Appearance of abnormal electrocorticogram patterns during umbilical cord compression in sheep fetus

A frequent cause of fetal acidemia, which sometimes results in hypoxic-ischemic encephalopathy, is umbilical cord compression associated with uterine contraction. Using a sheep model of fetal acidemia, we examined the changes in electrocorticogram (ECoG), carotid artery blood flow, arterial blood pressure and fetal heart rate during cord compression. A characteristic burst of ECoG spikes emerged during cord compression at fetal arterial pH 7.18 even before the pH went down to severe fetal acidemia (less than 7.10). The administration of a neuromuscular blocking agent to the fetus did not abolish the appearance of the spikes. These results suggest that cord compression may cause abnormal brain excitement even in the absence of severe fetal acidemia and that this abnormal excitement can lead to fetal brain dysfunction, if cord compression is repeated or prolonged.     

Characteristics of blood flow in intrauterine growth-restricted fetuses with hypercoiled cord.

OBJECTIVE: To clarify the characteristics of fetoplacental blood flow of growth-restricted fetuses with hypercoiled umbilical cord. SUBJECTS: Eight growth-restricted fetuses with hypercoiled cord. METHODS: Flow velocity waveforms of the umbilical cord artery and vein, fetal abdominal aorta and fetal inferior vena cava were analyzed. RESULTS: The resistance index in the umbilical artery in the hypercoiled cases was lower than that in normal fetuses. Early-diastolic reversed flow was observed in the abdominal aorta in some cases. In all cases, umbilical venous pulsation was observed in the entire cord until delivery. In one case, fetal heart failure occurred, resulting in pre-mature delivery. An atrophic type of single umbilical artery was observed in four cases. CONCLUSION: Fetal blood flow disturbance caused by a hypercoiled umbilical cord may be a cause of growth restriction.     

脉冲式多普勒测定胎儿C/P值及其与脐动脉低氧血症的相关性研究

研究胎儿大脑中动脉搏动指数(PI_MCA)和脐动脉搏动指数(PI_UA)之比(C/P)与新生儿脐动脉低氧血症的关系,使C/P值应用于临床诊断和预测。应用多普勒超声技术,对52例妊娠晚期妇女进行胎儿MCA和UA血流速度波型检查,将C/P值与选择性剖宫产相应新生儿脐动脉血气分析和围产儿结局比较。结果:正常妊娠胎儿C/P值为2.0,重度妊高征、过期妊娠及重度胎动异常孕妇胎儿C/P值小于1;C/P值的降低与新生儿脐动脉低氧、酸中毒及不良围产儿结局相关。结论:C/P值是估计妊娠晚朗胎儿宫内低氧、预测宫内窘迫的敏感指标。     

超声多普勒血流检测诊断胎儿脐带绕颈：附75例分析

本文应用超声血流分析仪对414例妊娠30—42w的孕妇进行了脐动脉血流检测,诊断脐带绕颈75例,经分娩证实72例,敏感性96%,特异性94.2%。本文还就胎儿颈部脐血流检测诊断脐带绕颈的部位进行了分析,提出胎儿颈部背、腹两侧皆有典型脐动脉血流波时敏感性、特异性最高,只有颈部腹侧有典型脐动脉血流波时敏感性,特异性最低。其次提出多普勒诊断胎儿脐带绕颈随孕周的增加准确性增加,多普勒诊断脐带绕颈的同时所检测脐动脉s/d比值可预测胎儿预后,特别是s/d比值连续升高时对推测脐带绕颈的松紧有所帮助,为临床选择恰当的分娩方式提供了更多指标,对降低围产儿死亡率有重要意义。     

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.     

Relationship between arterial and venous Doppler and perinatal outcome in fetal growth restriction.

OBJECTIVE: The aim of this investigation was to assess the relationship between abnormal arterial and venous Doppler findings and perinatal outcome in fetuses with intrauterine growth restriction (IUGR). METHODS: Doppler velocimetry of the umbilical artery (UA), middle cerebral artery (MCA), inferior vena cava (IVC), ductus venosus (DV) and free umbilical vein was performed in 121 IUGR fetuses with a UA pulsatility index (PI) > 2 SD above the gestational age mean and subsequent birth weight < 10th centile for gestational age. Groups based on the last Doppler exam were: 1 = abnormal UA-PI only (n = 42, 34.7%), 2 = MCA-PI > 2 SD below the gestational age mean (= 'brain sparing') in addition to abnormal UA-PI (n = 29, 24.0%), 3 = DV or IVC peak velocity index (PVIV) > 2 SD above the gestational age mean and/or pulsatile UV flow (n = 50, 41.3%). Z-scores (delta indices) were calculated for Doppler indices. Perinatal mortality, respiratory distress (RDS), bronchopulmonary dysplasia (BPD), intraventricular hemorrhage (IVH), necrotizing enterocolitis (NEC), circulatory failure and umbilical artery blood gases were recorded. RESULTS: Absence or reversal of umbilical artery end-diastolic flow was observed in 4 (9.5%) of fetuses in group 1, 10 (34.5%) fetuses in group 2 and 41 (82%) fetuses in group 3. A low middle cerebral artery pulsatility index was found in 39 (78%) fetuses in group 3. Multiple regression analysis with gestational age at delivery, delta indices and cord artery blood gas as independent parameters and individual perinatal outcomes as dependent variables was performed. In this analysis the association was strongest with gestational age for each complication. There were no significant differences in Apgar scores between groups. At delivery, 'brain sparing' was associated with hypoxemia and abnormal venous flows with acidemia. Perinatal mortality was highest in group 3 and stillbirth was only observed when venous flow was abnormal. All postpartum complications were more frequent in fetuses with abnormal venous flows. The only statistically significant relation between Doppler indices and outcome was the association between abnormal ductus venosus flow and fetal death (r2 = 0.24, P < 0.05). CONCLUSION: Growth restricted fetuses with abnormal venous flow have worse perinatal outcome compared to those where flow abnormality is confined to the umbilical or middle cerebral artery. In fetuses with low middle cerebral artery pulsatility, venous Doppler allows detection of further deterioration. While abnormal venous flows can be significantly associated with fetal demise, gestational age at delivery significantly impacts on all short-term outcomes.     

The natural history of an umbilical cord hemangioma

Umbilical cord hemangiomas are rare, and the natural history is poorly understood. We present a case where the clinical course was complicated by distal umbilical cord edema, episodes of proximal obstruction of umbilical artery blood flow, transient fetal pleural and pericardial effusions, and position‐dependent abnormal fetal heart rate monitoring with periods of sustained fetal tachycardia. Delivery was performed for fetal growth restriction with abnormal fetal surveillance. This case highlights possible mechanisms for fetal decompensation as well as the importance of a multifaceted approach to the management of an umbilical cord mass using multiple tools for fetal assessment. © 2016 Wiley Periodicals, Inc. J Clin Ultrasound 44 :455–458, 2016;     

孕中晚期卵圆孔瓣宫内闭合与脐带扭转的相关性研究

目的卵圆孔瓣宫内闭合是妊娠中晚期胎儿出现右心扩大、缺氧、胎儿水肿,甚至宫内死亡的重要原因之一。应用胎儿超声检查观察孕中晚期卵圆孔瓣闭合与脐带扭转之间的关系。方法 8例中晚期胎儿经超声检查发现胎儿心脏卵圆孔瓣宫内闭合。常规检测胎儿心脏结构,除外结构性心脏发育异常,检测胎儿心脏左、右心比例、卵圆孔径、由于卵圆孔瓣部分闭合剩余交通口径,卵圆孔过隔血流速度,静脉导管阻力指数,动脉导管血流速度。对胎儿进行常规生物学指标检测,重点观察胎儿脐带,计算脐带扭转指数。与出生后脐带状况对照。结果卵圆孔瓣宫内闭合的8例胎儿,右心与左心比例增大,卵圆孔瓣闭合呈瘤样膨隆,剩余交通口径明显减小,卵圆孔血流速度未见明显增快。静脉导管阻力指数轻度增高。部分胎儿动脉导管血流速度增加。脐静脉扭转指数均增加。其中顺产2例,剖宫产6例。出生后发现脐带扭转3例,脐带打真结1例,脐带绕颈极紧1例,球拍状胎盘1例。出生后脐带阳性表现占本研究病例75%。结论脐带宫内异常特别是扭转或打结以及其他因素致通过卵圆孔血流量减少,可能是孕中晚期胎儿卵圆孔瓣宫内闭合的重要原因,是胎死宫内的危险因素。     

Assessment of umbilical arterial and venous flow using color Doppler.

OBJECTIVE: To estimate the umbilical artery and vein blood volume flow using B-mode and Doppler ultrasound in the second and third trimesters of pregnancy. DESIGN: This was a cross-sectional study of 129 singleton, healthy pregnancies at 23-33 weeks' gestation. The umbilical artery and vein cross-sectional area, time-averaged velocity and pulsatility index were measured in a free loop of cord, and the fetal weight was estimated. Ranges for each parameter were obtained; from these the blood flow for the vein and artery was calculated, and the average flow corrected for fetal weight was derived. RESULTS: The median time for examination was 6 min. The mean cross-sectional area and time-averaged velocity for both the vein and artery increased linearly with gestation. The umbilical artery flow correlated closely with the average vein flow (r = 0.9, p < 0.001). There was a significant, though poor, inverse correlation between the umbilical artery pulsatility index and the average umbilical flow (r = -0.25, p < 0.05). The average umbilical flow (calculated from the mean of arterial and venous flow), corrected for estimated fetal weight, decreased from 189.2 ml/kg per min at 23 weeks to 176.2 ml/kg per min at 33 weeks' gestation. CONCLUSION: The estimates of fetal umbilical flow obtained by this Doppler method are consistent with previously published data. Averaging the arterial and venous flow is theoretically advantageous in reducing the inherent errors in estimating either the arterial or the venous flow. This method of measuring umbilical flow may have clinical potential in assessing fetal health and disease processes.     

Ductus venosus blood flow velocity characteristics of fetuses with single umbilical artery.

OBJECTIVES: Sonographic Doppler evaluation of the fetal ductus venosus has been proved to be useful in the evaluation of fetal cardiac function. The aim of this study was to investigate the ductus venosus blood flow profile in fetuses with single umbilical artery and to correlate it with the umbilical cord morphology. METHODS: Fetuses at >20 weeks' gestation with single umbilical artery who were otherwise healthy were consecutively enrolled into the study. The sonographic examination included evaluation of the following Doppler parameters: umbilical artery resistance index, maximum blood flow velocity of the ductus venosus during ventricular systole (S-peak) and atrial contraction (A-wave), ductus venosus time-averaged maximum velocity (TAMXV), and pulsatility index for veins (PIV). The cross-sectional area of the umbilical cord and its vessels were measured in all cases. The Doppler and morphometric values obtained were plotted on reference ranges. RESULTS: A total of 88 fetuses with single umbilical artery were scanned during the study period. Of these 52 met the inclusion criteria. The S-peak velocity, A-wave velocity, and TAMXV were below the 5th centile for gestational age in 57.7%, 59.6%, and 57.7% of cases, respectively. The PIV was within the normal range in 80.1% of cases. The umbilical vein cross-sectional area of fetuses with single umbilical artery was above the 95th centile for gestational age in 34.6% cases. CONCLUSIONS: The ductus venosus blood flow pattern is different in fetuses with single umbilical artery from that in those with a three-vessel cord. This difference may be caused in part by the particular morphology of umbilical cords with a single artery.     

胎心监护联合脐血流测定对胎儿宫内窘迫诊断的意义

目的：观察和评价胎心监护联合脐血流测定对诊断胎儿宫内窘迫的意义。方法选取208例单胎分娩孕妇作为研究对象,根据脐血流测定与胎心监护检查结果,将其分为A、B、C、D4个组,A组为脐血流测定、胎心监护均正常;B组为脐血流测定、胎心监护均异常;C组为脐血流测定异常而胎心监护正常;D组为脐血流正常而胎心监护异常。对研究对象产前、产时胎儿宫内窘迫发生率及胎儿预后进行观察和分析。结果4个组胎儿的1min新生儿评分（Apgar评分）均在4～10分,其中,A组中评分为8～10分的胎儿比例明显高于其他3个组,差异有统计学意义（P＜0．05）,而B、C、D3个组之间的差异无统计学意义（P＞0．05）;4个组胎儿间羊水污染程度的差异无统计学意义（P＞0．05）;A组和C组之间胎心异常率的差异无统计学意义（P＞0．05）,B组和D组之间胎心异常率的差异无统计学意义（P＞0．05）,但B组均明显高于A组与C组,且差异有统计学意义（P＜0．05）。结论胎心监控联合脐血流检查对于诊断胎儿宫内窘迫具有较高的意义和价值,可弥补单独应用一种方法的不足,提高诊断的可靠性,值得在临床上推广使用。     

多普勒超声联合母血VIP、NPY检测宫内胎羊缺氧

目的探讨胎羊脐动脉搏动指数（UAPI）、静脉导管搏动指数（DVPI）、肾动脉搏动指数（RAPI）联合母羊血清神经肽Y（NPY）、血管活性肠肽（VIP）评估胎羊宫内缺氧的意义。 方法实验组胎羊采用间断性脐带血流阻塞法（UCO），用多普勒超声测量实验组和对照组胎羊UAPI、RAPI、DVPI，测母羊血NPY和VIP浓度及胎羊血气分析。 结果UCO后实验组胎羊氧分压（PaO2）、pH下降，二氧化碳分压（PaCO2）、UAPI、DVPI、RAPI、VIP、NPY升高，VIP、NPY、血流动力学与血气及VIP、NPY与血流动力学有明显相关。 结论血流动力学检查联合NPY、VIP评估胎羊宫内缺氧可能更有意义。     

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。     

Antenatal umbilical coiling index and Doppler flow characteristics.

OBJECTIVE: To evaluate whether a relationship exists between the antenatal umbilical coiling index (UCI) and umbilical cord Doppler flow characteristics. METHODS: During the fetal anatomical survey in 200 consecutive pregnant patients at 18-23 weeks' gestation, we recorded umbilical coiling patterns and blood flow characteristics. The antenatal UCI, calculated as a reciprocal value of the distance between a pair of umbilical cord coils, was compared with Doppler parameters including umbilical vein blood flow volume (in mL/min/kg), and mean resistance index (RI) and peak systolic velocity (PSV in cm/s) averaged from both umbilical arteries. RESULTS: A total of 154 patients met the inclusion criteria of singleton pregnancy and having adequate sonographic umbilical cord images, Doppler flow indices, and all demographic, antenatal and labor data. The mean antenatal UCI was 0.40, with 10th and 90th centiles of 0.20 and 0.60, respectively. The mean +/- SD umbilical artery RI and PSV and umbilical vein blood flow volume were 0.74 +/- 0.07, 25.1 +/- 6.4 cm/s, and 264 +/- 106 mL/min/kg, respectively. All Doppler variables correlated significantly with antenatal UCI, with lower RI and higher PSV and umbilical vein blood flow volume values being associated with higher antenatal UCI (P = 0.016, P < 0.001, and P = 0.032, respectively). However, when stratified by antenatal UCI into hyper- (above 90th centile), normo- (10th-90th centile), and hypocoiled (below 10th centile) umbilical cord groups, a significant difference was observed for PSV only (P = 0.016). CONCLUSION: It appears that umbilical cord coiling modulates noticeably blood flow through the umbilical cord. We speculate that more prominent umbilical coiling (higher antenatal UCI values) has a protective effect on blood flow in terms of decreased arterial resistance and higher blood flow velocities, as well as increased venous blood flow. However, due to lack of significant differences between Doppler characteristics when stratified by antenatal UCI into hypo-, normo-, and hypercoiled groups, the clinical implications of this observation are uncertain.     

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.     

Fetal heart rate and umbilical artery velocity variability in fetuses with congenital cardiac defects: a preliminary study.

OBJECTIVE: To examine whether variabilities in fetal heart rate and umbilical artery flow velocity are possible markers for hemodynamic dysfunction in fetuses with a congenital heart defect. METHODS: Doppler studies of the umbilical artery velocity waveform were performed at 20-35 weeks of gestation in 13 patients with a congenital heart defect. We determined absolute and variability values for heart rate and flow velocities from umbilical artery velocity waveforms of at least 18 s duration. We compared these findings with normal controls matched for gestational age. RESULTS: Fetuses with a congenital heart defect displayed decreased umbilical artery peak systolic and time-averaged velocities. However, variability in peak systolic and time-averaged velocities and fetal heart rate variability were increased compared with normal controls. Absolute fetal heart rates were similar between the two groups. CONCLUSIONS: Marked cardiovascular changes occur in the fetus with a congenital heart defect compared with the normal healthy fetus. We propose that variability in fetal heart rate and umbilical artery blood flow velocity could be additional markers for impaired homeostasis in the presence of fetal congenital heart disease.     

Coronary artery blood flow visualization signifies hemodynamic deterioration in growth-restricted fetuses.

OBJECTIVE: To determine the relationship between fetal coronary blood flow (CBF) visualization in intrauterine growth restriction (IUGR), longitudinal changes in arterial and venous flow velocity waveforms and perinatal outcome. METHODS: A total of 48 IUGR fetuses (abdominal circumference below the 5th percentile for gestational age) with absent or reversed umbilical artery (UA) end-diastolic velocity (AREDV) were examined longitudinally by echocardiography attempting CBF visualization at each examination. Doppler evaluation of the middle cerebral artery, inferior vena cava (IVC), ductus venosus (DV) and umbilical vein (UV) was performed at each examination. Doppler measurements were correct for gestational age by conversion into Z-scores (delta-indices). Doppler results and outcome from fetuses in which CBF was visualized (group 1, n = 20) and those in which CBF was never visualized (group 2, n = 28) were compared. Outcome parameters analyzed included Apgar scores, cord arterial blood gases, perinatal mortality, respiratory distress, bronchopulmonary dysplasia, intraventricular hemorrhage, necrotizing enterocolitis and postpartum circulatory failure requiring pressor support. RESULTS: There was no difference in Doppler indices between groups at study entry. CBF visualization coincides with a significant increase of UA-, IVC- and DV delta-indices. The greatest rate of change was observed for indices in the ductus venosus which occurred in the 24 h preceding CBF visualization. Group 1 fetuses required earlier delivery (median 27 + 4, vs. median 30 + 0), had lower birthweight (682 +/- 305 g vs. 936 +/- 416 g), lower cord pH (7.21 +/- 0.1 vs. 7.27 +/- 0.06) and cord pO2 (13 +/- 4.5 vs. 24.1 +/- 13.5 mmHg) compared to group 2 (all values P < 0.05). Mortality was similar (group 1 = 6/20, 30%; group 2 = 6/28, 21.4%). CONCLUSIONS: In IUGR, fetuses with AREDV and centralization are at high risk for hypoxemia, acidemia and adverse outcome. CBF visualization coincides with deteriorating venous flows. Operator dependence of CBF visualization and the strong association with abnormal venous flow stresses the importance of venous Doppler surveillance in these fetuses.     

脐带绕颈胎儿脐动脉及大脑中动脉超声血流参数的特点及与胎儿宫内窘迫的相关性分析

目的探讨脐带绕颈胎儿脐动脉(UA)及大脑中动脉(MCA)超声血流参数的特点及与胎儿宫内窘迫的相关性。方法将106例胎儿脐带绕颈孕妇、100例正常孕妇分别纳入脐带绕颈组、非脐带绕颈组。根据不同孕周、是否发生胎儿宫内窘迫对脐带绕颈组孕妇进行再次分组,分别为28~36周组(52例)、≥37周组(54例);宫内窘迫组(28例)、非宫内窘迫组(78例)。比较各组UA、MCA的RI、PI、S/D。分析UA、MCA超声血流参数与胎儿宫内窘迫的相关性。结果脐带绕颈组UA、MCA的RI、PI、S/D均高于非脐带绕颈组(P<0.05)。28~36周组UA、MCA的RI、PI、S/D均低于≥37周组(P<0.05)。宫内窘迫组UA的PI、S/D高于非宫内窘迫组,MCA的RI、PI、S/D高于非宫内窘迫组(P<0.05)。Logistic回归分析结果显示,UA、MCA的PI、RI、S/D与胎儿宫内窘迫存在明显相关性(P<0.05)。结论脐带绕颈胎儿UA、MCA超声血流参数(RI、PI、S/D)均高于非脐带绕颈胎儿,且孕晚期更为突出,UA及MCA的RI、PI、S/D与胎儿宫内窘迫呈高度相关。     

Fused umbilical arteries: prenatal sonographic diagnosis and clinical significance.

This report describes a series of 5 fetuses with fused umbilical arteries that had the prenatal feature of a single umbilical artery near the placental insertion and the normal 2 umbilical arteries at the fetal end of the cord. In 1 case this vascular anomaly was associated with unilateral renal agenesis in a fetus with a subsequent diagnosis of Hallermann-Streiff syndrome. No perinatal complications were identified in the remaining 4 fetuses. Postpartum examination of the cord revealed that the 2 umbilical arteries fused to form 1 artery for a long segment of the distal portion of the cord. Our findings suggest that the prenatal evaluation of the umbilical cord to document the number of vessels should include multiple views of the cord and demonstration of the 2 intra-abdominal umbilical arteries with color Doppler imaging for a confident diagnosis. Our observation also suggests that, at least in some cases, single umbilical artery may result from incomplete splitting of the single artery normally present in early human embryos.     

Does acute hypoxia cause fetal arterial blood flow redistribution?

Chronic fetal hypoxia in fetal growth restriction due to impaired placentation is associated with centralization of blood flow to the vital organs, such as brain, heart and adrenal glands, in order to maintain oxygenation. There is a correlation between fetal hypoxemia and low impedance to blood flow in the middle cerebral artery. However, there is no association between abnormal flow velocity waveforms and fetal distress in an unselected population, and this reported case also suggests that Doppler ultrasound is of no value in identifying acute fetal distress.