彩色多普勒超声对宫内发育迟缓胎儿动静脉的血流动力学研究

目的应用彩色多普勒超声检测宫内发育迟缓(IUGR)胎儿动静脉的血流动力学参数。方法测量胎儿静脉导管和脐静脉的血流量,计算静脉导管(DV)分流率;测量胎儿脐动脉、大脑中动脉(MCA)、肾动脉的搏动指数(PI)、阻力指数(RI)及脐动脉收缩期最大流速与舒张末期流速的比值(S/D),结果进行对比分析。结果与对照组比较,IUGR组胎儿脐动脉的PI、RI、S/D及肾动脉的RI显著增高,MCA的PI、RI及S/D显著减低,DV分流率显著增加,差异均有统计学意义(P<0.05)。结论彩色多普勒超声通过综合监测胎儿血流动力学变化,可以全面、客观地评价胎儿的供血情况,预测胎儿宫内缺氧和IUCR情况。     

Longitudinal changes in the ductus venosus, cerebral transverse sinus and cardiotocogram in fetal growth restriction.

OBJECTIVE: To evaluate the changes in flow velocity waveforms in the transverse cerebral sinus in growth-restricted fetuses and to correlate these changes with (1) flow velocity waveforms in the ductus venosus and (2) changes in computerized analysis of the fetal cardiotocogram. DESIGN: Fetuses between 22 and 37 weeks' gestation with an estimated fetal weight below the fifth centile were included in this prospective longitudinal study. Doppler measurements of the umbilical artery, descending aorta, middle cerebral artery, transverse cerebral sinus and ductus venosus were recorded. Fetal heart rate was analyzed by a computer system according to the Dawes-Redman criteria. RESULTS: We measured a significant correlation between pulsatility index in the cerebral transverse sinus and in the ductus venosus over the study period and at delivery. There was a negative correlation between these indices and short- and long-term variability of the fetal heart rate. There was a parallel increase in pulsatility in the ductus venosus and the transverse cerebral sinus. These changes were inversely correlated with fetal heart rate variability and preceded fetal distress. CONCLUSION: Cerebral venous blood flow in IUGR fetuses may be a useful additional investigation to discriminate between fetal adaptation and fetal decompensation in chronic hypoxemia.     

Retrograde net blood flow in the aortic isthmus in relation to human fetal arterial and venous circulations.

OBJECTIVES: To characterize changes in the human fetal arterial and venous circulations associated with retrograde aortic isthmus net blood flow. METHODS: Study groups consisted of fetuses with placental insufficiency and/or fetal growth restriction and either antegrade (Group 1; n = 18) or retrograde (Group 2; n = 11) net blood flow in the aortic isthmus. The control group comprised 31 fetuses in uncomplicated pregnancies. Pulsatility indices of the umbilical, middle cerebral and proximal pulmonary arteries and the descending aorta, and pulsatility indices for veins of the ductus venosus and inferior vena cava were calculated. Right and left ventricular fractional shortenings were ascertained. The coronary artery blood flow was visualized and the presence of tricuspid regurgitation was noted. RESULTS: In the study groups, the umbilical artery and descending aorta pulsatility indices were significantly higher (P < 0.05), and those of the middle cerebral artery lower (P < 0.001), than in the control group, with no difference between the two study groups. The proximal pulmonary artery pulsatility index was significantly higher in Group 2 (P < 0.001) than in Group 1 and the control group. In Group 2, the right ventricular fractional shortening was significantly lower (P < 0.01) than in Group 1. Coronary artery blood flow was visualized significantly more often (P < 0.03) and tricuspid regurgitation was present more frequently (P < 0.003) in Group 2 than in Group 1. In Group 2, the ductus venosus pulsatility index for veins was significantly higher than in Group 1 (P < 0.01) and the control group (P < 0.01), with no difference in the inferior vena cava pulsatility index for veins. CONCLUSIONS: Fetuses with retrograde aortic isthmus net blood flow demonstrate a rise in right ventricular afterload and increased pulsatility in ductus venosus blood velocity waveforms.     

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

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

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.     

生长受限胎儿静脉导管、脐动脉彩色多普勒血流监测的临床价值

目的探讨彩色多普勒超声(CDFI)监测生长受限(FGR)胎儿静脉导管、脐动脉的血流参数的临床价值。方法 50例FGR组胎儿,80例正常胎儿为对照组,CDFI检测其静脉导管前负荷指数(PLI)、心室收缩期峰值流速/心房收缩谷流速(S/a)、脐动脉心室收缩峰值流速/心舒张末期流速(S/D)及搏动指数(PI)。结果与对照组比较,FGR组脐动脉S/D、PI、静脉导管S/a、PLI均增高(P0.05)。脐动脉S/D正常组与S/D异常组比较、静脉导管S/a正常组与S/D异常组比较,分娩时孕龄、出生时新生儿体质量、5 min Apart评分、剖宫产率及围生期死亡率差异均有统计学意义(P0.05)。采用静脉导管S/a和脐动脉S/D均异常较仅采用脐动脉S/D异常预测妊娠结局的误诊率低,诊断指数高。结论应用CDFI监测FGR胎儿静脉导管及脐动脉血流参数有重要的临床价值。     

The sequence of changes in Doppler and biophysical parameters as severe fetal growth restriction worsens.

OBJECTIVE: To test the hypothesis that hemodynamic changes depicted by Doppler precede deteriorating biophysical profile score in severe intrauterine growth restriction. METHODS: Intrauterine growth-restricted fetuses with elevated umbilical artery Doppler pulsatility index (PI) > 2 standard deviations above mean for gestational age and birth weight < 10th centile for gestational age were examined longitudinally. Fetal well-being was assessed serially with five-component biophysical profile scoring (tone, movement, breathing, amniotic fluid volume and non-stress test) and concurrent Doppler examination of the umbilical artery, middle cerebral artery and ductus venosus, inferior vena cava and free umbilical vein. For fetuses with a final biophysical profile score < 6/10, progression of biophysical profile scoring, arterial PI and venous peak velocity indices were analyzed longitudinally. Gestational age effect was removed by converting indices to Z-scores (deviation from gestational age mean, in standard deviations). RESULTS: Forty-four of 236 intrauterine growth-restricted fetuses (18.6%) required delivery for abnormal biophysical profile scoring. The median gestational age at entry was 25 weeks and 1 day and at delivery was 29 weeks and 6 days. The median interval between examinations was 1.5 days and the majority had daily testing in the week prior to delivery. Between first examination and delivery, significant deterioration was observed for Doppler criteria (chi-square, P < 0.001) and biophysical parameters (Fisher's exact, P = 0.02) predominantly confined to the week prior to delivery/stillbirth. Doppler variables changed first. In 42 fetuses (95.5%), one or more vascular beds deteriorated, accelerating especially in the umbilical artery and ductus venosus at a median of 4 days before biophysical profile scoring deteriorated. Two to 3 days before delivery, fetal breathing movement began to decline. The next day, amniotic fluid volume began to drop. Composite biophysical profile score dropped abruptly on the day of delivery, with loss of fetal movement and tone. Three principal patterns of Doppler deterioration were observed: (i) worsening umbilical artery PI, advent of brain sparing and venous deterioration (n = 32, 72.7%); (ii) abnormal precordial venous flows, advent of brain sparing (n = 6, 13.6%); and (iii) abnormal ductus venosus only (n = 4, 9.1%). In the majority (31, 70.5%), Doppler deterioration was complete 24 h before biophysical profile score decline. In the remainder (11, 25%), Doppler deterioration and biophysical profile score < 6/10 were simultaneous. CONCLUSION: In the majority of severely intrauterine growth-restricted fetuses, sequential deterioration of arterial and venous flows precedes biophysical profile score deterioration. Adding serial Doppler evaluation of the umbilical artery, middle cerebral artery and ductus venosus to intrauterine growth restriction surveillance will enhance the performance of the biophysical score in the detection of fetal compromise and therefore optimizing the timing of intervention.     

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.     

Doppler ultrasound measurements in the central circulation of anesthetized fetal sheep during obstruction of umbilical-placental blood flow.

OBJECTIVE: To establish by Doppler ultrasound the effects of acute blockage of umbilical cord vessels on the fetal central circulation. DESIGN: Experimental study in anesthetized pregnant sheep. METHODS: In 11 anesthetized pregnant sheep (0.66 of gestation), Doppler velocity profiles and/or venous flow rates were recorded in the ductus venosus, the fetal aorta, the umbilical arteries and the umbilical vein. This involved three phases. In Phase 1, the abdominal wall was closed (n = 9); Phase 2 was during fetoscopy after laparotomy (n = 8); Phase 3 was after coagulation of one of the umbilical arteries (n = 10). As an additional intervention in six fetuses, the umbilical cord was clamped for 5-15 s while blood flow velocity changes in the ductus venosus were observed. RESULTS: There were no significant differences between Doppler recordings in Phases 1 and 2. During Phase 3, the pulsatility index of the aorta and of the coagulated umbilical artery increased significantly. The umbilical vein blood flow rate was significantly reduced from a median of 408 (range, 243-575) mL/min/kg in Phase 1 to a median of 173 (range, 107-426) mL/min/kg in Phase 3, but the blood flow rate in the ductus venosus (median, 94; range, 56-148 mL/min/kg vs. median, 92; range, 33-237 mL/min/kg) remained unchanged. The ductus venosus/umbilical vein ratio increased from a median of 0.22 (range, 0.13-0.41) to 0.56 (range, 0.17-0.97) (P < 0.05). Compression of the cord (5-15 s) immediately reduced the time averaged maximum velocity in the ductus venosus from a mean of 51 (standard deviation, 11) cm/s to 20 (standard deviation, 6) cm/s (P < 0.001) without significant changes of the velocity profile. However, the pulsatility index increased from a mean of 0.55 (standard deviation, 0.19) to 1.89 (standard deviation, 0.73) (P < 0.001). CONCLUSION: Central venous flows in anesthetized fetal sheep are unaffected by laparotomy and hysterotomy. Obliteration of one umbilical artery increases the ductus venosus/umbilical vein volume flow (mL/min/kg) ratio. Compression of the umbilical cord shifts down blood flow velocity profiles in the ductus venosus, and the pulsatility index thus increases.     

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   

Fetal arterial and venous Doppler parameters in the interpretation of oligohydramnios in postterm pregnancies.

OBJECTIVE: The objective of the current study was to evaluate fetal arterial and venous Doppler parameters in postterm pregnancies with oligohydramnios and those with normal amniotic fluid. STUDY DESIGN: A cross-sectional study was performed in 38 pregnancies beyond 41 weeks' gestation. Pulsed Doppler imaging was used to determine the pulsatility index (PI) for the fetal middle cerebral artery (MCA), renal artery, umbilical artery, inferior vena cava (IVC) and ductus venosus. The amniotic fluid index (AFI) was used for semiquantitive assessment of amniotic fluid volume. Oligohydramnios was defined as an AFI < 5 cm. RESULTS: Oligohydramnios was detected in 10 cases, and a normal AFI was present in 28 cases. In the presence of oligohydramnios the PI of the MCA was decreased, while the renal artery PI and the MCA PI/UA PI ratio were found to be elevated. In cases of oligohydramnios the PI in the IVC was increased but was unchanged in the ductus venosus. CONCLUSION: Oligohydramnios in post-term pregnancies is associated with arterial redistribution of fetal blood flow typifying the brain sparing effect and with decreased resistance in the MCA and increased resistance in the fetal IVC.     

彩色多普勒观察高危妊娠时硝酸甘油对胎儿－胎盘血流动力学的影响

本文介绍应用彩色多普勒超声技术观察３０例高危妊娠孕妇口含硝酸甘油前后的脐动脉、胎儿大脑中动脉、胎儿腹主动脉的血流动力学改变。结果：用药后脐动脉的搏动指数（ＰＩ）、阻力指数（ＲＩ）和Ｓ／Ｄ值均有显著改变（Ｐ＜０．００１），胎儿大脑中动脉和胎儿腹主动脉的ＰＩ、ＲＩ和Ｓ／Ｄ值无显著变化。而孕妇血压、心率和胎心率未见明显改变，呈现良好的耐受性。表明应用硝酸甘油可明显降低脐－胎盘血管阻力，是改善胎儿血氧供应的简便、有效的方法。而彩色多普勒超声显像则为围产期好高征早期诊断及疗效观察提供了重要的依据。     

Changes in fetal hemodynamics with ritodrine tocolysis.

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

Maternal uterine artery Doppler studies at high altitude and sea level.

OBJECTIVE: To determine uterine artery impedance using Doppler in the second and third trimesters at sea level and at high altitude. METHODS: Uterine artery resistance and pulsatility indices (RI and PI, respectively) were obtained by Doppler velocimetry from 242 women in Cerro de Pasco (4300 m altitude) and 200 women in Lima (sea level), all with normal singleton pregnancies between 14 and 40 weeks of gestation. Impedance indices at high altitude and sea level were compared using fractional polynomial regression analysis. RESULTS: Impedance to uterine artery blood flow was lower at high altitude than at sea level (for PI ratio Lima/Cerro de Pasco = 1.06; P = 0.011). If gestation bands were compared, the difference was significant up to 25 weeks. CONCLUSION: At high altitude, pregnancy is associated with lower uteroplacental impedance than at sea level. This may reflect a compensatory mechanism of uteroplacental development to lower oxygen tension associated with altitude.     

Doppler assessment of the normal early fetal circulation.

Combined transvaginal and transabdominal Doppler ultrasound allows recording of fetal intra- and extracardiac flow velocity waveforms in late first- and early second- trimester pregnancies. At 10-12 weeks, end-diastolic flow velocities were always absent in the fetal descending aorta and umbilical artery, but were present in over half of the intracerebral artery waveforms. The pulsatility index in the three vessels decreased significantly with advancing gestational age, suggesting a reduction in fetal and umbilical placental vascular resistance. Peak velocities during atrial contraction (A-wave) were nearly twice as high as those during early diastolic filling (E-wave), reflecting low ventricular compliance. Continuous forward flow in the umbilical vein was associated with a pulsatile systolic and diastolic forward flow in the ductus venosus. Retrograde flow was only present in the inferior vena cava.     

Ductus venosus Doppler study in fetuses with homozygous alpha-thalassemia-1 at 12 to 13 weeks of gestation.

OBJECTIVE: Fetuses affected by homozygous alpha-thalassemia-1 are anemic from the first trimester of pregnancy. We investigated ductus venosus Doppler velocimetry in these affected fetuses at 12-13 weeks of gestation. DESIGN: Prospective observational study. SUBJECTS: Women referred for the prenatal diagnosis of homozygous alpha-thalassemia-1 before 14 weeks of gestation. METHODS: All fetuses underwent pulsed Doppler investigations following color flow mapping at 12 or 13 weeks of gestation. Homozygous alpha-thalassemia-1 was diagnosed by DNA or hemoglobin study. The ductus venosus Doppler indices--Vmax (peak velocity during ventricular systole), Vmin (minimum forward velocity during atrial systole), TAMX (time-averaged maximum velocity), PIV (pulsatility index for veins, Vmax-Vmin/TAMX), PLI (preload index, Vmax-Vmin/Vmax) and Vmax/Vmin ratio--were compared between the affected fetuses and fetuses unaffected by homozygous alpha-thalassemia-1. RESULTS: Between June 1998 and October 1999, 102 eligible women were recruited. Fetal ductus venosus Doppler study was successful in 96 pregnancies (94%). Of these, 20 fetuses were affected by homozygous alpha-thalassemia-1. None of them showed hydropic changes at the time of Doppler study. The affected fetuses had significantly higher ducts venosus Vmax (30% increase), Vmin (50% increase) and TAMX (20% increase) and significantly lower Vmax/Vmin ratio, PIV and PLI values. CONCLUSION: Fetuses affected by homozygous alpha-thalassemia-1 at 12-13 weeks had increased forward flow velocities in the ductus venosus throughout the cardiac cycle. The increase of venous return is consistent with our previous report of cardiac dilatation and an increase of cardiac output in the affected fetuses at this stage as a compensatory mechanism for anemia and hypoxia. However, extensive overlap of the ductus venosus Doppler indices between affected and unaffected fetuses precludes its use in predicting anemia at 12-13 weeks.     

彩色多普勒超声监测生长迟缓胎儿脐动脉血液循环的变化

目的 应用彩色多普勒超声监测生长迟缓（IUGR）胎儿的脐动脉血液循环。方法 测定130例妊娠20－42周妇女（其中正常49例,IUGR81例）脐动脉时间平均血流速度（TAMX）,收缩期最大血流速度与舒张末期血流速度的比值（S／D）,搏动指数（PI）,阻力指数（RI）,收缩期最大血流速度（Vmax)与舒张末期血流速度（Vmin)。结果 正常孕妇随孕龄增长,胎盘功能增强,胎儿血液循环日渐丰富,IUGR者则明显障碍,在20周时脐动脉TAMX显著下降,在30周后S／D,PI及RI显著升高,Vmin显著下降,在35周时Vmax显著下降,出现舒张期血流停止或倒流。结论 彩色多普勒超声可直接测定脐动脉血流循环,能在早期诊断UGR,判断病情及估计预后。     

Fetal brain/liver volume ratio and umbilical volume flow parameters relative to normal and abnormal human development.

OBJECTIVES: To estimate fetal brain volume from head circumference and published postmortem data; to determine normal values for the fetal brain/liver volume ratio relative to gestational age; to establish the relationship between the brain/liver volume ratio and fetal circulatory parameters during normal and restricted (SGA) fetal growth. PATIENTS AND METHOD: This was a cross-sectional study involving a total of 47 uncomplicated pregnancies appropriate-for-gestational age (AGA) and 23 pregnancies resulting in the delivery of a SGA fetus. At enrollment gestational age ranged between 20 and 36 weeks in both groups. Umbilical venous cross-sectional area and time-averaged velocity for calculation of volume flow as well as velocity waveforms from the umbilical artery, middle cerebral artery and ductus venosus, were recorded. Fetal liver volume measurements were obtained using three-dimensional ultrasound. Fetal brain volume was estimated from fetal head volume following comparison with published postmortem data on fetal brain weight. RESULTS: A significant correlation was observed between prenatally estimated fetal head volume and postmortem fetal brain volume. Fetal brain volume was approximately half that of fetal head volume. The normal fetal brain/liver volume ratio demonstrated a significant reduction with gestational age (R = -0.54; P < 0.001). The normal mean +/- standard deviation (SD) fetal brain/liver volume ratio (3.4 +/- 0.7) was significantly different (P < 0.001) from the mean fetal brain/liver volume ratio in the SGA group (n = 23) (5.9 +/- 1.9). A significant difference existed for mean umbilical venous volume flow between AGA (104.7 +/- 26.9 mL/min/kg) and SGA (59.6 +/- 22.7 mL/min/kg) fetuses. In the SGA fetus, there was a significant inverse relationship (P < 0.001) between fetal weight-related umbilical venous volume flow and fetal brain/liver volume ratio. In a subset of 16 SGA and 16 AGA fetuses matched for gestational age, a significant difference existed for umbilical artery pulsatility index (2.30 +/- 1.52 vs. 0.99 +/- 0.19), fetal middle cerebral artery pulsatility index (1.3 +/- 0.4 vs. 2.1 +/- 0.3) and late diastolic flow velocity in the fetal ductus venosus (6.9 +/- 14.2 cm/s vs. 23.9 +/- 8.8 cm/s), but not for peak systolic, early diastolic and time-averaged velocity in the ductus venosus. CONCLUSION: Sonographic estimates of fetal brain volume can be obtained. The fetal brain/liver volume ratio is a predictor of fetal outcome in the growth-restricted fetus. An inverse relationship exists in SGA fetuses between brain/liver volume ratio and fetal weight-related umbilical venous blood flow.     

多普勒超声对高原地区胎儿脐动脉血流的研究

目的运用多普勒超声测量高原地区正常妊娠胎儿脐动脉血流,观察高原环境对胎儿脐带胎盘循环的影响。方法随机选取在外院(海拔2300 m)进行产前检查的正常妊娠孕妇103例为高原观察组,随机选取同期在我院(海拔44 m)进行产前检查的正常妊娠孕妇216例为平原对照组。高原组与平原组均按照孕周分为五组:20~23+6周、24~27+6周、28~31+6周、32~35+6周、36~40周,运用多普勒超声对两组胎儿脐动脉血流搏动指数(PI)、阻力指数(RI)、收缩期峰值流速与舒张末期流速比值(S/D)进行测定。结果孕中晚期五组中,高原组与平原组正常妊娠胎儿PI、RI和S/D差异均无统计学意义(P>0.05)。结论海拔2300 m高原地区正常妊娠胎儿脐带胎盘循环阻力与平原地区无明显差异。     

Reference values of fetal aortic flow velocity waveforms and associated intra-observer reliability in normal pregnancies.

OBJECTIVES: It was the aim of the present study to calculate new Doppler reference ranges for blood flow velocities (Vmax, Vmean, Vmin) and resistance indices (PI, RI) for the fetal descending aorta by automatic waveform analysis. DESIGN: Cross-sectional prospective study. SUBJECTS: Nine hundred and twenty-six low-risk pregnancies at 18-41 weeks' gestation. METHODS: Aortic blood flow velocities were derived with pulsed-wave color Doppler. Measurements were carried out at the level of the diaphragm. Reference ranges for the individual measuring parameters were constructed based on a growth function from a four-parameter class of monotonic continuous functions according to the smallest square principle. Further investigated were intra-observer reliability and the influence exerted by different measuring sites (aortic arch, diaphragm, below the renal vessels) on the aortic Doppler flow spectrum. RESULTS: Although a significant increase in aortic blood flow velocity was observed at 18-41 weeks' gestation (Vmax = 48.2 cm/s to 110.3 cm/s (P < 0.001), Vmean = 20 cm/s to 47.5 cm/s (P < 0.001) and Vmin = 7.6 cm/s to 18.6 cm/s (P < 0.001)), there were no significant changes in the pulsatility or resistance indices. The resistance indices PI and RI as well as absolute blood flow velocities (Vmax, Vmin) were significantly lower with increasing distance from the heart. Initial decreases were measured between the aortic arch and the diaphragm: PI, 2.34 to 1.87 (P < 0.0001); RI, 0.87 to 0.79 (P < 0.0001); Vmin: 8.5 cm/s to 15.0 cm/s (P < 0.0001). Furthermore, systolic blood flow velocities (Vmax) were decreased below the renal vessels from 97 cm/s to 64 cm/s (P < 0.0007). No significant changes were recorded in intensity-weighted mean flow velocities (Vmean). The intra-observer reliability was low, but of no clinical relevance. CONCLUSIONS: At constant measuring conditions, the reference ranges for blood flow velocities and resistance indices in the fetal aorta calculated by the authors serve as the basis for Doppler ultrasound antenatal examinations in a normal patient population and enable the early diagnosis of fetal risk.