as well as the percentage reverse flow in the inferior vena cava. The values obtained were compared to previously constructed reference limits. No significant differences were found for any of the Doppler indices when the values obtained in pregnancies complicated by retroplacental hematomas were compared to the reference limits. Furthermore no significant relationships were found between the Doppler indices and either the size of hematoma or pregnancy outcome. In conclusion, retroplacental hematoma does not induce hemodynamic effects in the fetal circulation before 14 weeks, menstrual age. These data do not support the use of Doppler ultrasonography in early gestation for pregnancies complicated by bleeding and retroplacental hematomas. © 1995 John Wiley & Sons, Inc.     

Doppler ultrasonography in early pregnancy does not predict adverse pregnancy outcome.

A transvaginal color and pulsed Doppler study was performed on 330 pregnancies at 7-16 weeks of gestation. Blood flow velocity waveforms were recorded from the main uterine arteries and their branches (arcuate and trophoblastic vessels) and from the umbilical arteries. The systolic/diastolic velocity ratio and the pulsatility index were calculated as indices of vascular resistance, respectively, at uterine and umbilical levels. A total of 282 patients had an uneventful pregnancy outcome, 19 developed an early pregnancy failure (missed abortion, n = 8; anembryonic pregnancy, n = 11) and 29 developed later complications such us hypertension (n = 10), fetal growth retardation (n = 13) or both n = 6). In normal pregnancies, Doppler-measured vascular resistances significantly decreased with advancing gestation at the level of both uterine and umbilical circulations. When the Doppler indices of the patients with early pregnancy failure or with later complications were compared to those of normal pregnancies, no evident differences were found in either of the vascular districts considered. However, in the patients who developed hypertension and/or fetal growth retardation, abnormal velocity waveforms were frequently present in uterine and umbilical arteries during second- or third-trimester examinations. Our results suggest a limited clinical value of Doppler velocimetry in early pregnancy.     

Pulsed Doppler on a vaginal probe. Necessity,convenience, or luxury?

One hundred twenty-seven pregnancies were studied between 5 and 12 weeks of amenorrhea with Doppler ultrasound coupled with a vaginal probe. These biologically proven pregnancies had no clinical sign of abnormality; however, 29 were detected not to be evolving. Doppler signals were obtained from the embryonic heart, umbilical cord, trophoblastic crown, peritrophoblastic area, and from the uterine and ovarian arteries. In normally evolving pregnancies, no intratrophoblastic flow was detected, whereas it was present in all missed abortions. The peritrophoblastic area always generates a Doppler signal with an important diastolic component. The resistance index (RI) of uterine arteries was constant during the first trimester of pregnancy (RI = .77 +/- .15) and a protodiastolic notch was found in 58% of the cases. The combined use of these two modalities of examination was demonstrated. Although the clinical efficacy of the method has not yet been demonstrated, this combination of techniques opens new perspectives to echography and adds a dynamic dimension to morphologic studies.     

Functional assessment of uteroplacental and fetal circulations by means of color Doppler ultrasonography.

A study was made in order to assess whether the combined use of color flow mapping and conventional pulsed Doppler could improve the accuracy of blood flow velocity waveform analysis in fetal and placental circulations. Fifty patients were studied at 18 to 20 or 26 to 28 weeks of gestation by two trained investigators by means of either conventional Doppler or conventional Doppler plus color flow mapping. Recordings were performed at the level of the uterine arteries, umbilical artery, descending aorta, and internal carotid artery. The experimental procedure was repeated the following day with the patients undergoing the alternate technique of recording. In all the vascular districts investigated, color flow mapping allowed us to obtain a higher number of reliable recordings, to shorten the observation time, and to reduce the intra- and interobserver coefficient of variations.     

Neonatal nucleated red blood cell counts: relationship to abnormal fetoplacental circulation detected by Doppler studies.

Increased neonatal nucleated red blood cell counts are thought to be related to intrauterine hypoxemia. We sought to determine the effect of increasing circulatory impairment in fetuses on the neonatal nucleated red blood cell count. One hundred thirty-four singleton pregnancies were included in the study and were allocated to 4 study groups according to Doppler findings. The systolic-to-diastolic ratios of the umbilical artery, fetal aorta, middle cerebral artery, and uterine arteries were recorded. Fetuses were assigned to the following groups on the basis of the last Doppler examination before delivery: group 1, normal systolic-to-diastolic ratios in the examined vessels; group 2, a systolic-to-diastolic ratio greater than 2 SD above the mean for gestational age in the umbilical artery or fetal aorta and no abnormal Doppler findings in the uterine arteries; group 3, systolic-to-diastolic ratios greater than 2 SD above the mean for gestational age in all examined vessels; and group 4, absence of end-diastolic velocity in the umbilical artery or fetal aorta and systolic-to-diastolic ratios greater than 2 SD above the mean for gestational age in the uterine arteries. A blood sample from the umbilical artery was obtained within 1 minute after birth, and nucleated red blood cells per 100 white blood cells were counted by light microscopy. Nucleated red blood cell counts were higher in fetuses in group 4 (median, 72.0; range, 9-720; P < .001) and group 3 (median, 38.4; range, 7-201; P < .001) than in fetuses in group 1 (median, 5.1; range, 0-20). Neonates in group 4 had significantly lower birth weights (P < .001), lower arterial and venous pH values (P < .05), and lower Apgar scores after 5 minutes (P < .01) as well as an increased likelihood of cesarean delivery because of fetal distress (P < .001). The number of fetuses in group 4 with a cord blood base deficit of less than -8 mmol/L was increased. Nucleated red blood cell counts were comparable in fetuses in group 2 (median, 5.4; range, 0-37) and group 1. In groups 1 to 3 no brain-sparing effect occurred, whereas in 15 of 21 cases in group 4 a brain-sparing effect was present. Multivariate analysis revealed that Doppler results of the umbilical artery, fetal aorta, and uterine arteries were independent determinants of neonatal nucleated red blood cell count. Increasing abnormalities seen on fetoplacental Doppler studies are associated with increasing numbers of nucleated red blood cells at birth. Given the known relationship between abnormal Doppler flow and intrauterine hypoxemia, the neonatal nucleated red blood cell count might become an additional valuable tool in the surveillance of growth-restricted fetuses.     

彩色多普勒超声在产前诊断单脐动脉的临床价值

目的 评估彩色多普勒超声在产前诊断胎儿单脐动脉的临床价值。方法 在中孕期应用彩色多普勒超声观察单脐动脉的形态结构及多普勒血流信号特征，并与产后结果及病理学检查对照。结果 1．正常三支脐血管螺旋状排列特征消失，单脐动脉畸形时脐带内只有一条脐动脉和一条脐静脉，两支血管呈螺旋状排列或并行走行；2．单脐动脉多合并其它畸形、宫内发育迟缓、早产等情况；3．彩色多普勒可直观显示两支血管的血流方向，并且能够为明确其它畸形提供重要的诊断信息。结论 彩色多普勒超声在中孕期诊断单脐动脉具有重要的临床价值。     

Normal cardiac flow velocities at 14-16 weeks of gestation measured by transvaginal ultrasound.

OBJECTIVE: Doppler ultrasound has been used to study the flow velocities through the valves and arteries of the fetal heart. Using transvaginal sonography, we sought to determine normal values for flow velocities through the fetal heart valves at 14-16 weeks of gestation. METHODS: Eighty-seven normal fetuses were examined. The flow velocity waveforms were visualized using Doppler ultrasound with the sample volume calipers placed just distally to the four fetal valves. Peak E- and A-wave velocities were recorded for the tricuspid and mitral valves and peak systolic flow velocities were recorded for the ascending aorta and pulmonary arteries. Linear regression for comparison of flow velocities with gestational age was performed. RESULTS: There was no significant correlation between any of the velocities and gestational age. CONCLUSIONS: Flow velocities through the fetal cardiac valves remain unchanged at 14-16 weeks of gestation as measured by transvaginal Doppler sonography.     

Color Doppler imaging of the uteroplacental circulation in the middle trimester: observations on the development of a low-resistance circulation.

We aimed to study the changes in the flow dynamics of the uteroplacental and umbilical circulations in the middle trimester of normal pregnancy, and establish normal ranges for indices of the Doppler flow velocity waveforms (FVWs) from both circulations at 14, 18 and 24 weeks. A longitudinal study was conducted with the use of color Doppler imaging to localize both uterine arteries and umbilical arteries and obtain FVWs from 106 healthy nulliparous women with a singleton pregnancy. Of these, 70 did not have a complicated pregnancy outcome, defined as hypertension, growth retardation, preterm delivery or perinatal death. We measured the resistance index (RI), pulsatility index (PI), systolic/diastolic (S/D) ratio and presence of early diastolic notching in both uterine arteries, and RI, PI and S/D in one umbilical artery. The results showed a fall in all measured indices of blood flow impedance in the uteroplacental and umbilical circulations and a marked reduction in the incidence of the early diastolic notch in the uterine artery FVWs during the mid-trimester. Our conclusion was that color Doppler imaging allows for the accurate localization of both uterine and umbilical arteries. Doppler FVWs then obtained confirm the development of the low-resistance uteroplacental and umbilical circulations in the mid-trimester. Diastolic notching is common at 14 weeks in normal pregnancy but uncommon at 24 weeks.     

Three‐Dimensional Ultrasonographic Depiction of Fetal Abdominal Blood Vessels

Objective. The purpose of this study was to identify fetal abdominal vasculature with 3‐dimensional (3D) ultrasonography and to describe a systematic method for analysis of volume data sets. Methods. Three‐dimensional volumes of the fetal abdomen were acquired prospectively in 30 patients between 15 and 34 weeks' gestation with color Doppler, high‐definition (HD) flow, power Doppler, and B‐flow imaging. All volumes were analyzed offline by 2 examiners separately. The feasibility of identifying the fetal abdominal blood vessels was analyzed. A standardized approach was applied to identify specific vessels by correlating the images with known anatomic landmarks. Results. The volumes were rotated into an anatomic orientation in the multiplanar mode, and then the vessels were identified in the following order: aorta (30 of 30), celiac trunk (29 of 30), superior mesenteric vein (28 of 30 and 26 of 30 for readers 1 and 2, respectively), superior mesenteric artery (29 of 30), left renal artery (25 of 30 and 26 of 30), right renal artery (27 of 30), common iliac arteries (30 of 30), umbilical arteries (26 of 27), external iliac arteries (20 of 22), umbilical vein (29 of 30), ductus venosus (30 of 30), hepatic vein (29 of 30), right portal vein (29 of 30), inferior vena cava (28 of 30), adrenal artery (2 of 30), hepatic artery (24 of 30 and 23 of 30), splenic artery (24 of 30 and 23 of 30), gastric artery (14 of 30 and 9 of 30), splenic vein (19 of 30 and 15 of 30), and renal vein (1 of 30). A step‐by‐step systematic approach to identify the abdominal vasculature from the ultrasonographic volume data set was developed. Conclusions. Fetal abdominal vessels can be easily visualized when a systematic analysis is performed on 3D data set volumes. Visualization of the vessels was optimal when volumes were acquired with HD flow imaging.     

Fetal and uteroplacental blood flow in prolonged pregnancies. A clinical study.

In a prospective study during 1 year, 102 women with prolonged pregnancies (more than 294 completed gestational days) were followed with serial pulsed Doppler blood flow examinations every 2nd day, either to spontaneous onset of labor (n = 82) or to induction of labor due to subsequently occurring complications (n = 20). Mean aortic blood velocity did not change significantly with gestational age beyond 294 days either in fetuses with normal outcome or in fetuses that developed asphyxia at birth. The flow velocity waveforms in the descending aorta, the umbilical artery, the common carotid artery and the uterine artery did not change significantly compared to the values at term. Abnormal flow velocity waveforms in the fetal descending aorta, umbilical artery or uterine artery had no significant relationship to fetal asphyxia. Absence of diastolic flow velocities was not found in any of the vessels examined, indicating that the fetuses did not suffer from chronic hypoxia in utero and that aging of the placenta did not alter fetal and uteroplacental blood flow. Notching of the aortic flow velocity waveform was a common finding among prolonged pregnancies. The hemodynamic implications and consequences of this phenomenon are discussed.     

Doppler Ultrasound in Canine Pregnancy

Objective. The aim of this article is to review the current knowledge of Doppler ultrasound in canine pregnancy. A brief introduction of Doppler principles and their applications in human obstetrics is also included. Methods. A review of the peer‐reviewed published literature was conducted of the articles pertaining to the use of Doppler ultrasound in canine pregnancy, general Doppler principles, and Doppler applications in human obstetrics. Results. In bitches, Doppler ultrasound has been used to assess ovarian, uterine, umbilical, fetal aorta, common carotid artery, and fetal caudal vena cava blood flow during normal gestation. Most of these vessels increase their blood flow during normal pregnancy. The resistive index and systolic/diastolic ratio of the uterine arteries have been recently described in an experimental pharmacologically induced model of abnormal canine gestation. Both indices progressively increase up to abortion, probably because of progesterone deprivation. Moreover, resistive index abnormalities have been found in canine cases of spontaneous abnormal gestations as described in human medicine. Conclusions. Doppler ultrasound is a useful method for assessing development of the placental and fetal circulation during normal and abnormal canine pregnancy. Further studies are still necessary to widely use this technique in clinical practice.     

Precision and accuracy of Doppler flow measurements. In vitro and in vivo study of the applicability of the method in human fetuses

The precision of the Doppler method for quantitative blood flow measurement in the fetal descending thoracic aorta and in the umbilical vein and for estimation of the Pulsatility Index from the velocity curve from fetal aorta was tested in vivo by examination of six pregnant women eight times. Two investigators examined each patient twice in random order upon two successive days. The diameter of the vessel was measured using planimetry on a magnified time-motion image of the diameter variations during the heart cycle, while the angle between the ultrasound Doppler beam and the vessel of interest was measured on the hard copy image. No systematic variation was found between observers, days, repeated observations or repeated readings of curves and images. The mean coefficient of variations was 5.6% for the quantitative flow per kilogram estimated fetal weight measured in the fetal descending aorta, 6.8% for the quantitative flow per kilogram estimated fetal weight measured in the umbilical vein and 9.8% for the Pulsatility Index. When the diameter of aorta was calculated as the mean of the maximal and the minimal diameter measured on the hard copy image, the mean coefficient of variation for the flow increased to 9.4%. In vitro tests of the Doppler instrument and the real-time scanner revealed a systematic overestimation of Doppler measured flow of only 4.4% compared with the true flow, and a real-time scanner underestimation of vessel diameter of only 1.1%.     

New implanted Doppler sensors for the assessment of the main fetal hemodynamics.

If the fetal Doppler examination during human pregnancies provides useful information to the obstetrician, it does not allow us to collect all the biological and haemodynamic data required to understand the physiopathological mechanisms involved in the development of intrauterine growth retardation (IUGR) and hypoxia. With the animal model, it is possible to have access to the blood pressure, the blood velocity and volume, to collect blood sampling and to perform pharmacological tests, or to simulate some human pathology. Several studies have been already carried out on lamb fetuses using electromagnetic flowmeters placed around the cord and catheters, with pressure sensors placed inside the fetal aorta. Most of the time only the umbilical flow was assessed on the fetal side. The aim of the present work was to develop a new Doppler system able to monitor in real time and simultaneously, the fetal cerebral and the umbilical arterial flows as well as the uterine circulation. New flat Doppler probes have been designed, to be implanted on the fetus and on the mother, which makes possible the atraumatic assessment of fetal and maternal flows during approximately 20 days. The 4-MHz CW Doppler probe consists of two rectangular piezoelectric transducers of 13-mm wide, preoriented at 45 degrees from the surface of the probe, placed in a 6-mm-high plastic case in which small holes are made to sew the probe on the fetal skin. The sensors are fixed on the fetal skin, facing the umbilical cord, the fetal cerebral arteries and in front of the uterine arteries.(ABSTRACT TRUNCATED AT 250 WORDS)     

Color Doppler sonographic assessment of placental circulation in the first trimester of normal pregnancy.

Our aim was to study placental circulation during the first trimester of normal pregnancy. For this purpose, 108 single pregnancies from 4 to 15 gestational weeks were evaluated through conventional Doppler ultrasonography. The flow velocity waveforms from the retrochorionic arteries (spiral-radial arteries) and the umbilical artery were assessed using the peak systolic velocity, resistive index, and pulsatility index). Intervillous flow velocity waveform was evaluated from the maximum velocity. The earliest color signal from the retrochorionic circulation was registered at 4.5 weeks along with gestational sac visualization. The venous Doppler signal from the intervillous space and the Doppler signal from the umbilical artery were recorded with an embryo visible from the end of week 5 onward. The retrochorionic, intervillous, and umbilical peak systolic velocities increase, whereas the resistive and pulsatility indices decrease progressively during early pregnancy with a significant correlation with gestational age. Similarly, intervillous maximum velocity gradually increases throughout the first trimester of pregnancy. Despite some methodologic problems related to Doppler technology and the vessels studied color Doppler sonography appears to be an adequate tool to assess the physiologic changes in the placental circulation during early pregnancy.     

Changes in fetoplacental vessel flow velocity waveforms following maternal administration of betamethasone.

OBJECTIVE: To determine the timing of the onset of the umbilical artery flow velocity waveform changes following maternal administration of betamethasone in pregnancies complicated by umbilical artery absent end-diastolic flow, and to explore whether these changes are associated with flow velocity waveform changes in other fetoplacental vessels. SUBJECTS AND METHODS: This was a prospective study of 12 women with pregnancies complicated by umbilical artery absent end-diastolic flow. Flow velocity waveforms were recorded from the umbilical artery, fetal middle cerebral artery, renal artery, aorta and ductus venosus, before and after maternal betamethasone administration, using real-time pulsed wave Doppler. RESULTS: In all 12 pregnancies, the administration of maternal betamethasone was followed by the return of end-diastolic flow within 24 h. End-diastolic flow was first observed at 4 h and was present in all women studied at 8 h. In addition, there was a statistically significant decrease in the pulsatility index in the fetal aorta at 8 h and the middle cerebral artery at 24 h. No change was observed in the ductus venosus or the renal artery flow velocity waveforms. CONCLUSION: The findings suggest that, in pregnancies complicated by absent end-diastolic flow in the umbilical artery, maternally administered betamethasone induces a return in umbilical artery end-diastolic flow as early as 4 h, along with widespread vasodilatation throughout the fetoplacental vasculature.     

Waveform pattern recognition--a new semiquantitative method for analysis of fetal aortic and umbilical artery blood flow velocity recorded by Doppler ultrasound

A semiquantitative computerized waveform pattern recognition system for analysis of the fetal descending aortic and umbilical artery Doppler flow velocity waveforms is presented. Based on empirically and manually selected clinical recordings from both vessels, 11 computerized and normalized standard curves for the aorta (type curves A to K), and 10 curves for the umbilical artery (type curves a to j) were constructed. The best match between the normalized waveform and the standard curve was based on either the degree of absent diastolic flow or, in cases with positive diastolic flow, on the calculation of the least square sum of the difference. The pattern recognition was tested against conventional waveform indices and our older semiquantitative Blood Flow Class (BFC) system in 472 clinical consecutive Doppler recordings. A good correlation was found. This new relatively simple computer-based method for waveform analysis is now prospectively applied in clinical studies.