Nifedipine therapy for preterm labor: effects on placental, fetal cerebral and atrioventricular Doppler parameters in the first 48 hours.

OBJECTIVE: To assess the effect of nifedipine tocolysis on Doppler parameters of the uterine, umbilical and fetal middle cerebral arteries and atrioventricular valves in the first 48 h of therapy. METHODS: Doppler waveforms of uterine, umbilical and middle cerebral arteries and both atrioventricular valves were measured from 28 pregnant women and fetuses prior to and during nifedipine therapy for preterm labor. Maternal and fetal heart rates (FHR), maternal systolic and diastolic blood pressure, and the Doppler pulsatility index (PI) of the uterine, umbilical and middle cerebral arteries were measured. The cerebroplacental ratio (middle cerebral artery PI/umbilical artery PI) was calculated. The total time velocity integrals (TVIs) of tricuspid and mitral valves and their E- and A-wave peak velocity ratio (E/A) were measured. Friedman repeated-measures analysis of variance was used to compare the variables before and after nifedipine therapy. If significant differences were found, Wilcoxon's signed ranks test was used to analyze the difference between the two variables. A P-value of < 0.05 was considered significant. RESULTS: Nifedipine maintenance was associated with a significant decline in maternal systolic and diastolic blood pressure after 24 h, while maternal heart rate and FHR were unaffected. The uterine artery PI had decreased significantly at 24 and 48 h, while the umbilical artery PI did not change significantly. The middle cerebral artery PI had decreased significantly at 24 and again at 48 h. A significant fall in the cerebroplacental Doppler ratio was maintained beyond 24 h. The mean E/A values, TVIs and TVI x FHR values at 24 and 48 h were unchanged from the baseline values. CONCLUSIONS: Nifedipine maintenance tocolysis is associated with a significant decline in uterine artery and middle cerebral artery Doppler indices 24 h after the first dose. Fetal cardiac diastolic function is unaffected and the significant redistribution observed after 24 h is likely to be attributable to altered cerebral blood flow.     

彩色多普勒血流动力学指标预测胎儿缺氧及酸中毒的价值

目的： 评价血液动力学指标预测胎儿缺氧及酸中毒的价值。方法： 用彩色多普勒超声检测 ５４ 例正常晚 期妊娠 （正常组） 和 ３６ 例高危妊娠 （高危组） 妇女子宫动脉 （ＵｔＡ） 和胎儿脐动脉 （Ｕｍ Ａ）、大脑中动脉（Ｍ ＣＡ）、肾动脉 （ＲＡ） 的血流速度波型 （ＦＶＷ ｓ）, 并且测定高危组脐动脉血气。结果： 高危组ＵｔＡ、Ｕｍ Ａ、ＲＡ 的阻力指数 （ＲＩ） 搏动指数 （ＰＩ） 及收缩期最大血流速度与舒张末期血流速度的比值 （Ｓ／Ｄ） 均高于正常组, 而Ｍ ＣＡ的ＰＩ及Ｓ／Ｄ 值均明显低于正常组 （Ｐ＜ ００５）。与Ｕｍ Ａ 氧分压 （ＰＯ２） ＞ ２５ｋＰａ 的高危妊娠病例比较, Ｕｍ Ａ ＰＯ２＜２５ ｋＰａ 者ＵｔＡ 的Ｓ／Ｄ 值, Ｕｍ Ａ 的ＰＩ, Ｓ／Ｄ 值以及ＲＡ 的ＲＩ、ＰＩ、Ｓ／Ｄ 值均明显增高, Ｍ ＣＡ 的ＰＩ明显降低 （Ｐ＜００５）。Ｕｍ Ａ 及ＲＡ 的ＰＩ与Ｕｍ Ａ ＰＯ２ 的ｐＨ 值呈负相关, 与二氧化碳分压 （ＰＣＯ２） 呈正相关, Ｍ ＣＡ 的ＰＩ与Ｕｍ Ａ的 ｐＨ、ＰＯ２ 呈正相关, 与ＰＣＯ２ 呈负相关。结论： 高危妊娠胎儿缺氧时, Ｍ ＣＡ 血流阻力降低, 而周围血管, 特别是肾血管血流阻力明显升高。胎儿血液动力学变化与缺氧及酸碱平衡失     

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。     

彩色多普勒超声检测胎儿脐动脉及大脑中动脉血流频谱对预测宫内窘迫的临床意义

目的探讨运用彩色多普勒检测胎儿脐动脉(UA)及大脑中动脉(MCA)血流频谱相关数值对预测胎儿宫内窘迫的临床意义。方法选取2013年9月至2015年3月随机分层抽取行中晚期孕检孕妇44例,其中健康孕妇组35例,宫内窘迫孕妇组11例,应用彩色多普勒超声检测上述两组胎儿UA及MCA的阻力指数(RI)、血流搏动指数(PI)、收缩期与舒张期流速比(S/D)。结果与健康孕妇组相比,宫内窘迫孕妇组胎儿UA的RI、PI、S/D明显增高,而MCA各血流频谱指标明显下降,差异均有统计学意义(P0.05)。结论通过检测中晚期妊娠胎儿UA及MCA各血流频谱的指标有助于发现胎儿宫内窘迫的发生,为提高围产质量提供检查手段。     

多普勒频谱分析胎儿宫内缺氧

目的综合分析子宫动脉、脐动脉及大脑中动脉多普勒指标(PI值)变化关系对评价胎儿缺氧的意义。方法运用多普勒技术检测90例因不良妊娠住院患者子宫动脉、胎儿脐动脉及大脑中动脉搏动指数(PI),回顾分析妊娠结局与各频谱参数变化的关系。结果子宫动脉异常(PI≥95th)伴脐动脉参数升高(PI>50th)和(或)大脑中动脉参数降低(PI<50th)者妊娠结局不良,且脐动脉参数升高至异常时(PI≥95th)围产儿病死率增高;子宫动脉正常时(PI<95th),脐动脉参数异常(PI≥95th)伴大脑中动脉参数降低者(PI<50th)妊娠结局不良;大脑中动脉血流参数异常者(PI≤5th)妊娠结局不良;单一子宫动脉或脐动脉血流参数异常者(PI≥95th)妊娠结局良好。结论综合分析子宫动脉、脐动脉及大脑中动脉频谱指标变化关系,可判定及评估胎儿缺氧情况、提示预后。     

Abnormal cardiac function in fetuses with increased nuchal translucency.

OBJECTIVE: To evaluate cardiac function in structurally and chromosomally normal fetuses with increased nuchal translucency (NT). METHODS: Forty-two structurally and chromosomally normal fetuses with increased NT at 11-14 weeks of gestation underwent fetal echocardiographic examination at 20-23 weeks. Fifty fetuses with normal NT values were considered as controls. Pulmonary and aortic peak velocity and time to peak velocities were measured as indices of ventricular systolic function. The ratios between the E-wave and A-wave (E/A) and the ratios between the E-wave and time velocity integral (E/TVI) at the level of both atrioventricular valves were evaluated as indices of ventricular diastolic function. RESULTS: In fetuses with increased NT the E/A ratios were significantly decreased when compared to control fetuses at the level of both the mitral (0.52 +/- 0.09 vs. 0.60 +/- 0.10, P = 0.0002) and tricuspid (0.51 +/- 0.09 vs. 0.61 +/- 0.09, P < 0.0001) valves. Similar results were found for the E/TVI ratios (mitral valve 4.79 +/- 1.03 vs. 5.63 +/- 1.23, P = 0.0007 and tricuspid valve 4.40 +/- 0.88 vs. 5.19 +/- 0.82, P < 0.0001). No significant relationship was found between the degree of NT and the abnormalities in Doppler indices. There were no significant differences in Doppler systolic indices. CONCLUSION: Structurally and chromosomally normal fetuses with increased NT have low E/A and E/TVI ratios at 20-23 weeks of gestation. These findings might indicate cardiac diastolic dysfunction.     

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.     

中孕筛查期胎儿循环血流动力学参数及与胎儿生长发育的相关性

  目的  研究中孕筛查期正常胎儿大脑中动脉(middle cerebral artery, MCA)、脐动脉(umbilical artery, UmA)及孕妇子宫动脉(uterine artery, UtA)血流动力学参数的关系, 并探讨各项参数与胎儿生长发育的相关性。  方法  2011年6月至2012年7月于本院超声医学科就诊的常规中孕筛查期(20~24⁺⁶周)孕妇206名, 测量胎儿常规物理测量指标如双顶径、头围、腹围及股骨长; 测量MCA、UmA及UtA的血流动力学参数, 包括峰值流速(peak flow velocity, PSV)、阻力指数(resistance index, RI)、搏动指数(pulsatility index, PI), 计算大脑胎盘搏动指数比值(CPR=MCA-PI/UmA-PI)和阻力指数比值(CRR=MCA-RI/UmA-RI)。  结果  孕20~24⁺⁶周胎儿MCA-PSV范围为13.63~37.96 cm/s, 随孕周增加而呈递增趋势; 而MCA-RI、MCA-PI、UmA-RI、UmA-PI、UtA-RI、UtA-PI及CPR、CRR随孕周变化不明显。MCA-RI与UmA-RI(r=0.51, P < 0.01)、MCA-PI与UmA-PI呈显著相关性(r=0.65, P < 0.01), 而UtA-RI、UtA-PI与MCA和UmA的相应指数均无明显相关性。MCA-PSV(cm/s)和孕周(GA, 周)呈线性相关关系:MCA-PSV=-0.17+1.02×GA(r=0.67, P < 0.01)。MCA-PSV与双顶径、头围具有相关性(r=0.29, P < 0.01;r=0.32, P < 0.01)。  结论  中孕筛查期胎儿MCA的RI和PI与UmA相应指数密切相关, 而与UtA血流动力学参数的相关性不大; MCA-PSV与孕周关系密切, 并受脑部发育的影响。     

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.     

中孕筛查期胎儿循环血流动力学参数及与胎儿生长发育的相关性简

目的研究中孕筛查期正常胎儿大脑中动脉（middle cerebral artery,MCA）、脐动脉（umbilical artery,UmA）及孕妇子宫动脉（uterineartery,UtA）血流动力学参数的关系,并探讨各项参数与胎儿生长发育的相关性。方法2011年6月至2012年7月于本院超声医学科就诊的常规中孕筛查期（20—24“周）孕妇206名,测量胎儿常规物理测量指标如双顶径、头围、腹围及股骨长;测量MCA、UmA及UtA的血流动力学参数,包括峰值流速（peak flow velocity,PSV）、阻力指数（resistance index,RI）、搏动指数（pulsatility index,PI）,计算大脑胎盘搏动指数比值（CPR=MCA—PI／UmA-PI）和阻力指数比值（CRR=MCA．R／／UmA—RI）。结果孕20～24＋6周胎儿MCA—PSV范围为13．63—37．96cm／s,随孕周增加而呈递增趋势;而MCA—RI、MCA—PI、UmA—RI、UmA。PI、UtA．RI、UtA-PI及CPR、CRR随孕周变化不明显。MCA-RI与UmA—RI（r=0．51,P〈0．01）、MCA-PI与UmA-PI呈显著相关性（r=0．65,P〈0．01）,而UtA—R1、UtA—PI与MCA和UmA的相应指数均无明显相关性。MCA—PSV（cm／s）和孕周（GA,周）呈线性相关关系：MCA—PSV=-0．17＋1．02×GA（r=0．67,P〈0．01）。MCA．PSV与双顶径、头围具有相关性（r=0．29,P〈0．01;r=0．32,P〈0．01）。结论中孕筛查期胎儿MCA的RI和PT与UmA相应指数密切相关,而与UtA血流动力学参数的相关性不大;MCA—PSV与孕周关系密切,并受脑部发育的影响。     

The impact of maternal plasma volume expansion and antihypertensive treatment with intravenous dihydralazine on fetal and maternal hemodynamics during pre-eclampsia: a clinical, echo-Doppler and viscometric study.

OBJECTIVES: To establish the effects of plasma volume expansion (PVE) followed by intravenous dihydralazine (DH) administration on maternal whole blood viscosity (WBV) and hematocrit, uteroplacental and fetoplacental downstream impedance and umbilical venous (UV) volume flow in pre-eclampsia. METHODS: In 13 pre-eclamptic women maternal and fetal hemodynamics were established by means of combined measurement of maternal arterial blood pressure (BP), WBV, hematocrit and uterine artery (UtA) resistance index (RI) in addition to umbilical artery (UA) pulsatility index (PI) and UV volume flow obtained from UV vessel area and UV time-averaged flow velocity. In each woman all parameters were measured four times at baseline, after PVE, after DH and 24 h after the start of treatment. RESULTS: Maternal diastolic BP, hematocrit and WBV display a significant reduction after PVE. In the fetus UA PI decreases significantly whereas a significant increase in UV cross-sectional area was detected. After maternal DH administration, arterial systolic and diastolic BP and UA PI show a significant decrease compared with the measurements following PVE. At 24 h, only maternal systolic and diastolic BP display a significant further decrease. No significant changes were established for the UtA RI, UV time-averaged velocity and UV volume flow during the entire study period. CONCLUSIONS: During pre-eclampsia, maternal PVE followed by DH administration results in a significant reduction in maternal diastolic BP, maternal hematocrit and WBV. Maternal PVE is associated with a significant increase in UV cross-sectional area and a non-significant rise of 11% in UV volume flow. Maternal DH administration does not result in any change in UV cross-sectional area. However, UA PI decreases significantly after both PVE and DH treatment.     

Evaluation of Utero-placental and Fetal Hemodynamic Parameters Throughout Gestation in Pregnant Mice Using High-Frequency Ultrasound

Throughout gestation, changes in maternal and fetal Doppler parameters in pregnant mice, similar to those obtained in human fetuses, were detected using high-frequency ultrasound with a 55-MHz linear probe. In the uterine arteries (UtA), fetal umbilical artery (UA) and fetal ductus venosus (DV) peak systolic velocity increased (UtA, p = 0.04; UA, p = 0.0004; DV, p = 0.02), end-diastolic velocity increased (UtA, p < 0.001; UA, p < 0.0001; DV, p = 0.01) and resistance index decreased (UtA, p = 0.0004; UA, p = 0.0001; DV, p = 0.04) toward the end of pregnancy. In the middle cerebral and carotid arteries, end diastolic velocity increased (p = 0.02 and p < 0.0001) and resistance index decreased (both vessels, p < 0.0001). There was a reduction in the pulsatile pattern in the umbilical vein (p < 0.05). The increased velocities and reduced resistance index suggest a progressive increment in blood flow to the fetal mouse toward the end of pregnancy. Fetal and utero-placental vascular parameters in CD-1 mice can be reliably evaluated using high-frequency ultrasound.     

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。     

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.     

Fetal hemodynamics evaluated by Doppler velocimetry in the second half of pregnancy

The objective of our study was to assess fetal hemodynamics by Doppler velocimetry during the second half of pregnancy. We carried out a longitudinal study on 33 normal fetuses between the 22nd and 38th weeks of gestation. Doppler velocimetry was performed in the aorta, suprarenal (SRA) and infrarenal (IRA) segments, middle cerebral artery (MCA) and umbilical artery (UA), on the basis of fetal peak systolic velocity (SV), end-diastolic velocity (DV) and resistance index (RI). We used a sample volume of 1 mm, a wall filter of 50 to 100 Hz, a 5 degrees to 19 degrees insonation angle in the MCA and UA, and below 60 degrees in the SRA and IRA. Between the 22nd and 38th weeks of gestation, SV and DV increased in all fetal arteries (p<0.05), but SV decreased in the UA from 52.5 to 46.2 cm/s between the 34th and 38th gestational weeks (p<0.05). The RI was unchanged in the SRA and throughout most of the gestational weeks in the IRA (p>0.05), but decreased from 0.69 to 0.56 in the UA (p<0.05). In the MCA, it decreased from 0.85 to 0.75 between the 26th and 38th gestational weeks (p<0.05). In conclusion, the volume of blood flow in the fetal organs necessary for their development is related to increased SV and DV and to decreased RI. The Doppler velocimetry measurements for normal fetuses could be compared with those for fetuses in high-risk pregnancies.     

Abnormal fetal cerebral and umbilical Doppler measurements in fetuses with intrauterine growth restriction predicts the severity of perinatal morbidity

PURPOSE: This prospective study was performed to determine if the ratio of the middle cerebral artery (MCA) S/D ratio (ratio of peak systolic blood flow velocity to diastolic velocity) to the umbilical artery (UA) S/D ratio (MCA/UA S/D ratio) predicts the degree of neonatal morbidity in fetuses suspected of having intrauterine growth restriction (IUGR). METHODS: Sixty-one fetuses were identified prospectively by sonography as having an estimated fetal weight below the 10th percentile for gestational age. The 61 fetuses underwent Doppler sonography in the third trimester and then were stratified into 3 groups based on the MCA/UA S/D ratio: group A, MCA/UA S/D ratio > 1.0 (controls; n = 37); group B, MCA/UA S/D ratio < or = 1.0 (intracerebral blood flow redistribution; n = 16); and group C, reversed or absent UA diastolic flow (n = 8). Outcome variables assessed included gestational age at delivery, birth weight, UA pH, mode of delivery, respiratory distress syndrome requiring intubation, and intracranial hemorrhage. RESULTS: The mean MCA/UA S/D ratios in groups A and B were 1.69 + /- 0.61 and 0.59 + /- 0.24, respectively (p < 0.01). The mean gestational ages at delivery for groups A, B, and C were 34.7, 33.2, and 29.0 weeks, respectively. The mean birth weights were below the fifth percentile for age for groups B and C and significantly related to the severity of abnormal Doppler findings (p < 0.01) after correction for age. Mean UA pHs were 7.25 + /- 0.01, 7.19 + /- 0.01, and 7.14 + /- 0.13 for groups A, B, and C, respectively, with significant differences between groups A and B (p < 0.05) and groups A and C (p < 0.05). Respiratory distress syndrome and intracranial hemorrhage were not associated with abnormal Doppler findings after correction for gestational age. The interval between the abnormal Doppler examination and delivery (p < 0.001) and the occurrence of fetal distress requiring cesarean section (p < 0.001) were significantly related to the severity of Doppler findings. CONCLUSIONS: In fetuses with suspected IUGR, abnormal MCA/UA S/D ratios are strongly associated with low gestational age at delivery, low birth weight, and low UA pH. Abnormal MCA/UA S/D ratios are also significantly associated with shorter interval to delivery and the need for emergent delivery.     

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.     

彩超对胎儿大脑中动脉与脐动脉血流动力学的相关性研究

目的:探讨彩超对胎儿大脑中动脉(MCA)与脐动脉(UA)血流动力学之间的关系.方法:检查分析300例中、晚孕胎儿的MCA和UA的血流动力学参数,研究其间的关系.结果:(1)随着孕龄的增加,MCA和UA的峰值流速与舒张末期流速比值(S/D),阻力指数(RI),搏动指数(PI)均相应减小,MCA的各血流参数均相应大于UA的各血流参数(P＜0.01),(2)不论孕龄如何变化,MCA和UA的S/D、RI、PI关系密切,均呈直线正相关(P＜0.01),(3)收缩期峰值流速(PSV),舒张末期流速(EDV)相关性不明显(P>0.05).结论:UA血流动力学异常是造成脑血流动力学异常的重要因素,进一步证明了检测胎儿UA血流动力学变化对评价胎儿宫内生长发育的重要意义.     

Potential for diagnosing imminent risk to appropriate- and small-for-gestational-age fetuses by Doppler sonographic examination of umbilical and cerebral arterial blood flow.

In a prospective study, 215 pregnancies of known gestational age were investigated using Doppler sonography. Multiple pregnancies and pregnancies complicated by fetal malformations were excluded. A pulsed Doppler machine was used to record the flow velocity waveforms in the umbilical artery (UA) and middle cerebral artery (MCA). The pulsatility index (PI) of both vessels and the ratio of PI UA to PI MCA were calculated. A total of 127 pregnancies ended in the birth of appropriate-for-gestational age babies with no perinatal problems; these formed the normal group (Group A). Of the 88 pregnancies which made up the risk group, 17 were appropriate-for-gestational age babies with perinatal problems (Group B), 55 were small-for-gestational-age babies with no perinatal problems (Group C), and 16 were small-for-gestational age babies with perinatal problems (Group D). Normal ranges were calculated based on the results for Group A; the measured values for the risk groups were then compared to these. There were highly significant differences between values obtained from the risk groups and those of Group A with the exception of the umbilical artery in Group B and the middle cerebral artery in Group C. The best results came from the values for MCA in Group B (sensitivity = 71%), UA in Group D (sensitivity = 75%), and the PI ratio UA : MCA in Group D (sensitivity = 81%). The sensitivity for the ratio in Group D increased to 93% if only the last measurement for each patient taken within 14 days of delivery was analyzed. A drop in the MCA PI in appropriate-for-gestational-age fetuses was the best indicator of imminent risk of hypoxemia. The PI ratio of UA : MCA is valuable in monitoring small-for-gestational-age fetuses, particularly those with high UA PI levels, as a rise in the ratio provides an early indication of fetal risk.     

远程胎心监护联合超声检测对胎儿宫内缺氧的预测效果分析

目的观察远程胎心监护联合超声检测对胎儿宫内缺氧的预测效果,探讨最佳诊断措施。 方法选取2016年6月至2017年6月杭州市妇产医院收治的行超声检查且住院分娩的孕晚期孕妇210例,65例经临产前及产后诊断证实为宫内缺氧,将其作为观察组,同时期本院体检中心145例健康妊娠者,作为对照组,对所有研究对象均行远程胎心监护以及超声检测。测得大脑中动脉（MCA）、脐动脉（UA）以及大脑中动脉/脐动脉（MCA/UA）中的血流速度的比值（S/D）、阻力指数（RI）、搏动指数（PI）测值。观察组与对照组MCA、UA、MCA/UA等参数比较采用t检验;远程胎心监护情况（有反应型、无反应型、可疑型）观察组与对照组比较采用χ²检验。 结果观察组的胎心监护异常者58例,约占87.93%;对照组异常者20例,约占13.79%,两者比较,观察组高于对照组,差异有统计学意义（χ²=214.925,P<0.001）。与对照组比较,观察组的MCA中的S/D、RI、PI均降低明显,UA以及MCA/UA中的S/D、RI、PI均增加明显,差异均有统计学意义（t=8.91、10.23、8.46、5.20、4.66、16.57、10.99、14.71、13.8,P均<0.001）,进行指标的两两组合,结果发现,联合诊断的敏感度、Youden指数均最高。 结论远程胎心监护联合超声检测可较好的预测胎儿宫内缺氧情况,具有较好的应用价值。